Restricting Access through Router Help

[KeithO]

I wonder if anybody could help. I have a D-Link Wireless Router and a Buffalo LinkStation.

Reading the details I noticed that the LinkStation has a FTP server build it. Set it up and changed the router to allow access (from the internet) to the FTP server.

One thing I could not see was how to restrict the people (to my work machine) who has access. Would like to restrict all but certain IP addresses and would appreciate any help. I guess it would be on the router but I can only see Filters which are for access out.

Thanks in advance.

keith