either side must fordward some port above 1024 range to their computer...
probably server side so there's less work for clients.
consider reading
http://www.dslreports.com/forum/rema...p,16~mode=flat
http://www.dslreports.com/forum/rema...16%3Bmode=flat
http://www.dslreports.com/faq/linksys