Friday, September 18, 2009

Beating internet restrictions with ssh

In most of our schools and offices several websites are blocked. Most of these offices and schools are using a proxy server such as squid along with squidguard or danceguardian to achieve access restrictions on users. Most often, the sys admins forget to block internet traffic using other protocols such as ssh , ftp etc. You can beat the web filtering scheme of your network administrator if you can access a machine on internet via ssh. Open ssh server can act as a socks proxy.

So . install open ssh server on your home machine and leave it connected to internet. Note down the ipaddress of your home machine. If it uses DHCP , you can install some thing like dyndns client and keep track of the IP address. From your office/school connect to the home machine as below.

$ ssh -D 2345 ipaddress _of_home_machine

( You can use any other unused port no. instead of 2345. You may not be able to connect to home if the admin has blocked ssh port on the firewall. You can try running ssh server at home on a different port)

Open your firefox browser and select file=>preferences->advanced->network-settings. Fill in against the Socks host column and enter 2345 as port. Click ok to save.
All your webtraffic will now be tunneled to your home machine beating the local proxy. Enjoy unrestricted internet.

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