Recently some laptops in our network stopped downloading virus definitions. Our firewall was configured to allow traffic from the wireless vlan to our server, however, the port on version 10 has changed to 2967
After adding the new port we still were having intermittent virus update problems. We needed to add a local rule on the laptops for port 2967. Windows firewall was preventing the inbound connections on port 2967 (meaning we could not push updates from the mmc plugin). After adding an exception to the windows firewall, we were able to update virus definititions successfully.