LinuxInternetShare

Linux连接共享网关

Linux连接共享网关

网关设置脚本

#首先用lsmod看一下ipchains等模块有没有装入，如果已经装入，则用rmmod命令移走它们。
#modprobe ip_tables             #装入iptables

LAN_iface="wlan0"
LAN_ip="192.168.0.0/24"
INET_iface="ppp0"
#打开IP转发功能
# echo "net.ipv4.ip_forward=1" >> /etc/sysctl.conf && sysctl -p
echo 1 > /proc/sys/net/ipv4/ip_forward

#清除INPUT、FORWARD、POSTROUTING规则，设置默认转发策略
iptables -F INPUT
iptables -F FORWARD
iptables -F POSTROUTING -t nat
iptables -P FORWARD DROP

#转发本网段的机器到任何地方去的包
iptables -A FORWARD -s "$LAN_ip" -j ACCEPT
#对先前从防火墙外部接口出去的请求包的回复
iptables -A FORWARD -i "$INET_iface" -m state --state ESTABLISHED,RELATED -j ACCEPT
#SNAT(静态IP上网)
#iptables -t nat -A POSTROUTING -s $LAN_ip -o eth0 -j SNAT --to ip
#打开IP伪装(pppoe上网时)
iptables -t nat -A POSTROUTING -o "$INET_iface" -s "$LAN_ip" -j MASQUERADE
#目标端口为80的包可以进入
iptables -A INPUT -p tcp -i "$INET_iface" --syn --dport 80 -j ACCEPT
#拒绝不是目标端口是80的所求TCP新的连接请求包
iptables -A INPUT -p tcp -i "$INET_iface" --syn -j DROP

其他机器将路由指向该网关
```
route add default gw 192.168.0.100
```

查看iptables中的postrouting规则

iptables -t nat -L -v -n
iptables -t nat -L POSTROUTING -v -n

网关设置脚本2

InternetShare(){
    #InternetShare "enable" "192.168.0.0/24" "ppp0"
    #InternetShare "disable"
    local LAN_IP INET_IFACE
    case $1 in
    "enable")
        echo "Eable InternetShare set..."
        [ -n "$2" ] && echo "LAN_IP error!" && return 1
        [ -n "$3" ] && echo "INET_IFACE error!" && return 1
        LAN_IP=$2
        INET_IFACE=$3
        #打开IP转发功能
        echo 1 > /proc/sys/net/ipv4/ip_forward
        #清除 FORWARD、POSTROUTING规则，设置默认转发策略
        iptables -F INPUT
        iptables -F FORWARD
        iptables -F POSTROUTING -t nat
        iptables -P FORWARD DROP
        #转发本网段的机器到任何地方去的包
        iptables -A FORWARD -s "$LAN_IP" -j ACCEPT
        #对先前从防火墙外部接口出去的请求包的回复
        iptables -A FORWARD -i "$INET_IFACE" -m state --state ESTABLISHED,RELATED -j ACCEPT
        #打开IP伪装
        iptables -t nat -A POSTROUTING -o "$INET_IFACE" -s "$LAN_IP" -j MASQUERADE
        ;;
    *)
        #清除 FORWARD、POSTROUTING规则，设置默认转发策略
        echo "Disable InternetShare set..."
        iptables -F INPUT
        iptables -F FORWARD
        iptables -F POSTROUTING -t nat
        iptables -P FORWARD DROP
    ;;
    esac
} #InternetShare() end


== 无线ad-hoc模式共享上网 ==

{{{class="brush:bash"
#!/bin/sh

#starts the ad hoc server

sudo ifconfig wlan0 down
sudo iwconfig wlan0 mode ad-hoc
sudo iwconfig wlan0 key s:adhoc
sudo iwconfig wlan0 essid 'adam'
sudo ifconfig wlan0 10.0.0.1 up

#forwards the ad hoc network to the router
sudo iptables -A FORWARD -i wlan0 -o eth0 -s 10.0.0.0/24 -m state --state NEW -j ACCEPT
sudo iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
sudo iptables -A POSTROUTING -t nat -j MASQUERADE
sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"