Anomaly Detection in Carrier Networks Using Network-Wide Flow Data
In this presentation at NANOG35, we introduced a general system for detecting and classifying traffic anomalies in carrier networks. By leveraging network-wide flow data, we can identify a variety of anomalies associated with both operational and malicious events. We discussed the challenges of distinguishing normal from anomalous behavior in high-dimensional data and presented our Subspace Method for systematic anomaly detection. The approach uses statistical thresholds and clustering techniques to classify anomalies efficiently, minimizing false alarms while achieving high sensitivity.
Anomaly Detection in Carrier Networks Using Network-Wide Flow Data
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Presentation Transcript
Mining Anomalies in Network-Wide Flow Data Anukool Lakhina with Mark Crovella and Christophe Diot NANOG35, Oct 23-25, 2005
My Talk in One Slide • Goal: A general system to detect & classify traffic anomalies at carrier networks • Network-wide flow data (eg, via NetFlow) exposes a wide range of anomalies • Both operational & malicious events • I am here to seek yourfeedback
Network-Wide Traffic Analysis • Simultaneously analyze traffic flows across the network; e.g., using the traffic matrix • Network-Wide data we use: Traffic matrix views for Abilene and Géant at 10 min bins
NYC LA ATLA HSTN Power of Network-Wide Analysis Peak rate: 300Mbps; Attack rate ~ 19Mbps/flow IPLS Distributed Attacks easier to detect at the ingress
But, This is Difficult! How do we extract anomalies and normal behaviorfrom noisy, high-dimensional data in a systematic manner?
The Subspace Method[LCD:SIGCOMM ‘04] • An approach to separate normal & anomalous network-wide traffic • Designate temporal patterns most common to all the OD flows as the normal patterns • Remaining temporal patterns form the anomalous patterns • Detect anomalies by statistical thresholds on anomalous patterns
One Src-Dst Pair Dominates: 32% of B, 20% of P traffic Cause:Bandwidth Measurement using iperf by SLAC An example user anomaly
Multihomed customer CALREN reroutes around outage at LOSA An example operational anomaly
Summary of Anomaly Types Found[LCD:IMC04] False Alarms Unknown Traffic ShiftOutageWormPoint-Multipoint Alpha FlashEvents DOS Scans
Automatically Classifying Anomalies[LCD:SIGCOMM05] • Goal: Classify anomalies without restricting yourself to a predefined set of anomalies • Approach: Leverage 4-tuple header fields: SrcIP, SrcPort, DstIP, DstPort • In particular, measure dispersion in fields • Then, apply off-the-shelf clustering methods
(SrcIP) Example of Anomaly Clusters Dispersed Legend Code Red Scanning Single source DOS attack Multi source DOS attack (DstIP) (SrcIP) Dispersed Concentrated Summary: Correctly classified 292 of 296 injected anomalies
Summary • Network-Wide Detection: • Broad range of anomalies with low false alarms • In papers: Highly sensitive detection, even when anomaly is 1% of background traffic • Anomaly Classification: • Feature clusters automatically classify anomalies • In papers: clusters expose new anomalies • Network-wide data and header analysis are promising for general anomaly diagnosis
More information • Ongoing Work: implementing algorithms in a prototype system • For more information, see papers & slides at: http://cs-people.bu.edu/anukool/pubs.html • Your feedback much needed & appreciated!