NC STATE UNIVERSITY / MCNC Protecting Network Quality of Service Against Denial of Service Attacks...

NC STATE UNIVERSITY / MCNC

Protecting Protecting Network Quality of Network Quality of

Service Against Service Against Denial of Service AttacksDenial of Service Attacks

Douglas S. Reeves S. Felix Wu Fengmin Gong

Talk: “00-17 reeves”CACC Research Review Meeting

October 25, 2000

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New Capabilities...New Capabilities...• Discriminating between users; a

good thing!– Bandwidth, quality, response time, …

• Based on trust, need, importance, credit, urgency, .... : Policies!

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...New Vulnerabilities...New Vulnerabilities

• Steps– provisioning– user signaling– Admission control– network signaling– Traffic policing

• Each step is vulnerable!

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Attack 1: Excessive User Attack 1: Excessive User DemandsDemands

• Everyone asks for...– ...maximum resource amount– ...premium service

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Our Solution: Resource Our Solution: Resource PricingPricing

• (An example: Telephone Network)

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Resource Prices Based on Resource Prices Based on DemandDemand

• Predicted-load (static) pricing• Auction-based (semi-static) pricing• Congestion-based (dynamic) pricing• Combined approaches

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Policy Specification / Policy Specification / EnforcementEnforcement• What determines the price?

• How much can each user pay?

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Provable FairnessProvable Fairness

• Fairness is a policy• Achievable...

– Pareto optimal– Weighted max-min fair– Proportional fair– Equal QoS– Maximal aggregate utility– Maximum revenue

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Comparison With Other Comparison With Other Approaches Approaches • First-come, first-served

– “grab resources early and often”• Fixed (absolute) priority

– starvation problems• Non-weighted fairness (TCP)

– everyone is equal?• Other resource pricing work

– static / centralized, restricted fairness

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Future Work: Future Work: ImplementationImplementation

• Fall 2000 (management tools: Summer 2001)

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Fut. Wk.: 3rd Party Fut. Wk.: 3rd Party AuthorizationAuthorization

• Spring 2001

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Future Work: Service Class Future Work: Service Class ProvisioningProvisioning• Given predicted demand for each

service class...– how much of each service class should

network owner provision?– what price charge for each class?

• Goals: maximum profit, maximum utility, ...?

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Future Work: Protecting Future Work: Protecting the Pricing Mechanismthe Pricing Mechanism• Vulnerability to attack• Protecting…

– RSVP– COPS– SIP– Policy server and databases– Authorization server, user database,

billing database• Spring 2002

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Impact of This WorkImpact of This Work

• Disincentives for "bad" user behavior• Ability to flexibly specify and enforce

policies• Efficient (optimal) allocation• Economic incentives for deployment

of new services

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Attack 3: TCP Packet Attack 3: TCP Packet DroppingDropping• Congestion causes "normal" packet

dropping• Can malicious packet dropping (not

due to normal congestion) be detected?– due to corrupted routers– due to "unfriendly" users

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Attack 4: Compromised Attack 4: Compromised DiffServ RoutersDiffServ Routers

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Attack TypesAttack Types

• Dropping one data flow to benefit others

• Injecting(spoofing, flooding,...) packets to a high priority flow

• Remarking packets in a data flow• Delaying packets in a data flow• Compromised ingress, core, or

egress routers

NC STATE UNIVERSITY / MCNC Protecting Network Quality of Service Against Denial of Service Attacks...

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