Can you Change Ports used On Counter Strike?

I ask this question because I am behind a router that I dont have 100% controll over. Currently I am pritty sure that the ports used for Counter strike are closed but I know a few ports that are deffinatly open and not being used, would I therefore be able to use those ports instead?

Finally are the ports used in Counter Strike 1.6 the same as the ports used in Counter Strike Source
Thanks

Right click on your Counter Strike shortcut & select Properties. You can specify the port by adding -port xxxxx, e.g.
hlds.exe -game cstrike -port 27015
Same procedure for the old Counter Strike also if I remember rightly. Just click Apply & Ok then.

thanks ill give that a try and see what happens