I use the following with success... I have been using it for over a year now..anyone doing transparent smtp proxying? i use postfix and would like to prevent visiting laptops from trying to connect to their providers smtp server, relaying it instead via my smarthost. unfortunately postfix doesn't support transparent proxying. anyone got any pointers on this? perhaps a lightweight application proxy that i can drop in on the firewall instead of postfix? marty
iptables -t nat -A PREROUTING -i eth1 -p tcp -m tcp --dport 25 -j REDIRECT --to-ports 25
So anything outbound from eth1 (lan connection) on port 25 gets redirected to port 25 localhost which has its own smtp server running..