I am using the Virtual Server settings under NAT Forwarding to forward ssh (port 22) to a server on my lan.  I want to restrict access at the router to this server by IP address.  That is I only want one public ip address to have access to this server from the public internet.    

I can blocking this on the server but it would be more secure to not allow any other ip's to even get to the server for it to reject. 

Thanks.