请问以下的"WWW包过滤"怎么实现?哪位大侠能把实现的每个步骤教给我吗?
设置WWW包过滤
说明：WWW端口为80，采用tcp或udp协议。规则为：eth1=〉允许所有来自Intranet的WWW包；eth0=〉仅允许目的为内部网WWW服务器的包。
#Define HTTP packets
#Allow www request packets from Internet clients to www servers
/sbin/ipchains -A input -p tcp -s 0.0.0.0/0 1024: -d 198.168.80.11/32 www -i eth0 -j ACCEPT
/sbin/ipchains -A input -p udp -s 0.0.0.0/0 1024: -d 198.168.80.11/32 www -i eth0 -j ACCEPT
#Allow response from Intranet www servers to request Internet clients
/sbin/ipchains -A input -p tcp -s 198.168.80.11/32 www -d 0.0.0.0/0 1024: -i eth1 -j ACCEPT
/sbin/ipchains -A input -p udp -s 198.168.80.11/32 www -d 0.0.0.0/0 1024: -i eth1 -j ACCEPT
#Allow www request packets from Intranet clients to Internet www servers
/sbin/ipchains -A input -p tcp -s 198.168.80.0/24 1024: -d 0.0.0.0/0 www -i eth1 -j ACCEPT
/sbin/ipchains -A input -p udp -s 198.168.80.0/24 1024: -d 0.0.0.0/0 www -i eth1 -j ACCEPT
#Allow www response packets from Internet www servers to Intranet clients
/sbin/ipchains -A input -p tcp -s 0.0.0.0/0 www -d 198.168.80.0/24 1024: -i eth0 -j ACCEPT
/sbin/ipchains -A input -p udp -s 0.0.0.0/0 www -d 198.168.80.0/24 1024: -i eth0 -j ACCEPT
