1 eu sp security forum, december, 2008 vince fuller (for the lisp crew) introduction to lisp

1

EU SP Security Forum, December, 2008

Vince Fuller (for the LISP crew)http://www.lisp4.net/prezos/lisp-eusp.ppt

Introduction to LISPIntroduction to LISP

Introduction to LISPIntroduction to LISP EU SP Security Forum, December, EU SP Security Forum, December, 20082008

Slide Slide 22

AcknowledgementsAcknowledgements• This work is a collaborative effort, most notably

with my colleagues on the LISP “core” team:– Dino Farinacci – leader, instigator, and implementer– Dave Meyer – evangelist– Darrel Lewis – security geek

• Special thanks are due to J. Noel Chiappa who’s writings on naming and addressing opened my eyes to the concepts of “identifier” and “locator”– See: “Endpoints and Endpoint names: A Proposed

Enhancement to the Internet Architecture”, J. Noel Chiappa, 1999, http://users.exis.net/~jnc/tech/endpoints.txt

– “On the Naming and Binding of Network Destinations”, J. Saltzer, August, 1993, published as RFC1498, http://www.ietf.org/rfc/rfc1498.txt?number=1498


Slide Slide 33

AgendaAgenda• What is the problem?• What is LISP?• Why Locator/ID Separation?• Data Plane Operation• Finding Mappings – LISP+ALT• A word or two about “interworking”• Implementation and pilot network• Securiy considerations for LISP• Call for participation


Slide Slide 44

Problem StatementProblem Statement

• There are reasons to believe that current trends in the growth of routing and addressing state on the global Internet may cause difficulty in the long term

• The Internet needs an easier, more scalable mechanism for multi-homing with traffic engineering


Slide Slide 55

Problem StatementProblem Statement• An Internet-wide replacement of IPv4 with ipv6

represents a one-in-a-generation opportunity to either continue current trends or to deploy something truly innovative and sustainable

• As currently specified, routing and addressing with ipv6 is not significantly different than with IPv4 – it shares many of the same properties and scaling characteristics

• More at: www.vaf.net/prezos/rrg-prague.pdf


Slide Slide 66

Scaling of Global RoutingScaling of Global Routing


Slide Slide 77

Global Routing – Log viewGlobal Routing – Log view


Slide Slide 88

•Instead of IP addresses, two numbering spaces:

– Endpoint Identifiers (EIDs): hierarchically assigned to sites along administrative lines (like DNS hostnames) • Do not change on devices that remain associated with the site; think “PI” but not globally-routable

– Routing Locators (RLOCs): assigned according to network topology, like “PA” address assignments• Locators are aggregated/abstracted at topological boundaries to keep routing state scalable• When site’s connection to network topology changes, so do the locators – aggregation is preserved

What is ID/Loc Separation?What is ID/Loc Separation?


Slide Slide 99

Hierarchical EID Hierarchical EID assignmentassignment

Provider A10.0.0.0/8

Provider B11.0.0.0/8

R1 R2

PI EID-prefix 240.1.0.0/16

10.0.0.1 11.0.0

.1

ISP allocates 1 locator address per physical attachment point(follows network topology)

RIR allocates EID-prefixes(follows org/geo hierarchy)

SiteLegend:

EIDs -> Green

Locators -> Red


Slide Slide 1010



R1 R2

BGP

End Site Benefit

(1) Easier Transition to ipv6 (maybe)(2) Change provider without address change

Lower OpEx for Sites and Providers

(1) Improve site multi-homing(2) Improve provider traffic engineering(3) Reduce size of core routing tables

What Features do I get?What Features do I get?

Site withPI Addresses


Slide Slide 1111

What is LISP?What is LISP?

