This file documents Taylor UUCP, version 1.03.

Copyright © 1992 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.

Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the section entitled ``Copying'' are included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the section entitled ``Copying'' may be included in a translation approved by the author instead of in the original English.

Taylor UUCP 1.03
****************

This is the documentation for the Taylor UUCP package, version 1.03. The programs were written by Ian Lance Taylor.  The author can be reached at <ian@airs.com>, or, equivalently, <uunet!airs!ian>, or c/o Infinity Development, P.O. Box 520, Waltham MA, 02254.

There is a mailing list for discussion of the package.  To join the list, send a message to <taylor-uucp-request@gnu.ai.mit.edu>. Make sure you include the address you want to receive messages at; do not rely on the From: header.  To send a message to the list, send it to <taylor-uucp@gnu.ai.mit.edu>.

Taylor UUCP Copying Conditions
******************************

This package is covered by the GNU Public License.  See the file COPYING for details.  If you would like to do something with this package that you feel is reasonable but you feel is prohibited by the license, contact me to see if we can work it out.

Here is some propaganda from the Free Software Foundation.  If you find this stuff offensive or annoying, remember that you probably did not spend any money to get this code.  I did not write this code to make life easier for developers of UUCP packages, I wrote it to help end users, and I believe that these are the most appropriate conditions for distribution.

All the programs, scripts and documents relating to Taylor UUCP are free; this means that everyone is free to use them and free to redistribute them on a free basis.  The Taylor UUCP-related programs are not in the public domain; they are copyrighted and there are restrictions on their distribution, but these restrictions are designed to permit everything that a good cooperating citizen would want to do. What is not allowed is to try to prevent others from further sharing any version of these programs that they might get from you.

Specifically, we want to make sure that you have the right to give away copies of the programs that relate to Taylor UUCP, that you receive source code or else can get it if you want it, that you can change these programs or use pieces of them in new free programs, and that you know you can do these things.

To make sure that everyone has such rights, we have to forbid you to deprive anyone else of these rights.  For example, if you distribute copies of the Taylor UUCP related programs, you must give the recipients all the rights that you have.  You must make sure that they, too, receive or can get the source code.  And you must tell them their rights.

Also, for our own protection, we must make certain that everyone finds out that there is no warranty for the programs that relate to Taylor UUCP.  If these programs are modified by someone else and passed on, we want their recipients to know that what they have is not what we distributed, so that any problems introduced by others will not reflect on our reputation.

The precise conditions of the licenses for the programs currently being distributed that relate to Taylor UUCP are found in the General Public Licenses that accompany them.

Introduction to Taylor UUCP
***************************

General introductions to UUCP are available, and perhaps one day I will write one.  In the meantime, here is a very brief one that concentrates on the programs provided by Taylor UUCP.

Taylor UUCP is a complete UUCP package.  It is covered by the GNU Public License, which means that the source code is always available.  It is composed of several programs, the names of which were established by earlier UUCP packages.

uucp

     The uucp program is used to copy file between systems.  It is similar to the standard Unix cp program, except that you can refer to a file on a remote system by using system! before the file name.  For example, to copy the file notes.txt to the system airs, you would say uucp notes.txt airs!~/notes.txt.  In this example ~ is used to name the UUCP public directory on airs.

uux

     The uux program is used to request a program to be executed on a remote system.  This is how mail and news are transferred over UUCP.  As with uucp, programs and files on remote systems may be named by using system!.  For example, to run the rnews program on airs passing it standard input, you would say uux - airs!rnews.  The - means to read standard input and set things up so that when rnews runs on airs it will receive the same standard input.

Neither uucp nor uux actually do any work immediately. Instead, they queue up requests for later processing.  They then start a daemon process which processes the requests and calls up the appropriate systems.  Usually the daemon will also be started regularly to check if there is any work to be done and to do it.  The advantage of this system is that it all happens automatically.  You don't have to sit around waiting for the files to be transferred.  The disadvantage is that if anything goes wrong it might be a while before anybody notices.

uustat

     The uustat program does several things.  By default it will simply list all the jobs you have queued with uucp or uux that have not yet been processed.  You can use uustat to remove any of your jobs from the queue.  You can also it use it to show the status of the UUCP system in various ways, such as showing the connection status of all systems your system knows about.

uuname

     The uuname program by default lists all the remote systems your system knows about.  You can also use it to get the name of your local system.  It is mostly useful for shell scripts.

uulog

     The uulog program can be used to display entries in the UUCP log file.  It can select the entries for a particular system or a particular user.  You can use it to see what has happened to your queued jobs in the past.

These five programs just described, uucp, uux, uustat, uuname, and uulog, are the user programs provided by Taylor UUCP.  The first two add requests to the work queue, the third examines the work queue, the fourth examines the configuration files, and the last examines the log files.  The real work is actually done by two daemon processes, which are normally run automatically rather than by a user.

uucico

     The uucico daemon is the program which actually calls the remote system and transfers files and requests.  uucico is normally started automatically by uucp and uux.  Most systems will also start it periodically to make sure that all work requests are handled.  uucico checks the queue to see what work needs to be done, and then calls the appropriate systems.  If the call fails, perhaps because the phone line is busy, uucico leaves the requests in the queue and goes on to the next system to call.  It is also possible to force uucico to call a remote system even if there is no work to be done for it, so that it can pick up any work that may be queued up remotely.

uuxqt

     The uuxqt daemon processes execution requests made by the uux program on remote systems.  It also processes requests made on the local system which require files from a remote system.  It is normally started by uucico.

Suppose you, on the system bantam, want to copy a file to the system airs.  You would run the uucp command locally, with a command like uucp notes.txt airs!~/notes.txt.  This would queue up a request on bantam for airs, and would then start the uucico daemon.  uucico would see that there was a request for airs and attempt to call it.  When the call succeeded, another copy of uucico would be started on airs.  The two copies of uucico would tell each other what they had to do and transfer the file from bantam to airs.  When the file transfer was complete the uucico on airs would move it into the UUCP public directory.

UUCP is often used to transfer mail.  This is normally done automatically by mailer programs.  When bantam has a mail message to send to ian at airs, it executes uux - airs!rmail ian and writes the mail message to the uux process as standard input.  The uux program, running on bantam, will read the standard input and store it and the rmail request on the work queue for airs.  uux will then start the uucico daemon.  The uucico daemon will call up airs, just as in the uucp example, and transfer the work request and the mail message itself.  The uucico daemon on airs will put the files on a local work queue.  When the communication session is over, the uucico daemon on airs will start the uuxqt daemon.  uuxqt will see the request to run, and will run rmail ian with the mail message as standard input.  The rmail program, which is not part of the UUCP package, is then responsible for either putting the message in the right mailbox on airs or forwarding the message on to another system.

Taylor UUCP comes with two other programs that are useful when installing and configuring UUCP.

uuchk

     The uuchk program reads the UUCP configuration files and displays a rather lengthy description of what it finds.  This is very useful when configuring UUCP to make certain that the UUCP package will do what you expect it to do.

tstuu

     The tstuu program is a test harness for the UUCP package, which will help ensure that it has been configured and compiled correctly.  It does not test everything, however, and it only runs on Unix systems which support Berkeley style pseudo-terminals.  It can be useful when initially installing Taylor UUCP.

Taylor UUCP Overall Installation
********************************

These are the installation instructions for the Taylor UUCP package.

Configuring Taylor UUCP
=======================

You will have to decide what types of configuration files you want to use.  This package supports a new sort of configuration file; see Configuration files.  It also supports V2 configuration files (L.sys, L-devices, etc.) and BNU configuration files (Systems, Devices, etc.).  No documentation is provided for V2 or BNU configuration files.  All types of configuration files can be used at once, if you are so inclined.  Currently using just V2 configuration files is not really possible, because there is no way to specify a dialer (there are no built in dialers, and the program does not know how to read acucap or modemcap); however, V2 configuration files can be used with a new style dialer file (see dial file), or with a BNU Dialers file.

Use of BNU configuration files has two known bugs.  A blank line in the middle of an entry in the Permissions file will not be ignored as it should be.  Dialer programs are not recognized directly.  If you must use a dialer program, rather than an entry in Devices, you must use the chat-program command in a new style dialer file; see dial file.  You will have to invoke the dialer program via a shell script, since an exit code of 0 is required to recognize success.

If you are installing a new system, or you want to use the new form of configuration files, you must write the configuration files.

You must also decide what sort of spool directory you want to use.  If you will only be using these programs, I recommend SPOOLDIR_TAYLOR; otherwise select the spool directory corresponding to your existing UUCP package.  The details of the spool directory choices are described at somewhat tedious length in sys3.unx.

Compiling Taylor UUCP
=====================

 1. Take a look at the top of Makefile.in and set the appropriate values for your system.  These control where the program is installed and which user on the system owns them (normally they will be owned by a special user uucp rather than a real person; they should probably not be owned by root).

 2. Run the shell script configure.  This script was generated using David MacKenzie's autoconf program.  It takes a while to run.  It will generate a file conf.h, and copy Makefile.in to Makefile with substitions (specifically, it will replace all words between @ characters in Makefile.in).

     You can pass certain arguments to configure in the environment. Because configure will compile and run little test programs to see what is available on your system, you must tell it how to run your compiler.  It recognizes the following environment variables:

     CC
          The C compiler.  If this is not set, then if configure can find gcc it will use gcc -O, otherwise it will use cc.

     DEFS
          Flags to pass the C compiler during configuration testing.  If this is not set, configure will use the empty string.

     CFLAGS
          Flags to pass to the C compiler when compiling the actual code.  If this is not set, configure will use -g.

     LDFLAGS
          Flags to pass to the C compiler when only linking, not compiling.  If this is not set, configure will use the empty string.

     LIBS
          Libraries to pass to the C compiler.  If this is not set, configure will use the empty string.

     INSTALL
          The program to run to install UUCP in the binary directory.  If configure finds the BSD install program, it will set this to install -c; otherwise, it will use cp.

     INSTALLDATA
          The program to run to install UUCP data files, such as the man pages and the info pages.  If configure finds the BSD install program, it will set this to install -c -m 644; otherwise, it will use cp.

     Suppose you want to set the environment variable CC to rcc.  If you are using sh or bash, invoke configure as CC=rcc configure.  If you are using csh, do setenv CC rcc; sh configure.

     On some systems you will want to use LIBS=-lmalloc.  On some you will want LIBS=-lsocket.  On Xenix derived systems do not use LIBS=-lx because this will bring in the wrong versions of certain routines; if you want to use -lx you must specify LIBS=-lc -lx.

     If configure fails for some reason, or if you have a very wierd system, you may have to configure the package by hand.  To do this, copy the file conf.h-dist to conf.h and edit it for your system.  Then copy Makefile.in to Makefile, find the words within @ characters, and set them correctly for your system.

 3. You should verify that configure worked correctly by checking the files conf.h and Makefile.

 4. This package uses the alloca function.  The configure script will try to figure out how to make it work on your system.  If alloca cannot be found, a simplistic substitute from alloca.c will be used.  If you provide your own alloca.o file, it will be used instead; you might, for example, use the one from the GNU emacs distribution.  If none of this makes any sense to you, don't worry; everything will probably work fine.

 5. Edit policy.h for your local system.  The comments should explain the various choices.  The default values are intended to be reasonable, so you may not have to make any changes.

 6. Type make to compile everything.  You may get warnings about implicit function declarations; ignore these (if you think they can be eliminated, and you really know what you are talking about, you may tell me about them).  You may also get warnings about getopt.c (this is from the GNU library and I do not want to change it) and about a variable not protected from setjmp in sys2.c (the data flow ensures that this can never be a problem).  The tstuu.c file is not particularly portable; if you can't figure out how to compile it you can safely ignore it, as it is only used for testing.  If you have any other problems there is probably a bug in the configure script.

 7. Please report any problems you have.  That is the only way they will get fixed for other people.  Supply a patch if you can, or just ask for help.

Testing Taylor UUCP
===================

This package is in use at many sites, and has been running at airs.com for several months.  However, it will doubtless fail in some situations.  Do not rely on this code until you have proven to yourself that it will work.

You can use the uuchk program to test your configuration files. It will read them and print out a verbose description.  This is particularly important if you are using V2 or BNU configuration files, because there may be bugs in how they are read.  This program should not be made suid, because it will display passwords if it can read them.

If your system supports BSD style pseudo-terminals, and you compiled the code to support the new style of configuration files, you should be able to use the tstuu program to test the uucico daemon.  Just type tstuu with no arguments while logged in to the compilation directory (since it runs ./uucp, ./uux and ./uucico) to run a lengthy series of tests (it takes over ten minutes on a slow VAX).  You will need a fair amount of space available in /usr/tmp.  You will probably want to put it in the background. Do not use ^Z, because the program traps on SIGCHLD and winds up dying.  It will create a directory /usr/tmp/tstuu and fill it with configuration files, and create spool directories /usr/tmp/tstuu/spool1 and /usr/tmp/tstuu/spool2.

The program will finish with an execute file X.SOMETHING and a data file D.SOMETHING in /usr/tmp/tstuu/spool1 (or, more likely, in subdirectories, depending on the choice of SPOOLDIR in sysdep.h).  The log files /usr/tmp/tstuu/Log1 and /usr/tmp/tstuu/Log2 (or, if you have selected HAVE_BNU_LOGGING, /usr/tmp/tstuu/Log1/uucico/test2 and /usr/tmp/tstuu/Log2/uucico/test1) should look fairly normal.  You can test uuxqt by typing ./uuxqt -I /usr/tmp/tstuu/Config1.  This should leave a command file C.SOMETHING and a data file D.SOMETHING in /usr/tmp/tstuu/spool1 or in subdirectories.  Again, there should be no errors in the log file.

Assuming you compiled the code with debugging enabled, the -x switch can be used to set debugging modes; see the debug command for details (see Debugging Levels).  Use -x all to turn on all debugging and generate far more output than you will ever want to see.  The uucico daemons will put debugging output in /usr/tmp/tstuu/Debug1 and /usr/tmp/tstuu/Debug2.  At this point you're pretty much on your own.

On some systems you can also use tstuu to test my uucico against the system uucico, by using the -u switch.  For this to work, change the definitions of ZUUCICO_CMD and UUCICO_EXECL at the top of tstuu.c to something appropriate for your system.  The definitions in tstuu.c are what I used for Ultrix 4.0, in which /usr/lib/uucp/uucico is particularly obstinate about being run as a child; I was only able to run it by creating a login name with no password whose shell was /usr/lib/uucp/uucico.  Calling login in this way will leave fake entries in wtmp and utmp; if you compile tstout.c (in the contrib directory) as an suid root program, tstuu will run it to clear those entries out.  On most systems, such hackery should not be necessary, although on SCO I had to su to root (uucp might also have worked) before I could run /usr/lib/uucp/uucico.

You can test uucp and uux (give them the -r switch to keep them from starting uucico) to make sure they create the right sorts of files.  Unfortunately if you don't know what the right sorts of files are I'm not going to tell you here.

