Quote Originally Posted by Dave_Bechtel
(COMPLETE IPTABLES NEWBIE QUESTION) - After skimming thru the iptables tutorial and understanding about 2% of it, what about limiting your DROP rule to interface ppp0?

Quote Originally Posted by Stephen
Try /sbin/iptables -A INPUT -p tcp --dport 68 -j DROP a good tutorial and sample script are here and there are a couple of other firewalls available such as Guarddog and Bastille-Linux in Debian.
Most firewalls that I have seen do that when you are setting up the rules you have your external (internet) connection which is what you would be dropping the incoming packets on you can still establish outgoing connections to get what you require from the external interface unless you go out of your way to block outgoing connections on the ports. If you have an internal interface that you are using NAT on to share the connection it is usually on a trusted internal interface so you can have access to your internal network. This is what I do with my firewall machine from the outside my computer does not exist on the internet if you scan it but on the internal side my firewall machine runs only SSH so I can get to it to check for upgrades to my Woody (actually Mini-Woody now known as Bonzai Linux) install on it and HTTP so I can serve myself some web pages that I have.