iptable使用实例

  

一 firewall规则

说明:     

[使用了ipchains]一开始对所有input,output,forward接受； 然后对input, forward使用我定义

的规则链,开放22，23端口的tcp协议开放，另外开放指定的几个软件使用端口。

# Firewall configuration written by lokkit

# Manual customization of this file is not recommended.

# Note: ifup-post will punch the current nameservers through the

#       firewall; such entries will *not* be listed here.

*filter

:INPUT ACCEPT [0:0]

:FORWARD ACCEPT [0:0]

:OUTPUT ACCEPT [0:0]

:RH-Lokkit-0-50-INPUT - [0:0]

-A INPUT -j RH-Lokkit-0-50-INPUT

-A FORWARD -j RH-Lokkit-0-50-INPUT

-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 22 --syn -j ACCEPT

-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 23 --syn -j ACCEPT

-A RH-Lokkit-0-50-INPUT -i lo -j ACCEPT

-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 0:1023 --syn -j REJECT

-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 2049 --syn -j REJECT

-A RH-Lokkit-0-50-INPUT -p udp -m udp --dport 0:1023 -j REJECT

-A RH-Lokkit-0-50-INPUT -p udp -m udp --dport 2049 -j REJECT

-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 6000:6009 --syn -j REJECT

-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 7100 --syn -j REJECT

COMMIT

 

二 iptables脚本实例

说明：通过以上个步骤，我们建立了一个相对完整的防火墙。只对外开放了有限的几个端口，同时提供了客户对Internet的无缝访问，并且对ip碎片攻击和icmp的ping of death提供了有效的防护手段。

 

#!/bin/sh
echo "Starting iptables rules..."
#Refresh all chains
/sbin/iptables -F

############Define HTTP packets##################
#Allow www request packets from Internet clients to www servers
iptables -A FORWARD -p tcp -d 198.168.80.11 --dport www -i eth0 -j ACCEPT

##Define FTP packets

#Allow ftp request packets from Internet clients to Intranet ftp server
iptables -A FORWARD -p tcp -d 198.168.80.12 --dport ftp -i eth0 -j ACCEPT

##Define smtp packets
iptables -A FORWARD -p tcp -d 198.168.80.13 --dport smtp -i eth0 -j ACCEPT

##Define packets from Internet server to Intranet
iptables -A FORWARD -p tcp -s 0/0 --sport ftp-data -d 198.168.80.0/24 -i eth0 -j ACCEPT
iptables -A FORWARD -p tcp -d 198.168.80.0/24 ! -syn -i eth0 -j ACCEPT
iptables -A FORWARD -p udp -d 198.168.80.0/24 -i eth0 -j ACCEPT

##Define packets from Intranet to Internet
iptables -A FORWARD -s 198.168.80.0/24 -i eth1 -j ACCEPT

##Define fregment rule
iptables -A FORWARD -f -m limit --limit 100/s --limit-burst 100 -j ACCEPT

##Define icmp rule
iptables -A FORWARD -p icmp -m limit --limit 1/s --limit-burst 10 -j ACCEPT

 

三 禁止远程ping

说明：最简单有效的方法

echo 1 >/proc/sys/net/ipv4/icmp_echo_ignore_all