CentOS 打开mysql 3306端口
在CentOS系统中防火墙默认是阻止3306端口的，我们要是想访问mysql数据库，我们需要这个端口，命令如下：
1 /sbin/iptables -I INPUT -p tcp --dport 3306 -j ACCEPT
我们需要保存我们的操作，命令如下：
1 /etc/rc.d/init.d/iptables save
此时我们可以查看端口的状态，命令如下：
1 /etc/init.d/iptables status
当然如果你打开其他端口也一样，只需要把这个端口号换乘你需要的端口号即可。
Last login: Sat Jul 1 20:21:15 2017 from 218.77.94.241
[root@VM_0_8_centos ~]# /sbin/iptables -I INPUT -p tcp --dport 3306 -j ACCEPT
[root@VM_0_8_centos ~]# /etc/rc.d/init.d/iptables save
iptables: Saving firewall rules to /etc/sysconfig/iptables:[ OK ]
[root@VM_0_8_centos ~]# /etc/init.d/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:3306
2 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp spt:3306 dpt:3306
3 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp spt:3306 dpt:3306
4 RH-Firewall-1-INPUT all -- 0.0.0.0/0 0.0.0.0/0
Chain FORWARD (policy ACCEPT)
num target prot opt source destination
1 RH-Firewall-1-INPUT all -- 0.0.0.0/0 0.0.0.0/0
Chain OUTPUT (policy ACCEPT)
num target prot opt source destination
Chain RH-Firewall-1-INPUT (2 references)
num target prot opt source destination
1 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
2 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 255
3 ACCEPT esp -- 0.0.0.0/0 0.0.0.0/0
4 ACCEPT ah -- 0.0.0.0/0 0.0.0.0/0
5 ACCEPT udp -- 0.0.0.0/0 224.0.0.251 udp dpt:5353
6 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
7 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
8 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:21
9 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:80
10 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:8080
11 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpts:20000:20500
12 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
