1. CSE331: Introduction to Networks and Security Lecture 14 Fall 2002

2. CSE331 Fall 20022 Announcements Midterm on Wednesday Project 1 due today –Email submissions to achadha@gradient.cis.upenn.edu

3. CSE331 Fall 20023 Today Wrap up discussion of networks –Quality of service –Advanced Networking –Ethereal Review for Exam

4. CSE331 Fall 20024 Integrated Services (RSVP) Proposed in 1995-1997 Service Classes –Guaranteed arrival service For delay intolerant applications Guarantee a maximum delay –Controlled Load For loss tolerant, adaptive applications Emulate lightly loaded network

5. CSE331 Fall 20025 Implementation Mechanisms Flowspecs –Describe the kind of service needed “I need maximum delay of 100ms” “I need to use controlled load service” Admission Control –Network decides whether it can provide the desired service Resource Reservation Protocol (RSVP) –Mechanism to exchange info about requests –Soft state approach Packet Scheduling –Manage queuing and scheduling.

6. CSE331 Fall 20026 Advanced Networking Topics Multicast –Send the same message to a collection of receivers –How to do so efficiently? –Multicast trees

7. CSE331 Fall 20027 (Distributed) Denial of Service Flood a server with bogus requests –TCP SYN packet flood –Up to 600,000 packets per second –Uses up server’s resources, causing legitimate users to be denied service Detection & Assessment? –12,800 attacks at 5000 hosts in 3 week period! –IP Spoofing (forged source IP address) –http://www.cs.ucsd.edu/users/savage/papers/UsenixSec01.pdfhttp://www.cs.ucsd.edu/users/savage/papers/UsenixSec01.pdf Prevention? –Filtering? –Decentralized file storage?

8. CSE331 Fall 20028 Peer-to-Peer networking Gnutella – distributed file sharing –(Unlike Napster, which uses centralized servers) Freenet –Anonymous, decentralized file storage Distributed storage infrastructure –PAST (Rice and Microsoft Research, routing substrate - Pastry) –OceanStore (U.C.Berkeley, routing substrate - Tapestry) –Publius (AT&T) –Farsite (Microsoft Research) –CFS (MIT, routing substrate - Chord) –GRCD(UC Berkeley, builds on CAN)

9. CSE331 Fall 20029 Ad-hoc Networking Wireless Networks No fixed structure How to do routing? –Grid Project http://www.pdos.lcs.mit.edu/grid/http://www.pdos.lcs.mit.edu/grid/ –Make use of Geographic data

10. CSE331 Fall 200210 Active Networking Treat packets as programs The programs –Specify routing requests –Can check link state –Can make decisions based on network conditions Routers interpret these active packets Penn’s switchware project –http://www.cis.upenn.edu/~switchware/