一键配置CentOS iptables防火墙的Shell脚本分享

手里几台vps配置iptables太繁琐，看到了朱哥的lnmp脚本里有一个自动配置iptables防火墙的脚本，借来改了一下，给需要的人用；
只提供常用端口的设置，如果你有特殊需求只需自行添加或减少相应的端口即可；

使用方法：

chmod +x iptables.sh
./iptables.sh

设置iptables开机自动启动：

chkconfig --level 345 iptables on

完整shell：

#!/bin/bash
path=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export path
function support_distro(){
if [ -z "`egrep -i "centos" /etc/issue`" ];then
echo "sorry,iptables script only support centos system now."
exit 1
fi
}
support_distro
echo "============================iptables configure============================================"
# only support centos system
# 获取ssh端口
if grep "^port" /etc/ssh/sshd_config>/dev/null;then
sshdport=`grep "^port" /etc/ssh/sshd_config | sed "s/port\s//g" `
else
sshdport=22
fi
# 获取dns服务器ip
if [ -s /etc/resolv.conf ];then
nameserver1=`cat /etc/resolv.conf |grep nameserver |awk 'nr==1{print $2 }'`
nameserver2=`cat /etc/resolv.conf |grep nameserver |awk 'nr==2{print $2 }'`
fi
ipt="/sbin/iptables"
# 删除已有规则
$ipt --delete-chain
$ipt --flush
# 禁止进,允许出,允许回环网卡
$ipt -p input drop  
$ipt -p forward drop
$ipt -p output accept
$ipt -a input -i lo -j accept
# 允许已建立的或相关连接的通行
$ipt -a input -m state --state related,established -j accept
$ipt -a output -m state --state related,established -j accept
# 限制80端口单个ip的最大连接数为10
$ipt -i input -p tcp --dport 80 -m connlimit --connlimit-above 10 -j drop
# 允许80(http)/873(rsync)/443(https)/20,21(ftp)/25(smtp)端口的连接
$ipt -a input -p tcp -m tcp --dport 80 -j accept
$ipt -a input -p tcp -m tcp --dport 873 -j accept
$ipt -a input -p tcp -m tcp --dport 443 -j accept
$ipt -a input -p tcp -m tcp --dport 20 -j accept
$ipt -a input -p tcp -m tcp --dport 21 -j accept
$ipt -a input -p tcp -m tcp --dport 25 -j accept
# 允许ssh端口的连接,脚本自动侦测目前的ssh端口,否则默认为22端口
$ipt -a input -p tcp -m tcp --dport $sshdport -j accept
# 允许ping
$ipt -a input -p icmp -m icmp --icmp-type 8 -j accept
$ipt -a input -p icmp -m icmp --icmp-type 11 -j accept
# 允许dns
[ ! -z "$nameserver1" ] && $ipt -a output -p udp -m udp -d $nameserver1 --dport 53 -j accept
[ ! -z "$nameserver2" ] && $ipt -a output -p udp -m udp -d $nameserver2 --dport 53 -j accept
# 保存规则并重启iptables
service iptables save
service iptables restart
echo "============================iptables configure completed============================================"