1. Security and Cooperation in Ad Hoc Networks Gaia Maselli IIT - CNR gaia.maselli@iit.cnr.it

2. The availability problem Problem: how to avoid that some nodes misbehave to find out a mechanism to detect and isolate misbehaving nodes Cooperation misbehavior Malicious misbehavior: intentional DoS attack Selfishness: no routing/forwarding to save resources

3. Current approaches Watchdog + Reputation system Watchdog weaknesses: a node might not detect a misbehaving node in presence of –collisions –no homogeneous transmission ranges Drawbacks of cooperation in security mechanisms –overhead (additional traffic) –wrong accusations spreading

4. A different approach? New challenges –Detection of misbehaving nodes without watchdog –No spreading of false information ?