SANOG 34: Securing Internet Routing
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This document discusses securing internet routing by validating route origins and paths. It describes some of the issues with the current routing system, including that there is no single authority and routing works based on rumors. It then introduces the Resource Public Key Infrastructure (RPKI) system, which uses digital signatures and certificates to validate route origins by tying IP addresses and autonomous system numbers to their legitimate holders. This allows for route origin validation using Route Origin Authorizations (ROAs). It notes that AS path validation is also needed to fully secure routing, but faces challenges in terms of resources and adoption. Basic routing security practices and industry initiatives are recommended in the meantime.
SANOG 34: Securing Internet Routing
- 1. 1 Securing Internet Routing Tashi Phuntsho (tashi@apnic.net) Senior Network Analyst/Technical Trainer
- 2. 22 Why should we bother? • As a Manager – I don’t want to be front page news of a IT paper, or an actual newspaper for routing errors
- 7. 77 Headlines
- 8. 88 Why do we keep seeing these? • Because NO ONE is in charge? – No single authority model for the Internet • No reference point for what’s right in routing
- 9. 99 Why do we keep seeing these? • Routing works by RUMOUR – Tell what you know to your neighbors, and Learn what your neighbors know – Assume everyone is correct (and honest) • Is the originating network the rightful owner?
- 10. 1010 Why do we keep seeing these? • Routing is VARIABLE – The view of the network depends on where you are • Different routing outcomes at different locations – ~ no reference view to compare the local view L
- 11. 1111 Why do we keep seeing these? • Routing works in REVERSE – Outbound advertisement affects inbound traffic – Inbound (Accepted) advertisement influence outbound traffic
- 12. 1212 Why do we keep seeing these? • And as always, there is no E-bit – a bad routing update does not identify itself as BAD • RFC 3514 😉 • So tools/techniques try to identify GOOD updates
- 13. 1313 Why should we worry? • Because it’s just so easy to do bad in routing! By Source (WP:NFCC#4), Fair use, https://en.wikipedia.org/w/index.php?curid=42515224
- 14. 1414 Why should we bother? • As a Engineer – I don’t want to be told at 3AM my routing is broken
- 16. 1616 Tools & Techniques LOA Check Whois (manual) Letter of Authority IRR (RPSL)
- 17. 1717 Tools & Techniques • Look up whois – verify holder of a resource
- 18. 1818 Tools & Techniques • Ask for a Letter of Authority – Absolve from any liabilities
- 19. 1919 Tools & Techniques • Look up/ask to enter details in IRR – describes route origination and inter-AS routing policies
- 20. 2020 Tools & Techniques • IRR – Helps generate network (prefix & as-path) filters using RPSL tools • Filter out route advertisements not described in the registry
- 21. 2121 Tools & Techniques • Problem(s) with IRR – No single authority model • How do I know if a RR entry is genuine and correct? • How do I differentiate between a current and a lapsed entry? – Many RRs • If two RRs contain conflicting data, which one do I trust and use? – Incomplete data - Not all resources are registered in an IRR • If a route is not in a RR, is the route invalid or is the RR just missing data? – Scaling • How do I apply IRR filters to upstream(s)?
- 22. 2222 Back to basics – identify GOOD • Using digital signatures to convey the “authority to use”? – A private key to sign the authority, and – the public key to validate that authority
- 23. 2323 How about trust? • Follows the resource allocation/delegation hierarchy IANA à RIRs à NIRs/LIRs à End Holders | V End Holders
- 24. 2424 Chain of Trust - RPKI IANA RIPE-NCCLACNICARIN APNICAFRINIC NIR ISP ISP ISP ISP Allocation Hierarchy Trust Anchor Certificate Certificate chain mirrors the allocation hierarchy Cert (CA) Cert (EE) Cert (EE) Cert (EE) Cert (EE) Cert (CA) Cert (CA)
- 25. 2525 Resource Certificates • When an address holder A (*IRs) allocates resources (IP address/ASN) to B (end holders) – A issues a resource certificate that binds the allocated address with B’s public key, all signed by A’s (CA) private key – proves the holder of the private key (B) is the legitimate holder of the resource!
- 26. 2626 Route Origin Authority • B can now sign authorities using its private key, – which can be validated by any third party against the TA • For routing, the address holder can authorize a network (ASN) to originate a route, and sign this permission with its private key (ROA) Prefix 202.144.128.0/19 Max-length /24 Origin ASN AS17660
- 27. 2727 Filtering with ROAs – Route Origin Validation RPKI-to-Router (RtR) rsync/RRDP RPKI Validator/ RPKI Cache server 2406:6400::/32-48 17821 .1/:1 .2/:2 AS17821 ASXXXX Global (RPKI) Repo ROA 2406:6400::/32-48 17821 TA TA TA 2406:6400::/48
- 28. 2828 Are ROAs enough? • What if I forge the origin AS in the AS path? – Would be accepted as “good” – pass origin validation! • Which means, we need to secure the AS path as well – need AS path validation (per-prefix)
- 29. 2929 AS-PATH validation (BGPsec) – A BGPsec speaker validates the received update by checking: • If there is a ROA that describes the prefix and origin AS, and • If the received AS path can be validated as a chain of signatures (for each AS in the AS path) using the AS keys AS1 AS2 AS3 AS4 AS1 -> AS2 (Signed AS1) AS1 -> AS2 (Signed AS1) AS2->AS3 (signed AS2) AS1 -> AS2 (Signed AS1) AS2->AS4 (signed AS2)
- 30. 3030 AS-PATH validation issues… • More resources – CPU - high crypto overhead to validate signatures, and – Memory • Updates in BGPsec would be per prefix – update packing?? • New attributes carrying signatures and certs/key-id for every AS in the AS path • How do we distribute the certificates required? • Can we have partial adoption? • Given so much overhead, can it do more - Route leaks?
- 31. 3131 So, what can we do? • Basic BGP OpSec hygiene – RFC7454/RFC8212 – RFC 8212 – BGP default reject or something similar – Filters with your customers and peers • Prefix filters, Prefix limit • AS-PATH filters, AS-PATH limit • Use IRR objects (source option) or ROA-to-IRR – Filter what you receive from your upstream(s) – Create ROAs for your resources – Filter inbound routes based on ROAs ~ ROV • Join industry initiatives like MANRS • https://www.manrs.org/
- 33. 3333 Acknowledgement • Geoff Huston, APNIC • Randy Bush, IIJ Labs/Arrcus
- 34. 34 THANK YOU