| iptables -A INPUT -p tcp --dport 22 -j ACCEPT |
| iptables -A OUTPUT -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT |
| iptables -A OUTPUT -p udp --dport 53 -j ACCEPT |
| iptables -A INPUT -p udp --sport 53 -j ACCEPT |
| iptables -A INPUT -s 127.0.0.1 -d 127.0.0.1 -j ACCEPT |
| iptables -A OUTPUT -s 127.0.0.1 -d 127.0.0.1 -j ACCEPT |
| iptables -A INPUT -p tcp -s 0/0 --dport 80 -j ACCEPT |
| iptables -A OUTPUT -p tcp --sport 80 -m state --state ESTABLISHED -j ACCEPT |
| iptables-save > /etc/sysconfig/iptables |
命令及配置文件/etc/sysconfig/iptablesservice iptables restart#start 开启#restart 重启永久性关闭防火墙chkconfig --level 35 iptables off//=================================================================CentOS 5.2 防火墙设置例如开启80端口通过/etc/init.d/iptables status命令查询是否有打开80端口，如果没有可通过两种方式处理：1.修改vi /etc/sysconfig/iptables命令添加使防火墙开放80端口-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT2.关闭防火墙/etc/init.d/iptables stop#start 开启#restart 重启永久性关闭防火墙chkconfig --level 35 iptables off/etc/init.d/iptables stopiptables -P INPUT DROP# 打开主动模式21端口iptables -A INPUT -p tcp --dport 21 -j ACCEPT# 打开被动模式49152~65534之间的端口iptables -A INPUT -p tcp --dport 49152:65534 -j ACCEPTiptables -A INPUT -i lo -j ACCEPTiptables -A INPUT -m state --state ESTABLISHED -j ACCEPT//=======================================================================================================那么下面我们来设置一下防火墙：打开iptables的配置文件：vi /etc/sysconfig/iptables注意：一定要给自己留好后路,留VNC一个管理端口和SSh的管理端口下面是一个iptables的示例：# 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-prohibitedCOMMIT需要注意的是，你必须根据自己服务器的情况来修改这个文件。举例来说，如果你不希望开放80端口提供web服务，那么应该相应的删除这一行：-A RH-Firewall-1-INPUT -m state –state NEW -m tcp -p tcp –dport 80 -j ACCEPT全部修改完之后重启iptables:service iptables restart你可以验证一下是否规则都已经生效：iptables -L
