Of course you can redirect!
BUT you must do it in outside world!
You must point
www.yourdomain.com to server.yourdomain.com:82 (for example)
AND on your router or firewall redirect port 82 to server on port 80.
I use all time on my clients. I have ADSL (here in Brazil is 256/128K) with dynamic IP and have LOTs of servers running on this!