If tstuu passes, or you can't run it for some reason or other, move on to testing with some other system.  Set up the configuration files (see Configuration files), or use an existing configuration. Tell uucico to dial out to the system by using the -s system switch (e.g.  uucico -s uunet).  The log file should tell you what happens.

If you compiled the code with debugging enabled, you can use debugging mode to get a great deal of information about what sort of data is flowing back and forth; the various possibilities are described under the debug command (see Debugging Levels).  When initially setting up a connection -x chat is probably the most useful (e.g. uucico -s uunet -x chat); you may also want to use -x handshake,incoming,outgoing.  You can use -x multiple times on one command line, or you can give it comma separated arguments as in the last example.  Use -x all to turn on all possible debugging information.  The debugging information is written to a file, normally /usr/spool/uucp/Debug although the default can be changed in policy.h and the configuration file can override the name with the debugfile command.  The debugging file may contain passwords and some file contents as they are transmitted over the line, so the debugging file is only readable by the uucp user.

You can use the -f switch to force uucico to call out even if the last call failed recently; using -S when naming a system has the same effect.  Otherwise the status file (in the .Status subdirectory of the main spool directory, normally /usr/spool/uucp) will prevent too many attempts from occurring in rapid succession.

Again, let me know about any problems you have and how you got around them.

Installing Taylor UUCP
======================

You can install by suing to root and typing make install. Or you can look at what make install does and do it by hand.  It tries to preserve your old programs, if any.  You can retrieve them by typing make uninstall.

Using Taylor UUCP
=================

This package does not come with any fancy shell scripts or scheduling programs.  Maybe someday.  If you have another package, you may well be able to use the scheduling mechanisms it provides.

Otherwise, the program can be used by making crontab entries. Whenever you want to call all systems with outstanding work, use

     uucico -r1

Whenever you want to call a specific system foo, use

     uucico -s foo

If you want to make sure that a system foo gets retried if the original call fails, create an empty work file for it.  For example, if using SPOOLDIR_TAYLOR,

     touch /usr/spool/uucp/foo/C./C.A0000

If using SPOOLDIR_BNU, use

     touch /usr/spool/uucp/foo/C.fooA0000

I use the following crontab entries locally:

     45 * * * * /bin/echo /usr/lib/uucp/uucico -r1 | /bin/su uucpa
     40 4,10,15 * * * touch /usr/spool/uucp/uunet/C./C.A0000

Every hour, at 45 minutes past, this will check if there is any work to be done.  Also, at 4:40am, 10:40am and 3:40pm this will create an empty work file for uunet, forcing the next check to call uunet.

You will also want to periodically trim the log files, which by default are /usr/spool/uucp/Log and /usr/spool/uucp/Stats.  The savelog program in the contrib directory may be of use.

TCP together with Taylor UUCP
=============================

If your system has a Berkeley style socket library, you can compile the code to permit making connections over TCP.  Specifying that a system should be reached via TCP is easy, but nonobvious.

If you are using the new style configuration files, see Configuration files.  Basically, you can just add the line port type tcp to the entry in the system configuration file.  By default UUCP will get the port number by looking up uucp in /etc/services; if uucp is not found, port 540 will be used.  You can set the port number to use with the command port service XXX, where XXX can be either a number or a name to look up in /etc/services.  You can specify the address of the remote host with address A.B.C; if you don't give an address, the remote system name will be used.  You should give an explicit chat script for the system when you use TCP; the default chat script begins with a carriage return, which will not work with some UUCP TCP servers.

If you are using V2 configuration files, add a line like this to L.sys:

     foo Any TCP uucp foo.domain chat-script

This will make an entry for system foo, to be called at any time, over TCP, using port number uucp (as found in /etc/services; this may be specified as a number), using remote host foo.domain, with some chat script.

If you are using BNU configuration files, add a line like this to Systems:

     foo Any TCP - foo.domain chat-script

and a line like this to Devices:

     TCP uucp - -

You only need one line in Devices regardless of how many systems you contact over TCP.  This will make an entry for system foo, to be called at any time, over TCP, using port number uucp (as found in /etc/services; this may be specified as a number), using remote host foo.domain, with some chat script.

The uucico daemon can also be run as a TCP server.  This code mostly works, but it's not perfect.  I don't recommend investigating it unless you are willing to tinker a bit.  You will not be able to use the default port number because uucico will not be running as root and will therefore not be able to bind a reserved port.

Basically, you must define a port, either using the port file (see port file) if you are using the new configuration method or with an entry in Devices if you are using BNU; there is no way to define a port using V2.  If you are using BNU the port must be named TCP; a line as shown above will suffice.  You can then start uucico as uucico -p TCP (after the -p, name the port; in BNU it must be TCP).  This will wait for incoming connections, and fork off a child for each one.  Each connection will be prompted with login: and Password:; the results will be checked against the UUCP (not the system) password file (see Configuration File Names).  Of course, you can get a similar effect by using the BSD uucpd program.

You can also have inetd start up uucico with the -l switch, which will cause it to prompt with login: and Password: and check the results against the UUCP (not the system) password file.  This may be used in place of uucpd.

Taylor UUCP Configuration Files
*******************************

This chapter describes the configuration files accepted by the Taylor UUCP package if compiled with HAVE_TAYLOR_CONFIG defined in conf.h.

The configuration files are normally found in the directory NEWCONFIGDIR, which is defined by the Makefile variable newconfigdir; by default NEWCONFIGDIR is /usr/local/lib/uucp.  However, the main configuration file, config, is the only one which must be in that directory, since it may specify a different location for any or all of the other files.  You may run any of the UUCP programs with a different main configuration file by using the -I option; this can be useful when testing a new configuration.  When you use the -I option the programs will revoke their setuid privileges.

Configuration File Format
=========================

All the configuration files follow a simple line-oriented KEYWORD VALUE format.  Empty lines are ignored, as are leading spaces; unlike BNU, lines with leading spaces are read.  The first word on each line is a keyword.  The rest of the line is interpreted according to the keyword.  Most keywords are followed by numbers, boolean values or simple strings with no embedded spaces.

The # character is used for comments.  Everything from a # to the end of the line is ignored unless the # is preceded by a \ (backslash); if the # is preceeded by a \, the \ is removed but the # remains in the line.  This can be useful for a phone number containing a #.  To enter the sequence \#, you would use \\#.

The backslash character may be used to continue lines.  If the last character in a line is a backslash, the backslash is removed and the line is continued by the next line.  The second line is attached to the first with no intervening characters; if you want any whitespace between the end of the first line and the start of the second line, you must insert it yourself.

However, the backslash is not a general quoting character.  For example, you cannot use it to get an embedded space in a string argument.

Everything after the keyword must be on the same line.  A BOOLEAN may be specified as y, Y, t, or T for true and n, N, f, or F for false; any trailing characters are ignored, so true, false, etc., are also acceptable.

Examples of Configuration Files
===============================

All the configuration commands are explained in the following sections. However, I'll start by giving a few examples of configuration files. For a more complete description of any of the commands used here see the appropriate section of this chapter.

config File Examples
--------------------

To start with, here are some examples of uses of the main configuration file, config.  For a complete description of the commands that are permitted in config, see config file.

In many cases you will not need to create a config file at all. The most common reason to create one is to give your machine a special UUCP name.  Other reasons might be to change the UUCP spool directory or to permit any remote system to call in.

If you have an internal network of machines, then it is likely that the internal name of your UUCP machine is not the name you want to use when calling other systems.  For example, here at airs.com our mail/news gateway machine is named elmer.airs.com (it is one of several machines all named LOCALNAME.airs.com).  If we did not provide a config file, then our UUCP name would be elmer; however, we actually want it to be airs. Therefore, we use the following line in config:

     nodename airs

The UUCP spool directory name is set in policy.h when the code is compiled.  You might at some point decide that it is appropriate to move the spool directory, perhaps to put it on a different disk partition. You might use the following commands in config to change to directories on the partition /uucp:

     spool /uucp/spool
     pubdir /uucp/uucppublic
     logfile /uucp/spool/Log
     debugfile /uucp/spool/Debug

You would then move the contents of the current spool directory to /uucp/spool.  If you do this, make sure that no UUCP processes are running while you change config and move the spool directory.

Suppose you wanted to permit any system to call in to your system and request files.  This is generally known as anonymous UUCP, since the systems which call in are effectively anonymous.  By default, unknown systems are not permitted to call in.  To permit this you must use the unknown command in config.  The unknown command is followed by any command that may appear in the system file; for full details, see sys file.

I will show two possible anonymous UUCP configurations.  The first will let any system call in and download files, but will not permit them to upload files to your system.

     # No files may be transferred to this system
     unknown request no
     # The public directory is /usr/spool/anonymous
     unknown pubdir /usr/spool/anonymous
     # Only files in the public directory may be sent (the default anyhow)
     unknown remote-send ~

Setting the public directory is convenient for the systems which call in.  It permits to request a file by prefixing it with ~/.  For example, assuming your system is known as server, then to retrieve the file /usr/spool/anonymous/INDEX a user on a remote site could just enter uucp server!~/INDEX ~; this would transfer INDEX from server's public directory to the user's local public directory.  Note that when using csh or bash the ! and the second ~ must be quoted.

The next example will permit remote systems to upload files to a special directory /usr/spool/anonymous/upload.  Permitting a remote system to upload files permits it to send work requests as well; this example is careful to prohibit commands from unknown systems.

     # No commands may be executed (the list of permitted commands is empty)
     unknown commands
     # The public directory is /usr/spool/anonymous
     unknown pubdir /usr/spool/anonymous
     # Only files in the public directory may be sent; users may not download
     # files from the upload directory
     unknown remote-send ~ !~/upload
     # May only upload files into /usr/spool/anonymous/upload
     unknown remote-receive ~/upload

Leaf Example
------------

A relatively common simple case is a leaf site, a system which only calls or is called by a single remote site.  Here is a typical sys file that might be used in such a case.  For full details on what commands can appear in the sys file, see sys file.

This is the sys file that is used at airs.com.  We use a single modem to dial out to uunet.  This example shows how you can specify the port and dialer information directly in the sys file for simple cases.  It also shows the use of the following:

call-login
     Using call-login and call-password allows the default login chat script to be used.  In this case, the login name is specified in the call-out login file (see Configuration File Names).

call-timegrade
     uunet is requested to not send us news during the daytime.

chat-fail
     If the modem returns BUSY or NO CARRIER the call is immediately aborted.

protocol-parameter
     Since uunet tends to be slow, the default timeout has been increased.

This sys file relies on certain defaults.  It will allow uunet to queue up rmail and rnews commands.  It will allow users to request files from uunet into the UUCP public directory.  It will also uunet to request files from the UUCP public directory; in fact uunet never requests files, but for additional security we could add the line request false.

     # The following information is for uunet
     system uunet

     # The login name and password are kept in the callout password file
     call-login *
     call-password *

     # We can send anything at any time.
     time any

     # During the day we only accept grade 'Z' or above; at other times
     # (not mentioned here) we accept all grades.  uunet queues up news
     # at grade 'd', which is lower than 'Z'.
     call-timegrade Z Wk0755-2305,Su1655-2305

     # The phone number.
     phone 7389449

     # uunet tends to be slow, so we increase the timeout
     chat-timeout 120

     # We are using a preconfigured Telebit 2500.
     port type modem
     port device /dev/ttyd0
     port baud 19200
     port carrier true
     port dialer chat "" ATZ\r\d\c OK ATDT\D CONNECT
     port dialer chat-fail BUSY
     port dialer chat-fail NO\sCARRIER
     port dialer complete \d\d+++\d\dATH\r\c
     port dialer abort \d\d+++\d\dATH\r\c

     # Increase the timeout and the number of retries.
     protocol-parameter g timeout 20
     protocol-parameter g retries 10

Gateway Example
---------------

Many organizations have several local machines which are connected by UUCP, and a single machine which connects to the outside world.  This single machine is often referred to as a gateway machine.

For this example I will assume a fairly simple case.  It should still provide a good general example.  There are three machines, elmer, comton and bugs.  elmer is the gateway machine for which I will show the configuration file.  elmer calls out to uupsi.  As an additional complication, uupsi knows elmer as airs; this will show how a machine can have one name on an internal network but a different name to the external world. elmer has two modems.  It also has an TCP/IP connection to uupsi, but since that is supposed to be reserved for interactive work (it is, perhaps, only a 9600 baud SLIP line) it will only use it if the modems are not available.

A network this small would normally use a single sys file. However, for pedagogical purposes I will show two separate sys files, one for the local systems and one for uupsi.  This is done with the sysfile command in the config file.  Here is the config file.

     # This is config
     # The local sys file
     sysfile /usr/local/lib/uucp/sys.local
     # The remote sys file
     sysfile /usr/local/lib/uucp/sys.remote

Using the defaults feature of the sys file can greatly simplify the listing of local systems.  Here is sys.local.  Note that this assumes that the local systems are trusted; they are permited to request any world readable file and to write files into any world writable directory.

     # This is sys.local
     # Get the login name and password to use from the call-out file
     call-login *
     call-password *

     # The systems must use a particular login
     called-login Ulocal

     # Permit sending any world readable file
     local-send /
     remote-send /

     # Permit requesting into any world writable directory
     local-receive /
     remote-receive /

     # Call at any time
     time any

     # Use port1, then port2
     port port1

     alternate

     port port2

     # Now define the systems themselves.  Because of all the defaults we
     # used, there is very little to specify for the systems themselves.

     system comton
     phone 5551212

     system bugs
     phone 5552424

The sys.remote file describes the uupsi connection.  The myname command is used to change the UUCP name to airs when talking to uupsi.

     # This is sys.remote
     # Define uupsi
     system uupsi

     # The login name and password are in the call-out file
     call-login *
     call-password *

     # We can call out at any time
     time any

     # uupsi uses a special login name
     called-login Uuupsi

     # uuspi thinks of us as `airs'
     myname airs

     # The phone number
     phone 5554848

     # We use port2 first, then port1, then TCP

     port port2

     alternate

     port port1

     alternate

     # We don't bother to make a special entry in the port file for TCP, we
     # just describe the entire port right here.  We use a special chat
     # script over TCP because the usual one confuses some TCP servers.
     port type TCP
     address uu.psi.com
     chat ogin: \L word: \P

The ports are defined in the file port (see port file).  For this example they are both connected to the same type of 2400 baud Hayes-compatible modem.

     # This is port

     port port1
     type modem
     device /dev/ttyd0
     dialer hayes
     speed 2400

     port port2
     type modem
     device /dev/ttyd1
     dialer hayes
     speed 2400

Dialers are described in the dial file (see dial file).

     # This is dial

     dialer hayes

     # The chat script used to dial the phone.  \D is the phone number.
     chat "" ATZ\r\d\c OK ATDT\D CONNECT

     # If we get BUSY or NO CARRIER we abort the dial immediately
     chat-fail BUSY
     chat-fail NO\sCARRIER

     # When the call is over we make sure we hangup the modem.
     complete \d\d+++\d\dATH\r\c
     abort \d\d+++\d\dATH\r\c

Time Strings
============

Several commands use time strings to specify a range of times.  This section describes how to write time strings.

A time string may be a list of simple time strings separated with a vertical bar | or a command ,.

