shootback – a reverse TCP tunnel let you access target behind NAT or firewall

shootback is a reverse TCP tunnel let you access target behind NAT or firewall
Consumes less than 1% CPU and 8MB memory under 800 concurrency.
slaver is single file and only depends on python(2.7/3.4+) standard library.

How it works

Typical Scene

  1. Access company/school computer(no internet IP) from home
  2. Make private network/site public.
  3. Help private network penetration.
  4. Help CTF offline competitions.
  5. Connect to device with dynamic IP, such as ADSL

Getting started

  1. requirement:
    • Master: Python3.4+, OS independent
    • Slaver: Python2.7/3.4+, OS independent
    • no external dependencies, only python std lib
  2. download git clone https://github.com/aploium/shootback
  3. (optional) if you need a single-file slaver.py, run python3 build_singlefile_slaver.py
  4. run these command
    # master listen :10000 for slaver, :10080 for you
    python3 master.py -m 0.0.0.0:10000 -c 127.0.0.1:10080

    # slaver connect to master, and use example.com as tunnel target
    # ps: you can use python2 in slaver, not only py3
    python3 slaver.py -m 127.0.0.1:10000 -t example.com:80

    # doing request to master
    curl -v -H "host: example.com" 127.0.0.1:10080
    # -- some HTML content from example.com --
    # -- some HTML content from example.com --
    # -- some HTML content from example.com --
  5. a more reality example:
    assume your master is 22.33.44.55 (just like the graph above)
    # slaver_local_ssh <---> slaver <--> master(22.33.44.55) <--> You

    # ---- master ----
    python3 master.py -m 0.0.0.0:10000 -c 0.0.0.0:10022

    # ---- slaver ----
    python(or python3) slaver.py -m 22.33.44.55:10000 -t 127.0.0.1:22

    # ---- YOU ----
    ssh 22.33.44.55 -p 10022
  6. for more help, please see python3 master.py --help and python3 slaver.py --help

Tips

  1. run in daemon:
    nohup python(or python3) slaver.py -m host:port -t host:port -q &
    or:
    # screen is a linux command
    screen
    python(or python3) slaver.py -m host:port -t host:port
    # press ctrl-a d to detach screen
    # and if necessary, use "screen -r" to reattach
  2. ANY service using TCP is shootback-able. HTTP/FTP/Proxy/SSH/VNC/…
  3. shootback itself just do the transmission job, do not handle encrypt or proxy.
    however you can use a 3rd party proxy (eg: shadowsocks) as slaver target.
    for example:
    shadowsocks_server<-->shootback_slaver<-->shootback_master<-->shadowsocks_client(socks5)

Warning

  1. in windows, due to the limit of CPython select.select() , shootback can NOT handle more than 512 concurrency, you may meet
    ValueError: too many file descriptors in select()
    If you have to handle such high concurrency in windows, Anaconda-Python3 is recommend, it’s limit in windows is 2048

Performance

  1. in my laptop of intel I7-4710MQ, win10 x64:
    • 1.6Gbits/s of loopback transfer (using iperf), with about 5% CPU occupation.
    • 800 thread ApacheBench, with less than 1% CPU and 8MB memory consume

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