#!/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

# 獲取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

# 獲取DNS服務器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"

# 刪除已有規(guī)則

$IPT --delete-chain

$IPT --flush

# 禁止進,允許出,允許回環(huán)網(wǎng)卡

$IPT -P INPUT DROP   

$IPT -P FORWARD DROP 

$IPT -P OUTPUT ACCEPT

$IPT -A INPUT -i lo -j ACCEPT

# 允許已建立的或相關(guān)連接的通行

$IPT -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

$IPT -A OUTPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

# 限制80端口單個IP的最大連接數(shù)為10

$IPT -I INPUT -p tcp --dport 80 -m connlimit --connlimit-above 10 -j DROP

# 允許80(HTTP)/873(RSYNC)/443(HTTPS)/20,21(FTP)/25(SMTP)端口的連接

$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

# 允許SSH端口的連接,腳本自動偵測目前的SSH端口,否則默認為22端口

$IPT -A INPUT -p tcp -m tcp --dport $sshdport -j ACCEPT

# 允許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

# 允許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

# 保存規(guī)則并重啟IPTABLES

service iptables save

service iptables restart

echo "============================iptables configure completed============================================"