Each simple time string must begin with Su, Mo, Tu, We, Th, Fr, or Sa, or Wk for any weekday, or Any for any day.

Following the day may be a range of hours separated with a hyphen using 24 hour time.  The range of hours may cross 0; for example 2300-0700 means any time except 7 AM to 11 PM.  If no time is given, calls may be made at any time on the specified day(s).

The time string may also consist of the single word Never, which does not match any time, or a single word with a name defined in a previous timetable command (see Miscellaneous (sys)).

Here are a few sample time strings with an explanation of what they mean.

Wk2305-0855,Sa,Su2305-1655

     This means weekdays before 8:55 AM or after 11:05 PM, any time Saturday, or Sunday before 4:55 PM or after 11:05 PM.  These are approximately the times during which night rates apply to phone calls in the U.S.A.  Note that this time string uses, for example, 2305 rather than 2300; this will ensure a cheap rate phone call even if the computer clock is running up to five minutes ahead of the real time.

Wk0905-2255,Su1705-2255

     This means weekdays from 9:05 AM to 10:55 PM, or Sunday from 5:05 PM to 10:55 PM.  This is approximately the opposite of the previous example.

Any

     Since no time is specified, this means any time on any day.

Chat Scripts
============

Chat scripts are used in several different places, such as dialing out on modems or logging in to remote systems.  Chat scripts are made up of pairs of strings.  The program waits until it sees the first string, known as the expect string, and then sends out the second string, the send string.

Each chat script is defined using a set of commands.  These commands always end in a string beginning with chat, but may start with different strings.  For example, in the sys file there is one set of commands beginning with chat and another set beginning with called-chat.  The prefixes are only used to disambiguate different types of chat scripts, and this section ignores the prefixes when describing the commands.

chat STRINGS

     Specify a chat script.  The arguments to the chat command are pairs of strings separated by whitespace.  The first string of each pair is an expect string, the second is a send string.  The program will wait for the expect string to appear; when it does, the program will send the send string.  If the expect string does not appear within a certain number of seconds (as set by the chat-timeout command) the chat script fails and, typically, the call is aborted.  If the final expect string is seen (and the optional final send string has been sent), the chat script is successful.

     An expect string may contain additional subsend and subexpect strings, separated by hyphens.  If the expect string is not seen, the subsend string is sent and the chat script continues by waiting for the subexpect string.  This means that a hyphen may not appear in an expect string; use \055 instead.

     An expect string may simply be "", meaning to skip the expect phase.  Otherwise, the following escape characters may appear in expect strings:

     \b
          a backspace character

     \n
          a newline or line feed character

     \N
          a null character (for BNU compatibility)

     \r
          a carriage return character

     \s
          a space character

     \t
          a tab character

     \\
          a backslash character

     \DDD
          character DDD, where DDD are up to three octal digits

     \xDDD
          character DDD, where DDD are hexadecimal digits.

     As in C, there may be up to three octal digits following a backslash, but the hexadecimal escape sequence continues as far as possible.  To follow a hexadecimal escape sequence with a hex digit, interpose a send string of "".

     A send string may also simply be "" to skip the send phase. Otherwise, all of the escape characters legal for expect strings may be used, and the following escape characters are also permitted:

     EOT
          send an end of transmission character (^D)

     BREAK
          send a break character (may not work on all systems)

     \c
          suppress trailing carriage return at end of send string

     \d
          delay sending for 1 second

     \e
          disable echo checking

     \E
          enable echo checking (wait for echo before continuing)

     \K
          same as BREAK (for BNU compatibility)

     \p
          pause sending for a fraction of a second

     Some specific types of chat scripts also define additional escape sequences that may appear in the send string.  For example, the login chat script defines \L and \P to send the login name and password, respectively.

     A carriage return will be sent at the end of each send string, unless the \c escape sequence appears in the string.  Note that some UUCP packages use \b for break, but here it means backspace.

     Echo checking means that after writing each character the program will wait until the character is echoed.  Echo checking must be turned on separately for each send string for which it is desired; it will be turned on for characters following \E and turned off for characters following \e.

chat-timeout NUMBER

     The number of seconds to wait for an expect string in the chat script before timing out and sending the next subsend or failing the chat script entirely.  The default value is 10 for a login chat or 60 for any other type of chat.

chat-fail STRING

     If the STRING is seen at any time during a chat script, the chat script is aborted.  The string may not contain any whitespace characters; escape sequences must be used for them.  Multiple chat-fail commands may appear in a single chat script.  The default is to have none.

     This permits a chat script to be quickly aborted if an error string is seen.  For example, a script used to dial out on a modem might use the command chat-fail BUSY to stop the chat script immediately if the string BUSY was seen.

chat-seven-bit BOOLEAN

     If the argument is true, all incoming characters are stripped to seven bits when being compared to the expect string.  Otherwise all eight bits are used in the comparison.  The default is true because some Unix systems generate parity bits during the login prompt which must be ignored while running a chat script.  This has no effect on any chat-program, which must ignore parity by itself if necessary.

chat-program STRINGS

     Specify a program to run before executing the chat script.  This program could run its own version of a chat script, or it could do whatever it wants.  If both chat-program and chat are specified, the program is executed first followed by the chat script.

     The first argument to the chat-program command is the program name to run.  The remaining arguments are passed to the program.  The following escape sequences are recognized in the arguments:

     \Y
          port device name

     \S
          port speed

     \\
          backslash

     Some specific uses of chat-program define additional escape sequences.

     Arguments other than escape sequences are passed exactly as they appear in the configuration file, except that sequences of whitespace are compressed to a single space character; this exception may be removed in the future.

     If the chat-program command is not used, no program is run.

     On Unix, the standard input and standard output of the program will be attached to the port in use.  Anything the program writes to standard error will be written to the UUCP log file.  No other file descriptors will be open.  If the program does not exit with a status of 0, it will be assumed to have failed; this means that the dialing programs used by some versions of BNU may not be used directly, although of course a shell script could be used as an interface.

     The program will be run as the uucp user, and the environment will be that of the process that started uucico, so care must be taken to maintain security.

     No search path is used to find the program; a full path name must be given.  If the program is an executable shell script, it will be passed to /bin/sh even on systems which are unable to execute shell scripts.  It is also easy to invoke /bin/sh directly.

Here is a simple example of a chat script that might be used to reset a Hayes compatible modem.

     chat "" ATZ OK-ATZ-OK

The first expect string is "", so it is ignored.  The chat script then sends ATZ.  If the modem responds with OK, the chat script finishes.  If 60 seconds (the default timeout) pass before seeing OK, the chat script sends another ATZ.  If it then sees OK, the chat script succeeds.  Otherwise, the chat script fails.

For a more complex chat script example, see Logging In.

The Main Configuration File
===========================

The main configuration file is named config.

Since all the values that may be specified in the main configuration file also have defaults, there need not be a main configuration file at all.

Miscellaneous config File Commands
----------------------------------

nodename STRING
hostname STRING
uuname STRING

     These keywords are equivalent.  They specify the UUCP name of the local host.  If there is no configuration file, an appropriate function will be used to get the host name, if possible.

spool STRING

     Specify the spool directory.  The default is from policy.h. Command files, work files, temporary files, etc., are stored in this directory and in subdirectories of it.

pubdir STRING

     Specify the public directory.  The default is from policy.h.  On Unix, when a file is named using a leading ~/, it is taken from or to the public directory.  Each system may use a separate public directory by using the pubdir command in the system configuration file; see Miscellaneous (sys).

unknown STRING ...

     The STRING and subsequent arguments are treated as though they appeared in the system file (see sys file).  They are used to apply to any unknown systems that may call in, probably to set file transfer permissions and the like.  If the unknown command is not used, unknown systems are not permitted to call in.

max-uuxqts NUMBER

     Specify the maximum number of uuxqt processes which may run at the same time.  Having several uuxqt processes running at once can significantly slow down a system, but since uuxqt is automatically started by uucico, it can happen quite easily.  The default for max-uuxqts is 0, which means that there is no limit. If BNU configuration files are being read and the code was compiled without HAVE_TAYLOR_CONFIG, then if the file Maxuuxqts in the configuration directory contains a readable number it will be used as the value for max-uuxqts.

v2-files BOOLEAN

     If the code was compiled to be able to read V2 configuration files, a false argument to this command will prevent them from being read. This can be useful while testing.  The default is true.

bnu-files BOOLEAN

     If the code was compiled to be able to read BNU configuration files, a false argument to this command will prevent them from being read. This can be useful while testing.  The default is true.

Configuration File Names
------------------------

sysfile STRINGS

     Specify the system file(s).  The default is the file sys in the directory NEWCONFIGDIR.  These files hold information about other systems with which this system communicates; see sys file. Multiple system files may be given on the line, and the sysfile command may be repeated; each system file has its own set of defaults.

portfile STRINGS

     Specify the port file(s).  The default is the file port in the directory NEWCONFIGDIR.  These files describe ports which are used to call other systems and accept calls from other systems; see port file.  No port files need be named at all.  Multiple port files may be given on the line, and the portfile command may be repeated.

dialfile STRINGS

     Specify the dial file(s).  The default is the file dial in the directory NEWCONFIGDIR.  These files describe dialing devices (modems); see dial file.  No dial files need be named at all. Multiple dial files may be given on the line, and the dialfile command may be repeated.

dialcodefile STRINGS

     Specify the dialcode file(s).  The default is the file dialcode in the directory NEWCONFIGDIR.  These files specify dialcodes that may be used when sending phone numbers to a modem.  This permits using the same set of phone numbers in different area-codes or with different phone systems, by using dialcodes to specify the calling sequence.  When a phone number goes through dialcode translation, the leading alphabetic characters are stripped off.  The dialcode files are read line by line, just like any other configuration file, and when a line is found whose first word is the same as the leading characters from the phone number, the second word on the line (which would normally consist of numbers) replaces the dialcode in the phone number.  No dialcode file need be used.  Multiple dialcode files may be specified on the line, and the dialcodefile command may be repeated; all the dialcode files will be read in turn until a dialcode is located.

callfile STRINGS

     Specify the call out login name and password file(s).  The default is the file call in the directory NEWCONFIGDIR.  If the call out login name or password for a system are given as * (see Logging In), these files are read to get the real login name or password.  Each line in the file(s) has three words: the system name, the login name, and the password.  This file is only used when placing calls to remote systems; the password file described under passwdfile below is used for incoming calls.  The intention of the call out file is to permit the system file to be publically readable; the call out files must obviously be kept secure.  These files need not be used.  Multiple call out files may be specified on the line, and the callfile command may be repeated; all the files will be read in turn until the system is found.

passwdfile STRINGS

     Specify the password file(s) to use for login names when uucico is doing its own login prompting, which it does when given the -e, -l or -w switch.  The default is the file passwd in the directory NEWCONFIGDIR.  Each line in the file(s) has two words: the login name and the password (e.g. Ufoo foopas).  The login name is accepted before the system name is known, so these are independent of which system is calling in; a particular login may be required for a system by using the called-login command in the system file (see Accepting a Call).  These password files are optional, although one must exist if uucico is to present its own login prompts.  Multiple password files may be specified on the line, and the passwdfile command may be repeated; all the files will be read in turn until the login name is found.

Log File Names
--------------

logfile STRING

     Name the log file.  The default is from policy.h.  Logging information is written to this file.  If HAVE_BNU_LOGGING is defined in conf.h, then by default a separate log file is used for each system.  Using this command to name a log file will cause all the systems to use it.

statfile STRING

     Name the statistics file.  The default is from policy.h. Statistical information about file transfers is written to this file.

debugfile STRING

     Name the file to which debugging information is written.  The default is from policy.h.  This command is only effective if the code has been compiled to include debugging (this is controlled by the DEBUG variable in policy.h).  After the first debugging message has been written, messages written to the log file are also written to the debugging file to make it easier to keep the order of actions straight.  The debugging file is different from the log file because information such as passwords can appear in it, so it must be not be publically readable.

Debugging Levels
----------------

debug STRING ...

     Set the debugging level.  This command is only effective if the code has been compiled to include debugging.  The default is to have no debugging.  The arguments are strings which name the types of debugging to be turned on.  The following types of debugging are defined:

     abnormal
          Output debugging messages for abnormal situations, such as recoverable errors.

     chat
          Output debugging messages for chat scripts.

     handshake
          Output debugging messages for the initial handshake.

     uucp-proto
          Output debugging messages for the UUCP protocol itself.

     proto
          Output debugging messages for the individual protocols.

     port
          Output debugging messages for actions on the communication port.

     config
          Output debugging messages while reading the configuration files.

     spooldir
          Output debugging messages for actions in the spool directory.

     execute
          Output debugging messages whenever another program is executed.

     incoming
          List all incoming data in the debugging file.

     outgoing
          List all outgoing data in the debugging file.

     all
          All of the above.

     The debugging level may also be specified as a number.  A 1 will set chat debugging, a 2 will set both chat and handshake debugging, and so on down the possibilities.  Currently an 11 will turn on all possible debugging, since there are 11 types of debugging messages listed above; more debugging types may be added in the future.  The debug command may be used several times in the configuration file; every debugging type named will be turned on.  When running any of the programs, the -x switch (actually, for uulog it's the -X switch) may be used to turn on debugging.  The argument to the -x switch is one of the strings listed above, or a number as described above, or a comma separated list of strings (e.g.  -x chat,handshake).  The -x switch may also appear several times on the command line, in which case all named debugging types will be turned on.  The -x debugging is in addition to any debugging specified by the debug command; there is no way to cancel debugging information.  The debugging level may also be set specifically for calls to or from a specific system with the debug command in the system file (see Miscellaneous (sys)).

     The debugging messages are somewhat idiosyncratic; it may be necessary to refer to the source code for additional information in some cases.

The System Configuration File
=============================

By default there is a single system configuration, named sys in the directory NEWCONFIGDIR.  This may be overridden by the sysfile command in the main configuration file; see Configuration File Names.

These files describe all remote systems known to the UUCP package.

Defaults and Alternates
-----------------------

The first set of commands in the file, up to the first system command, specify defaults to be used for all systems in that file.  Each system file uses a different set of defaults.

Subsequently, each set of commands from system up to the next system command describe a particular system.  Default values may be overridden for specific systems.

Each system may then have a series of alternate choices to use when calling out or calling in.  The first set of commands for a particular system, up to the first alternate command, provide the first choice.  Subsequently, each set of commands from alternate up to the next alternate command describe an alternate choice for calling out or calling in.

When a system is called, the commands before the first alternate are used to select a phone number, port, and so forth; if the call fails for some reason, the commands between the first alternate and the second are used, and so forth.  Well, not quite.  Actually, each succeeding alternate will only be used if it is different in some relevant way (different phone number, different chat script, etc.).  If you want to force the same alternate to be used again (to retry a phone call more than once, for example), enter the phone number (or any other relevant field) again to make it appear different.

The alternates can also be used to give different permissions to an incoming call based on the login name.  This will only be done if the first set of commands, before the first alternate command, uses the called-login command.  The list of alternates will be searched, and the first alternate with a matching called-login command will be used.  If no alternates match, the call will be rejected.