• Locator/ID Separation Protocol• Ground rules for LISP:

– Network-based solution– No changes to hosts whatsoever– No new addressing changes to site devices– Very few configuration file changes– Imperative to be incrementally deployable– Address family agnostic


Slide Slide 1212

New Network ElementsNew Network Elements

• Ingress Tunnel Router (ITR)– Finds EID to RLOC mapping– Encapsulates to Locators at source site

• Egress Tunnel Router (ETR)– Owns EID to RLOC mapping– Decapsulates at destination site


Slide Slide 1313

Packet ForwardingPacket Forwarding



S

ITR

DITR

ETR

ETR

Provider Y13.0.0.0/8

Provider X12.0.0.0/8S1

S2

D1

D2

PI EID-prefix 1.0.0.0/8 PI EID-prefix 2.0.0.0/8

DNS entry:D.abc.com A 2.0.0.2

EID-prefix: 2.0.0.0/8

Locator-set:

12.0.0.2, priority: 1, weight: 50 (D1)

13.0.0.2, priority: 1, weight: 50 (D2)

Mapping

Entry

1.0.0.1 -> 2.0.0.2

1.0.0.1 -> 2.0.0.2

11.0.0.1 -> 12.0.0.2

Legend:

EIDs

Locators

1.0.0.1 -> 2.0.0.2

11.0.0.1 -> 12.0.0.2

1.0.0.1 -> 2.0.0.2

12.0.0.2

13.0.0.2

10.0.0.1

11.0.0.1

Policy controlledby destination site


Slide Slide 1414

When the ITR has no MappingWhen the ITR has no Mapping

• ITR needs RLOCs from a site ETR for a particular EID prefix

• ITR sends Map Request (or Data Probe)• ETR returns Map Reply• But how does the ITR find the right

ETR?– Using the mapping system…


Slide Slide 1515

Mapping System: What and Mapping System: What and WhyWhy

• Need a scalable EID to Locator mapping lookup mechanism

• Network based solutions– Have query/reply latency– Can have packet loss characteristics– Or, have a full table like BGP does

• How does one design a scalable Mapping Service?


Slide Slide 1616

Scaling ConstraintsScaling Constraints

• Build a large distributed mapping database service• Scalability paramount to solution• How to scale:

(state * rate)• If both factors large, we have a problem

– state will be O(1010) hosts• Aggregate EIDs into EID-prefixes to reduce state

– rate must be small• Dampen locator reachability status and locator-set

changes• Each mapping system design does it differently


Slide Slide 1717

Tough Questions/IssuesTough Questions/Issues• Where to store the mappings?• How to find the mappings?• Push model or pull model?• Full database or cache? Secondary

storage?• How to secure mapping entries?• How to secure control messages?• Protecting infrastructure from attacks• Control over packet loss and latency


Slide Slide 1818

Ideas ConsideredIdeas Considered• DNS – considered, many issues• DHTs – considered, research pending• CONS – new protocol, hybrid push+pull

– Push EID-prefixes at top levels of hierarchy– Pull mappings from lower levels of hierarchy

• EMACS – multicast-group-based• NERD – pure Push design• ALT – GRE/BGP based, current focus


Slide Slide 1919

Why LISP+ALT was SelectedWhy LISP+ALT was Selected

• Use existing technology where reasonable

• Low memory impact on ITR• Optional data path to reduce latency

(deprecated data probes)• Allow infrastructure players to achieve

new revenue source


Slide Slide 2020

LISP+ALT: What and HowLISP+ALT: What and How• Hybrid push/pull approach

– ALT pushes aggregates - find ETRs for EID– ITR uses LISP to find RLOCs for specific EID

• Hierarchical EID prefix assignment– Aggregation of EID prefixes

• Tunnel-based overlay network• BGP used to advertise EIDs on overlay• Option for data-triggered Map-Replies

(deprecated for now)


Slide Slide 2121

LISP-ALT Routers and the ALTLISP-ALT Routers and the ALT

• LISP+ALT routers form “Alternative Logical Topology” (ALT)– Interconnected by tunnels (GRE or …)– eBGP used for EID prefix propagation– Isomorphic topology and EID assignment

• ITRs and ETRs connect at “edge”


