tun2socks

A tun2socks implementation written in Go.

forked & modified from eycorsican/go-tun2socks

Preview

Tun2socks status web view (-monitor option is required)

What's the difference with the original project

• Add new features (listed below)
• Optimize handlers (e.g. new TCP/UDP proxy handler)
• Rewrite and remove some implementations

Main Features

Previous Features

• Support both TCP and UDP
• Support both IPv4 and IPv6
• Support proxy handler: SOCKS5
• ICMP echoing

New Features

• Fake DNS (Fake IP range: 198.18.0.0/15)
• Backend DNS (resolve non-TypeA query)
• Hijack DNS (force the specific DNS to get a fake address)
• Hosts mapping (e.g. localhost->127.0.0.1)
• Web statistics monitor

Tun2socks Usage

Usage of tun2socks:
  -backendDNS string
    	Backend DNS to resolve non-TypeA or non-ClassINET query (must support tcp) (default "8.8.8.8:53,8.8.4.4:53")
  -fakeDNS
    	Enable fake DNS
  -fakeDNSAddr string
    	Listen address of fake DNS (default ":53")
  -hijackDNS string
    	Hijack the specific DNS query to get a fake ip, e.g. '*:53', '8.8.8.8:53,8.8.4.4:53'
  -hosts string
    	DNS hosts mapping, e.g. 'example.com=1.1.1.1,example.net=2.2.2.2'
  -loglevel string
    	Logging level [info, warning, error, debug, silent] (default "info")
  -monitor
    	Enable session statistics monitor
  -monitorAddr string
    	Listen address of session monitor, open in your browser to view statistics (default "localhost:6001")
  -proxyServer string
    	Proxy server address
  -tunAddr string
    	TUN interface address (default "240.0.0.2")
  -tunDNS string
    	DNS resolvers for TUN interface (Windows Only) (default "8.8.8.8,8.8.4.4")
  -tunGw string
    	TUN interface gateway (default "240.0.0.1")
  -tunMask string
    	TUN interface netmask (default "255.255.255.0")
  -tunName string
    	TUN interface name (default "utun0")
  -tunPersist
    	Persist TUN interface after the program exits or the last open file descriptor is closed (Linux only)
  -udpTimeout duration
    	UDP session timeout (default 30s)
  -version
    	Show current version of tun2socks

How to Build

go-tun2socks is using cgo and go modules, thus a C compiler and GO version >= 1.13 are required.

git clone https://github.com/xjasonlyu/tun2socks.git
cd tun2socks && go mod download
make clean && make build
./bin/tun2socks -h

My Daily Using (Alpine Demo)

This project is running on my server as a second gateway, so my Apple TV and other devices could access the full internet and AD block function without complex configuration.

Here is my Running Environment

• Linux alpine 4.19.79-0-virt (VM)
• Proxy Server: 10.0.0.3
• Alpine Address: 10.0.0.2
• Router Gateway: 10.0.0.1
• Apple TV Address: 10.0.0.120

This is my alpine tun2socks service file

#!/sbin/openrc-run

### tun2socks options
TUN="utun0"
ETH="eth0"
ETHGW="10.0.0.1"
TUNGW="240.0.0.1"
SOCKS="10.0.0.3:1080"
MONITOR="0.0.0.0:80"
HIJACKDNS=""
BACKENDDNS="1.2.4.8:53,1.1.1.1:53"
HOSTS="localhost=127.0.0.1"
OPTIONS="-loglevel warning -tunName $TUN -proxyServer $SOCKS -monitor -monitorAddr $MONITOR -fakeDNS -hosts $HOSTS -backendDNS $BACKENDDNS"

### openrc options
description="the tun2socks route process"
name=$RC_SVCNAME
pidfile="/var/run/$RC_SVCNAME.pid"
logfile="/var/log/$RC_SVCNAME.log"
command="/usr/local/bin/tun2socks"
command_args=$OPTIONS
command_user="root"
command_background="yes"

depend() {
    #after *
    before chronyd
    after firewall
    use dns
}

_set_dns() {
    option=$1
    case $option in
        0)
        einfo "DNS settings updated"
        [ -f /etc/resolv.conf.copy ] || mv /etc/resolv.conf /etc/resolv.conf.copy
        cat > /etc/resolv.conf << EOF
nameserver $TUNGW
EOF
        ;;
        1)
        einfo "DNS settings restored"
        cp -f /etc/resolv.conf.copy /etc/resolv.conf
        ;;
        *)
        return 0
        ;;
    esac
    eend $?
}

start_pre() {
    if [ "${RC_CMD}" = "restart" ]; then
        ip link delete $TUN 2> /dev/null
    fi

    # enable ip_forward
    einfo $(sysctl -w net.ipv4.ip_forward=1) && eend $?

    # create tun device
    ip tuntap add mode tun dev $TUN
    ip addr add $TUNGW/24 dev $TUN
    ip link set dev $TUN up
    einfo "tun device created: $TUN" && eend $?

