HEya Henry -
the linksys router has an administrative interface that your friend might be able to get into - usually it lives at 192.168.0.1 so he can point his web browser to http://192.168.0.1 and perhaps log in
and then look at the DMZ and port mapping.

Linksys web site ? I don't look at it usually - so have no idea ...
I usually 'get by' from using the vendor supplied software .

hth - mondo regards [Bill]