How to open .rar files in Ubuntu?

Is there any trick/technique that I can open .rar, .cab files in Ubuntu without installing any new software. Actually, I have Ubuntu OS in my office and I can’t install anything (restrictions). So, how to open .rar and .cab files?
Answer #1
If you have a working net connection, its as simple as going to the ‘Software Center’ (I might be mistaken over there, don’t remember the exact name) and search for ‘RAR’ and hit ‘Install’.
Answer #2
I cannot install any software. Restrictions. We have to work builtin programs. Actually I download Need Timesheet for my team and microsoft provides .cab folder, and i cannot open it.
Answer #3
Then it’s not possible without being able to agt-get or install packages through system installer.
Answer #4
Use this site, it uncompresses files on it’s server for you so you don’t have to install anything:
http://wobzip.org/index.php
Answer #5
Thanks. Solved