To know how to unblock, you need to know how it's blocked.
How did I block FB in my office? I do it at the DNS level. In my office, anyone why tries to go to FB ends up at google. smile.gif I point facebook.com and www.facebook.com at www.google.com. If your admin points it at some non existent IP address, it would just timeout after a very long delay.
It's simple enough to bypass. Go home, ping www.facebook.com and get the IP address. Put it into your host file on your PC in the office.
Or you can use the tmnet DNS server instead of the one in our office. But that would cause other problems. Network printers and intra office webapps might become inaccessible.
There's this one girl who loves to waste her time on the www. Her job does not require access to the www. So I blocked her computer based on her PC's IP address. This is done with iptables on the gateway machine to the Internet.
The way to bypass this is also easy. Just change the IP address of the PC. But again, this would cause problems with some webapps that are locked to a few IP addresses. So you need to change the IP address now and then.
But my office is not filled with IT gurus. Even after reading this post, they still wouldn't know what to do. One or two might know, but they're smart enough to not get caught by the boss using FB at work.
If FB is being blocked by the firewall in your office, yes, you can use a proxy or tunnel. But that is a deliberate attempt to bypass the network security. They will have good reason to fire you on the spot. So beware.
source : http://forum.lowyat.net/topic/1810704
