I once packages a copy of the Freenet software for Debian, back in the old days when I was was young and patient. I haven't maintained that package in a long time, but it's still available from some Debian servers. You can get more information here:
- http://packages.debian.org/oldstable/net/freenet
- http://packages.debian.org/oldstable/net/freenet-unstable
I'm afraid I can't offer any support -- another Debian developer took over the package after I started it, and I don't even know if the software works any more. As of this writing, Freenet is now at version 0.7 or something, so these debs are also extremely out of date.