linux下firewall简易设置[原创]

What Is a Linux Firewall?

 

A Linux firewall is a solution or service that regulates, protects, and blocks network traffic as it passes to and from a Linux-based environment. 

iptables.rule为firewall总规则;

iptables.allow为充许进入的主机;

iptables.deny为不许放的主机；

iptables.allow代码如下：

#!/bin/bash

# This is an esay firewall.

# the inside interface. if you don't have this one

# and you must let this be black ex> INIF=""

INIF="eth0"

INNET="192.168.160.0/20"

# 2.0 load the right module

  PATH=/sbin:/bin:/usr/sbin:/usr/bin

  export PATH EXTIF INIF INNET

  modprobe ip_tables  > /dev/null 2>&1

  modprobe iptable_nat  > /dev/null 2>&1

  modprobe ip_nat_ftp   > /dev/null 2>&1

  modprobe ip_nat_irc  >  /dev/null 2>&1

  modprobe ip_conntrack > /dev/null 2>&1

  modprobe ip_conntrack_ftp > /dev/null 2>&1

  modprobe ip_conntrack_irc > /dev/null 2>&1

# 3.0 clear iptables rule

  /sbin/iptables -F

  /sbin/iptables -X

  /sbin/iptables -Z

  /sbin/iptables -F -t nat

  /sbin/iptables -X -t nat

  /sbin/iptables -Z -t nat

  /sbin/iptables -P INPUT  DROP

  /sbin/iptables -P OUTPUT  ACCEPT

  /sbin/iptables -P FORWARD ACCEPT

  /sbin/iptables  -t nat -P PREROUTING ACCEPT

  /sbin/iptables  -t nat -P POSTROUTING ACCEPT

  /sbin/iptables  -t nat -P OUTPUT  ACCEPT

# 4.0 start loading trusted and denied file.

if [ -f /usr/local/virus/iptables/iptables.allow ]; then

   sh /usr/local/virus/iptables/iptables.allow

fi

if [ -f /usr/local/virus/iptables/iptables.deny ]; then

   sh /usr/local/virus/iptables/iptables.deny

fi

# 5.0 if the following file exist ,please executed

if [ -f /usr/local/virus/httpd-err/iptables.http ];then

   sh /usr/local/virus/httpd-err/iptables.http

fi

# 6.0 allow icmp data packet and the establishd data

  /sbin/iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

AICMP="0 3 3/4 4 11 12 14 16 18"

for tyicmp in $AICMP

do

  /sbin/iptables -A INPUT -i $EXTIF="eth0" -p icmp --icmp-type $tyicmp -j ACCEPT

done

# 7.0 open the other service ports

   /sbin/iptables -A INPUT -p TCP -i $EXTIF="eth0" --dport 25 -j ACCEPT # SMTP

   /sbin/iptables -A INPUT -p TCP -i $EXTIF="eth0" --dport 53 -j ACCEPT # DNS

   /sbin/iptables -A INPUT -p TCP -i $EXTIF="eth0" --dport 80 -j ACCEPT # WWW

   /sbin/iptables -A INPUT -p TCP -i $EXTIF="eth0" --dport 110 -j ACCEPT # POP3

   /sbin/iptables -A INPUT -p TCP -i $EXTIF="eth0" --dport 113  -j ACCEPT #AUTH

   /sbin/iptables -A INPUT -p TCP -i $EXTIF="eth0" --dport 22222 -j ACCEPT #SSH    

   /sbin/iptables -A INPUT -p UDP -i $EXTIF="eth0" --dport 138 -j ACCEPT #138

   /sbin/iptables -A INPUT -p TCP -i $EXTIF="eth0" --dport 139 -j ACCEPT #139

   /sbin/iptables -A INPUT -p UDP -i $EXTIF="eth0" --dport  137 -j ACCEPT #137

  /sbin/iptables -A INPUT -p TCP -i $EXTIF="eth0" --dport 445 -j ACCEPT #445

iptables.allow代码如下

#!/bin/bash

# this program is used to allow some IP or hosts to access your server

  /sbin/iptables -A INPUT -i $EXTIF="eth0" -s 192.168.161.242 -j ACCEPT

  /sbin/iptables -A INPUT -i $EXTIF="eth0" -s 192.168.160.178 -j ACCEPT

  /sbin/iptables -A INPUT -i $EXTIF="eth0" -s 192.168.160.218 -j ACCEPT

iptables.deny代码如下

#! /bin/bash

# This script will deny some IPs that I don't want in IN

/sbin/iptables -A INPUT -i $EXTIF="eth0"  -s 192.168.160.242 -j DROP

以上的三个文件都放在/usr/local/virus/iptables目录下，最在修改此文件/etc/rc.d/rc.local成如下代码

­

#!/bin/sh

#

# This script will be executed *after* all the other init scripts.

# You can put your own initialization stuff in here if you don't

# want to do the full Sys V style init stuff.

touch /var/lock/subsys/local

#1. Starting firewall settings

    /usr/local/virus/iptables/iptables.rule

以上就是linux下firewall简易设置啦