The alternate command may also be used in the file-wide defaults (the set of commands before the first system command).  This might be used to specify a list of ports which are available for all systems (for an example of this, see Gateway Example) or to specify permissions based on the login name used by the remote system when it calls in.  The first alternate for each system will default to the first alternate for the file-wide defaults (as modified by the commands used before the first alternate command for this system), the second alternate for each system to the second alternate for the file-wide defaults (as modified the same way), and so forth.  If a system specifies more alternates than the file-wide defaults, the trailing ones will default to the last file-wide default alternate.  If a system specifies fewer alternates than the file-wide defaults, the trailing file-wide default alternates will be used unmodified.  The default-alternates command may be used to modify this behaviour.

This can all get rather confusing, although it's easier to use than to describe concisely; the uuchk program may be used to ensure that you are getting what you want.

Naming the System
-----------------

system STRING

     Specify the remote system name.  Subsequent commands up to the next system command refer to this system.

alternate [STRING]

     Start an alternate set of commands (see Defaults and Alternates). An optional argument may be used to name the alternate.  This name will be put in the log file if the alternate is used to call the system. There is no way to name the first alternate (the commands before the first alternate command).

default-alternates BOOLEAN

     If the argument is false, any remaining default alternates (from the defaults specified at the top of the current system file) will not be used.  The default is true.

alias STRING

     Specify an alias for the current system.  The alias may be used by local uucp and uux commands.  The default is to have no aliases.

myname STRING

     Specifies a different system name to use when calling the remote system. Also, if called-login is used and is not ANY, then, when a system logs in with that login name, STRING is used as the system name.  Because the local system name must be determined before the remote system has identified itself, using myname and called-login together for any system will set the local name for that login; this means that each locally used system name must have a unique login name associated with it.  This allows a system to have different names for an external and an internal network.  The default is to not use a special local name.

Calling Out
-----------

This section describes commands used when placing a call to another system.

When to Call
............

time STRING [NUMBER]

     Specify when the system may be called.  The first argument is a time string; see Time Strings.  The optional second argument specifies a retry time in minutes.  If a call made during a time that matches the time string fails, no more calls are permitted until the retry time has passed.  By default an exponentially increasing retry time is used: after each failure the next retry period is longer.  A retry time specified in the time command is always a fixed amount of time.

     The time command may appear multiple times in a single alternate, in which case if any time string matches the system may be called.  The default time string is Never.

timegrade CHARACTER STRING [NUMBER]

     The CHARACTER specifies a grade.  It must be a single letter or digit.  The STRING is a time string (see Time Strings).  All jobs of grade CHARACTER or higher (where 0 > 9 > A > Z > a > z) may be run at the specified time. An ordinary time command is equivalent to using timegrade with a grade of z, permitting all jobs.  If there are no jobs of a sufficiently high grade according to the time string, the system will not be called.  Giving the -s switch to uucico to force it to call a system causes it to assume there is a job of grade 0 waiting to be run.

     The optional third argument specifies a retry time in minutes.  See the time command, above, for more details.

     Note that the timegrade command serves two purposes: 1) if there is no job of sufficiently high grade the system will not be called, and 2) if the system is called anyway (because the -s switch was given to uucico) only jobs of sufficiently high grade will be transferred.  However, if the other system calls in, the timegrade commands are ignored, and jobs of any grade may be transferred (but see call-timegrade below).  Also, the timegrade command will not prevent the other system from transferring any job it chooses, regardless of who placed the call.

     The timegrade command may appear multiple times without using alternate.  If this command does not appear, there are no restrictions on what grade of work may be done at what time.

call-timegrade CHARACTER STRING

     The CHARACTER is a single character A to Z, a to z, or 0 to 9 and specifies a grade.  The STRING is a time string as described under the time command.  If a call is placed to the other system during a time which matches the time string, the remote system will be requested to only run jobs of grade CHARACTER or higher.  Unfortunately, there is no way to guarantee that the other system will obey the request (this UUCP package will, but there are others which will not); moreover job grades are historically somewhat arbitrary, so specifying a grade will only be meaningful if the other system cooperates in assigning grades.  This grade restriction only applies when the other system is called, not when the other system calls in.

     The call-timegrade command may appear multiple times without using alternate.  If this command does not appear, or if none of the time strings match, the remote system will be allowed to send whatever grades of work it chooses.

Placing the Call
................

baud NUMBER
speed NUMBER

     Specify the speed (the term baud is technically incorrect, but widely understood) at which to call the system.  This will try all available ports with that baud rate until an unlocked port is found. The ports are defined in the port file.  If both baud and port commands appear, both are used when selecting a port.  To allow calls at more than one baud rate, the alternate command must be used (see Defaults and Alternates).  If this command does not appear, there is no default; the baud rate may be specified in the port file, but if it is not then the natural baud rate of the port will be used (whatever that means on the system).  Specifying an explicit baud rate of 0 will request the natural baud rate of the port, overriding any default baud rate from the defaults at the top of the file.

port STRING

     Name a particular port or type of port to use when calling the system. The information for this port is obtained from the port file.  If this command does not appear, there is no default; a port must somehow be specified in order to call out (it may be specified implicitly using the baud command or explicitly using the next version of port).  There may be many ports with the same name; each will be tried in turn until an unlocked one is found which matches the desired baud rate.

port STRING ...

     If more than one string follows the port command, the subsequent strings are treated as commands that might appear in the port file (see port file).  If a port is named (by using a single string following port) these commands are ignored; their purpose is to permit defining the port completely in the system file rather than always requiring entries in two different files.  In order to call out, a port must be specified using some version of the port command, or by using the baud command to select ports from the port file.

phone STRING
address STRING

     Give a phone number to call (when using a modem port) or a remote host to contact (when using a TCP port).  The commands phone and address are equivalent, but are intended to be more mnemonic depending on the type of port in use.

     When used with a modem port, an = character in the phone number means to wait for a secondary dial tone (although only some modems support this); a - character means to pause while dialing for 1 second (again, only some modems support this).  If the system has more than one phone number, each one must appear in a different alternate. The phone command must appear in order to call out on a modem; there is no default.

     When used with a TCP port, the string names the host to contact.  It may be a domain name or a numeric Internet address.  If no address is specified, the system name is used.

     When used with a port that neither is a modem nor TCP, this command is ignored.

Logging In
..........

chat STRINGS

chat-timeout NUMBER

chat-fail STRING

chat-seven-bit BOOLEAN

chat-program STRINGS

     These commands describe a chat script to use when logging on to a remote system.  Chat scripts are explained in Chat Scripts.

     Two additional escape sequences may be used in send strings.

     \L
          Send the login name, as set by the call-login command.

     \P
          Send the passowrd, as set by the call-password command.

     Three additional escape sequences may be used with the chat-program command.  These are \L and \P, which become the login name and password, respectively, and \Z, which becomes the name of the system of being called.

     The default chat script is:

          chat "" \r\c ogin:-BREAK-ogin:-BREAK-ogin: \L word: \P

     This will send a carriage return (the \c suppresses the additional trailing carriage return that would otherwise be sent) and waits for the string ogin: (which would be the last part of the login: prompt supplied by a Unix system).  If it doesn't see ogin:, it sends a break and waits for ogin: again.  If it still doesn't see ogin:, it sends another break and waits for ogin: again. If it still doesn't see ogin:, the chat script aborts and hangs up the phone.  If it does see ogin: at some point, it sends the login name (as specified by the call-login command) followed by a carriage return (since all send strings are followed by a carriage return unless \c is used) and waits for the string word: (which would be the last part of the Password: prompt supplied by a Unix system).  If it sees word:, it sends the password and a carriage return, completing the chat script.  The program will then enter the handshake phase of the UUCP protocol.

     This chat script will work for most systems, so you will only be required to use the call-login and call-password commands. In fact, in the file-wide defaults you could set defaults of call-login * and call-password *; you would then just have to make an entry for each system in the call-out login file.

     Some systems seem to flush input after the login: prompt, so they may need a version of this chat script with a \d before the \L.  When using UUCP over TCP, some servers will not be handle the initial carriage return sent by this chat script; in this case you may have to specify the simple chat script ogin: \L word: \P.

call-login STRING

     Specify the login name to send with \L in the chat script.  If the string is * (e.g. call-login *) the login name will be fetched from the call out login name and password file (see Configuration File Names).  There is no default.

call-password STRING

     Specify the password to send with \P in the chat script.  If the string is * (e.g. call-password *) the password will be fetched from the call-out login name and password file (see Configuration File Names).  There is no default.

Accepting a Call
----------------

called-login STRINGS

     The first STRING specifies the login name that the system must use when calling in.  If it is ANY (e.g. called-login ANY) any login name may be used; this is useful to override a file-wide default and to indicate that future alternates may have different login names. Case is significant.  The default value is ANY.

     Different alternates (see Defaults and Alternates) may use different called-login commands, in which case the login name will be used to select which alternate is in effect; this will only work if the first alternate (before the first alternate command) uses the called-login command.

     Additional strings may be specified after the login name; they are a list of which systems are permitted to use this login name.  If this feature is used, then normally the login name will only be given in a single called-login command.  Only systems which appear on the list, or which use an explicit called-login command, will be permitted to use that login name.  If the same login name is used more than once with a list of systems, all the lists are concatenated together.  This feature permits you to restrict a login name to a particular set of systems without requiring you to use the called-login command for every single system; you can achieve a similar effect by using a different system file for each permitted login name with an appropriate called-login command in the file-wide defaults.

callback BOOLEAN

     If BOOLEAN is true, then when the remote system calls uucico will hang up the connection and prepare to call it back. This is false by default.

called-chat STRINGS

called-chat-timeout NUMBER

called-chat-fail STRING

called-chat-seven-bit BOOLEAN

called-chat-program STRINGS

     These commands may be used to define a chat script (see Chat Scripts) that is run whenever the local system is called by the system being defined.  The chat script defined by the chat command (see Logging In), on the other hand, is used when the remote system is called.  This called chat script might be used to set special modem parameters that are appropriate to a particular system.  It is run after protocol negotiation is complete, but before the protocol has been started.  See Logging In for additional escape sequence which may be used besides those defined for all chat scripts.  There is no default called chat script.  If the called chat script fails, the incoming call will be aborted.

Protocol Selection
------------------

protocol STRING

     Specifies which protocols to use for the other system, and in which order to use them.  This would not normally be used.  For example, protocol tfg.

     The default depends on the characteristics of the port and the dialer, as specified by the seven-bit and reliable commands.  If neither the port nor the dialer use either of these commands, the default is to assume an eight-bit reliable connection.  The commands seven-bit true or reliable false might be used in either the port or the dialer to change this.  Each protocol has particular requirements that must be met before it will be considered during negotiation with the remote side.

     The t and e protocols are intended for use over TCP or some other communication path with end to end reliability, as they do no checking of the data at all.  They will only be considered on a TCP port which is both reliable and eight bit.

     The g protocol is robust, but requires an eight-bit connection.

     The f protocol is intended for use with X.25 connections; it checksums each file as a whole, so any error causes the entire file to be retransmitted.  It requires a reliable connection, but only uses seven-bit transmissions.  It is a streaming protocol, so, while it can be used on a serial port, the port must be completely reliable and flow controlled; many aren't.

     The protocols will be considered in the order shown above.  This means that if neither the seven-bit nor the reliable command are used, the t protocol will be used over a TCP connection and the g protocol will be used over any other type of connection (subject, of course, to what is supported by the remote system; it may be assumed that all systems support the g protocol).

     Note that currently specifying both seven-bit true and reliable false will not match any protocol.  If this occurs through a combination of port and dialer specifications, you will have to use the protocol command for the system or no protocol will be selected at all (the only reasonable choice would be protocol f).

     A protocol list may also be specified for a port (see port file), but if there is a list for the system the list for the port is ignored.

protocol-parameter CHARACTER STRING ...

     CHARACTER is a single character specifying a protocol.  The remaining strings are a command specific to that protocol which will be executed if that protocol is used.  A typical command is something like window 7.  The particular commands are protocol specific.

     The g protocol supports the following commands, all of which take numeric arguments:

     window
          The window size to request the remote system to use.  This must be between 1 and 7 inclusive.  The default is 7.

     packet-size
          The packet size to request the remote system to use.  This must be a power of 2 between 32 and 4096 inclusive.  The default is 64, which is the only packet size supported by many older UUCP packages.  Some UUCP packages will even dump core if a larger packet size is requested.

     startup-retries
          The number of times to retry the initialization sequence.  The default is 8.

     init-retries
          The number of times to retry one phase of the initialization sequence (there are three phases).  The default is 4.

     init-timeout
          The timeout in seconds for one phase of the initialization sequence.  The default is 10.

     retries
          The number of times to retry sending either a data packet or a request for the next packet.  The default is 6.

     timeout
          The timeout in seconds when waiting for either a data packet or an acknowledgement.  The default is 10.

     garbage
          The number of unrecognized bytes to permit before dropping the connection.  This must be larger than the packet size.  The default is 10000.

     errors
          The number of errors (malformed packets, out of order packets, bad checksums, or packets rejected by the remote system) to permit before dropping the connection.  The default is 100.

     remote-window
          If this is between 1 and 7 inclusive, the window size requested by the remote system is ignored and this is used instead.  This can be useful when dealing with some poor UUCP packages.  The default is 0, which means that the remote system's request is honored.

     remote-packet-size
          If this is between 32 and 4096 inclusive the packet size requested by the remote system is ignored and this is used instead.  There is probably no good reason to use this.  The default is 0, which means that the remote system's request is honored.

     The f protocol is intended for use with error-correcting modems only; it checksums each file as a whole, so any error causes the entire file to be retransmitted.  It supports the following commands, both of which take numeric arguments:

     timeout
          The timeout in seconds before giving up.  The default is 120.

     retries
          How many times to retry sending a file.  The default is 2.

     The t and e protocols are intended for use over TCP or some other communication path with end to end reliability, as they do no checking of the data at all.  They both support a single command, which takes a numeric argument:

     timeout
          The timeout in seconds before giving up.  The default is 120.

     The protocol parameters are reset to their default values after each call.

File Transfer Control
---------------------

call-request BOOLEAN

     The BOOLEAN is checked when the local system places the call.  It determines whether the remote system may request any file transfers. The default is yes.

called-request BOOLEAN

     The BOOLEAN is checked when the remote system calls in.  It determines whether the remote system may request any file transfers. The default is yes.

request BOOLEAN

     Equivalent to specifying both call-request BOOLEAN and called-request BOOLEAN.

call-transfer BOOLEAN

     The BOOLEAN is checked when the local system places the call.  It determines whether the local system may do file transfers queued up for the remote system.  The default is yes.

called-transfer BOOLEAN

     The BOOLEAN is checked when the remote system calls in.  It determines whether the local system may do file transfers queued up for the remote system.  The default is yes.

transfer BOOLEAN

     Equivalent to specifying both call-transfer BOOLEAN called-transfer BOOLEAN.

call-local-size NUMBER STRING

     The STRING is a time string (see Time Strings).  The NUMBER is the size in bytes of the largest file that should be transferred at a time matching the time string if the local system placed the call and the request was made by the local system.  This command may appear multiple times in a single alternate.  If this command does not appear, or if none of the time strings match, there are no size restrictions.

