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

2

NC STATE UNIVERSITY / MCNC

New Capabilities...New Capabilities...

• Discriminating between users; a good thing!– Bandwidth, quality, response time, …

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

3

NC STATE UNIVERSITY / MCNC

...New Vulnerabilities...New Vulnerabilities

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

• Each step is vulnerable!

4

NC STATE UNIVERSITY / MCNC

Attack 1: Excessive User Attack 1: Excessive User DemandsDemands

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

5

NC STATE UNIVERSITY / MCNC

Our Solution: Resource Our Solution: Resource PricingPricing

• (An example: Telephone Network)

6

NC STATE UNIVERSITY / MCNC

Resource Prices Based on Resource Prices Based on DemandDemand

• Predicted-load (static) pricing

• Auction-based (semi-static) pricing

• Congestion-based (dynamic) pricing

• Combined approaches

7

NC STATE UNIVERSITY / MCNC

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

• How much can each user pay?

8

NC STATE UNIVERSITY / MCNC

Provable FairnessProvable Fairness

• Fairness is a policy

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

9

NC STATE UNIVERSITY / MCNC

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

10

NC STATE UNIVERSITY / MCNC

Future Work: Future Work: ImplementationImplementation

• Fall 2000 (management tools: Summer 2001)

11

NC STATE UNIVERSITY / MCNC

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

• Spring 2001

12

NC STATE UNIVERSITY / MCNC

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, ...?

13

NC STATE UNIVERSITY / MCNC

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

14

NC STATE UNIVERSITY / MCNC

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

15

NC STATE UNIVERSITY / MCNC

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

16

NC STATE UNIVERSITY / MCNC

Attack 4: Compromised Attack 4: Compromised DiffServ RoutersDiffServ Routers

17

NC STATE UNIVERSITY / MCNC

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