System Administration Guide
Chapter 7, Connecting to other computers with UUCP

Connecting two local systems using a direct wire

Connecting two local systems using a direct wire

If you are using UUCP to connect remote machines, you can skip this section. To connect two computers with a direct wire, you need to choose a serial port on each machine, connect a serial wire (RS-232) between the two machines using the chosen serial ports, and edit the UUCP configuration files.

Choosing a serial port
On each machine, choose the RS-232 serial port (/dev/ttynn) you want to use. If there are no ports available, you must install a new serial line or make one available by removing any device connected to it. Before you remove a terminal, make sure no one is logged in on it.

Find the name of the device special file associated with the line. The device name should have the form: 


where nn is the number of the corresponding line. For example, /dev/tty1a usually corresponds to COM1. You need the name of the actual line for later steps. Be sure and use the non-modem control port (for example, /dev/tty1a instead of /dev/tty1A).

The serial port should be owned by uucp. To make sure the line is owned by uucp, enter this command:

chown uucp /dev/ttynn

where nn is the number of the corresponding line.

Connecting a serial cable
Connect two computers together using an RS-232 cable. The actual pin configurations sometimes vary between machines.

The cable should connect pins 2, 3, and 7 on one computer to the same pins on the second computer. Typically, the cable must be nulled, which means that pin 2 on one machine is connected to pin 3 on the other, and 3 to 2. Because the connections can vary, check the hardware manuals for each computer to determine the proper pin connections.

Editing the UUCP configuration files
You should edit the UUCP files as instructed in ``Configuring UUCP'', except you should use the keyword Direct instead of ACU in the Systems files.

Testing a direct wire connection
The following steps will enable you to use the cu command on the local machine to log in to the remote machine.

  1. Enable the port of the remote machine:

    enable /dev/ttynn

    where nn is the serial port you are using.

  2. Disable the port of the local machine:

    disable /dev/ttynn

    where nn is the serial port you are using.

To connect to the remote machine from the local machine, type:

cu -x9 -lttynn dir

where nn is the port of the main machine.

Press the <Bksp> key until the lines are synchronized and you get a login prompt. To log in, you must have an account on the remote machine.

If you do not get a login prompt, read the cu -x9 output for any clues of what could be wrong. See ``Common UUCP error messages''.