例(li)：當修改了ssh遠程連接端口(kou)，如何在iptables上打開新的端口(kou)（這里將默認(ren)22端口(kou)號修改為33端口(kou)號）

#輸入命令打開33端口。

[root@niaoyun ~]# iptables -I INPUT -p tcp --dport 33 -j ACCEPT
#查看防火墻規則，發現33端口號已經打開了。
[root@niaoyun ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:33 
295 23186 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
34 2310 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
2342 200K REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
Chain OUTPUT (policy ACCEPT 15 packets, 1412 bytes)
pkts bytes target prot opt in out source destination
#iptables規則已經更改，我們需要對規則進行保存。
[root@niaoyun ~]# service iptables save
iptables: Saving firewall rules to /etc/sysconfig/iptables:[ OK ]
#保存完畢，重啟iptables服務。
[root@niaoyun ~]# service iptables restart
iptables: Setting chains to policy ACCEPT: filter [ OK ]
iptables: Flushing firewall rules: [ OK ]
iptables: Unloading modules: [ OK ]
iptables: Applying firewall rules: [ OK ]

#同樣，用此方法也可以打開web的默認端口80

iptables -I INPUT -p tcp --dport 80 -j ACCEPT && service iptables save && service iptables restart