     With all the size control commands, the size of a file from the remote system (as opposed to a file from the local system) will only be checked if the other system is running this package; other UUCP packages will not understand a maximum size request, nor will they inform this package of the size of remote files.

call-remote-size NUMBER STRING

     Specify the size in bytes of the largest file that should be transferred at a given time by remote request when the local system placed the call.  This command may appear multiple times in a single alternate.  If this command does not appear, there are no size restrictions.

called-local-size NUMBER STRING

     Specify the size in bytes of the largest file that should be transferred at a given time by local request when the remote system placed the call. This command may appear multiple times in a single alternate. If this command does not appear, there are no size restrictions.

called-remote-size NUMBER STRING

     Specify the size in bytes of the largest file that should be transferred at a given time by remote request when the remote system placed the call.  This command may appear multiple times in a single alternate. If this command does not appear, there are no size restrictions.

local-send STRINGS

     Specifies that files in the directories named by the STRINGS may be sent to the remote system when requested locally (using uucp or uux).  The directories in the list should be separated by whitespace.  A ~ may be used for the public directory.  On a Unix system, this is typically /usr/spool/uucppublic; the public directory may be set with the pubdir command.  Here is an example of local-send:

          local-send ~ /usr/spool/ftp/pub

     Listing a directory allows all files within the directory and all subdirectories to be sent.  Directories may be excluded by preceding them with an exclamation point.  For example:

          local-send /usr/ftp !/usr/ftp/private ~

     means that all files in /usr/ftp or the public directory may be sent, except those files in /usr/ftp/private.  The list of directories is read from left to right, and the last directory to apply takes effect; this means that directories should be listed from top down.  The default is the root directory (i.e., any file at all may be sent by local request).

remote-send STRINGS

     Specifies that files in the named directories may be sent to the remote system when requested by the remote system.  The default is ~.

local-receive STRINGS

     Specifies that files may be received into the named directories when requested by a local user.  The default is ~.

remote-receive STRINGS

     Specifies that files may be received into the named directories when requested by the remote system.  The default is ~.  On Unix, the remote system may only request that files be received into directories that are writeable by the world, regardless of how this is set.

Miscellaneous sys File Commands
-------------------------------

sequence BOOLEAN

     If BOOLEAN is true, then conversation sequencing is automatically used for the remote system, so that if somebody manages to spoof as the remote system, it will be detected the next time the remote system actually calls.  This is false by default.

command-path STRING

     Specifies the path (a list of whitespace separated directories) to be searched to locate commands to execute.  This is only used for commands requested by uux, not for chat programs.  The default is from policy.h.

commands STRINGS

     The list of commands which the remote system is permitted to execute locally.  For example: commands rnews rmail.  If the value is ALL (case significant), all commands may be executed.  The default is rnews rmail.

free-space NUMBER

     Specify the minimum amount of file system space (in bytes) to leave free after receiving a file.  If the incoming file will not fit, it will be rejected.  This will only work when talking to another instance of this package, since older UUCP packages do not provide the file size of incoming files.  There is no provision for reserving space, so it is still possible for multiple uucico daemons to use up all available file space; a sufficiently large value for free-space will avoid this problem to some extent.  The default is from policy.h.  Not all systems may be able to provide the amount of available space.

pubdir STRING

     Specifies the public directory that is used when ~ is specifed in a file transfer or a list of directories.  This essentially overrides the public directory specified in the main configuration file for this system only.  The default is the public directory specified in the main configuration file (which defaults to a value from policy.h).

debug STRING ...

     Set additional debugging for calls to or from the system.  This may be used to debug a connection with a specific system.  It is particularly useful when debugging incoming calls, since debugging information will be generated whenever the call comes in.  See the debug command in the main configuration file (see Debugging Levels) for more details.  The debugging information specified here is in addition to that specified in the main configuration file or on the command line.

max-remote-debug STRING ...

     When the system calls in, it may request that the debugging level be set to a certain value.  This command may be used to put a limit on the debugging level which the system may request, to avoid filling up the disk with debugging information.  Only the debugging types named in the max-remote-debug command may be turned on by the remote system. To prohibit any debugging, use max-remote-debug none.  The default is abnormal,chat,handshake; to turn off these default entries, you must use max-remote-debug none followed by other max-remote-debug commands specifying the settings you want.

timetable STRING STRING

     This is actually not specific to a system; it can appear anywhere in the file(s).  In a future release this command will probably be moved to the main configuration file.

     The timetable defines a timetable that may be used in subsequently appearing time strings; Time Strings.  The first string names the timetable entry; the second is a time string.

     The following timetable commands are predefined.  The NonPeak timetable is included for compatibility.  It originally described the offpeak hours of Tymnet and Telenet, but both have since changed their schedules.

          timetable Evening Wk1705-0755,Sa,Su
          timetable Night Wk2305-0755,Sa,Su2305-1655
          timetable NonPeak Wk1805-0655,Sa,Su

     If this command does not appear, then obviously no additional timetables will be defined.

Default sys File Values
-----------------------

The following are used as default values for all systems; they can be considered as appearing before the start of the file.

     timetable Evening Wk1705-0755,Sa,Su
     timetable Night Wk2305-0755,Sa,Su2305-1655
     timetable NonPeak Wk1805-0655,Sa,Su
     time Never
     chat "" \r\c ogin:-BREAK-ogin:-BREAK-ogin: \L word: \P
     chat-timeout 10
     callback n
     sequence n
     request y
     transfer y
     local-send /
     remote-send ~
     local-receive ~
     remove-receive ~
     command-path [ from policy.h ]
     commands rnews rmail
     max-remote-debug abnormal,chat,handshake

The Port Configuration File
===========================

The port files may be used to name and describe ports.  The first command in each file must be port.  All command up to the next port command then describe that port.  There are different types of ports; each type supports its own set of commands.  Each command indicates which types of ports support it.  There may be many ports with the same name; if a system requests a port by name then each port with that name will be tried until an unlocked one is found.

port STRING

     Introduces and names a port.

type STRING

     Define the type of port.  The default is modem.  If this command appears, it must immediately follow the port command.  The type defines what commands are subsequently allowed.  Currently the types are:

     modem
          For a modem hookup.

     stdin
          For a connection through standard input and standard output, as when uucico is run as a login shell.

     direct
          For a direct connection to another system.

     tcp
          For a connection using TCP.

protocol STRING

     Specify a list of protocols to use for this port.  This is just like the corresponding command for a system (see Protocol Selection).  A protocol list for a system takes precedence over a list for a port.

protocol-parameter CHARACTER STRINGS [ any type ]

     The same command as the protocol-parameter command used for systems (see Protocol Selection).  This one takes precedence.

seven-bit BOOLEAN [ any type ]

     This is only used during protocol negotiation; if the argument is true, it forces the selection of a protocol which works across a seven-bit link.  It does not prevent eight bit characters from being transmitted.  The default is false.

reliable BOOLEAN [ any type ]

     This is only used during protocol negotiation; if the argument is false, it forces the selection of a protocol which works across an unreliable communication link.  The default is true.  It would be more common to specify this for a dialer rather than a port.

device STRING [ modem and direct only ]

     Names the device associated with this port.  If the device is not named, the port name is taken as the device.  Device names are system dependent, but a Unix example would be /dev/ttyd0.

baud NUMBER [ modem and direct only ]
speed NUMBER [modem and direct only ]

     The speed this port runs at.  If a system specifies a speed but no port name, then all ports which match the speed will be tried in order.  If the speed is not specified here and is not specified by the system, the natural speed of the port will be used by default.

baud-range NUMBER NUMBER [ modem only ]
speed-range NUMBER NUMBER [ modem only ]

     Specify a range of speeds this port can run at.  The first number is the minimum speed, the second number is the maximum speed.  These numbers will be used when matching a system which specifies a desired speed. The simple speed (or baud) command is still used to determine the speed to run at if the system does not specify a speed. For example, the command speed-range 300 19200 means that the port will match any system which uses a speed from 300 to 19200 baud (and will use the speed specified by the system); this could be combined with speed 2400, which means that when this port is used with a system that does not specify a speed, the port will be used at 2400 baud.

carrier BOOLEAN [ modem only ]

     The argument indicates whether the port supports carrier.  If it does not, carrier will never be required on this port, regardless of what the modem chat script indicates.  The default is true.

dial-device STRING [ modem only ]

     Dialing instructions should be output to the named device, rather than to the normal port device.  The default is to output to the normal port device.

dialer STRING [ modem only ]

     Name a dialer to use.  The information is looked up in the dialer file. There is no default.  Some sort of dialer information must be specified to call out on a modem.

dialer STRING ... [ modem only ]

     Execute a dialer command.  If a dialer is named (by using the first form of this command, described just above), these commands are ignored. They may be used to specify dialer information directly in simple situations without needing to go to a separate file.  There is no default.  Some sort of dialer information must be specified to call out on a modem.

dialer-sequence STRINGS [ modem only ]

     Name a sequence of dialers and tokens (phone numbers) to use.  The first argument names a dialer, and the second argument names a token.  The third argument names another dialer, and so on.  If there are an odd number of arguments, the phone number specified with a phone command in the system file is used as the final token.  The token is what is used for \D or \T in the dialer chat script.  If the token in this string is \D, the system phone number will be used; if it is \T, the system phone number will be used after undergoing dialcodes translation.  A missing final token is taken as \D.

     This command currently does not work if dial-device is specified; to handle this correctly will require a more systematic notion of chat scripts.  Moreover, only the complete and abort chat scripts from the first dialer specified are used, and only the protocol parameters from the first dialer are used.

lockname STRING [ modem and direct only ]

     Give the name to use when locking this port.  On Unix, this is the name of the file that will be created in the lock directory.  It is used as is, so on Unix it should generally start with LCK...  For example, if a single port were named both /dev/ttycu0 and /dev/tty0 (perhaps with different characteristics keyed on the minor device number), then the command lockname LCK..ttycu0 could be used to force the latter to use the same lock file name as the former.

service STRING [ tcp only ]

     Name the TCP port number to use.  This may be a number.  If not, it will be looked up in /etc/services.  If this is not specified, the string uucp is looked up in /etc/services.  If it is not found, port number 540 (the standard UUCP-over-TCP port number) will be used.

The Dialer Configuration File
=============================

The dialer configuration files define dialers.  The first command in each file must be a dialer command, which names the dialer. Subsequent commands up to the next dialer command are associated with the named dialer.

dialer STRING

     Introduces and names a dialer.

chat STRINGS

chat-timeout NUMBER

chat-fail STRING

chat-seven-bit BOOLEAN

chat-program STRINGS

     Specify a chat script to be used to dial the phone.  See Chat Scripts for full details on chat scripts.

     Taylor UUCP will sleep for one second between attempts to dial out on a modem.  If your modem requires a longer wait period, you must start your chat script with delays (\d in a send string).

     The chat script will be read from and sent to the port specified by the dial-device command for the port, if there is one.

     The following escape addition escape sequences may appear in send strings:

     \D
          send phone number without dialcode translation

     \T
          send phone number with dialcode translation

     \M
          do not require carrier

     \m
          require carrier (fail if not present)

     See the description of the dialcodes file (see Configuration File Names) for a description of dialcode translation.  If the port does not support carrier (as set by the carrier command in the port file) \M and \m are ignored.  If both the port and the dialer support carrier (as set by the carrier command in the port file and the carrier command in the dialer file), then every chat script implicitly begins with \M and ends with \m.  There is no default chat script for dialers.

     The following additional escape sequences may be used in chat-program:

     \D
          phone number without dialcode translation

     \T
          phone number with dialcode translation

     If the program changes the port in any way (e.g., sets parity) the changes will be preserved during protocol negotiation, but once the protocol is selected it will change the port settings.

dialtone STRING

     A string to output when dialing the phone number which causes the modem to wait for a secondary dial tone.  This is used to translate the = character in a phone number.  The default is a comma.

pause STRING

     A string to output when dialing the phone number which causes the modem to wait for 1 second.  This is used to translate the - character in a phone number.  The default is a comma.

carrier BOOLEAN

     If the argument is true, the dialer supports the modem carrier signal.  After the phone number is dialed, uucico will require that carrier be on.  One some systems, it will be able to wait for it. If the argument is false, carrier will not be required.  The default is true.

carrier-wait NUMBER

     If the port is supposed to wait for carrier, this may be used to indicate how many seconds to wait.  The default is 60 seconds.  Only some systems support waiting for carrier.

dtr-toggle BOOLEAN BOOLEAN

     If the first argument is true, then DTR is toggled before using the modem.  This is only supported on some systems and some ports.  The second BOOLEAN need not be present; if it is, and it is true, the program will sleep for 1 second after toggling DTR. The default is not to toggle DTR.

complete-chat STRINGS

complete-chat-timeout NUMBER

complete-chat-fail STRING

complete-chat-seven-bit BOOLEAN

complete-chat-program STRINGS

     These commands define a chat script (see Chat Scripts) which is run when a call is finished normally.  This allows the modem to be reset. There is no default.  No additional escape sequences may be used.

complete STRING

     This is a simple use of complete-chat.  It is equivalent to complete-chat "" STRING; this has the effect of sending STRING to the modem when a call finishes normally.

abort-chat STRINGS

abort-chat-timeout NUMBER

abort-chat-fail STRING

abort-chat-seven-bit BOOLEAN

abort-chat-program STRINGS

     These commands define a chat script (see Chat Scripts) to be run when a call is aborted.  They may be used to interrupt and reset the modem.  There is no default.  No additional escape sequences may be used.

abort STRING

     This is a simple use of abort-chat.  It is equivalent to abort-chat "" STRING; this has the effect of sending STRING to the modem when a call is aborted.

protocol-parameter CHARACTER STRINGS

     Set protocol parameters, just like the protocol-parameter command in the system configuration file or the port configuration file; see Protocol Selection.  These parameters take precedence, then those for the port, then those for the system.

seven-bit BOOLEAN

     This is only used during protocol negotiation; if it is true, it forces selection of a protocol which works across a seven-bit link.  It does not prevent eight bit characters from being transmitted.  The default is false.  It would be more common to specify this for a port than for a dialer.

reliable BOOLEAN

     This is only used during protocol negotiation; if it is false, it forces selection of a protocol which works across an unreliable communication link.  The default is true.

Security
========

This discussion of UUCP security applies only to Unix.  It is a bit cursory; suggestions for improvement are solicited.

UUCP is traditionally not very secure.  Taylor UUCP addresses some security issues, but is still far from being a secure system.

If security is very important to you, then you should not permit any external access to your computer, including UUCP.  Any opening to the outside world is a potential security risk.

By default Taylor UUCP provides few mechanisms to secure local users of the system from each other.  You can allow increased security by putting the owner of the UUCP programs (normally uucp) into a separate group; the use of this is explained in the following paragraphs, which refer to this separate group as uucp-group.

