#下面规则做参考啊，新手别完全照抄。
*nat
:PREROUTING ACCEPT [39:3503]
:POSTROUTING ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A POSTROUTING -s 192.168.18.0/24 -o eth0 -j MASQUERADE
COMMIT
# Completed on Thu Jun 28 15:50:40 2012
# Generated by iptables-save v1.4.7 on Thu Jun 28 15:50:40 2012
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [121:13264]
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 53 -j ACCEPT
-A INPUT -p udp -m state --state NEW -m udp --dport 53 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 1194 -j ACCEPT
-A INPUT -p udp -m state --state NEW -m udp --dport 1701 -j ACCEPT
-A INPUT -p udp -m state --state NEW -m udp --dport 500 -j ACCEPT
-A INPUT -p udp -m state --state NEW -m udp --dport 4500 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -d 192.168.18.0/24 -j ACCEPT
-A FORWARD -s 192.168.18.0/24 -j ACCEPT
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT
# Completed on Thu Jun 28 15:50:40 2012
