mgetty and other programsNormally, after a caller enters his login name, mgetty calls
/bin/login to do the password checking and system login.
In some special cases, you may want to call other programs instead of
/bin/login. For example, you could want to call
/usr/lib/uucp/uucico -L <username> for all login names starting with
‘U*’ (to have uucico do the authentication, works only with
taylor uucp 1.05 or taylor uucp 1.04 with my patch in
patches/taylor.p1), or /usr/lib/fnet/ifcico for incoming
FidoNet calls (using ifcico from Eugene Crosser’s ifmail
package).
mgetty can do all this. It’s controlled by a configuration file
login.config, normally located in
/usr/local/etc/mgetty+sendfax/ (definition LOGIN_CFG_FILE in
policy.h). I have provided a sample file with lots of comments,
please look into that file for the syntax to use. To make mgetty
understand incoming fido calls, you have to compile it with -DFIDO.
If you are worrying about security, you can also use this mechanism: just
call /bin/login only for trusted, known users, and /bin/false
for every other login name - so, only those listed in login.config
will be able to log in.
This mechanism can also be used to automatically start up a PPP
server if an incoming client sends PPP packets. This feature is called
AutoPPP. For it to work, you have to compile mgetty with
-DAUTO_PPP (added to CFLAGS in Makefile). After this,
mgetty will detect incoming PPP packets, and run the program that
is specified in login.config by the special user name
"/AutoPPP/". See the sample login.config file for an example.
Which options should be specified depends on your PPP server program and your local setup. Don’t ask me about that – I wouldn’t know. Instead, please check the relevant man pages.