When the uucp program is invoked to copy a file to a remote system, it will by default copy the file into the UUCP spool directory. When the uux program is used, the -C switch must be used to copy the file into the UUCP spool directory.  In any case, once the file has been copied into the spool directory, other local users will not be able to access it.  In version 1.03 there is a security hole in that for the file to be copied it must be readable by uucp. Changing the group of the file to uucp-group and making it group readable will permit UUCP to read it without granting access to other users.

When a file is requested from a remote system, UUCP will only permit it to be placed in a directory which is writable by the requesting user. The directory must also be writable by UUCP.  A local user can create a directory with a group of uucp-group and set the mode to permit group write access.  This will allow the file be requested without permitting it to be viewed by any other user.

There is no provision for security for uucp requests (as opposed to uux requests) made by a user on a remote system.  A file sent over by a remote request may only be placed in a directory which is world writable, and the file will be world readable and writable.  This will permit any local user to destroy or replace the contents of the file.  A file requested by a remote system must be world readable, and the directory it is in must be world readable.  Any local user will be able to examine, although not necessarily modify, the file before it is sent.

There are some security holes and race conditions that apply to the above discussion which I will not elaborate on.  They are not hidden from anybody who reads the source code, but they are somewhat technical and difficult (but scarcely impossible) to exploit.  Suffice it to say that even under the best of conditions UUCP is not completely secure.

For many sites, security from remote sites is a more important consideration.  Fortunately, Taylor UUCP does provide some support in this area.

The greatest security is provided by always dialing out to the other site.  This prevents anybody from pretending to be the other site.  Of course, only one side of the connection can do this.

If remote dialins must be permitted, then it is best if the dialin line is used only for UUCP.  If this is the case, then you should create a call-in password file (see Configuration File Names) and let uucico do its own login prompting.  For example, to let remote sites log in on a port named entry in the port file (see port file) you might invoke uucico -p entry.  This would cause uucico to enter an endless loop of login prompts and daemon executions.  The advantage of this approach is that even if remote users break into the system by guessing or learning the password, they will only be able to do whatever uucico permits them to do.  They will not be able to start a shell on your system.

If remote users can dial in and log on to your system, then you have a security hazard more serious than that posed by UUCP.  But then, you probably knew that already.

Once your system has connected with the remote UUCP, there is a fair amount of control you can exercise.  You can use the remote-send and remote-receive commands to control the directories the remote UUCP can access.  You can use the request command to prevent the remote UUCP from making any requests of your system at all; however, if you do this it will not even be able to send you mail or news.  If you do permit remote requests, you should be careful to restrict what commands may be executed at the remote system's request.  The default is rmail and rnews, which will suffice for most systems.

If different remote systems call in and they must be granted different privileges (perhaps some systems are within the same organization and some are not) then the called-login command should be used for each system to require that they different login names.  Otherwise it would be simple for a remote system to use the myname command and pretend to be a different system.  The sequence command can be used to detect when one system pretended to be another, but since the sequence numbers must be reset manually after a failed handshake this can sometimes be more trouble than it's worth.

UUCP protocol internals
***********************

This chapter describes how the various UUCP protocols work, and discusses some other internal UUCP issues.

This chapter is quite technical.  You do not need to understand it, or even read it, in order to use Taylor UUCP.  It is intended for people who are interested in how UUCP code works.

Most of the discussion covers the protocols used by all UUCP packages, not just Taylor UUCP.  Any information specific to Taylor UUCP is indicated as such.  There are some pointers to the actual functions in the Taylor UUCP source code, for those who are extremely interested in actual UUCP implementation.

UUCP Grades
===========

Modern UUCP packages support grades for each command.  The grades generally range from A (the highest) to Z followed by a to z.  Taylor UUCP also supports 0 to 9 before A.  Some UUCP packages may permit any ASCII character as a grade.

On Unix, these grades are encoded in the name of the command file.  A command file name generally has the form

     C.nnnngssss

where NNNN is the remote system name for which the command is queued, G is a single character grade, and SSSS is a four character sequence number.  For example, a command file created for the system airs at grade Z might be named

     C.airsZ2551

The remote system name will be truncated to seven characters, to ensure that the command file name will fit in the 14 character file name limit of the traditional Unix file system.  UUCP packages which have no other means of distinguishing which command files are intended for which systems thus require all systems they connect to to have names that are unique in the first seven characters.  Some UUCP packages use a variant of this format which truncates the system name to six characters.  BNU uses a different spool directory format, which allows up to fourteen characters to be used for each system name.  The Taylor UUCP spool directory format is configurable.  The new Taylor spool directory format permits system names to be as long as file names; the maximum length of a file name depends on the particular Unix file system being used.

The sequence number in the command file name may be a decimal integer, or it may be a hexadecimal integer, or it may contain any alphanumeric character.  Different UUCP packages are different.

Taylor UUCP creates command files in the function zsysdep_spool_commands.  The file name is constructed by the function zsfile_name, which knows about all the different types of spool directories supported by Taylor UUCP.  The Taylor UUCP sequence number can contain any alphanumeric character; the next sequence number is determined by the function fscmd_seq.

I do not know how command grades are handled in non-Unix UUCP packages.

Modern UUCP packages allow you to restrict file transfer by grade depending on the time of day.  Typically this is done with a line in the Systems (or L.sys) file like this:

     airs Any/Z,Any2305-0855 ...

This allows only grades Z and above to be transferred at any time.  Lower grades may only be transferred at night.  I believe that this grade restriction applies to local commands as well as to remote commands, but I am not sure.  It may only apply if the UUCP package places the call, not if it is called by the remote system.  Taylor UUCP can use the timegrade and call-timegrade commands (see When to Call) to achieve the same effect (and supports the above format when reading Systems or L.sys).

This sort of grade restriction is most useful if you know what grades are being used at the remote site.  The default grades used depend on the UUCP package.  Generally uucp and uux have different defaults.  A particular grade can be specified with the -g option to uucp or uux.  For example, to request execution of rnews on airs with grade d, you might use something like

     uux -gd - airs!rnews <article

uunet queues up mail at grade Z and news at grade d.  The example above would allow mail to be received at any time, but would only permit news to be transferred at night.

UUCP Lock File Format
=====================

This discussion applies only to Unix.  I have no idea how UUCP locks ports on other systems.

UUCP creates files to lock serial ports and systems.  On most (if not all) systems, these same lock files are also used by cu to coordinate access to serial ports.  On some systems getty also uses these lock files.

The lock file normally contains the process ID of the locking process. This makes it easy to determine whether a lock is still valid.  The algorithm is to create a temporary file and then link it to the name that must be locked.  If the link fails because a file with that name already exists, the existing file is read to get the process ID.  If the process still exists, the lock attempt fails.  Otherwise the lock file is deleted and the locking algorithm is retried.

Older UUCP packages put the lock files in the main UUCP spool directory, /usr/spool/uucp.  BNU UUCP generally puts the lock files in a directory of their own, usually /usr/spool/locks or /etc/locks.

The original UUCP lock file format encoded the process ID as a four byte binary number.  The order of the bytes was host-dependent.  BNU UUCP stores the process ID as a ten byte ASCII decimal number, with a trailing newline.  For example, if process 1570 holds a lock file, it would contain the eleven characters space, space, space, space, space, space, one, five, seven, zero, newline.  Some versions of UUCP add a second line indicating which program created the lock (uucp, cu, or getty).  I have also seen a third type of UUCP lock file which did not contain the process ID at all.

The name of the lock file is generally "LCK.." followed by the base name of the device.  For example, to lock /dev/ttyd0 the file LCK..ttyd0 would be created.  There are various exceptions.  On SCO Unix, the lock file name is always forced to lower case even if the device name has upper case letters.  System V Release 4 UUCP forms the lock file name using the major and minor device numbers rather than the device name (this is pretty sensible if you think about it).

Taylor UUCP can be configured to use various different types of locking. The actual locking code is in the function fsdo_lock.

The Common UUCP Protocol
========================

The UUCP protocol is a conversation between two UUCP packages.  A UUCP conversation consists of three parts: an initial handshake, a series of file transfer requests, and a final handshake.

Before the initial handshake, the caller will usually have logged in the called machine and somehow started the UUCP package there.  On Unix this is normally done by setting the shell of the login name used to uucico.

Initial Handshake
-----------------

All messages in the initial handshake begin with a ^P (a byte with the octal value \020) and end with a null byte (\000).

Taylor UUCP implements the initial handshake for the calling machine in fdo_call, and for the called machine in faccept_call.

The initial handshake goes as follows.  It is begun by the called machine.

called: \020Shere=HOSTNAME\000
     The HOSTNAME is the UUCP name of the called machine.  Older UUCP packages do not output it, and simply send \020Shere\000.

caller: \020SHOSTNAME OPTIONS\000
     The HOSTNAME is the UUCP name of the calling machine.  The following OPTIONS may appear (or there may be none):

     -QSEQ
          Report sequence number for this conversation.  The sequence number is stored at both sites, and incremented after each call.  If there is a sequence number mismatch, something has gone wrong (somebody may have broken security by pretending to be one of the machines) and the call is denied.  If the sequence number changes on one of the machines, perhaps because of an attempted breakin or because a disk backup was restored, the sequence numbers on the two machines must be reconciled manually.

     -xLEVEL
          Requests the called system to set its debugging level to the specified value.  This is not supported by all systems.  Taylor UUCP currently never generates this switch.  When it sees it, it restricts the value according to max-remote-debug (see Miscellaneous (sys)).

     -pGRADE
     -vgrade=GRADE
          Requests the called system to only transfer files of the specified grade or higher.  This is not supported by all systems.  Some systems support -p, some support -vgrade=.  Taylor UUCP supports both.

     -R
          Indicates that the calling UUCP understands how to restart failed file transmissions.  Supported only by System V Release 4 UUCP.

     -ULIMIT
          Reports the ulimit value of the calling UUCP.  The limit is specified as a base 16 number in C notation (e.g., -U0x1000000). This number is the number of 512 byte blocks in the largest file which the calling UUCP can create.  The called UUCP may not transfer a file larger than this.  Supported by System V Release 4 UUCP.  Taylor UUCP understands this option, but never generates it.

     -N
          Indicates that the calling UUCP understands the Taylor UUCP size limiting extensions.  Supported only by Taylor UUCP.

called: \020ROK\000
     There are actually several possible responses.

     ROK
          The calling UUCP is acceptable, and the handshake proceeds to the protocol negotiation.  Some options may also appear; see below.

     ROKN
          The calling UUCP is acceptable, it specified -N, and the called UUCP also understands the Taylor UUCP size limiting extensions. Supported only by Taylor UUCP.

     RLCK
          The called UUCP already has a lock for the calling UUCP, which normally indicates the two machines are already communicating.

     RCB
          The called UUCP will call back.  This may be used to avoid impostors. Note that only one machine out of each pair should call back, or no conversation will ever begin.

     RBADSEQ
          The call sequence number is wrong (see the -Q discussion above).

     RLOGIN
          The calling UUCP is using the wrong login name.

     RYou are unknown to me
          The calling UUCP is not known to the called UUCP, and the called UUCP does not permit connections from unknown systems.

     If the response is ROK, the following options are supported by System V Release 4 UUCP.

     -R
          The called UUCP knows how to restart failed file transmissions.

     -ULIMIT
          Reports the ulimit value of the called UUCP.  The limit is specified as a base 16 number in C notation.  This number is the number of 512 byte blocks in the largest file which the called UUCP can create.  The calling UUCP may not send a file larger than this.

     -xLEVEL
          I'm told that this is sometimes sent by SVR4 UUCP, but I'm not sure exactly what it means.  It may request the calling UUCP to set its debugging level to the specified value.

     If the response is not ROK (or ROKN) both sides hang up the phone, abandoning the call.

called: \020PPROTOCOLS\000
     The P is a literal character.  Note that the called UUCP outputs two strings in a row.  The PROTOCOLS string is a list of UUCP protocols supported by the caller.  Each UUCP protocol has a single character name.  For example, the called UUCP might send \020Pgf\000.

caller: \020UPROTOCOL\000
     The U is a literal character.  The calling UUCP selects which PROTOCOL to use out of the protocols offered by the called UUCP. If there are no mutually supported protocols, the calling UUCP sends \020UN\000 and both sides hang up the phone.  Otherwise the calling UUCP sends something like \020Ug\000.

Most UUCP packages will consider each locally supported protocol in turn and select the first one supported by the called UUCP.  With some versions of BNU UUCP, this can be modified by giving a list of protocols after the device name in the Devices file or the Systems file. Taylor UUCP provides the protocol command which may be used either for a system (see Protocol Selection) or a port (see port file).

After the protocol has been selected and the initial handshake has been completed, both sides turn on the selected protocol.  For some protocols (notably g) a further handshake is done at this point.

Each protocol supports a method for sending a command to the remote system.  This method is used to transmit a series of commands between the two UUCP packages.  At all times, one package is the master and the other is the slave.  Initially, the calling UUCP is the master.

If a protocol error occurs during the exchange of commands, both sides move immediately to the final handshake.

File Requests
-------------

The master will send one of four commands: S, R, X or H.

Any file name referred to below is either an absolute pathname beginning with /, a public directory pathname beginning with ~/, a pathname relative to a user's home directory beginning with ~USER/, or a spool directory file name.  File names in the spool directory are not pathnames, but instead are converted to pathnames within the spool directory by UUCP.  They always begin with C. (for a command file created by uucp or uux), D. (for a data file created by uucp, uux or by an execution, or received from another system for an execution), or X. (for an execution file created by uux or received from another system).

Taylor UUCP chooses which request to send next in the function fuucp.  This is also where Taylor UUCP processes incoming commands from the remote system.

S Request
.........

master: S FROM TO USER -OPTIONS TEMP MODE NOTIFY SIZE

The S and the - are literal characters.  This is a request by the master to send a file to the slave.  Taylor UUCP handles the S request in the function fsend_file.

from
     The name of the file to send.  If the C option does not appear in OPTIONS, the master will actually open and send this file. Otherwise the file has been copied to the spool directory, where it is named TEMP.  The slave ignores this field unless TO is a directory, in which case the basename of FROM will be used as the file name.  If FROM is a spool directory filename, it must be a data file created for or by an execution, and must begin with D..

to
     The name to give the file on the slave.  If this field names a directory the file is placed within that directory with the basename of FROM.  A name ending in / is taken to be a directory even if one does not already exist with that name.  If TO begins with X., an execution file will be created on the slave.  Otherwise, if TO begins with D. it names a data file to be used by some execution file.  Otherwise, TO should not be in the spool directory.

user
     The name of the user who requested the transfer.

options
     A list of options to control the transfer.  The following options are defined (all options are single characters):

     C
          The file has been copied to the spool directory (the master should use TEMP rather than FROM).

     c
          The file has not been copied to the spool directory (this is the default).

     d
          The slave should create directories as necessary (this is the default).

     f
          The slave should not create directories if necessary, but should fail the transfer instead.

     m
          The master should send mail to USER when the transfer is complete.

     n
          The slave should send mail to NOTIFY when the transfer is complete.

temp
     If the C option appears in OPTIONS, this names the file to be sent.  Otherwise if FROM is in the spool directory, TEMP is the same as FROM.  Otherwise TEMP is a dummy string, normally D.0.  After the transfer has been succesfully completed, the master will delete the file TEMP.

mode
     This is an octal number giving the mode of the file on the master.  If the file is not in the spool directory, the slave will always create it with mode 0666, except that if (MODE & 0111) is not zero (the file is executable), the slave will create the file with mode 0777.  If the file is in the spool directory, some UUCP packages will use the algorithm above and some will always create the file with mode 0600 (Taylor UUCP does the latter).

notify
     This field is only used if the n option appears in OPTIONS. Otherwise, it may not appear, or it may be the string dummy, or it may simply be a pair of double quotes.  If the n option is specified, then when the transfer is successfully completed the slave will send mail to NOTIFY, which must be a legal mailing address on the slave.

size
     This field is only present when doing size negotiation, either with Taylor UUCP or SVR4 UUCP.  It is the size of the file in bytes.  SVR4 UUCP sends the size in base 16 as 0x... while Taylor UUCP sends the size as a decimal integer (a later version of Taylor UUCP will probably change to the SVR4 behaviour).