    # change default gateway
    ip route del default 2> /dev/null
    ip route add default via $TUNGW dev $TUN

    # add to ip route
    #ip route add 1.1.1.1/32 via $ETHGW

    # DNS settings
    _set_dns 0
}

stop_post() {
    # disable ip_forward
    einfo $(sysctl -w net.ipv4.ip_forward=0) && eend $?

    # delete from ip route
    #ip route del 1.1.1.1/32 via $ETHGW

    # change default gateway
    # ip route del default
    ip route add default via $ETHGW dev $ETH 2> /dev/null

    # delete tun device
    #ip link set dev $TUN down
    #ip addr del $TUNGW/24 dev $TUN
    #ip tuntap del mode tun dev $TUN
    ip link delete $TUN 2> /dev/null
    einfo "tun device deleted: $TUN" && eend $?

    # DNS settings
    _set_dns 1
}

start() {
    ebegin "Starting $RC_SVCNAME"
	start-stop-daemon --start --quiet \
        --background --exec $command \
        --user $command_user \
        --make-pidfile --pidfile $pidfile \
        --stdout $logfile --stderr $logfile \
        -- $command_args
	eend $?
}

stop() {
    if [ "${RC_CMD}" = "restart" ]; then
        _pid=$(pgrep $RC_SVCNAME)
        if [ "$_pid" != "$(cat $pidfile)" ]; then
            echo $_pid > $pidfile
        fi
    fi

	ebegin "Stopping $RC_SVCNAME"
	start-stop-daemon --stop --quiet --exec "$command" \
		--pidfile "$pidfile"
	eend $?

	if [ "$RC_RUNLEVEL" = "shutdown" ]; then
		_pid=$(pgrep $RC_SVCNAME)
        if [ -n $_pid ]; then
            kill -9 $_pid > /dev/null 2>&1
        fi
        rm -rf $pidfile
	fi
}

Follow 3 Steps

• Simply put this config in /etc/init.d/
• Give it executable permission chmod +x tun2socks
• Launch the service rc-service tun2socks start

Finally, all you need to do is modify your internet settings.

In this case, I just need configure my Apple TV internet settings from DHCP to Static, and change my gateway and DNS to 10.0.0.2.

Done!

Run

tun2socks -loglevel warning -tunName utun0 -proxyServer 1.2.3.4:1080 -monitor -monitorAddr 0.0.0.0:80 -fakeDNS -hosts localhost=127.0.0.1 -backendDNS 1.1.1.1:53,8.8.8.8:53

Note that the TUN device may have a different name, and it should be a different name on Windows unless you have renamed it, so make sure use ifconfig, ipconfig or ip addr to check it out.

Create TUN device and Configure Routing Table

Suppose your original gateway is 192.168.0.1. The proxy server address is 1.2.3.4.

The following commands will need root permissions.

macOS

The program will automatically create a TUN device for you on macOS. To show the created TUN device, use ifconfig.

Delete original gateway:

route delete default

Add our TUN interface as the default gateway:

route add default 240.0.0.1

Add a route for your proxy server to bypass the TUN interface:

route add 1.2.3.4/32 192.168.0.1

Linux

The program will not create the TUN device for you on Linux. You need to create the TUN device by yourself:

ip tuntap add mode tun dev tun1
ip addr add 240.0.0.1 dev tun1
ip link set dev tun1 up

Delete original gateway:

ip route del default

Add our TUN interface as the default gateway:

ip route add default via 240.0.0.1

Add a route for your proxy server to bypass the TUN interface:

ip route add 1.2.3.4/32 via 192.168.0.1

Windows

使用教程 - Tutorial in Chinese

To create a TUN device on Windows, you need Tap-windows, refer here for more information.

Add our TUN interface as the default gateway:

# Using 240.0.0.1 is not allowed on Windows, we use 10.0.0.1 instead
route add 0.0.0.0 mask 0.0.0.0 10.0.0.1 metric 6

Add a route for your proxy server to bypass the TUN interface:

route add 1.2.3.4 192.168.0.1 metric 5

This project is using lwIP

This project is using a modified version of lwIP, you can checkout this repo to find out what are the changes: https://github.com/eycorsican/lwip (original author)

Many thanks to the following projects

• https://savannah.nongnu.org/projects/lwip
• https://github.com/ambrop72/badvpn
• https://github.com/zhuhaow/tun2socks
• https://github.com/yinghuocho/gotun2socks
• https://github.com/v2ray/v2ray-core
• https://github.com/shadowsocks/go-shadowsocks2
• https://github.com/Dreamacro/clash
• https://github.com/songgao/water
• https://github.com/nadoo/glider
• https://github.com/miekg/dns
• https://github.com/sirupsen/logrus