Opening/Closing Ports on Debian 3.0
I was wondering, basically, how to open or close ports, and keep them open or closed.
I'm having to setup a Virtual Private Network with our provider, and in order to do that, I have to have PPTP enabled on our gateway/firewall, which is running Debian 3.0. We can connect to the VPN a few times--or for a little while--and then we're not able to until I restart the 'networking' script in /etc/init.d/ (which may not be good to keep restarting--I'm not sure).
PPTP uses tcp port 1723, so I put this line in /etc/services:
pptp 1723/tcp # PPTP for VPNs
..but that didn't help as far as I can tell.
Any help is greatly appreciated. I'm really quite new indeed!