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Architectural issues for network-layer identifiers

Architectural issues for network-layer identifiers. Stefan Savage Dept of Computer Science & Engineering UC San Diego. Historical context. I n the beginning... it was amazing the net worked at all. Everyone was a good actor. Existing Internet design. Focused on universal connectivity

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Architectural issues for network-layer identifiers

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  1. Architectural issues for network-layer identifiers Stefan Savage Dept of Computer Science & Engineering UC San Diego

  2. Historical context In the beginning... it was amazing the net worked at all. Everyone was a good actor.

  3. Existing Internet design • Focused on universal connectivity • IP address Identifiers purely for the purpose of connectivity • Dst address for routing, Src to identify destination for replies • Strictly voluntary • Actively trying to introduce homogeneous substrate • Unbound usage model • Security not a significant consideration in the network layer; trust everyone equally • Cryptography expensive relative to transport • Cryptographic abstractions limited • True when IPSec designed also

  4. What has changed? • Many users/providers don’t want homogeneity • Most src addresses today are NATed • We want to limit who can talk to whom • Huge growth in criminal activity • 10s of millions of compromised machines • Sophisticated abuse of network layer

  5. Problems • Network architecture provides “how” • Security questions are mainly about “who” and “what” • Ad hoc, brittle mappings between two • Firewalls (address, port) • Ingress/egress filtering • DDoS filtering (ttl hack, blackholing, etc) • Key issue • Can’t count on src address being correct or global • Even if it is correct only represents existence of endpoint

  6. Worth rethinking… • How might we design packet identifiers to provide useful attribution? • Attribution – working definition: The act of linking identity with action • Uses • Authentication: who wants to do that? • Access control • Situational awareness: who is doing that now? • Operational response (e.g. filtering DDoS, BotNet C&C) • Forensics: who did that in the past? • Investigatory, evidentiary

  7. Design options • Meaning of identifier • Network attribute • IP address: topological endpoint • Path: topological route (StackPI) • Physical attribute • Location: place packet sent from (used today in payment sys) • Originator: machine packet sent from • User attribute • Capability: right to access something • Principal: evidence of individual • Scope of identifier (local, global, in-between) • Who can interpret (anyone, trusted party, hybrid)

  8. New opportunity • Crypto has advanced significantly • Many operations are comparatively cheap now • 10’s of microseconds • Line-rate hardware implementations feasible • Completely new kinds of cryptography • Groups, aggregates, append-only, IBE, Attribute-based crypto, homomorphic crypto, broadcast systems, etc • Its not just encrypt, hash and sign anymore… • New tools provide new design opportunities

  9. Remaining agenda • Revisiting the Cryptographic toolbox (Boneh) • Local identifiers for access control (Casado) • Global identifiers for forensics (Savage)

  10. Attribution • To whom

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