squid+iptables网关防火墙的实现


利用squid+iptables实现网关防火墙是非常容易的，跟着我一步一步走，就能学会！

需求说明：此服务器用作网关、MAIL(开启web、smtp、pop3)、FTP、DHCP服务器，内部一台机器(192.168.0.254)对外提供dns服务,为了不让无意者轻易看出此服务器开启了ssh服务器，故把ssh端口改为2018.另把proxy的端口改为60080

eth0:218.28.20.253,外网口

eth1:192.168.0.1/24,内网口

[jackylau@proxyserver init.d]$cat /etc/squid/squid.conf(部份如下)

http_port 192.168.0.1:60080

httpd_accel_port 80

httpd_accel_host virtual

httpd_accel_with_proxy on

httpd_accel_uses_host_header on

acl allow_lan src 192.168.0.0/24

http_access allow allow_lan

visible_hostname proxyserver

[jackylau@proxyserver init.d]$ cat firewall

  1. #!/bin/sh  
  2.  
  3. # Author: jackylau ;  
  4.  
  5. # chkconfig: 2345 08 92  
  6.  
  7. # description: firewall  
  8.  
  9. # Time on 2005.08.02  
  10.  
  11. # killproc  
  12.  
  13. # Set ENV  
  14.  

INET_IP="218.28.20.253"

INET_IFACE="eth0"

LAN_IP="192.168.0.1"

LAN_IP_RANGE="192.168.0.0/24"

LAN_BROADCAST_ADDRESS="192.168.0.255"

LAN_IFACE="eth1"

LO_IFACE="lo"

LO_IP="127.0.0.1"

IPTABLES="/sbin/iptables"

start(){

echo -n $"Starting firewall:"

/sbin/depmod -a

/sbin/modprobe ip_tables

/sbin/modprobe ip_conntrack

/sbin/modprobe iptable_filter

/sbin/modprobe iptable_mangle

/sbin/modprobe iptable_nat

/sbin/modprobe ipt_LOG

/sbin/modprobe ipt_limit

/sbin/modprobe ipt_state

echo "1" >; /proc/sys/net/ipv4/ip_forward

# Set policies

$IPTABLES -P INPUT DROP

$IPTABLES -P OUTPUT DROP

$IPTABLES -P FORWARD DROP

# Add bad_tcp_packets, allowed and icmp_packets

$IPTABLES -N bad_tcp_packets

$IPTABLES -N tcp_packets

$IPTABLES -N udp_packets

$IPTABLES -N allowed

$IPTABLES -N icmp_packets

# bad_tcp_packets

$IPTABLES -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j LOG --log-level INFO --log-prefix "New not syn:"

$IPTABLES -A bad_tcp_packets -p TCP ! --syn -m state --state NEW -j DROP

# allowed

$IPTABLES -A allowed -p TCP --syn -j ACCEPT

$IPTABLES -A allowed -p TCP -m state --state ESTABLISHED,RELATED -j ACCEPT

$IPTABLES -A allowed -p TCP -j DROP

$IPTABLES -A INPUT -p ALL -i $LAN_IFACE -d $LAN_BROADCAST_ADDRESS -j ACCEPT

# TCP rules

$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 20 -j allowed

$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 21 -j allowed

$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 25 -j allowed

$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 80 -j allowed

$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 110 -j allowed

$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 2018 -j allowed

# UDP rules

$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 67 -j ACCEPT

# ICMP rules

$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 8 -j ACCEPT

$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 11 -j ACCEPT

# INPUT chain

$IPTABLES -A INPUT -p tcp -j bad_tcp_packets

$IPTABLES -A INPUT -p ALL -i $LAN_IFACE -s $LAN_IP_RANGE -j ACCEPT

$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $LO_IP -j ACCEPT

$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $LAN_IP -j ACCEPT

$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $INET_IP -j ACCEPT

$IPTABLES -A INPUT -p ALL -d $INET_IP -m state --state ESTABLISHED,RELATED -j ACCEPT

$IPTABLES -A INPUT -p TCP -i $INET_IFACE -j tcp_packets

$IPTABLES -A INPUT -p UDP -i $INET_IFACE -j udp_packets

$IPTABLES -A INPUT -p ICMP -i $INET_IFACE -j icmp_packets

$IPTABLES -A INPUT -m limit --limit 3/minute --limit-burst 3 -j LOG --log-level DEBUG --log-prefix "IPT INPUT packet died: "

# FORWARD chain

$IPTABLES -A FORWARD -p tcp -j bad_tcp_packets

$IPTABLES -A FORWARD -i $LAN_IFACE -j ACCEPT

$IPTABLES -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT

$IPTABLES -A FORWARD -m limit --limit 3/minute --limit-burst 3 -j LOG --log-level DEBUG --log-prefix "IPT FORWARD packet died: "

# OUTPUT chain

$IPTABLES -A OUTPUT -p tcp -j bad_tcp_packets

$IPTABLES -A OUTPUT -p ALL -s $LO_IP -j ACCEPT

$IPTABLES -A OUTPUT -p ALL -s $LAN_IP -j ACCEPT

$IPTABLES -A OUTPUT -p ALL -s $INET_IP -j ACCEPT

$IPTABLES -A OUTPUT -m limit --limit 3/minute --limit-burst 3 -j LOG --log-level DEBUG --log-prefix "IPT OUTPUT packet died: "

# SNAT table

$IPTABLES -t nat -A POSTROUTING -o $INET_IFACE -j SNAT --to-source $INET_IP

# DNAT table

$IPTABLES -t nat -A PREROUTING -p ! icmp -d $INET_IP -dport 53 -j DNAT --to-destination 192.168.0.254:53

# REDIRECT

$IPTABLES -t nat -A PREROUTING -i $LAN_IFACE -p tcp -s $LAN_IP_RANGE --dport 80 -j REDIRECT --to-ports 60080

touch /var/lock/subsys/firewall

}

stop(){

echo -n $"Stoping firewall:"

echo "0">;/proc/sys/net/ipv4/ip_forward

$IPTABLES -P INPUT ACCEPT

$IPTABLES -P FORWARD ACCEPT

$IPTABLES -P OUTPUT ACCEPT

$IPTABLES -t nat -P PREROUTING ACCEPT

$IPTABLES -t nat -P POSTROUTING ACCEPT

$IPTABLES -t nat -P OUTPUT ACCEPT

$IPTABLES -t mangle -P PREROUTING ACCEPT

$IPTABLES -t mangle -P OUTPUT ACCEPT

$IPTABLES -F

$IPTABLES -t nat -F

$IPTABLES -t mangle -F

$IPTABLES -X

$IPTABLES -t nat -X

$IPTABLES -t mangle -X

rm -f /var/lock/subsys/firewall

}

status(){

clear

echo "-------------------------------------------------------------------"

$IPTABLES -L

echo "-------------------------------------------------------------------"

$IPTABLES -t nat -L POSTROUTING

echo "-------------------------------------------------------------------"

$IPTABLES -t nat -L PREROUTING

}

case "$1" in

start)

start

;;

stop)

stop

;;

restart)

stop

start

;;

*)

echo "$0 [start|stop|restart|status]"

;;

esac

cp firewall /etc/init.d/

chmod 700 /etc/init.d/firewall

chkconfig --add firewall

通过文章的介绍和代码的分析，我们对用squid和iptables来实现网关防火墙的功能有了一定的掌握，学会的朋友快跟朋友分享吧！

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  • iptables防火墙配置工具ShoreWall进阶实用介绍
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