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Hash-Based IP Traceback. U Kang Computer Science Department 15-744 Computer Networks. Motivation. Our network or hosts have been compromised How can we trace the attackers identity?. 2. Problem Definition. IP traceback problem Given packets of interest,
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Hash-Based IP Traceback U Kang Computer Science Department 15-744 Computer Networks
Motivation Our network or hosts have been compromised How can we trace the attackers identity? 2
Problem Definition IP traceback problem Given packets of interest, 1. Identify the source of the packets 2. Construct an attack graph composed of the attack paths for attack packets that arrived at the victim Attack Graph 3
Log-based Traceback • Routers keep the log of packets • If an attack occurs, routers are queried for attack packets
Challenges C1: Minimizing Cost Storage used to keep information C2: Accuracy No false negative Minimize false positive C3: Maintaining Privacy A tracing system should not adversely impact the privacy of legitimate users 5
Proposed Method Source Path Isolation Engine(SPIE) Audit traffic by storing 32-bit packet digests rather than the packets themselves Solves “C1: Minimizing Cost”, “C3: Maintaining Privacy” Bloom Filters to Minimize False Positive Solves “C2: Accuracy” Bloom Filter - add() - isMember() 6
SPIE Infrastructure 1. IDS detects an attack packet 2. IDS issue a traceback request to STM 3. STM asks all SCARS in its domain to poll their respective DGAs for the relevant traffic digests 4. SCARs construct attack subgraphs STM: Traceback Manager SCAR: Collection and Reduction Agents DGA: Data Generation Agent 7
Discussion Deployment: can the SPIE infrastructure be deployed over multiple ISPs? Memory Requirements? A core router with a max. capacity of 640M pkts/sec requires 23 GB for one minute’s storage 8