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Policy and mechanism in the future Internet. Michael Walfish The University of Texas at Austin in collaboration with: Arun Seehra (UT Austin), Jad Naous (Stanford), David Mazières (Stanford), Antonio Nicolosi (Stevens), and Scott Shenker (UC Berkeley/ICSI).
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Policy and mechanism in the future Internet Michael Walfish The University of Texas at Austin in collaboration with: Arun Seehra (UT Austin), Jad Naous (Stanford), David Mazières (Stanford), Antonio Nicolosi (Stevens), and Scott Shenker (UC Berkeley/ICSI)
Who should control communications?What should they control? • Many stakeholders:senders, receivers, transit providers, edge providers, middleboxes, … • Each has many policy- and security-related goals scrubbing service • Where do your sympathies lie?
Many network-layer proposals and defenses • ACLs, NATs, VPNs, Platypus, TVA, NUTSS, i3, DOA, NIRA, LSRR, firewalls, source routing, whitelisting, blacklisting, securing BGP, provider filtering based on sender, provider filtering based on receiver, signature matching, network capabilities, telephoning your ISP, telephoning your attacker’s ISP, …
source routing xo o o o o Secure BGP NIRA Capabilities Platypus Filters - -- o x o - -o x o o - o x o o o ox o o o o x o o - -- -- - oo x o - - - -x xooo o o o --x- o o -x - - o ox - - - o o ---x o o --x- o o -x - - o ox - - - o Prior works: large union, small intersection • Proposals generally choose particular concerns • To the exclusion of other concerns
What are our options? • Embrace the status quo: do nothing • This is unsatisfactory • Make a hard choice: select the “right” subset • This would be a gamble … • … on a choice that might last another 30 years … • … by a community not known for accurate predictions • Choose “all of the above”:take a principled union • This is the most future-proof strategy possible • And it empowers all stakeholders (at least potentially)
We propose a unified policy framework xo o oo o o ooo o o o x ooox o o o o x oooo o o o ooox o o o xooo o o o ooxo o policy principle: • Let every participant formulate policies based on: • Packets’ end-to-end paths at the domain level • Intra-domain handling (links, router queues, …) • Arbitrary other information (billing, time of day, …) • Subsumes goals of prior network-layer proposals • Obvious in hindsight
xo o oo o o ooo o o o x ooox o o o o x oooo o o o ooox o o o xooo o o o ooxo o • What policy considerations should a future Internet support? • Can we build a supporting mechanism? • There are many challenges here • My goal is to convince you it’s feasible … • … with ICING, which we implemented in hardware • What are the uses of ICING?
What are the technical challenges? • Letting the control plane specify arbitrary policies • Requires new interface between control/data planes • Enforcing policy decisions in the data plane • Requires new packet authentication techniques • Delegating policy decisions • Bootstrapping
What should be the control/data plane interface? • Policy decisions need to be prior to packet flow • So move policy from routers to evolvable servers • Servers can delegate or abdicate their control General-purpose servers path, info. stuff payload other stuff
What is needed to enforce policy at high speed? • Data plane must check that path is authorized • Data plane must check that path was followed • This is a hard technical problem • Status quo not even close (BGP only advisory) • Target environment rules out previous techniques • Backbone speeds preclude digital signatures • Federated nature of Internet precludes central root of trust, pre-configured shared secrets, etc.
ICING’s data plane in a nutshell • Binds a packet to its path • Packet carries path (list of public keys), verifiers • Realms use ki,j to transform verifiers • For j<i, Riverifies provenance using kj,i • For j>i, Riproves provenance to Rj using ki,j • No key distribution: Ri derives ki,j from Rj’s name • Resists attack: forgery, injection, short-circuiting, … • Feasibility:is required space, computation tolerable?
R0 R1 R2 R3 R4 M 18 bytes 24 bytes (ECC) ICING is feasible • Space overhead? • Average ICING header: ~250 bytes • Average packet size: ~1300 bytes [CAIDA] • So, total overhead from ICING: ~20% more space • What is the hardware cost? • NetFPGA gate counts: ICING is 13.4 M, IP is 8.7 M • NetFPGA forwarding speed: ICING is ~80% of IP • ICING vs. simple IP in gates/(Gbits/sec): ~2x
xo o oo o o ooo o o o x ooox o o o o x oooo o o o ooox o o o xooo o o o ooxo o • What policy considerations should a future Internet support? (A: Those given by the policy principle) • Can we build a supporting mechanism? (A: Yes. ICING is an existence proof.) • What are the uses of ICING? (Quick preview: • New kinds of routing, • Flexible network access control, • New provider business models, and more)
BGP’s choice of paths, enforced BGP BGP consent server 1 consent server 2 consent server 3 “dest” Data plane Data plane Data plane sender R3 R2 R1 dest. path = <sender R1 R2 R3 dest> use <PoC1 PoC2 PoC3 PoCdest> <R2 R3 dest>, <s2 s3 sdest >
ICING permits “sink routing” <S R1 R2 R3 dest> < PoC2 PoC3 PoCdest > • Analogous to source routing • Lets receivers choose paths to minimize latency, cost • (As CDNs do today using crude DNS tricks) • Lets receivers choose trustworthy providers to carry sensitive data to them consent server 3 R2 S dest R1 R3
Special case of sink routing:forcing flows through offsite scrubbing services consent server sender enterprise offsite scrubber dest.
ICING provides flexible access control consent server • Can delegate consent-granting to specialist • Or let some clients (employees) mint PoCs • And restrict which servers employees can reach employee
Other uses of ICING • Many control planes work with ICING’s data plane • ICING can emulate TVA, NIRA, Pathlets, LSRR, etc. • New provider business models • Sell transit to anyone, not just direct neighbors • (Not a new vision, but ICING’s enforcement is key) • Fine-grained intra-domain packet disposition • Senders, providers can negotiate over this • Key mechanism: per-realm vnodes in packets
Limitations…. … of this talk • Didn’t talk about network failure • Didn’t talk about expiration and revocation • Didn’t talk about deployment … of ICING • Does not prevent transparent outsourcing of transit • But lets senders choose whom to trust • Cannot forward packets differently based on payload • Cannot modify packet payload during transit
Future work • Defending against intelligent replay attacks • Detecting unsatisfactory service by providers • Preventing unauthorized subcontracting of transit • E.g., prevent ISP from redirecting through country X
Recap • Many good policies; no consensus on “best” • So try to uphold “all of the above”: • ICING is our candidate mechanism • Binds data plane to dictates of control plane • Today: not implausible. Tomorrow: not impractical. • 100,000-foot view: bandwidth and computation keep increasing, so use them to buy new properties • We think ICING’s properties are worth its price xo o oo o o ooo o o o x ooox o o o o x oooo o o o ooox o o o xooo o o o ooxo o