1. Architectural Considerations for Protecting End Hosts Vern Paxson International Computer Science Institute and Lawrence Berkeley National Laboratory vern@icir.org June 28, 2007

2. Overview Previous session looked at architectural issues for the network securing its own infrastructure Now, we consider the networks role (if any) in protecting end systems Two parts: –What should its role be? –Architectural approaches for DoS defense

3. Agenda, Part 1 What should the networks role be? –Its inevitable that the network will be intrusive with end system traffic, lets architect for it (Vern Paxson) –No lets not, #1 (Paul Syverson) –No lets not, #2 (Nick Weaver) –Discussion

4. Agenda, Part 2 How should the network protect against DoS? –Framing of problem space (Stefan Savage) –The role of identifiers (Stefan Savage) –The role of indirection (Angelos Keromytis) –The role of capabilities (Xiaowei Yang) –Discussion

5. A Glum Vision That We Had Better Plan For Network operators want to control traffic –Control = inspect, modify, tune, censor, confine … for a large variety of reasons: –Policy enforcement –Endhost security –Wiretap / legal intercept –Censorship –Walled gardens / business reasons –Performance engineering

6. Glum Vision, cont Furthermore, they have the power to do so since they hold the fundamental property of connectivity … … unless they are constrained: –By law Unpredictably difficult to shape in a useful fashion –By competitive concerns But these are trumped by law and sole-sourcing

7. Glum Vision, cont We have existence proofs that network operators will go to significant lengths to shoehorn in such control Question: would we like this stuff shoehorned into our future Internet, or directly recognized as a tussle? (Q: will end-to-end crypto save us? A: No, reduces to steganography.)

8. How to Architect for this Tussle? One approach (w/ S. Shenker, M. Allman): –When instantiating communication, end nodes negotiate with network regarding degree of inspection/meddling What will be revealed, what can be modified How to express range of semantics? –If unacceptable, seek alternate paths –Both parties require mechanisms to police for adherence –Already today for SIP proxies, P3P