初级iptables命令
iptables -t filter -L show all chains of filtering table
iptables -t nat -L show all chains of nat table
iptables -t filter -F clear all rules from filtering table
iptables -t nat -F clear all rules from table nat
iptables -t filter -X delete any chains created by user
iptables -t filter -A INPUT -p tcp –dport telnet -j ACCEPT allow telnet connections to input
iptables -t filter -A OUTPUT -p tcp –dport http -j DROP block HTTP connections to output
iptables -t filter -A FORWARD -p tcp –dport pop3 -j ACCEPT allow POP3 connections to forward chain