Linux下防火墙开启相关端口及查看已开启端口

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我是靠谱客的博主呆萌长颈鹿，最近开发中收集的这篇文章主要介绍Linux下防火墙开启相关端口及查看已开启端口，觉得挺不错的，现在分享给大家，希望可以做个参考。

默认情况下Linux的防火墙都是在关闭状态下的
[root@test etc]# service iptables status
Firewall is stopped.
[root@test etc]#
防火墙开通的情况
[root@test ~]# service iptables start
iptables: Applying firewall rules: [ OK ]
[root@test ~]# service iptables status
Table: filter
Chain INPUT (policy ACCEPT)
num target prot opt source destination
1 ACCEPT all – 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
2 ACCEPT icmp – 0.0.0.0/0 0.0.0.0/0
3 ACCEPT all – 0.0.0.0/0 0.0.0.0/0
4 ACCEPT tcp – 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
5 REJECT all – 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain FORWARD (policy ACCEPT)
num target prot opt source destination
1 REJECT all – 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain OUTPUT (policy ACCEPT)
num target prot opt source destination

[root@test ~]#

以上可以看出，防火墙开通的端口为22 state NEW tcp dpt:22
还有其他一些状态信息

开通特定端口，比如tcp 80 和 5666端口
[root@test ~]# iptables -I INPUT -p tcp –dport 80 -j ACCEPT
保存并重启防火墙
[root@test ~]# service iptables save
iptables: Saving firewall rules to /etc/sysconfig/iptables: [ OK ]
[root@test ~]# service iptables restart
iptables: Flushing firewall rules: [ OK ]
iptables: Setting chains to policy ACCEPT: filter [ OK ]
iptables: Unloading modules: [ OK ]
iptables: Applying firewall rules: [ OK ]
[root@test ~]# service iptables status
Table: filter
Chain INPUT (policy ACCEPT)
num target prot opt source destination
1 ACCEPT tcp – 0.0.0.0/0 0.0.0.0/0 tcp dpt:80
2 ACCEPT all – 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
3 ACCEPT icmp – 0.0.0.0/0 0.0.0.0/0
4 ACCEPT all – 0.0.0.0/0 0.0.0.0/0
5 ACCEPT tcp – 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
6 REJECT all – 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited