/go-tun2socks

A tun2socks implementation written in Go.

Primary LanguageCMIT LicenseMIT

go-tun2socks

Build Status

A tun2socks implementation written in Go.

Tested and worked on macOS, Linux, Windows and iOS (as a library).

Overview

                                      core.NewLWIPStack()
                                           +
                                           |
                                           |
                                           |
                                           |                TCP/UDP             core.RegisterTCPConnectionHandler()
                                           |
                          core.Input()     |           core.Connection          core.RegisterUDPConnectionHandler()
                                           v
Application +------> TUN +-----------> lwIP stack +------------------------------> core.ConnectionHandler +-------> Remote proxy server +--> Destination


                         <-----------+
                    core.RegisterOutputFn()

Features

  • Support both TCP and UDP
  • Support both IPv4 and IPv6
  • Support ICMP local echoing with configurable packet delay time
  • Support proxy handlers: SOCKS5, Shadowsocks, V2Ray (DNS cache is enabled in these handlers by default)
  • Dynamically adding routing rules according to V2Ray's routing results (V2Ray proxy handler only)

Build

go-tun2socks is using cgo, thus a C compiler is required.

go get github.com/eycorsican/go-tun2socks
cd $GOPATH/src/github.com/eycorsican/go-tun2socks
go get -d ./...
make clean && make build
./build/tun2socks -h

An alternative way to build (or cross compile) tun2socks is to use xgo, to use xgo, you also need docker:

# install docker: https://docs.docker.com/install

# install xgo
go get github.com/karalabe/xgo

go get github.com/eycorsican/go-tun2socks
cd $GOPATH/src/github.com/eycorsican/go-tun2socks
go get -d ./...
make clean && make xbuild
ls ./build

Run

./build/tun2socks -tunName tun1 -tunAddr 240.0.0.2 -tunGw 240.0.0.1 -proxyType socks -proxyServer 1.2.3.4:1086

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

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

A few notes for using V2Ray proxy handler

  • Using V2Ray proxy handler: tun2socks -proxyType v2ray -vconfig config.json
  • V2Ray proxy handler dials connections with a V2Ray Instance
  • Configuration file V2Ray must in JSON format
  • Proxy server addresses in the configuration file should be IPs and not domains except your system DNS will match "direct" rules
  • Configuration file should not contain direct domain rules, since they cause infinitely looping requests
  • Dynamic routing happens prior to packets input to lwIP, the V2Ray Router is used to check if the IP packet matching "direct" tag, information available for the matching process are (protocol, destination ip, destination port)
  • To enable dynamic routing, just set the -gateway argument, for example: tun2socks -proxyType v2ray -vconfig config.json -gateway 192.168.0.1
  • The tag "direct" is hard coded to identify direct rules, which if dynamic routing is enabled, will indicate adding routes to the original gateway for the corresponding IP packets
  • Inbounds are not necessary

TODO

  • Built-in routing rules and routing table management
  • Support ICMP packets forwarding

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

Many thanks to the following projects