APNIC Senior Network Analyst and Training Manager Tashi Phuntsho presents on why securing Internet routing is important, and outlines some tools and techniques that can help network operators.

1. 1 v1.01
Securing Internet
Routing
Tashi Phuntsho (tashi@apnic.net)
Senior Network Janitor/Technical Trainer

2. 2 v1.02
Why should we bother?
• As a Manager
q I don’t want to be front page news of a IT paper, or an actual
newspaper for routing errors

3. 3 v1.03
Headlines
https://blog.thousandeyes.com/internet-vulnerability-takes-down-google/

4. 4 v1.04
Headlines
https://blog.cloudflare.com/bgp-leaks-and-crypto-currencies

5. 5 v1.05
Headlines
After leak (JP->JP)
After leak (EU->EU)
https://dyn.com/blog/large-bgp-leak-by-google-disrupts-internet-in-japan/

6. 6 v1.06
Headlines

7. 7 v1.07
Why do we keep seeing these?
• Because NO ONE is in charge?
q No single authority model for the Internet
q No reference point for what’s right in routing

8. 8 v1.08
Why do we keep seeing these?
• Routing works by RUMOUR
q Tell what you know to your neighbors, and Learn what your
neighbors know
q Assume everyone is correct (and honest)
§ Is the originating network the rightful owner?

9. 9 v1.09
Why do we keep seeing these?
• Routing is VARIABLE
q The view of the network depends on where you are
§ Different routing outcomes at different locations
q ~ no reference view to compare the local view L

10. 10 v1.010
Why do we keep seeing these?
• Routing works in REVERSE
q Outbound advertisement affects inbound traffic
q Inbound (Accepted) advertisement influence outbound traffic

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Why do we keep seeing these?
• And as always, there is no E-bit
q A bad routing update does not identify itself as BAD
• So tools/techniques try to identify GOOD updates

12. 12 v1.012
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

13. 13 v1.013
Why should we bother?
• As a Engineer
q I don’t want to be told at 3AM my routing is broken
q Or while on a holiday

14. 14 v1.014
Current practice
Peering/Transit
Request
LOA Check
Filters (in/out)

15. 15 v1.015
Tools & Techniques
LOA Check
Whois
(manual)
Letter of
Authority
IRR (RPSL)

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Tools & Techniques
• Look up whois
q verify holder of
a resource

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Tools & Techniques
• Ask for a Letter of Authority
q Absolve from any liabilities

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Tools & Techniques
• Look up/ask to enter details
in internet routing registries
(IRR)
q describes route origination and
inter-AS routing policies

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Tools & Techniques
• IRR
q Helps auto generate network
(prefix/as-path) filters using RPSL
tools
§ Filter out route advertisements not
described in the registry

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Tools & Techniques
• Problem(s) with IRR
q 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?
q Many RRs
§ If two RRs contain conflicting data, which one do I trust and use?
q 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?
q Scaling
§ How do I apply IRR filters to upstream(s)?

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Back to basics – identifying GOOD
• Using digital signatures to convey the “authority to use”?
q A private key to sign the authority, and
q the public key to validate that authority

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How about trust in this framework?
• Follows the resource allocation/delegation hierarchy
IANA à RIRs à NIRs/LIRs à End Holders
|
V
End Holders

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RPKI Chain of Trust
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)
Image 4

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Resource Certificates
• When an address holder A (*IRs) allocates resources (IP
address/ASN) to B (end holders)
q A issues a resource certificate that binds the allocated address with
B’s public key, all signed by A’s (CA) private key
q proves the holder of the private key (B) is the legitimate holder of
the resource!

25. 25 v1.025
Route Origin Authorization (ROA)
• 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 203.176.32.0/19
Max-length /24
Origin ASN AS17821

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Route Origin Validation (ROV)
RPKI-to-Router
(RtR)
rsync/RRDP
RPKI Validator/
RPKI Cache server
2406:6400::/32-48
17821
.1/:1
.2/:2
AS17821
ASXXXX
Global
(RPKI)
Repository
ROA
2406:6400::/32-48
17821
TA
TA
TA
2406:6400::/48

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Are ROAs enough?
• What if I forge the origin AS in the AS path?
q Would be accepted as “good” – pass origin validation!
• Which means, we need to secure the AS path as well
q Need AS path validation (per-prefix)

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AS path validation - BGPsec
AS1 AS2
AS3
AS4
AS1 -> AS2
(Signed AS1)
AS1 -> AS2
(Signed AS1)
AS2->AS3
(signed AS2)
AS1 -> AS2
(Signed AS1)
AS2->AS4
(signed AS2)
q A BGPsec speaker validates the received update by checking:
§ If there is a ROA that describes the prefix and origin AS
§ If the received AS path can be validated as a chain of signatures (for each AS
in the AS path) using the AS keys

29. 29 v1.029
AS path validation issues…
• More resources
q CPU - high crypto overhead to validate signatures, and
q Memory
§ Updates in BGPsec would be per prefix
§ 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?

30. 30 v1.030
What can we do?
• Basic BGP OpSec hygiene – RFC7454/RFC8212
q RFC 8212 – BGP default reject or something similar
q 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
q Filter what you receive from your upstream(s)
q Create ROAs for your resources
q Filter inbound routes based on ROAs -> ROV
• Join industry initiatives like MANRS
§ https://www.manrs.org/

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ROV – Industry trends
dropping Invalids!

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Acknowledgement
5280
• Geoff Huston, APNIC
• Randy Bush, IIJ Labs/Arrcus

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Any questions?