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Internet Security Professional Reference:Using UUCP
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The System V Basic Networking Utilities UUCP

With the release of System V Release 3 from AT&T, a new UUCP version appeared. This version is known by a number of names, most notably the Basic Networking Utilities, or HoneyDanBer (HDB) UUCP. HDB provides capabilities that version 2 UUCP lacks, and corrects some design deficiencies of version 2. Additional functions include the support for newer modems and networks.

The fastest way to know if you have Version 2 or BNU is to look in the directory, /usr/lib/uucp, or /etc/uucp. If you see a file named “Systems,” then you have BNU. If you find “L.sys,” then you have the Version 2 implementation of UUCP, which is described later in the chapter.

UUCP File Layout

UUCP is set up in three directories: /usr/bin, /usr/lib/uucp, and /usr/spool/uucp. A brief description of each file can be found in the following output:

    /usr/bin
        This contains the user commands, such as
            cu         * interactive dialup access
            uucp       * job scheduler
            uudecode   * decode files
            uuencode   * encode files
            uulog      * show UUCP log files
            uuname     * get UUCP names
            uupick     * pick files
            uustat     * get UUCP status
            uuto       * send files
            uux        * command execution

    /usr/lib/uucp or /etc/uucp
            Devices          * Device Configuration
            Dialcodes        * Dial code prefix expansion
            Dialers          * dialer programs
            Maxuuscheds      * configuration parameters
            Maxuuxqts        * configuration parameters
            Permissions      * Security Controls
            Poll             * Polling configuration
            Sysfiles         * file configuration
            Systems          * Calling System information
            Uutry            * debuging/text program
            remote.unknown   * handle unknown callers
            uucheck          * check configuration files
            uucico           * transfer program
            uucleanup        * maintenance program
            uudemon.admin    * maintenance program
            uudemon.cleanu   * maintenance program
            uudemon.hour     * maintenance program
            uudemon.poll     * maintenance program
            uugetty          * UUCP getty program
            uusched          * UUCP job scheduler
            uutry            * debuging/text program
            uuxqt            * remote execution program

The location of your system’s UUCP files depends on the operating system that you are running. Most System V implementations, for example, have UUCP files in /usr/lib/uucp. Many BSD versions use the directory /etc/uucp. Your system may have other related files in these directories. For example, SCO Unix has a number of files, such as binary dialer programs for specific modems, in these directories.

Configuring UUCP

Only three files must be modified to bring up a UUCP connection:

  Devices
  Systems
  Permissions

Even if you leave all of the other files the same as they were shipped from the vendor, changing only these three files results in a functioning UUCP system. To make these modifications easier, the files are typically shipped full of comments; you may never need to use any documentation.

The Devices File

Before a connection can be established, the modem and serial devices that can be used must be defined. These devices range from serial lines direct to another computer, to modems, and UUCP over TCP/IP or X.25 connections. The Devices file controls what physical devices are available for carrying UUCP connections, and their configuration parameters. Each entry consists of these fields:

Name    Device    dialer-port    speed    dialer-token pairs
HAYES    tty2A    -        Any    hayes    \T

Each field is required, and must contain either a value or a placeholder (a hyphen). The fields, allowable values, and their purposes are listed in table 3.2.

Table 3.2
The BNU Devices File

Field Name Allowed Values Description

Name This field is the name or type of the device. In the preceding example, the name HAYES is used.
ACU This is an Automatic Call Unit, or modem. The modem may be directly attached to the computer, or accessed through a LAN switch, according to the UUCP documentation. ACUs or modems are usually attached directly to the system.
Direct This field indicates that this is a Direct link to a remote system, modem, or LAN Switch. The uucico program does not use lines of this type, only cu does. Note the capital D; this is an important note when looking at the available dialers. In the case of modems, a Direct line is also defined so that a command like “cu -l tty??” will work. This entry is also useful for configuring the modem.
sysname This field is an entry for connection to a specific system, perhaps using some other specialized dialer for routing through a LAN switch.

Device This is the actual device that is used to establish the connection. For direct serial and modem links, this field contains the name of the actual device. For TCP connections, this field will say “TCP.”

dialer-port This is a carryover from the days when the dialer was separate from the modem. This is an optional field, and may be used if the Name keyword is “ACU” and the dialer is an 801 dialer. If you don’t have an 801 dialer, put a hyphen (-) in this field.

speed a single speed
a range
Any
This is the speed that connections will be accepted at for this device. It may be a single speed, such as 2400, or the word “Any”, which will match any requested speed, as defined in the Systems file. The speed may also be a range of values indicated by value–value, as in 300–2400.

dialer-token pairs This field identifies the dialer program that will be used in conjunction with a specific modem dialer. The token parameter identifies what type of processing is to be used on the phone number. Often no token is used. The two tokens available are \T, which advises uucico that the phone number should be processed using the dialcodes file, and \D, which indicates that the phone number in the Systems file is to be used. The dialer program named in this field can be a binary program in some implementations of UUCP, direct for use with direct serial connections, or the name of a dialer program (found in the Dialers file).

Sample Device file entries and explanations are shown here:

Name/Type    Device    Dialer    Speed    dialer-token
INTACU       tty01     -         1200     intacu

This entry defines a device named INTACU, which is accessed through /dev/tty01, using the intacu dialer program, at only 1200 baud.

TBIT         tty17     -         Any      TBIT


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