UTCS Colloquium/FACULTY CANDIDATE: Michael Walfish - FACULTY CANDIDATE Massachusetts Institute of Technology CSAIL Defending Networked Resources Against Floods of Unwelcome Requests ACES 2.302 Thursday April 26 2007 at 11:00 a.m.

Contact Name: 
Jenna Whitney
Apr 26, 2007 11:00am - 12:00pm

There is a signup schedule for this event.
Speaker Name: Michael Walfish - FACULTY CANDIDATE

Speaker Aff

iliation: Massachusetts Institute of Technology CSAIL

Date: April
26 2007

Start Time: 11:00a.m.

End Time: 12:00p.m.

Location: ACES 2.302

Host: Lorenzo Alvisi

Talk Title: Defe

nding Networked Resources Against Floods of Unwelcome Requests



The Internet is afflicted by unwelcome requests defined b

as claims on a scarce resource such as a server''s CPU (in

the case of spurious traffic whose purpose is to deny service)
or a hum

an''s attention (in the case of spam). Traditional
responses to these p

roblems apply heuristics: they try to
identify bad requests based on th

eir content (e.g. in
the way that spam filters analyze an email''s tex

t). This
talk argues that heuristic attempts at filtering are inherent

gameable and instead presents two systems that limit request

umes directly. The first is a denial-of-service mitigation
in which cli

ents are encouraged to automatically send *more*
traffic to a besieged

server. The good clients can thereby
compete equally with the bad ones.
The second is a system
for enforcing *per-sender email quotas* to cont

rol spam.
This system scales to a workload of millions of requests

per second tolerates Byzantine faults in its constituent
hosts and re

sists a variety of attacks.