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4. Logging in via kermit.

Configuring Linux to use the Mac as a login: terminal is even easier. kermit is ideal for this purpose, because it is one of the few free communication programs which provides credible VT100/120/220 emulation.

Essentially, what you want to do is start kermit on the Macintosh side as in the previous section, but rather than issue server commands, you enter connect mode. This is the normal terminal emulation mode that most people use, anyway.

On the Linux side, the serial line must be configured with a getty on it to start a login: shell. To do this, you need to tell init that the serial line has a terminal on it. In your /etc/inittab file you will need a line something like this:

T1:23:respawn:/sbin/getty -L ttyS0 9600 vt100

This command tells getty to start login (the -L switch) on the terminal display, and, when the login times out, to re-start (respawn) the login program until someone logs in. If no device is connected to the serial line, or if the connection is defective, you may see a message on the system console like: /dev/ttyS0 respawning too fast: disabling for 5 minutes. If this happens, you can return things to normal by (as root) killing the getty process, or using the init q command. Both of them have the effect of re-spawning the getty processe(s). If everything is in order, you should see the Linux banner and login prompt on the Mac's kermit window. That's all there is to it.

Also, if you use something besides vanilla getty, like getty_ps, the command above will look somewhat different. The important thing to remember is that everything to the right of /sbin/getty is an argument for getty itself; not init. You should look at the manual pages for getty, init,and inittab if you have questions concerning the setup of init and getty.

The Serial HOWTO provides helpful details on how to configure /etc/inittab for getty_ps, if that's what your system uses.

To transfer files back and forth between the Macintosh and the Linux machine, you can (via the Mac's Kermit) issue the kermit -x command to start the Linux kermit in server mode. You can then use the normal file transfer commands to send files across the serial line. It's useful to set a prompt in your ~/.kermrc with a line like

set prompt Linux-kermit >

4.1 Other Mac terminal programs.

This method should work equally well for any other Mac terminal program. If you have ZTerm, you can use rz and sz on the Linux machine to transfer files via the ZModem protocol. If Microphone Lite came bundled with your fax modem, that works equally well, albeit without kermit's superior scripting and configuration facilities.