> Hello everyone,
> Is it possible to have a firewall to protect the private network
> from the dial-in users ?
could you please clarify what you mean?
I never heard of such things, but here is my suggestions
1. If you don't want anyone and anything to dial-in in your system
just turn off all modems.
2. if you would want some certain users not to be allowed to dial-in,
under Unix write simple code (C perefarble...shell scripts allow
to interrupt them sometimes with ^C). which would just check user's tty
and if it is ttySXX (serial line) would break connection, otherwise
exec desirable shell.