一个NAT+SQUID+DNAT+FORWARD+反弹式FIREWALL的例子

以下是我自己的一个防火墙例子 , 对大家最近提出的DNAT(端口映射)的问题很有帮助

环境:
ADSL(eth0)网卡启动时不激活
内网(eth1)192.168.0.1/24
代码:
#! /bin/bash
/sbin/modprobe ip_conntrack_ftp
/sbin/modprobe ip_nat_ftp
/sbin/iptables -F -t filter
/sbin/iptables -F -t nat
/sbin/iptables -P INPUT DROP
/sbin/iptables -P OUTPUT ACCEPT
/sbin/iptables -P FORWARD DROP
/sbin/iptables -t nat -P PREROUTING ACCEPT
/sbin/iptables -t nat -P POSTROUTING ACCEPT
/sbin/iptables -t nat -P OUTPUT ACCEPT

# ALLOW ALL in PRIVATE NET
/sbin/iptables -A INPUT -i lo -j ACCEPT
/sbin/iptables -A INPUT -i eth1 -j ACCEPT

# NAT
/sbin/iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -j MASQUERADE

# DNAT RADMIN to PRIVATE in platinum.3322.org
/sbin/iptables -A PREROUTING -t nat -p tcp -s ! 192.168.0.0/24 --dport 4899 -j DNAT --to 192.168.0.2:4899
/sbin/iptables -A PREROUTING -t nat -p tcp -s ! 192.168.0.0/24 --dport 5000 -j DNAT --to 192.168.0.3:4899

# SQUID
/sbin/iptables -A PREROUTING -t nat -p tcp -s 192.168.0.0/24 --dport 80 -j DNAT --to 192.168.0.1:3128

# FORWARD edit by Platinum
/sbin/iptables -A FORWARD -p tcp --dport 21 -j ACCEPT# FTP
/sbin/iptables -A FORWARD -p tcp --dport 22 -j ACCEPT# SSH
/sbin/iptables -A FORWARD -p udp --dport 53 -j ACCEPT# DNS
/sbin/iptables -A FORWARD -p tcp --dport 80 -j ACCEPT# HTTP
/sbin/iptables -A FORWARD -p tcp --dport 443 -j ACCEPT# HTTPS
/sbin/iptables -A FORWARD -p udp --dport 8000 -j ACCEPT # QQ
/sbin/iptables -A FORWARD -p tcp --dport 25 -j ACCEPT# SMTP
/sbin/iptables -A FORWARD -p tcp --dport 110 -j ACCEPT# POP3
/sbin/iptables -A FORWARD -p tcp --dport 4899 -j ACCEPT; # RADMIN
/sbin/iptables -A FORWARD -p tcp --dport 1863 -j ACCEPT # MSN (you must allow port 443)
/sbin/iptables -A FORWARD -p icmp -j ACCEPT

# allow the third handshake
/sbin/iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
/sbin/iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT

# exchange the other packets" "SOURCE" and "TARGET", and SEND it !!!
/sbin/iptables -A INPUT -j MIRROR


此防火墙适用于静态IP及动态IP地址
原文请参考 http://bbs.chinaunix.net/forum/4/20040622/353019.html

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