We use a Linux server to act as router for local network accessing Internet and it's necessary to let local machine access ftp server on the Internet. How to setup iptables when using active ftp connection (that's PORT mode not PASV mode). Thanks in advance. The iptable is as following. *nat :PREROUTING ACCEPT [19679:1112350] :POSTROUTING ACCEPT [47:2939] :OUTPUT ACCEPT [549:33489] -A POSTROUTING -o ppp0 -j MASQUERADE -A POSTROUTING -s 192.168.1.0/255.255.255.0 -o ppp0 -j MASQUERADE COMMIT # Completed on Mon Nov 25 16:20:25 2002 # Generated by iptables-save v1.2.3 on Mon Nov 25 16:20:25 2002 *filter :INPUT ACCEPT [24909:3228138] :FORWARD ACCEPT [806467:523158528] :OUTPUT ACCEPT [22048:8745798] -A INPUT -p tcp -m tcp --dport 21 -m state --state NEW,ESTABLISHED -j ACCEPT -A INPUT -p tcp -m tcp --dport 20 -m state --state ESTABLISHED -j ACCEPT -A INPUT -p tcp -m tcp --sport 21 -m state --state ESTABLISHED -j ACCEPT -A INPUT -p tcp -m tcp --sport 20 -m state --state RELATED,ESTABLISHED -j ACCEPT COMMIT

I don't know, but check out http://www.linuxnewbie.org/nhf/