gtk-gnutella 0.96.4 is over a year old. It is considered outdated and will no longer bootstrap automatically. Your best option is to update but if that isn't possible, you can still bootstrap it manually. All you have to do is connect a single Gnutella peer that you know.

Here is further information on compiling gtk-gnutella yourself or bootstrapping it manually:
https://bugs.launchpad.net/ubuntu/+s...55/comments/12