1. P2P Networking: Freenet Adriane Lau November 9, 2004 MIE456F

2. Agenda What is P2P networking? What is Freenet? Philosophy behind Freenet How does Freenet work? Comparison with other P2P networks Future work

3. *From http://en.wikipedia.org/wiki/Peer-to-peer What is P2P Networking? Direct communication between clients (nodes) No dedicated servers Nodes function as both clients and servers

4. *From http://freenetproject.org/index.php?page=whatis What is Freenet? Decentralized P2P network Allows anonymity of publishers and consumers Shared file storage Encrypted data

5. *From http://freenetproject.org/index.php?page=philosophy Philosophy Behind Freenet Importance of free flow of information, communication & knowledge Democracy assumes a well-informed population Censorship restricts freedom Anonymity protects freedom of speech

6. *From http://freenet.sourceforge.net/papers/freenet-ieee.pdf How Does Freenet Work? Privacy  Messages travel through node chains  Nodes can’t tell difference between original & forwarded messages Globally Unique Identifiers (GUID)  Content-hash keys (CHK)  Signed-subspace keys (SSK)

7. *From http://freenet.sourceforge.net/papers/freenet-ieee.pdf How Does Freenet Work? Routing  Forward query to nodes closest to target Requesting files  Requests forwarded until data holder is found Adding files  Generate GUID key & search for it  If “all clear”, data is stored & documented

8. *Adapted from http://freenetproject.org/papers/freenet-ieee.pdf How Does Freenet Work? a b c d e f Data request Failed request Data reply

9. *From http://freenet.sourceforge.net/papers/freenet-ieee.pdf How Does Freenet Work? Adding a node  Send an announcement to a node  Announcement forwarded randomly; nodes add information about new node Training routes  Nodes on the way back may cache copies  Nodes specialize in searching certain keys

10. *From http://freenet.sourceforge.net/papers/freenet-ieee.pdf How Does Freenet Work? Searching  Currently no search algorithm exists  Proposed solution: keyword files Managing storage  File insertion & storage not restricted  Files prioritized according to popularity; unpopular files deleted when node disk space runs out

11. Comparison Napster  Centralized server Gnutella  Inefficient broadcasting OceanStore, Cooperative File System, PAST  Data placement dependent on node location

12. *From http://freenet.sourceforge.net/papers/freenet-ieee.pdf Future Work Next generation routing protocol  Aimed to make nodes even “smarter” in routing requests  Each node stores detailed information about other nodes Response time for particular keys Proportion of successful requests Connection time

13. *From http://freenet.sourceforge.net/papers/freenet-ieee.pdf Future Work Search mechanism  Metadata Prevention of denial-of-service attacks Better ways to locate data

14. Conclusion Freenet is a P2P architecture aimed to protect freedom of speech Messages are forwarded back and forth; nodes can’t tell where a message originated

15. Thank you! Questions