Need help to run the tunnel

[sohrabp72]

root@Helsinki:~# udptunnel -s 444 -v 127.0.0.1/433
Listening for TCP connections on port 444
setup_udp_recv: bind: Address already in use

Newbie here.
Correct me if I'm wrong, the above command will accept any incoming TCP traffic on port 444 and then forward that traffic to UDP port 433 on the server, and on the server there should be a process listening to UDP port 433 to get traffic for further process.
If I change 127.0.0.1/433 to 127.0.0.1/436 for example, the command will run without any problem, but there is no process listening on port 436 to get traffic.