The preceding line deals only with file transfers requested or sent from your machine. If you want to enable requests for transfers from the remote machine, you need to add two more lines:

remote-send    /usr/lib/uucppublic

remote-request    /usr/lib/uucppublic

This forces the remote machine to request files and send them only to the /usr/lib/uucppublic directory. Again, you can offer several choices if you want, as long as they are separated by spaces.

Finally, UUCP allows machines to forward data through other machines, a process called hopping. In other words, if you want to send mail to the system warlock but can only get there through the system wizard, you have to instruct UUCP that your local system can get to warlock through wizard. You add a forward command to the /usr/lib/uucp/sys file:

system    wizard

…

forward    warlock

You should then add an entry for the warlock system that tells UUCP that any mail for you will be coming back through wizard. The matching entry is

system    warlock

…

forward-to    merlin

The forward-to entry is necessary so that any files returned by warlock are passed to merlin, the local host machine. Otherwise, they are discarded by UUCP as not being routable.

By default, Taylor UUCP does not allow forwarding, so system administrators should think carefully about allowing it because the potential for abuse is high.

HDB UUCP Configuration

HDB UUCP is a more recent version of UUCP and its configuration files are different. In many ways, the HDB configuration is easier than Taylor UUCP’s, although neither is difficult once you know the basic process.

The name of the local system is not set in the UUCP configuration files but by the Linux hostname itself. To set the system name use the hostname command.

The names of the remote systems are stored in the file /usr/lib/uucp/Systems (some older versions used the name /usr/lib/uucp/L.sys). There is a single line for each remote system that you will be connected to. The format of each line is as follows:

sitename schedule device_type speed phone login_script

sitename is the name of the remote machine, schedule is when it can be connected, device_type is the type of device to use to call the remote system, speed is the speed (or range of speeds) that can be used to connect, phone is the telephone number, and login_script is the script used when a connection is made (such as the chat script in Taylor UUCP). For example, to call the remote system arthur, the /usr/lib/uucp/Systems file will have a line like this:

arthur Any ACU 9600 555-1212 login: uucp password: secret1

The Any entry in the schedule field tells UUCP that it can call at any time. The ACU entry in the device field tells UUCP to use the ACU (automatic calling unit) defined in the /usr/lib/uucp/Devices file.

The /usr/lib/uucp/Devices file (or /usr/lib/uucp/L-devices file in some older versions) contains information about the devices that can be used to call the remote systems. The Devices file follows this syntax:

devicetype ttyline dialerline speed dialer [token Dialer …]

devicetype is the name of the device (which should match the device name in the /usr/lib/uucp/Systems file), ttyline is the device driver to be used for the connecting port (usually a serial line, such as /dev/tty2a or /dev/modem), dialerline is an obsolete field left as a hyphen, speed is the speed range of the device, and dialer is the name of the file that tells UUCP how to use the device. A sample line for a Hayes 9600 baud modem used to connect on the second serial port of the system might have an entry in the /usr/lib/uucp/Devices file such as

ACU tty2A - 9600 dialHA96

This identifies the ACU entry as a 9600 baud connection through /dev/tty2A (the /dev portion of the name is not needed with HDB UUCP), and it uses a program called dialHA96 to handle the setup and dialing of the modem. There are usually programs available for most popular modems that set the modem configuration parameters automatically, leaving Linux out of that process.

If a modem program is not available to handle the modem, an entry in the file /usr/lib/uucp/Dialers can be used. The format of the Dialers entries is

dialer translation expect send …

dialer is the name of the dialer (matching the Devices file), translation is the translation table to use for the phone number (converting characters when necessary to pauses, beeps, and so on), and the expect and send entries are the chat script to set up the modem. White space in the script is ignored unless it is in quotation marks. A sample line in the Dialers file looks like this:

hayes1200 =,-,    “” AT\r\c OK\r \EATDT\T\r\c CONNECT

This is the entry for a Hayes 1200 Smartmodem, identified by the name hayes1200, with translations for the = and - characters, followed by the AT commands used to set up the modem. Because these entries are usually supplied in the Dialers file for most popular modems, we won’t bother going into detail about them.