Python script for SSH tunneling on Mac OS X

digital_ocean_instructions.md

Creating and configuring a DigitalOcean droplet for SSH tunneling

Creating the droplet on DigitalOcean

1. Click Create Droplet
2. Name it 'tunnel'
3. Select $5/mo
4. Select Singapore
5. Select Ubuntu 14.04
6. Add your SSH key (probably already there if you've created other droplets)

Adding your user

adduser username
visudo

Add this line: username ALL=(ALL:ALL) ALL

cd /home/username
mkdir .ssh
cd /home/fhsu/
mkdir .ssh
cd .ssh
nano authorized_keys   # copy in the keys
chmod 600 authorized_keys
chown username:username authorized_keys

Remember that you can always reset your root password in the control panel.

tunnel.py

#!/usr/bin/env python
"""
A simple program for starting a SOCKS proxy and configuring your Mac OS X system
settings to use it by default.

Usage:

tunnel.py  128.123.123.12 22 wifi

Source: http://pixelsvsbytes.com/blog/2011/09/easy-ssh-tunnelling-for-the-mac/

"""
import argparse
from subprocess import Popen, call, check_output


def tunnel(ip_addr, port, service):
    service = {
        'wifi': 'Wi-Fi',
        'ethernet': 'Ethernet',
    }[service]

    # Establish the SSH tunnel.
    cmd = [
        'ssh', 
        '-D', port,
        '-N',       # no interactive shell
        '-C',       # compression
        ip_addr,
    ]
    proc = Popen(cmd)

    # Set socks proxy parameters.
    cmd = ['networksetup', '-setsocksfirewallproxy', service, '127.0.0.1', port,
        'off']
    run(cmd)
    # Turn on socks proxy.
    cmd = ['networksetup', '-setsocksfirewallproxystate', service, 'on']
    run(cmd)

    # Show the IP address after tunneling. Note that curl won't use the proxy
    # by default.
    cmd = ['curl', '-s', '--proxy', 'socks5://127.0.0.1:' + port, 
        'http://ipecho.net/plain']
    result = check_output(cmd)
    print 'Your IP address is now ' + result

    raw_input('Press any key to shut off socks proxy')

    # Turn off socks proxy.
    cmd = ['networksetup', '-setsocksfirewallproxystate', service, 'off']
    run(cmd)

    # Shut down the tunnel. 
    proc.kill()


def run(cmd):
    print ' '.join(cmd)
    call(cmd)


if __name__ == '__main__':
    import argparse

    parser = argparse.ArgumentParser(description='Set up an SSH tunnel.')
    parser.add_argument('ip_address', 
        help='The IP address of the virtual private server')
    parser.add_argument('port', 
        help='The port number of the SSH tunnel process')
    parser.add_argument('service', default='wifi',
        help='The service you want to tunnel (wifi|ethernet)')

    args = parser.parse_args()
    tunnel(args.ip_address, args.port, args.service)