#!SUITSSydney University IT Society

If you are a student at the School of IT, then you are lucky enough to be able to access unlimited internet through the SIT computers for free.

If you are not in the school, or not using School of IT Computers, there is still a method you can use to access the internet for free. To do this, we are going to use SSH to connect to the SIT computers and create a tunnel to the web proxy through the SIT server, on the usyd wireless network. On Windows, to accomplish this, we can use a program called PuTTY, which is available as a free download at this following address: http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html.

Once you have downloaded (and installed, if you downloaded the installable version), open PuTTY. You will open to a basic connection screen, as shown in the screenshot.  Fill out the options as given below:

Host: ucpu0.ug.it.usyd.edu.au
Port: 22

Once you have filled out these details, you have to tell PuTTY about the tunnels you want to create. On the left most menu, select ‘Connection’=>’SSH’=>’Tunnels’. Under the ‘Add new forwarded port:’ group box, type:

Source port: 8080
Destination: www-cache.usyd.edu.au:8080

Leave the radio buttons in the position they are in by default, namely ‘Local’ and ‘Auto’. Click the ‘Add’ button. The details appear under the ‘Forwarded ports:’ list.

Once you have done this, you have the option of saving your connection details, so that you do not have to do it every time you connect. Click on the ‘Session’ button on the left most menu (you may have to scroll up to see it, it is the first option). Type a name for your settings into the ‘Saved Sessions’ text box, and click ‘Save’.

After you have completed this, you need to set your proxy settings in your web browser. Each web browser will have a different place to set these settings. In the interest of brevity, I won’t go through the process for each web browser, but a quick search on Google will give you instructions. The settings will be:

Proxy: localhost
Port: 8080

Congratulations, you know how access to the internet anywhere around campus.

Why This Works

What we want to do is to create a connection to the University of Sydney web proxy (www-cache.usyd.edu.au). On the wireless network, this proxy will not allow you to access the internet. However, the School of IT has got (virtually) unlimited access to the internet. Therefore, we need to connect to the proxy through the SIT computers. By connecting to the ucpu0 computer, we now have a computer in SIT. The ucpu0 computer, being inside SIT has access to the proxy. Now we just need to find a way to connect to the proxy as if we were connecting through SIT.

So we utilize SSH’s built in tunneling capacity. This essentially allows your computer to send its data to the ucpu0 server through PuTTY, and then the ucpu0 server will send it on to the proxy. So all the proxy server sees is your internet data coming through from ucpu0. It doesn’t know that your computer is sitting behind it. For this to work, you need to tell your web browser to send its data to PuTTY. So instead of setting the proxy to www-cache… you set the proxy to localhost:8080, which is where you told PuTTY to listen to the data (‘Source Port’ option under the Tunneling tab).

So PuTTY (or any SSH client for that matter) is there acting as a sort of middle man, passing packets between the proxy and your computer.

Disclaimer

Please use the internet responsibly. Since you are logged into ucpu0 with your unikey account, your traffic can be tracked by the Uni and SIT.  The IT guys in the School of IT are pretty smart guys, and if you use the internet to do anything illegal, they will most likely know about it.