server code or tips on IP validation

[mnicolet]

I need to use FileZilla clients using a zebedee 'tunnel' to a UNIX server.
This is somewhat tricky, because of IP validation for data streams against the control connection. I saw a 'recipe' ( http://www.evidentdata.com/Secure_File_ ... V3.doc.pdf ) using both FileZilla Client and Server.
For the UNIX box, I have only a legacy ftpd source code. I would like to see the relevant portions of the FileZilla Server code which implements
the config options the paper suggest, to 'paste' them into my source.
Also .. why not the full FileZilla Server source code ? Even if not directly portable to the UNIX box.