[CentOS] IP tables 已经加入3306 端口，但外部访问不了

[root@centos-0 ~]# iptables --list
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED
ACCEPT icmp -- anywhere anywhere
ACCEPT all -- anywhere anywhere
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:ssh
REJECT all -- anywhere anywhere reject-with icmp-host-prohibited
ACCEPT tcp -- anywhere anywhere tcp dpt:http
ACCEPT tcp -- anywhere anywhere tcp dpt:mysql

Chain FORWARD (policy ACCEPT)
target prot opt source destination
REJECT all -- anywhere anywhere reject-with icmp-host-prohibited

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

Mysql在本机访问操作是没有问题的，但使用其它机器访问就提示连接不了，使用telnet 3306 端口也提示连不通。
关闭iptables后，外部访问是正常的。

请问是为什么？

补充：系统 CentOS 6