A Gentle Introduction to Taylor UUCP

To say that UUCP configuration is hard would be an understatement. It is really a hairy subject, and the sometimes terse format of the configuration files doesn't make things easier (although the Taylor format is almost easy reading compared to the older formats in HDB or Version-2).

To give you a feel how all these files interact, we will introduce you to the most important ones, and have a look at sample entries of these files. We won't explain everything in detail now; a more accurate account is given in separate sections below. If you want to set up your machine for UUCP, you had best start with some sample files, and adapt them gradually. You can pick either those shown below, or those included in your favorite distribution.

All files described in this section are kept in /usr/lib/uucp or a subdirectory thereof. Some distributions contain UUCP binaries that have support for both HDB and Taylor configuration enabled, and use different subdirectories for each configuration file set. There will usually be a README file in /usr/lib/uucp.

For UUCP to work properly, these files must be owned by the uucp user. Some of them contain passwords and telephone numbers, and therefore should have permissions of 600.

The central UUCP configuration file is /usr/lib/uucp/config, and is used to set general parameters. The most important of them (and for now, the only one), is your host's UUCP name. At the Virtual Brewery, they use vstout as their UUCP gateway:

The next important configuration file is the sys file. It contains all system-specific information of sites you are linked to. This includes the site's name, and information on the link itself, such as the telephone number when using a modem link. A typical entry for a modem-connected site called pablo would be

The port names a port to be used, and time specifies the times at which it may be called. chat describes the login chat scripts-- the sequence of strings that must be exchanged between to allow uucico to log into pablo. We will get back to chat scripts later. The port command does not name a device special file such as /dev/cua1, but rather names an entry in the port file. You can assign these names as you like as long as they refer to a valid entry in port.

The port file holds information specific to the link itself. For modem links, it describes the device special file to be used, the range of speeds supported, and the type of dialing equipment connected to the port. The entry below describes /dev/cua1 (a.k.a. COM 2), to which a NakWell modem is connected that is capable of running at speeds up to 38400bps. The entry's name way chosen to match the port name given in the sys file.

The information pertaining to the dialers itself is kept in yet another file, called-- you guessed it: dial. For each dialer type, it basically contains the sequence of commands to be issued to dial up a remote site, given the telephone number. Again, this is specified as a chat script. For example, the entry for the above NakWell might look like this:

The line starting with chat specifies the modem chat, which is the sequence of commands sent to and received from the modem to initialize it and make it dial the desired number. The ``T'' sequence will be replaced with the phone number by uucico.

Figure: Interaction of Taylor UUCP Configuration Files.

To give you a rough idea how uucico deals with these configuration files, assume you issued the command

on the command line. The first thing uucico does is look up pablo in the sys file. From the sys file entry for pablo it sees that it should use the serial1 port to establish the connection. The port file tells it that this is a modem port, and that it has a NakWell modem attached.

uucico now searches dial for the entry describing the NakWell modem, and having found one, opens the serial port /dev/cua1 and executes the dialer chat. That is, it sends ``ATZ'', waits for the ``OK'' response, etc. When encountering the string ``T'', it substitutes the phone number (123-456) extracted from the sys file.

After the modem returns CONNECT, the connection has been established, and the modem chat is complete. uucico now returns to the sys file and executes the login chat. In our example, it would wait for the ``login:'' prompt, then send its user name (neruda), wait for the ``password:'' prompt, and send its password, ``lorca''.

After completing authorization, the remote end is assumed to fire up its own uucico. The two will then enter the handshake phase described in the previous section.

The way the configuration files depend on each other is also shown in figure-.