The slave then responds with an S command response.  Taylor UUCP generates these responses in freceive_file and ftransfer_fail.

SY START
     The slave is willing to accept the file, and file transfer begins.  The START field will only be present when using SVR4 file restart.  It specifies the byte offset into the file at which to start sending.  If this is a new file, START will be 0x0.

SN2
     The slave denies permission to transfer the file.  This can mean that the destination directory may not be accessed, or that no requests are permitted.  It implies that the file transfer will never succeed.

SN4
     The slave is unable to create the necessary temporary file.  This implies that the file transfer might succeed later.

SN6
     This is only used by Taylor UUCP size negotiation.  It means that the slave considers the file too large to transfer at the moment, but it may be possible to transfer it at some other time.

SN7
     This is only used by Taylor UUCP size negotiation.  It means that the slave considers the file too large to ever transfer.

If the slave responds with SY, a file transfer begins.  When the file transfer is complete, the slave sends a C command response. Taylor UUCP generates this confirmation in fprecfile_confirm and checks it in fpsendfile_confirm.

CY
     The file transfer was successful.

CN5
     The temporary file could not be moved into the final location.  This implies that the file transfer will never succeed.

After the C command response has been received (in the SY case) or immediately (in an SN case) the master will send another command.

R Request
.........

master: R FROM TO USER -OPTIONS SIZE

The R and the - are literal characters.  This is a request by the master to receive a file from the slave.  I do not know how SVR4 UUCP implements file transfer restart in this case.  Taylor UUCP implements the R request in freceive_file.

from
     This is the name of the file on the slave which the master wishes to receive.  It must not be in the spool directory, and it may not contain any wildcards.

to
     This is the name of the file to create on the master.  I do not believe that it can be a directory.  It may only be in the spool directory if this file is being requested to support an execution either on the master or on some system other than the slave.

user
     The name of the user who requested the transfer.

options
     A list of options to control the transfer.  The following options are defined (all options are single characters):

     d
          The master should create directories as necessary (this is the default).

     f
          The master should not create directories if necessary, but should fail the transfer instead.

     m
          The master should send mail to USER when the transfer is complete.

size
     This only appears if Taylor UUCP size negotiation is being used.  It specifies the largest file which the master is prepared to accept (when using SVR4 UUCP, this was specified in the -U option during the initial handshake).

The slave then responds with an R command response.  Taylor UUCP generates these responses in fsend_file and ftransfer_fail.

RY MODE
     The slave is willing to send the file, and file transfer begins. MODE is the octal mode of the file on the slave.  The master uses this to set the mode of the file on the master's system just as the slave does the MODE argument in the send command (see S Request).

RN2
     The slave is not willing to send the file, either because it is not permitted or because the file does not exist.  This implies that the file request will never succeed.

RN6
     This is only used by Taylor UUCP size negotiation.  It means that the file is too large to send, either because of the size limit specifies by the master or because the slave considers it too large.  The file transfer might succeed later, or it might not (this will be cleared up in a later release of Taylor UUCP).

If the slave responds with RY, a file transfer begins.  When the file transfer is complete, the master sends a C command.  The slave pretty much ignores this, although it may log it.  Taylor UUCP sends this confirmation in fprecfile_confirm and checks it in fpsendfile_confirm.

CY
     The file transfer was successful.

CN5
     The temporary file could not be moved into the final location.

After the C command response has been sent (in the RY case) or immediately (in an RN case) the master will send another command.

X Request
.........

master: X FROM TO USER -OPTIONS

The X and the - are literal characters.  This is a request by the master to, in essence, execute uucp on the slave.  The slave should execute uucp FROM TO.  Taylor UUCP generates the X request in fxcmd and handles it in fdo_xcmd.

from
     This is the name of the file or files on the slave which the master wishes to transfer.  Any wildcards are expanded on the slave.  If the master is requesting that the files be transferred to itself, the request would normally contain wildcard characters, since otherwise an R command would suffice.  The master can also use this command to request that the slave transfer files to a third system.

to
     This is the name of the file or directory to which the files should be transferred.  This will normally use a UUCP name.  For example, if the master wishes to receive the files itself, it would use MASTER!PATH.

user
     The name of the user who requested the transfer.

options
     A list of options to control the transfer.  It is not clear which, if any, options are supported by most UUCP packages.  Taylor UUCP ignores the options field.

The slave then responds with an X command response.  Taylor UUCP sends this response in either fxcmd_confirm or ftransfer_fail.

XY
     The request was accepted, and the appropriate file transfer commands have been queued up for later processing.

XN
     The request was denied.  No particular reason is given.

In either case, the master will then send another command.

H Request
.........

master: H

This is used by the master to hang up the connection.  The slave will respond with an H command response.  Taylor UUCP processes this request in fhangup_request, fhangup_reply, and fgetcmd.

HY
     The slave agrees to hang up the connection.  In this case the master sends another HY command.  In some UUCP packages, including Taylor UUCP, the slave will then send a third HY command.  At this point the protocol is shut down, and the final handshake is begun.

HN
     The slave does not agree to hang up.  In this case the master and the slave exchange roles.  The next command will be sent by the former slave, which is the new master.  The roles may be reversed several times during a single connection.

Final Handshake
---------------

After the protocol has been shut down, the final handshake is performed.  This handshake has no real purpose, and some UUCP packages simply drop the connection rather than do it (in fact, some will drop the connection immediately after both sides agree to hangup, without even closing down the protocol).  Taylor UUCP always sends the appropriate final handshake string (in fdo_call or faccept_call) but ignores the handshake string from the other side unless it is in handshake debugging mode.

caller: \020OOOOOO\000

called: \020OOOOOOO\000

That is, the calling UUCP sends six letter O's and the called UUCP replies with seven letter O's.  Some UUCP packages always send six O's.

The UUCP g Protocol
===================

The g protocol is a packet based flow controlled error correcting protocol that requires an eight bit clear connection.  It is the original UUCP protocol, and is supported by all UUCP implementations. Many implementations of it are only able to support small window and packet sizes, specifically a window size of 3 and a packet size of 64 bytes, but the protocol itself can support up to a window size of 7 and a packet size of 4096 bytes.  Complaints about the inefficiency of the g protocol generally refer to specific implementations, rather than the correctly implemented protocol.

The g protocol was originally designed for general packet drivers, and thus contains some features that are not used by UUCP, including an alternate data channel and the ability to renegotiate packet and window sizes during the communication session.

The g protocol is spoofed by many Telebit modems.  When spoofing is in effect, each Telebit modem uses the g protocol to communicate with the attached computer, but the data between the modems is sent using a Telebit proprietary error correcting protocol.  This allows for very high throughput over the Telebit connection, which, because it is half-duplex, would not normally be able to handle the g protocol very well at all.

This discussion of the g protocol explains how it works, but does not discuss useful error handling techniques.  Some discussion of this can be found in Jamie E. Hanrahan's paper (see Documentation references).  A detailed examination of the source code would also be profitable.

The Taylor UUCP code to handle the g protocol is in the file protg.c.  There are a number of functions; the most important ones are fgstart, fgsend_control, fgsenddata, and fgprocess_data.

All g protocol communication is done with packets.  Each packet begins with a six byte header.  Control packets consist only of the header.  Data packets contain additional data.

The header is as follows:

\020
     Every packet begins with a ^P.

K (1 <= K <= 9)
     The K value is always 9 for a control packet.  For a data packet, the K value indicates how must data follows the six byte header. The amount of data is 2 ** (K + 4), where ** indicates exponentiation.  Thus a K value of 1 means 32 data bytes and a K value of 8 means 4096 data bytes.  The K value for a data packet must be between 1 and 8 inclusive.

checksum low byte
checksum high byte
     The checksum value is described below.

control byte
     The control packet indicates the type of packet, and is described below.

xor byte
     This byte is the xor of K, the checksum low byte, the checksum high byte and the control byte (i.e. the second, third, fourth and fifth header bytes).  It is used to ensure that the header data is valid.

The control byte in the header is composed of three bit fields, referred to here as TT (two bits), XXX (three bits) and YYY (three bits).  The complete byte is TTXXXYYY, or (TT << 6) + (XXX << 3) + YYY.

The TT field takes on the following values:

0
     This is a control packet.  In this case the K byte in the header must be 9.  The XXX field indicates the type of control packet; the types are described below.

1
     This is an alternate data channel packet.  This is not used by UUCP.

2
     This is a data packet, and the entire contents of the attached data field (whose length is given by the K byte in the header) are valid.  The XXX and YYY fields are described below.

3
     This is a short data packet.  Let the length of the data field (as given by the K byte in the header) be l.  Let the first byte in the data field be b1.  If b1 is less than 128 (if the most significant bit of b1 is 0), then there are l - b1 valid bytes of data in the data field, beginning with the second byte.  If b1 >= 128, let b2 be the second byte in the data field. Then there are l - ((b1 & 0x7f) + (b2 << 7)) valid bytes of data in the data field, beginning with the third byte.  In all cases l bytes of data are sent (and all data bytes participate in the checksum calculation) but some of the trailing bytes may be dropped by the receiver.  The XXX and YYY fields are described below.

In a data packet (short or not) the XXX field gives the sequence number of the packet.  Thus sequence numbers can range from 0 to 7, inclusive.  The YYY field gives the sequence number of the last correctly received packet.

Each communication direction uses a window which indicates how many unacknowledged packets may be transmitted before waiting for an acknowledgement.  The window may range from 1 to 7 packets, and may be different in each direction. For example, if the window is 3 and the last packet acknowledged was packet number 6, packet numbers 7, 0 and 1 may be sent but the sender must wait for an acknowledgement before sending packet number 2.  This acknowledgement could come as the YYY field of a data packet or as the YYY field of a RJ or RR control packet (described below).

Each packet must be transmitted in order (the sender may not skip sequence numbers).  Each packet must be acknowledged, and each packet must be acknowledged in order.

In a control packet, the XXX field takes on the following values:

1 CLOSE
     The connection should be closed immediately.  This is typically sent when one side has seen too many errors and wants to give up.  It is also sent when shutting down the protocol.  If an unexpected CLOSE packet is received, a CLOSE packet should be sent in reply and the g protocol should halt, causing UUCP to enter the final handshake.

2 RJ or NAK
     The last packet was not received correctly.  The YYY field contains the sequence number of the last correctly received packet.

3 SRJ
     Selective reject.  The YYY field contains the sequence number of a packet that was not received correctly, and should be retransmitted. This is not used by UUCP, and most implementations will not recognize it.  Taylor UUCP will recognize it but not generate it.

4 RR or ACK
     Packet acknowledgement.  The YYY field contains the sequence number of the last correctly received packet.

5 INITC
     Third initialization packet.  The YYY field contains the maximum window size to use.

6 INITB
     Second initialization packet.  The YYY field contains the packet size to use.  It requests a size of 2 ** (YYY + 5).  Note that this is not the same coding used for the K byte in the packet header (it is 1 less).  Some UUCP implementations can handle any packet size up to that specified; some can only handled exactly the size specified.  Taylor UUCP will always accept any packet size.

7 INITA
     First initialization packet.  The YYY field contains the maximum window size to use.

To compute the checksum, call the control byte (the fifth byte in the header) c.

The checksum of a control packet is simply 0xaaaa - c.

The checksum of a data packet is 0xaaaa - (CHECK ^ c) (^ denotes exclusive or, as in C), and CHECK is the result of the following routine run on the contents of the data field (every byte in the data field participates in the checksum, even for a short data packet).  Below is the routine used by Taylor UUCP; it is a slightly modified version of a routine which John Gilmore patched from G.L.  Chesson's original paper.  The z argument points to the data and the c argument indicates how much data there is.

     int
     igchecksum (z, c)
          register const char *z;
          register int c;
     {
       register unsigned int ichk1, ichk2;

       ichk1 = 0xffff;
       ichk2 = 0;

       do
         {
           register unsigned int b;

           /* Rotate ichk1 left.  */
           if ((ichk1 & 0x8000) == 0)
             ichk1 <<= 1;
           else
             {
               ichk1 <<= 1;
               ++ichk1;
             }

           /* Add the next character to ichk1.  */
           b = *z++ & 0xff;
           ichk1 += b;

           /* Add ichk1 xor the character position in the buffer
              counting from the back to ichk2.  */
           ichk2 += ichk1 ^ c;

           /* If the character was zero, or adding it to ichk1
              caused an overflow, xor ichk2 to ichk1.  */
           if (b == 0 || (ichk1 & 0xffff) < b)
             ichk1 ^= ichk2;
         }
       while (--c > 0);

       return ichk1 & 0xffff;
     }

When the g protocol is started, the calling UUCP sends an INITA control packet with the window size it wishes the called UUCP to use. The called UUCP responds with an INITA packet with the window size it wishes the calling UUCP to use.  Pairs of INITB and INITC packets are then similarly exchanged.  When these exchanges are completed, the protocol is considered to have been started.  The window size is sent twice, with both the INITA and the INITC packets.

When a UUCP package transmits a command, it sends one or more data packets.  All the data packets will normally be complete, although some UUCP packages may send the last one as a short packet.  The command string is sent with a trailing null byte, to let the receiving package know when the command is finished.  Some UUCP packages require the last byte of the last packet sent to be null, even if the command ends earlier in the packet.  Some packages may require all the trailing bytes in the last packet to be null, but I have not confirmed this.

When a UUCP package sends a file, it will send a sequence of data packets.  The end of the file is signalled by a short data packet containing zero valid bytes (it will normally be preceeded by a short data packet containing the last few bytes in the file).

Note that the sequence numbers cover the entire communication session, including both command and file data.

When the protocol is shut down, each UUCP package sends a CLOSE control packet.

The UUCP f Protocol
===================

The f protocol is a seven bit protocol which checksums an entire file at a time.  It only uses the characters between \040 and \176 (ASCII space and ~) inclusive as well as the carriage return character.  It can be very efficient for transferring text only data, but it is very inefficient at transferring eight bit data (such as compressed news).  It is not flow controlled, and the checksum is fairly insecure over large files, so using it over a serial connection requires handshaking (XON/XOFF can be used) and error correcting modems.  Some people think it should not be used even under those circumstances.

