Transparent proxy in Linux

tp.sh

#!/bin/bash

# SOCKS5 服务器的 IP 地址
REMOTE_SERVER_IP=

# 本地 SOCKS5 服务器的端口
LOCAL_LISTEN_PORT=0

# 自动获取家用网关（路由器）的 IP 地址，你也可以手动指定，如 192.168.28.2
REAL_GATEWAY=$(ip route | grep "default .* dhcp" | awk '{print $3}')

# 选一个不冲突的 tun 设备号
TUN_NETWORK_DEV=tun0

# 选一个不冲突的内网 IP 段的前缀
TUN_NETWORK_PREFIX=10.0.0
TUN_NETWORK_IP=${TUN_NETWORK_PREFIX}.1
TUN_NETWORK_GATEWAY=${TUN_NETWORK_PREFIX}.2

RUN_FLAG="error"

function check_args() {
    while getopts s:p:r: flag
    do
        case "${flag}" in
            s) REMOTE_SERVER_IP=${OPTARG};;
            p) LOCAL_LISTEN_PORT=${OPTARG};;
            r) RUN_FLAG=${OPTARG};;
        esac
    done

    if [ -z ${REMOTE_SERVER_IP} ] || [ ${LOCAL_LISTEN_PORT} -eq 0 ] || ([[ ${RUN_FLAG} != start ]] && [[ ${RUN_FLAG} != stop ]]) ; then
        cat << EOF

脚本 "$(basename $0)" 使用方法:
script "$(basename $0)" usage:

$0 -s REMOTE_SERVER_IP -p LOCAL_LISTEN_PORT -r start/stop

EOF
        exit 1
    fi
}


function check_root_account() {
    if [ `id -u` != 0 ]; then
        echo -e "当前账号不是 root 账号，请切换到 root 账号再运行本脚本。"
        echo -e "Current account is not root user, please switch to root user and re-execute this script."
        exit 1
    fi
}

function start_tun_fwd() {
    # 添加虚拟网卡
    ip tuntap add dev ${TUN_NETWORK_DEV} mode tun

    if false; then
        # 给虚拟网卡绑定 IP 地址
        ifconfig ${TUN_NETWORK_DEV} ${TUN_NETWORK_IP} netmask 255.255.255.0

        # 启动虚拟网卡
        ip link set ${TUN_NETWORK_DEV} up

        route add ${REMOTE_SERVER_IP} gw ${REAL_GATEWAY} metric 4
        route add default gw ${TUN_NETWORK_GATEWAY} metric 6
    else
        # 给虚拟网卡绑定 IP 地址
        ip addr add ${TUN_NETWORK_IP}/24 dev ${TUN_NETWORK_DEV}

        # 启动虚拟网卡
        ip link set ${TUN_NETWORK_DEV} up

        ip route del default via ${REAL_GATEWAY}
        ip route add ${REMOTE_SERVER_IP} via ${REAL_GATEWAY}

        # 特殊ip段走家用网关（路由器）的 IP 地址（如局域网联机）
        # ip route add "172.16.39.0/24" via ${REAL_GATEWAY}

        ## 国内网段走家用网关（路由器）的 IP 地址
        #for i in $(cat /home/yang/bin/路由表/cn_rules.conf); do
        #    ip route add "$i" via ${REAL_GATEWAY}
        #done

        # 将默认网关设为虚拟网卡的 IP 地址
        ip route add 0.0.0.0/1 via ${TUN_NETWORK_IP}
        ip route add 128.0.0.0/1 via ${TUN_NETWORK_IP}
        # 以上兩句可以使用以下一句代替
        # ip route add 0.0.0.0/0 via ${TUN_NETWORK_IP}
    fi

    sleep 1

    badvpn-tun2socks --tundev ${TUN_NETWORK_DEV} --netif-ipaddr ${TUN_NETWORK_GATEWAY} --netif-netmask 255.255.255.0 --socks-server-addr 127.0.0.1:${LOCAL_LISTEN_PORT} --socks5-udp &
}


function stop_tun_fwd() {

    killall -w badvpn-tun2socks

    sleep 1

    if false; then
        route del ${REMOTE_SERVER_IP} gw ${REAL_GATEWAY} metric 4
        route del default gw ${TUN_NETWORK_GATEWAY} metric 6
    else
        ip route del 128.0.0.0/1 via ${TUN_NETWORK_IP}
        ip route del 0.0.0.0/1 via ${TUN_NETWORK_IP}
        #for i in $(cat /home/yang/bin/路由表/cn_rules.conf); do
        #    ip route del "$i" via ${REAL_GATEWAY}
        #done
        #ip route del "172.16.39.0/24" via ${REAL_GATEWAY}
    fi

    ip route del ${REMOTE_SERVER_IP} via ${REAL_GATEWAY}
    ip route add default via ${REAL_GATEWAY}

    ip link set ${TUN_NETWORK_DEV} down
    ip addr del ${TUN_NETWORK_IP}/24 dev ${TUN_NETWORK_DEV}
    sleep 1
    ip tuntap del dev ${TUN_NETWORK_DEV} mode tun
}

function main() {
    check_root_account
    check_args $@

    stop_tun_fwd

    if [[ ${RUN_FLAG} == stop ]]; then
        exit 0
    elif [[ ${RUN_FLAG} == start ]]; then
        start_tun_fwd
    fi
}

main $@

exit 0