1. Vulnerabilities of Reliable Multicast Protocols Thomas M. Park, David A. Kassay, Clifford J. Weinstein Massachusetts Institute of Technology Lincoln Laboratory Lexinton, Massachusetts Reviewed by: Siu Fung (Andes) Chin

2. Vulnerabilities of Reliable Multicast Protocols Outline Introduction Types of Protocols Attacks Defenses Conclusion

3. Introduction Multiple unicast transmission TCP/IP Multicast transmission RMP SRM

4. Introduction (cond.) Why reliable multicast transmission? More efficient Problems? Lack of security Solutions? Network-level security (IPSEC) Secret-key algorithm Risk management approach

5. Types of reliable multicast protocols Sender-initiated reliability protocol Positive acknowledgment (ACK) ACK implosion Example: RMP(Reliable Multicast Protocol) Token around ring

6. Types of reliable multicast protocols (cont) Receiver-initiated reliability protocol Negative acknowledgment (NCK) NCK implosion Example: SRM(Scalable Reliable Multicast Protocol) Suppress excess NAK

7. Vulnerabilities Flooding attack Consume network bandwidth/process time Forged data attack Corruption of files transmitted (RMP) Premature ACK Assign incorrect sequence no. (RMP) NAK and retransmission suppression Interfare retransmissions (SRM)

8. Defense Fliter received packets Block attacker’s packet Digitally signed messages Identify legitimate members Employ IGMP v3 (Internet Group Management Protocol) Prevent flooding Simple authentication protocol Prevent spoofing

9. Conclusion Different types reliable multicast protocol Different types attack Different types defense Increase protection – increase cost Questions?