I believe the f protocol originated in BSD versions of UUCP.  It was originally intended for transmission over X.25 PAD links.

The Taylor UUCP code for the f protocol is in protf.c.

The f protocol has no startup or finish protocol.  However, both sides typically sleep for a couple of seconds before starting up, because they switch the terminal into XON/XOFF mode and want to allow the changes to settle before beginning transmission.

When a UUCP package transmits a command, it simply sends a string terminated by a carriage return.

When a UUCP package transmits a file, each byte b of the file is translated according to the following table:

            0 <= b <=  037: 0172, b + 0100 (0100 to 0137)
          040 <= b <= 0171:       b        ( 040 to 0171)
         0172 <= b <= 0177: 0173, b - 0100 ( 072 to  077)
         0200 <= b <= 0237: 0174, b - 0100 (0100 to 0137)
         0240 <= b <= 0371: 0175, b - 0200 ( 040 to 0171)
         0372 <= b <= 0377: 0176, b - 0300 ( 072 to  077)

That is, a byte between \040 and \171 inclusive is transmitted as is, and all other bytes are prefixed and modified as shown.

When all the file data is sent, a seven byte sequence is sent: two bytes of \176 followed by four ASCII bytes of the checksum as printed in base 16 followed by a carriage return.  For example, if the checksum was 0x1234, this would be sent: "\176\1761234\r".

The checksum is initialized to 0xffff.  For each byte that is sent it is modified as follows (where b is the byte before it has been transformed as described above):

     /* Rotate the checksum left.  */
     if ((ichk & 0x8000) == 0)
       ichk <<= 1;
     else
       {
         ichk <<= 1;
         ++ichk;
       }

     /* Add the next byte into the checksum.  */
     ichk += b;

When the receiving UUCP sees the checksum, it compares it against its own calculated checksum and replies with a single character followed by a carriage return.

G
     The file was received correctly.

R
     The checksum did not match, and the file should be resent from the beginning.

Q
     The checksum did not match, but too many retries have occurred and the communication session should be abandoned.

The sending UUCP checks the returned character and acts accordingly.

The UUCP t Protocol
===================

The t protocol is intended for TCP links.  It does no error checking or flow control, and requires an eight bit clear channel.

I believe the t protocol originated in BSD versions of UUCP.

The Taylor UUCP code for the t protocol is in prott.c.

When a UUCP package transmits a command, it first gets the length of the command string, C.  It then sends ((C / 512) + 1) * 512 bytes (the smallest multiple of 512 which can hold C bytes plus a null byte) consisting of the command string itself followed by trailing null bytes.

When a UUCP package sends a file, it sends it in blocks.  Each block contains at most 1024 bytes of data.  Each block consists of four bytes containing the amount of data in binary (most significant byte first, the same format as used by the Unix function htonl) followed by that amount of data.  The end of the file is signalled by a block containing zero bytes of data.

The UUCP e Protocol
===================

The e protocol is similar to the t protocol.  It does no flow control or error checking and is intended for use over TCP.

The e protocol originated in versions of BNU UUCP.

The Taylor UUCP code for the e protocol is in prote.c.

When a UUCP package transmits a command, it simply sends the command as an ASCII string terminated by a null byte.

When a UUCP package transmits a file, it sends the complete size of the file as an ASCII decimal number.  The ASCII string is padded out to 20 bytes with null bytes (i.e., if the file is 1000 bytes long, it sends 1000\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0).  It then sends the entire file.

The UUCP x Protocol
===================

I believe that the x protocol was intended for use over X.25 virtual circuits.  It relies on a write of zero bytes being read as zero bytes without stopping communication.  I have heard that it does not work correctly.  If someone would care to fill this in more, I would be grateful.  Taylor UUCP does not implement the x protocol.

The UUCP d Protocol
===================

This is apparently used for DataKit connections, and relies on a write of zero bytes being read as zero bytes, much as the x protocol does.  I don't really know anything else about it.  Taylor UUCP does not implement the d protocol.

The UUCP G Protocol
===================

The G protocol is apparently simply the g protocol, except that it is known to support all possible window and packet sizes.  It was introduced by SVR4 UUCP; the SVR4 implementation of the g protocol is apparently fixed at a packet size of 64 and a window size of 7.  Taylor UUCP does not recognize the G protocol.  It does support all window and packet sizes for the g protocol.

Documentation References
========================

I took a lot of the information from Jamie E. Hanrahan's paper in the Fall 1990 DECUS Symposium, and from Managing UUCP and Usenet by Tim O'Reilly and Grace Todino (with contributions by several other people). The latter includes most of the former, and is published by O'Reilly & Associates, Inc.

Some information is originally due to a Usenet article by Chuck Wegrzyn. The information on the g protocol comes partially from a paper by G.L. Chesson of Bell Laboratories, partially from Jamie E. Hanrahan's paper, and partially from source code by John Gilmore.  The information on the f protocol comes from the source code by Piet Berteema. The information on the t protocol comes from the source code by Rick Adams.  The information on the e protocol comes from a Usenet article by Matthias Urlichs.

Hacking Taylor UUCP
*******************

This chapter provides the briefest of guides to the Taylor UUCP source code itself.

System Dependence
=================

The code is carefully segregated into a system independent portion and a system dependent portion.  The system dependent code is in sys?.* and tcp.c.  Note that sysh.* is included as sysdep.h.  Currently the only system dependent files are for Unix, and the file name for all of them ends in .unx.  Hopefully the code will eventually be ported to other systems.

With the right configuration parameters, the system independent code calls only ANSI C functions.  Some of the less common ANSI C functions are also provided in util.c.  The replacement function strtol in util.c assumes that the characters A to F and a to f appear in strictly sequential order.  The function igradecmp in config.c assumes that the upper and lower case letters appear in order.  Both assumptions are true for ASCII and EBCDIC, but neither is guaranteed by ANSI C.  The replacement function memmove in util.c assumes that two arbitrary pointers may be safely compared.  Disregarding these caveats, I believe that the system independent portion of the code is strictly conforming.

That's not too exciting, since all the work is done in the system dependent code.  I think that this code can conform to POSIX 1003.1, given the right compilation parameters.  I'm a bit less certain about this, though.

The code is in use on a 16 bit segmented system with no function prototypes, so I'm certain that all casts to long and pointers are done when necessary.

The code uses alloca extensively.  It comes with a simple replacement, in alloca.c (otherwise I would lost ANSI C conformance, after all).  Using a real alloca function will be considerably more efficient.  It will also cause significant stack usage, which may be a problem on systems without virtual memory.

Naming Conventions
==================

I use a modified Hungarian naming convention for my variables and functions.  As with all naming conventions, the code is rather opaque if you are not familiar with it, but becomes clear and easy to use with time.

The first character indicates the type of the variable (or function return value).  Sometimes additional characters are used.  I use the following type prefixes:

a
     array; the next character is the type of an element

b
     byte or character

c
     count of something

e
     stdio FILE *

f
     boolean

i
     generic integer

l
     double

o
     file descriptor (as returned by open, creat, etc.)

p
     generic pointer

q
     pointer to structure

s
     structure

u
     void (function return values only)

z
     character string

A generic pointer ('p') is sometimes a void *, sometimes a function pointer in which case the prefix is pf, and sometimes a pointer to another type, in which case the next character is the type to which it points (pf is overloaded).

An array of strings (char *[]) would be named az (array of string).  If this array were passed to a function, the function parameter would be named paz (pointer to array of string).

Note that the variable name prefixes do not necessarily indicate the type of the variable.  For example, a variable prefixed with i may be int, long or short.  Similarly, a variable prefixed with b may be a char or an int; for example, the return value of getchar would be caught in an int variable prefixed with b.

For a non-local variable (extern or file static), the first character after the type prefix is capitalized.

Most static variables and functions use another letter after the type prefix to indicate which module they come from.  This is to help distinguish different names in the debugger.  For example, all static functions in protg.c, the g protocol source code, use a module prefix of g.  This isn't too useful, as a number of modules use a module prefix of s.

Patches
=======

I am always grateful for any patches sent in.  Much of the flexibility and portability of the code is due to other people.  Please do not hesitate to send me any changes you have found necessary or useful.

I rarely apply the patches directly.  Instead I work my way through them and apply each one separately.  This ensures that the naming remains consistent and that I understand all the code.

Acknowledgements
****************

This is a list of people who gave help or suggestions while I was working on the Taylor UUCP project.  Appearance on this list does not constitute endorsement of the program, particularly since some of the comments were criticisms.  I've probably left some people off, and I apologize for any oversight; it does not mean your contribution was unappreciated.

First of all, I would like to thank the people at Infinity Development Systems (formerly AIRS, which lives on in the domain name, at least for now) for permitting me to use their computers and uunet access. I would also like to thank Richard Stallman <rms@gnu.ai.mit.edu> for founding the Free Software Foundation and John Gilmore <gnu@cygnus.com> for writing the initial version of gnuucp which was a direct inspiration for this somewhat larger project.  Chip Salzenberg <chip@tct.com> contributed many early patches. Franc,ois Pinard <pinard@iro.umontreal.ca> tirelessly tested the code and suggested many improvements.  He also put together the initial version of this document.  Finally, Verbus M. Counts <verbus@westmark.com> and Centel Federal Systems, Inc. deserve special thanks, since they actually paid me money to port this code to System III.

In alphabetical order:

     "Earle F. Ake - SAIC" <ake@Dayton.SAIC.COM>
     mra@searchtech.com (Michael Almond)
     cambler@zeus.calpoly.edu (Christopher J. Ambler)
     Brian W. Antoine <briana@tau-ceti.isc-br.com>
     jantypas@soft21.s21.com (John Antypas)
     nba@sysware.DK (Niels Baggesen)
     uunet!hotmomma!sdb (Scott Ballantyne)
     magus!dolphin!zack (Zacharias Beckman)
     mike@mbsun.ann-arbor.mi.us (Mike Bernson)
     bob@usixth.sublink.org (Roberto Biancardi)
     Marc Boucher <marc@CAM.ORG>
     dean@coplex.com (Dean Brooks)
     dave@dlb.com (Dave Buck)
     gordon@sneaky.lonestar.org (Gordon Burditt)
     mib@gnu.ai.mit.edu (Michael I Bushnell)
     Brian Campbell <brianc@quantum.on.ca>
     verbus@westmark.westmark.com (Verbus M. Counts)
     cbmvax!snark.thyrsus.com!cowan (John Cowan)
     denny@dakota.alisa.com (Bob Denny)
     dje@ersys.edmonton.ab.ca (Doug Evans)
     fenner@jazz.psu.edu (Bill Fenner)
     "David J. Fiander" <golem!david@news.lsuc.on.ca>
     Thomas Fischer <batman@olorin.dark.sub.org>
     erik@eab.retix.com (Erik Forsberg)
     Lele Gaifax <piggy@idea.sublink.org>
     Peter.Galbavy@micromuse.co.uk
     hunter@phoenix.pub.uu.oz.au (James Gardiner [hunter])
     Terry Gardner <cphpcom!tjg01>
     jimmy@tokyo07.info.com (Jim Gottlieb)
     ryan@cs.umb.edu (Daniel R. Guilderson)
     greg@gagme.chi.il.us (Gregory Gulik)
     Michael Haberler <mah@parrot.prv.univie.ac.at>
     guy@auspex.auspex.com (Guy Harris)
     Petri Helenius <pete@fidata.fi>
     Peter Honeyman <honey@citi.umich.edu>
     bei@dogface.austin.tx.us (Bob Izenberg)
     harvee!esj (Eric S Johansson)
     chris@cj_net.in-berlin.de (Christof Junge)
     tron@Veritas.COM (Ronald S. Karr)
     kent@sparky.IMD.Sterling.COM (Kent Landfield)
     lebaron@inrs-telecom.uquebec.ca  (Gregory LeBaron)
     karl@sugar.NeoSoft.Com (Karl Lehenbauer)
     libove@libove.det.dec.com (Jay Vassos-Libove)
     bruce%blilly@Broadcast.Sony.COM (Bruce Lilly)
     Ted Lindgreen <tlindgreen@encore.nl>
     "Arne Ludwig" <arne@rrzbu.hanse.de>
     Matthew Lyle <matt@mips.mitek.com>
     djm@eng.umd.edu (David J. MacKenzie)
     John R MacMillan <chance!john@sq.sq.com>
     mem@mv.MV.COM (Mark E. Mallett)
     martelli@cadlab.sublink.org (Alex Martelli)
     Yanek Martinson <yanek@mthvax.cs.miami.edu>
     les@chinet.chi.il.us (Leslie Mikesell)
     mmitchel@digi.lonestar.org (Mitch Mitchell)
     rmohr@infoac.rmi.de (Rupert Mohr)
     service@infohh.rmi.de (Dirk Musstopf)
     lyndon@cs.athabascau.ca (Lyndon Nerenberg)
     nolan@helios.unl.edu (Michael Nolan)
     david nugent <david@csource.oz.au>
     abekas!dragoman!mikep@decwrl.dec.com (Mike Park)
     "Mark Pizzolato 415-369-9366" <mark@infocomm.com>
     dplatt@ntg.com (Dave Platt)
     eldorado@tharr.UUCP (Mark Powell)
     pozar@kumr.lns.com (Tim Pozar)
     putsch@uicc.com (Jeff Putsch)
     Jarmo Raiha <jarmo@ksvltd.FI>
     mcr@Sandelman.OCUnix.On.Ca (Michael Richardson)
     ross@sun490.fdu.edu (Jeff Ross)
     Aleksey P. Rudnev <alex@kiae.su>
     wolfgang@wsrcc.com (Wolfgang S. Rupprecht)
     tbr@tfic.bc.ca (Tom Rushworth)
     rsalz@bbn.com (Rich Salz)
     sojurn!mike@hobbes.cert.sei.cmu.edu (Mike Sangrey)
     swiers@plains.NoDak.edu
     s4mjs!mjs@nirvo.nirvonics.com (M. J. Shannon Jr.)
     peter@ficc.ferranti.com (Peter da Silva)
     frumious!pat (Patrick Smith)
     roscom!monty@bu.edu (Monty Solomon)
     chs@antic.apu.fi (Hannu Strang)
     ralf@reswi.ruhr.de (Ralf E. Stranzenbach)
     Oleg Tabarovsky <olg@olghome.pccentre.msk.su>
     John Theus <john@theus.rain.com>
     rmtodd@servalan.servalan.com (Richard Todd)
     Len Tower <tower-prep@ai.mit.edu>
     mju@mudos.ann-arbor.mi.us (Marc Unangst)
     jv@mh.nl (Johan Vromans)
     rna-nl!gerben@relay.nluug.nl (Drs. Gerben C. Th. Wierda)
     frnkmth!twwells.com!bill (T. William Wells)
     mauxci!eci386!woods@apple.com (Greg A. Woods)
     jon@console.ais.org (Jon Zeeff)
     Eric Ziegast <uunet!ziegast>