aMule dev: July 2008

GonoszTopi ported Kademlia version 8, which will be intregrated into our next release. I quote the Changelog:

When calculating the total user count, Kad now uses (if available) the real number of firewalled clients for the calculation instead a fixed value. This will take more effect when 0.49+ nodes become common

Kad no longer tries to add UDP firewalled (and therefore mostly unreachable) nodes into its routing table, reducing overhead and increasing reliability [Idea: Netfinity]

Optimized the Kad packettracking code to only track packets which we check later, to save resources

Fixed a bug which let Kad sometimes assume a Kad2 contact to be Kad1 after probing for both versions

Did first small step in dropping Kad1 support by not probing unknown Kad contacts for Kad1 anymore to save overhead. Kad1 clients will nevertheless still be work for now.

Several changes were made to Kad in order to defy routing attacks researched by University of Minnesota guys [Peng Wang, James Tyra, Eric Chan-Tin, Tyson Malchow, Denis Foo Kune, Nicholas Hopper, Yongdae Kim], in particular:
- Kad contacts will only be able to update themself in others routing tables if they provide the proper key (supported by 0.49a+ nodes) in order to make it impossible to hijack them
- Kad uses now a three-way-handshake (or for older version a similar check) for new contacts, making sure they do not use a spoofed IP
- Unverified contacts are not used for routing tasks
- When reading a nodes.dat without any verified contacts (possible an old file version), aMule will assume all contacts to be verified to avoid slowing down the connecting process

aMule dev