Hello, I work in an ISP and we use PeerAp for caching some repetitive contents: - videos (via HTTP or p2p) - windows and antivirus updates It works quite right... but it's not fully open source. It's Linux based (SSH, BASH, iptables,...) but the interesting part is closed :-) Globallly, its based on the hash of the N-th firt bytes of a ressource. If you have an idea of what it is, would you know an equivalent, but open source? This is their website: http://www.peerapp.com some blog talking about it http://www.israel-on-blog.com/peerapp-unclogging-the-video-internet-traffic/ -- Architecte Informatique chez Blueline/Gulfsat: Administration Systeme, Recherche & Developpement +261 33 11 207 36