OSX: Start SSH socks proxy and change network settings from the command line

Everybody loves to travel. I also enjoy to experience the internet from other places, but this I can do without leaving my house. All I need is a remote unix computer which I can access by SSH.

The script below sets up SSH dynamic port forwarding and changes the network proxy settings all by itself. When communication is cut, with Ctrl-D, it goes back to the usual proxy configuration (no proxy). Tested on OSX 10.6.8.

#!/bin/bash
#title           :socksProxySSH.sh
#description     :initiates SSH dynamic port forwarding and sets up 
#                 the network proxy settings for you
#author          :Gabriele Facciolo (http://linuxtoosx.blogspot.com/)
#date            :20130615
#version         :1.0
#OSX version     :Tested on OSX 10.6.8  
#usage           :socksProxySSH.sh [remoteHost [localPort (default:1080)]]

DEFAULTSSHHOST=""
DEFAULTLOCALSOCKSPORT=1080

# DEAL WITH COMMAND LINE PARAMETERS
if [ "${1}" != "" ]
then
   SSHHOST=$1
else
   SSHHOST=$DEFAULTSSHHOST
fi
if [ "${2}" != "" ]
then
   LOCALSOCKSPORT=$2
else
   LOCALSOCKSPORT=$DEFAULTLOCALSOCKSPORT
fi
# SORRY NO SSHHOST
if [ "${SSHHOST}" == "" ]
then 
   echo "${0}: initiates SSH dynamic port forwarding and "
   echo "sets up the network proxy settings for you."
   echo ""
   echo "    Usage:   ${0} [remoteHost [localPort(default:1080)]]"
   echo ""
   echo "Indicate a remoteHost, or set the DEFAULTSSHHOST variable" 
   exit 1
fi


# ENABLE SOCKS ON ACTIVE INTERFACES 
networksetup -listallnetworkservices | grep -v asterisk | while read line ; do 
t=`networksetup -getinfo "$line" | grep "IP address" | grep -v none`
if [ "$t" ]; then
   tt=`networksetup -getsocksfirewallproxy "$line" | grep -v Authenticated | grep "Enabled: No"` 
   if [ "$tt" ]; then
      echo Enabling SOCKS on $line
      networksetup -setsocksfirewallproxy "$line" localhost $LOCALSOCKSPORT
   fi
fi
done 


# OPEN CONNECTION AND INITIATE SOCKS SERVER
echo ""
echo "INITIATING SSH CONNECTION AND SOCKS SERVER..."
echo "========================================================="
echo "TO DISCONNECT FIRST HIT Ctrl-D, WAIT A SECOND THEN Ctrl-C"
echo "========================================================="
echo ""
ssh -C -D *:$LOCALSOCKSPORT $SSHHOST


# DISABLE SOCKS ON ACTIVE INTERFACES 
networksetup -listallnetworkservices | grep -v asterisk | while read line ; do 
t=`networksetup -getinfo "$line" | grep "IP address" | grep -v none`
if [ "$t" ]; then
   tt=`networksetup -getsocksfirewallproxy "$line" | grep -v Authenticated | grep "Enabled: Yes"` 
   if [ "$tt" ]; then
      echo Disabling SOCKS on $line
      networksetup -setsocksfirewallproxystate "$line" off
   fi
fi
done 

Description of the key commands:

• networksetup -listallnetworkservices
  Displays a list of all the network services on the server's hardware ports. An asterisk (*) denotes that a network service is disabled.
  Sample output:
           USB Ethernet
           AirPort
           Bluetooth DUN

• networksetup -getinfo "Airport"
  Displays the IP address, subnet mask, router, and hardware address for the device that you specify.

• networksetup -getsocksfirewallproxy Airport
  Displays SOCKS proxy (server, port, enabled value) info for the device.
  Sample output:
           Enabled: No
           Server: localhost
           Port: 1080
           Authenticated Proxy Enabled: 0

• networksetup -setsocksfirewallproxy Airport localhost 1080
  Set and enable the SOCKS proxy server  localhost:1080.

•  ssh -C -D *:1080 your.remote.host
  Launch ssh with dynamic port forwarding

• networksetup -setsocksfirewallproxystate Airport off
  Disables SOCKS proxy.

Sources:

http://stackoverflow.com/questions/6796442/change-network-proxy-settings-in-via-commandline-in-mac-os-x-lion

http://linuxtoosx.blogspot.fr/2011/11/ssh-dynamic-port-forwarding-socks.html

https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man8/networksetup.8.html