Auto Tun2Socks

What ?

This program is basically a wrapper around the great tun2socks project, it also uses the netlink module.

https://github.com/xjasonlyu/tun2socks
https://github.com/vishvananda/netlink

Why ?

In large scope penetration tests with a large amount of subnets that are accessible from a single pivot point, this tool comes in handy.
The idea is to automatically configure the tun0 interface and populate the routes for tun2socks.
This prevents having to run a bunch of ip route add ... if a lot of precise addresses have to be added to your routes.
This way, if you have any tunnel with a supported protocol you can instantly add all your routes and pivot.

Usage

Usage of ./auto-t2s:
  -device string
        Use this device [driver://]name
  -fwmark int
        Set firewall MARK (Linux only)
  -interface string
        Interface name (default "tun0")
  -loglevel string
        Log level [debug|info|warning|error|silent] (default "info")
  -mtu int
        Set device maximum transmission unit (MTU)
  -proxy string
        Use this proxy [protocol://]host[:port]
  -restapi string
        HTTP statistic server listen address
  -route-file string
        Route File, containing one route per line to configure.
  -tcp-auto-tuning
        Enable TCP receive buffer auto-tuning
  -tcp-rcvbuf string
        Set TCP receive buffer size for netstack
  -tcp-sndbuf string
        Set TCP send buffer size for netstack
  -tun-post-up string
        Execute a command after TUN device setup
  -tun-pre-up string
        Execute a command before TUN device setup
  -udp-timeout duration
        Set timeout for each UDP session

routes file example:

10.0.2.1/24
10.4.1.1/24

It runs just like normal tun2socks:

auto-t2s -interface wlan0 -mtu 1500 -proxy socks5://localhost:8081 -device tun0 -routes-file './routes'

This will create the tun0 device, then bring the link up.

Afterwards, the routes will be populated, both of the first steps use netlink.
Finally, the tun2socks engine will be started and the forwarding of packets through the socks proxy will start.

curl https://10.100.1.100
...

Now the specified routes should be accessible.
The caveat is that since the tool uses netlink it needs higher privileges.

Disclaimer:

This could probably have been achieved with a -tun-post-up command pointing to a script.
I wanted to play with tun2socks, netlink and gvisor , I feel like there is potential to learn these projects to create interesting tools.

Installation

go get github.com/vishvananda/netlink
go get github.com/xjasonlyu/tun2socks/v2
go build .

Ramoreik / auto-t2s