Slide Slide 2222

Tunnel and BGP OperationTunnel and BGP Operation• EID prefixes originated into BGP at edge

– advertised by ETR to its first-hop ALT router

• ITR learns EID prefixes via eBGP– advertised by first-hop ALT router to ITR

• Map-Request forwarded into the ALT via first-hop ALT router– intermediate ALT routers forward Map-Request

to ETR that “owns” an EID prefix

• ALT routers aggregate prefixes “upward” in the alternative topology


Slide Slide 2323

Legend:

EIDs -> Green

Locators -> Red

GRE Tunnel

Low Opex

Physical link

Data Packet

Map-Request

Map-Reply

ETR

ETR

ETR

ITR

ITR

EID-prefix

240.1.1.0/24

ALT

240.0.0.1 -> 240.1.1.1

1.1.1

.1

2.2.2.2

3.3.3.3

240.0.0.1 -> 240.1.1.1EID-prefix

240.0.0.0/24

1.1.1.1 -> 11.0.0.1240.0.0.1 -> 240.1.1.1

11.0.0.1 -> 1.1.1.1

ALT-rtr

ALT-rtr

ALT-rtr

ALT-rtr

ALT-rtr

ALT-rtr

12.0.0.1

11.0.0.1

?

240.0.0.1 -> 240.1.1.1

11.0.0.1 -> 240.1.1.1

? 240.0.0.1 -> 240.1.1.1

11.0.0.1 -> 240.1.1.1

?<- 240.1.1.0/24

<- 240.1.2.0/24

< - 240.1.0.0/16

?

LISP+ALT in actionLISP+ALT in action


Slide Slide 2424

““low-opex” xTR – what & low-opex” xTR – what & whywhy

• BGP configuration complexity is a barrier to site-multihoming

• Remove xTR/CPE BGP requirement:– ITR has “static default EID-prefix route” to

“first hop” ALT router– “first hop” ALT router has “static EID-prefix

route” pointing to ETR– originates EID prefix on behalf of ETR

• Considering new “map-server” element


Slide Slide 2525

A few open ALT issuesA few open ALT issues• Who runs the ALT network?

– What’s the business model?– Should it be rooted at/run by the RIRs? IXCs?

Some other neutral parties?– Different levels run by different orgs– Should it be free?

• OK to renumber to get “PI” EID prefix?• Interworking/transition strategies (later)• Work in standards/ops community (later)• Others?


Slide Slide 2626

InterworkingInterworking• LISP will not be deployed overnight

– And may never be deployed at some sites• Need “Interworking” between LISP sites

and non-LISP sites• Two choices:

– Proxy Tunnel Routers – advertise EID space to Internet; act as ITR for non-LISP sites

– LISP-NAT – LISP site xTR translates EIDs into “legacy” Internet addresses

• draft-lewis-lisp-interworking-01.txt

Review: LISP in one SlideReview: LISP in one Slide

Today’s Internet - Data Plane

LISP-ALT Control PlaneLISP Site

Non-LISP Site

LISP Site

GRE TunnelsGRE Tunnels

Physical Links Phys

ical

Lin

ks

CE

LISP Routers

LISP Routers

RLOCsRLOCs

RLOCs

RLOCs

EIDsEIDs

EIDs assigned by Internet Registries

RLOCs assigned by Service Providers

Configure EID -> RLOCsdatabase mappings

for local site

Stores EID -> RLOCscache mappingsfor remote sites

Benefits:• Improved low-opex multihoming• Site based policy and reachability• Reduces routing tables in core routers• No site renumbering when changing ISPs• No changes to site hosts• No changes to site switches/routers• No changes to core routers• No DNS changes• No site addressing changes• Works with PI or PA prefixes• Supports 4to4-over-6 and 6to6-over-4• Sites authoritative for their mappings• Interworks with non-LISP sites using

translation or PTRs

Costs:• Mapping system required• New Software in CE routers• New LISP-ALT infrastructure

