Controlling access to a file includes selecting, by a first network node in a peer to peer file sharing system, a file to make available for sharing with a second network node in the peer to peer file sharing system, the file being stored on the first network node. The first network node sends index information associated with the selected file to the second network node. The second network node subsequently performs a local search of a set of index information associated with a set of files stored in the peer to peer file sharing system to locate the index information for the selected file; and requests a copy of the selected file from the first network node using the index information.