Only if you are seeding illegal content (ex. OSX86).
You can be found (MPAA and RIAA have bots that check out their peers ip. They send automated threats to your ISP). Enabling encryption is recommended. Stealing Starbucks wifi is even safer

. Most of the bots are on movies torrents (especially aXXo) and music torrents. They generally don't bother with linux though (it's not illegal

).
Peer guardian is a recommendation, but it blocks alot of legitimate ip addresses also
Cheers