1-Open control panel
2-Network connection
3-Press on local are connection
then properties
press advanced
then press Settings
open Firewall then exceptions
then press add ports

Code:
Name: Crossfire
Port: 13008
Protocol: TCP

Name: Xtrap1
Port: 10009
Protocol: TCP

Name: Xtrap2
Port: 16666
Protocol: TCP

Name: Crossfire
Port: 13008
Protocol: UDP

Name: Xtrap1
Port: 10009
Protocol: UDP

Name: Xtrap2
Port: 16666
Protocol: UDP

And you are done