I need my torrent client 'Transmission' to say to a torrent-tracker that it is another torrent client (uTorrent).
How can I do it? May be there is a simple way...
If no, the question is - where can I edit sources of the transmission port on FreeBSD and then install it?
Masquerading as another torrent client is something to look in the options for.
If you want to edit the sources, though, run "make patch" in the port directory, and then look in the work subdirectory for the sources. (patch will have run the FreeBSD specific patches after unpacking the code)