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On the Accurate Identification of Network Service Dependencies in Distributed System
Barry Peddycord IIIon 13 December 2012
Transcript of On the Accurate Identification of Network Service Dependencies in Distributed System
NC State University
@isharacomix On the Accurate Identification of Network
Service Dependencies in Distributed Systems Motivation USENIX LISA '12
#NSDMiner MySQL DB Web Portal Shibboleth Client Machine Local-Remote Dependency Remote-Remote Dependency Approaches that involve installing an agent on the machines to be monitored in the form of a kernel module or middleware. Host-Based Approaches Example NSDMiner Evaluation Deployment Conclusions Problem Network Service Dependencies Defined by configuration parameters and source code
Each service does it differently!
Often very intricate and subtle
Hard to keep track
How good are YOUR docs?
Want to identify them automatically Prior Work Two Paradigms Patterns in the behavior of the network can model its structure
Previous approaches fall into two categories: A dependency is a relationship between two services A and B such that A (the depending service) contacts B (the depended service) to complete a task. A network service is a software application that runs on a server and listens on a port for connections from other applications. Host-Based Accurate, but intrusive Install an agent (i.e. a kernel module) to track socket/application behavior
Magpie [OSDI 2004]
Pinpoint [NSDI 2004]
Macroscope [CoNEXT 2009]
Intrusiveness makes them unattractive
Resource contention Network-Based Treat hosts as black boxes Data-mine on-the-wire network traffic to extract relationships
Sherlock [SIGCOMM 2007]
eXpose [SIGCOMM 2008]
Orion [OSDI 2008]
NSDMiner [INFOCOM 2011]
High-false positive/false negative rates Why bother? Know thyself If dependencies are discovered after a failure occurs, it's too late
Knowing in advance
Improves response time
Allows pro-active action to be taken on mission-critical services
Networks are dynamic Intuition NSDMiner Non-intrusive and fairly accurate
Open Source Python Module
Future work includes
Making it work in real time
Identifying remote-remote dependencies This work is supported by the U.S. Army Research Office (ARO) under MURI grant W911NF-09-1-0525 Dr. Peng Ning
NC State University
email@example.com Dr. Sushil Jajodia
George Mason University
firstname.lastname@example.org Ranking Confidence equals: log( number of nested A->B flows )
log( number of times A is accessed ) Post-processing Given a Communication Graph Less-used services are vulnerable to false positive, false negative
Post-processing uses overall structure to fine-tune results Why logs? Two Important Properties Not all nested flows are equal
Give candidates with more evidence more weight
"every other flow" means more when it's 10000 than 100
Later flows are worth less
Is 90% less convincing than 95%? Inference Clustering The Output List of Dependency Candidates Returns each network service and all of its dependency candidates
Dependencies ordered by most-likely to least-likely
Should be verified by hand, so a few false positives are acceptable Design NSDMiner Clustering Inference Open Source Available on SourceForge Written as a Python Module
Comes with a command-line interface for processing data What's needed Collect the Data Collect all network traffic from network switches
Export netflows from switches
Use packet mirroring - forward and save all pcap headers of packets
Usually a week of packets is needed Using NSDMiner Just install and run! Run 'nsdminer' to process your data
Command line options let you choose various parameters
Detailed in the paper and README
Output will be a list of services, dependencies, and confidence values Going Beyond Extend and improve NSDMiner using the features of the 'nsdminer' Python library.
Use it in your own networks and let us know how it works for you in the SourceForge forum! Intuition Consider a Web Host Many servers are configured the same way (HTTPD) with the same dependencies (MySQL, SMTP, etc)
Some are more popular than others, having more traffic
Identify dependencies of less used servers by identifying 'similar' services Example Ground truth: All A's depend on D's Observed traffic: Sim 2/3 Sim 1/2 Similarity(X,Y) = shared deps
total deps Intuition Backups and Load-Balancing In a load-balancing cluster, a depending service will eventually utilize all cluster nodes
In a backup-cluster, a service will use the primary nodes until they fail, then move to backup nodes
In both cases, if a service uses one node in a cluster, it uses them all Example 75% Agreement 75% Agreement 100% Agreement Algorithm Identify all pairs of similar services above a certain similarity threshold
Combine pairs into similarity groups
Calculate agreement on dependency candidates
Infer dependencies from members of similarity group to most agreed-upon candidates Algorithm Count the number of times that pairs of services are depended upon by the same service
For services that have support above a certain threshold, these services are considered to be in clusters
Re-interpret services that depend on services in clusters as depending on the entire cluster itself.