1 Towards Secure Interdomain Routing For Dr. Aggarwal Win 2004

2 Content Background Current protocol Security problems Solutions Conclusion Reference

3 Background Routing Determine the path that IP packets take to go from their source to their destination Interdomain Routing Routers (compute desired path) are grouped together called Autonomous Systems (Management Domains). Inter-Autonomous System routing.

4 Current Protocol Border Gateway Protocol RFC 1771 & 1772, March 1995 BGP-4 along with Interior Gateway Protocol (IGP) AS announces IP address ranges called prefixes Full AS paths enforces routing policies Local traffic, transit traffic AS – Stub AS, Multihomed AS, Transit AS

5 Attributes Weight Local preference Multi-exit discriminator Origin AS_path NextHop Community

6 Security Problems Message may not be correct and authentic Path may not be authentic AS may not have the authority to advertise a prefix

7 Solutions Secure Border Gateway Protocol (S- BGP) Internet Route validation (IRV) Secure Origin BGP (soBGP) Origin Authentication Services

8 S-BGP IP security protocol suite Encapsulating Security Payload (ESP) new BGP path attribute with attestations - route attestations - address attestations Public Key Infrastrcture(PKI) - public key certificates

9 IRV IRV servers maintain routing data received and advertised Validation by out-of-band mechanism and potentially secure protocol

10 soBGP EntityCert – ties an AS number to a public key with attested keys as root keys AuthCert (in Prefix PolicyCert) – ties an AS to a block of addresses ASPolicyCert – verifies that the advertiser does have a path to the destination Note: new BGP message (SECURITY)

11 Deployment Option Direct Certificate Exchange - exchange certificates with their peers Exchange by Edge Router - edge routers exchange certificates - internal servers process information

12 Origin Authentication Services Formalization Modeling Simulation Evaluation

13 Formalization ASN = {1,2,…K} be the set of all Autonomous System Numbers, K = 2 16 O be the set of all organizations which can own prefixes S be the set of all BGP speaking organizations C be an organization; C  S and ASN(C) be the set of AS numbers current assigned to C IPA = {0,1} l be the set of all l -bit IP addresses; l =32 for IPv4 and l =64 for IPv6 x/j is the address prefix (often called prefix) If y/k is a prefix of C. Address assignments or delegations can be formally expressed as a) (C, y/k, n) where n ASN; C assigns y/k to an AS number n b) (C, y/k, C’) where C’ O; C delegates y/k to C’ c) (C, y/k, R); C declares y/k as RESERVED thus neither advertised nor delegated

14 Delegation Path Valid - ownership source is IANA - path is monotonic - path is acyclic - assignment edge is ASN-respecting ( ASN(C), R or  )

15 Modeling Origin Authentication Services - Delegation path is valid - Set of delegation attestations is verified - assignment edge is certified Delegation Attestations - Simple delegation attestation - Authenticated delegation list - Authentication Delegation Tree - Authentication Delegation Dictionaries

16 Simulation Trace-based simulation on a single BGP speaker on April 2, UPDATE messages are recorded over a 24 hour period Four models are implemented:- - simple attestation - AS authenticated delegation list - Authenticated list - Authenticated delegation trees

17 Observation Signature validation (ordered most costly to the least) - simple attestation - AS authenticated delegation list - Authenticated list - Authenticated delegation trees On-line and Off-line Origin Authentication - Authenticated delegation lists are significantly more expensive Caching - Tree scheme outperforms the others Caching without organization load - authenticated delegation lists out-performs AS authenticated delegation list

18 Evaluation Discussed Origin Authentication Services Models are feasible Approximation of the delegation graph is supported by studies of BGP Underestimated ownership sources and delegation would not affect the quality of the result

19 Conclusion BGP is problematic Secure Border Gateway Protocol - studied since 1996 is not complete Internet Route Verification - solved only part of the problems Secure Origin Border Gateway Protocol - not deployed Origin authentication service – resource costs can be significantly reduced

20 Reference 1. W. Aiello, J. Ioannidis, P. McDaniel. Origin Authentication in Interdomain Routing. In Proceedings of the 10 th ACM Conference on Computer and Communication Security, page 165 – 178, October 2003, Washington, DC, USA 2. K. Seo, C. Lynn, and S. Kent. Public-Key Infrastruture for the Secure Border Gateway Protocol (S-BGP). In Proceedings of DARPA Information Survivability Conference and Exposition II. IEEE, June Y. Rekhter and T. Li. A Border Gateway Protocol 4 (BGP4). Internet Engineering Task Force, March RFC Y. Rekhter and P. Gross. Application of the Border Gateway Protocol in the Internet, March RFC 1772