一个NAT脚本

支持直接接入方式和PPPOE拨号方式，前部分有配置和注解，应该不难看懂 #! /bin/bash # Project by Platinum, 2005-05-12 # Debug on 2005-05-20 # Set MODE (LAN or ADSL) MODE="ADSL" # Set default gateway (如果MODE==ADSL，此项可以忽略) GATEWAY="外网网关" # Set Interface WAN (如果MODE==ADSL，此项可以忽略) WAN_IP="外网IP地址" WAN_ETH="外网网卡" WAN_MASK="外网掩码" # Set Interface LAN LAN_IP="内网IP地址" LAN_NET="内网网络地址" LAN_ETH="内网网卡" LAN_MASK="内网掩码" # Set manager MANAGER_IP="内网管理员IP" MANAGER_MAC="内网管理员MAC" # Initialize modules modprobe ip_nat_ftp modprobe ip_conntrack_ftp echo 1 > /proc/sys/net/ipv4/ip_forward # Initialize Interface LAN ifconfig $LAN_ETH $LAN_IP netmask $LAN_MASK # Initialize policy iptables -P INPUT DROP iptables -P FORWARD ACCEPT iptables -F iptables -t nat -F # Deny ACK attack iptables -A INPUT -p tcp ! --syn -m state --state NEW -j DROP iptables -A FORWARD -p tcp ! --syn -m state --state NEW -j DROP # Initialize Rules iptables -A INPUT -i lo -j ACCEPT iptables -A INPUT -i $LAN_ETH -s $MANAGER_IP -m mac --mac-source $MANAGER_MAC -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT case "$MODE" in   LAN)      # Initialize Interface WAN      ifconfig $WAN_ETH $WAN_IP netmask $WAN_MASK      iptables -t nat -A POSTROUTING -s $LAN_NET -o $WAN_ETH -j SNAT --to $WAN_IP   ;;   ADSL)      iptables -t nat -A POSTROUTING -s $LAN_NET -o ppp0 -j MASQUERADE      GATEWAY=`ifconfig ppp0|grep inet|awk '{print $3}'|awk -F: '{print $2}'`   ;; esac ip route replace default via $GATEWAY