Hamachi:Call of Duty 4
From LogMeInWiki
Detail
Call of Duty 4 requires the following ports to be allowed in your software firewall for the Hamachi network:
TCP:
- 28960
UDP:
- 20500,20510,28960
These do not need to be put in a port forward on your router, only in exceptions for your software firewall.
Other than that, follow the normal Gaming tips to resolve any other connectivity related issues.