Info file uucp.info, produced by Makeinfo, -*- Text -*- from input file uucp.texi. This file documents Taylor UUCP, version 1.03. Copyright (C) 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.  File: uucp.info, Node: Miscellaneous (sys), Next: Default sys File Values, Prev: File Transfer Control, Up: sys File 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 (*note 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; *Note 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.  File: uucp.info, Node: Default sys File Values, Prev: Miscellaneous (sys), Up: sys File 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  File: uucp.info, Node: port File, Next: dial File, Prev: sys File, Up: Configuration Files 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 (*note 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 (*note 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.  File: uucp.info, Node: dial File, Next: Security, Prev: port File, Up: Configuration Files 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 *Note 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 (*note 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 (*note 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 (*note 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 *Note 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'.  File: uucp.info, Node: Security, Prev: dial File, Up: Configuration Files 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 (*note 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 (*note 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.  File: uucp.info, Node: Protocols, Next: Hacking, Prev: Configuration Files, Up: Top 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. * Menu: * Grades:: UUCP grades * Lock Files:: UUCP lock file format * UUCP Protocol:: The common UUCP protocol * g Protocol:: The UUCP `g' protocol * f Protocol:: The UUCP `f' protocol * t Protocol:: The UUCP `t' protocol * e Protocol:: The UUCP `e' protocol * x Protocol:: The UUCP `x' protocol * d Protocol:: The UUCP `d' protocol * Capital G Protocol:: The UUCP `G' protocol * Documentation References:: Documentation references  File: uucp.info, Node: Grades, Next: Lock Files, Prev: Protocols, Up: Protocols 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 (*note 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