CentOS防火墙默认是打开的，设置CentOS防火墙开放port方法例如以下：
打开iptables的配置文件：
vi /etc/sysconfig/iptables
改动CentOS防火墙时注意：一定要给自己留好后路,留VNC一个管理port和SSh的管理port
以下是一个iptables的演示样例：
# Firewall configuration written by system-config-securitylevel
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:RH-Firewall-1-INPUT - [0:0]
-A INPUT -j RH-Firewall-1-INPUT
-A FORWARD -j RH-Firewall-1-INPUT
-A RH-Firewall-1-INPUT -i lo -j ACCEPT
-A RH-Firewall-1-INPUT -p icmp –icmp-type any -j ACCEPT
-A RH-Firewall-1-INPUT -p 50 -j ACCEPT
-A RH-Firewall-1-INPUT -p 51 -j ACCEPT
-A RH-Firewall-1-INPUT -m state –state ESTABLISHED,RELATED -j ACCEPT
-A RH-Firewall-1-INPUT -m state –state NEW -m tcp -p tcp –dport 53 -j ACCEPT
-A RH-Firewall-1-INPUT -m state –state NEW -m udp -p udp –dport 53 -j ACCEPT
-A RH-Firewall-1-INPUT -m state –state NEW -m tcp -p tcp –dport 22 -j ACCEPT
-A RH-Firewall-1-INPUT -m state –state NEW -m tcp -p tcp –dport 25 -j ACCEPT
-A RH-Firewall-1-INPUT -m state –state NEW -m tcp -p tcp –dport 80 -j ACCEPT
-A RH-Firewall-1-INPUT -m state –state NEW -m tcp -p tcp –dport 443 -j ACCEPT
-A RH-Firewall-1-INPUT -j REJECT –reject-with icmp-host-prohibited
COMMIT
改动CentOS防火墙须要注意的是，你必须依据自己server的情况来改动这个文件。
举例来说，假设你不希望开放80port提供web服务，那么应该对应的删除这一行：
-A RH-Firewall-1-INPUT -m state –state NEW -m tcp -p tcp –dport 80 -j ACCEPT
所有改动完之后重新启动iptables:
service iptables restart
你能够验证一下是否规则都已经生效：iptables -L
这样，我们就完毕了CentOS防火墙的设置改动。