Legend:EIDs (End Site IDs) in greenRLOCs (Routing Locators) in redCE: Customer Premise Edge RouterALT: Alternative LISP TopologyOH: Outer header, CE to CEIH: Inner header, host to host

“Separating ID and Location in an IP address through a level of indirection”

CE

Advertises RLOCs to maintain aggregationand provide reachability to sites

RLOCs EIDs

Data Packet

Payload

OH IH Host Data

Wed Nov 26 16:23:38 PST 2008

CE

Advertises EID-prefixes to find mappings


Slide Slide 2828

Implementation StatusImplementation Status• cisco has a LISP prototype implementation

– Started in March 2007– Testing on pilot network since summer ‘07

• OS platform is NX-OS (on top of Linux)• Hardware platform is Titanium

– 1 RU dual-core off-the-shelf PC with 7 GEs• Based on draft-farinacci-lisp-10.txt• Software switching only• Supports both IPv4 and ipv6• Includes ALT and Interworking• Traceroute and debugging features


Slide Slide 2929

Implementation StatusImplementation Status• IOS 12.4T prototype is in the works• OpenLISP implementation:

draft-iannone-openlisp-implementation-00.txt

• Would really like to see more


Slide Slide 3030LISP: Practice & ExperienceLISP: Practice & Experience NANOG 44NANOG 44 Slide Slide 3030

Deployment status – ALT Deployment status – ALT pilotpilot

LISP: Practice & ExperienceLISP: Practice & Experience Slide Slide 3030NANOG 44NANOG 44


Slide Slide 3131

Security in LISPSecurity in LISP• Control Plane Security

– What’s going on in the ALT?• Data Plane Security

– What are the implications of security in a loc/id split world

• Site Security– What needs to be able to talk to my

RLOCs?• Likely more work needed…


Slide Slide 3232

Control Plane SecurityControl Plane Security• Use existing/proposed BGP security

mechanisms– Filtering of ETR-to-ALT announcements– MD5 authentication of sessions– S-BGP/SO-BGP as they are developed– SIDR for address assignment checking

• GRE Tunnels need love too– ACLs to prevent anything other than BGP,

ICMP, and UDP 4342– Likely need something other than just GRE in

the longer term due to data-insertion issues


Slide Slide 3333

Data Plane SecurityData Plane Security• In the Core, things look… different with

lots of LISP flows– All LISP data is encapsulated into UDP4341– The inner header/data is there, 36 Bytes from

the start– Think about how to look at that data…

• Spoofing, and (spoofing)– Outer Header spoofing is no different than

UDP today– Inner header spoofing is a little bit more tricky


Slide Slide 3434

ITR/ETR/ALT are vulnerableITR/ETR/ALT are vulnerable• ITRs and ETRs represent new targets for

attacks (as do ALT routers)• Nonce in LISP request/reply exchange

– Guards against third-party spoofing– But doesn’t prevent “man-in-the-middle” attacks

• Mitigation using well-known control plane protection techniques (infrastructure hiding, iACLs, rACLs, CoPP, etc.)

• More work likely needed…• …must balance against deployability


Slide Slide 3535

Site SecuritySite Security• At the site, securing your xTR is pretty

straightforward.– Allow LISP (data & control) packets to your

RLOCs– Allow GRE (for ALT) to your RLOCs– Allow for ICMP to your RLOCs– LISP enforces spoofing on decapsulation

• Outgoing– LISP enforces uRPF on encapsulation so you

are prohibited from spoofing inner headers


Slide Slide 3636

Site Security (Continued)Site Security (Continued)• Post encapsulation, your site’s

policies can remain the same• Flexible packet matching is an

existing IOS tool that can be used to build ACLs on inner/lisp/outer header chains (12.4T)

• More work needed here so if you’re interested…


Slide Slide 3737

Interested in more?Interested in more?• Considering additional external test sites

– Must be able to dedicate minimum of 1 day a week

• Goals:– Test multiple implementations– Experience with operational practices– Learn about revenue making opportunities

• Developers at: [email protected]• Discussion at: [email protected]


Slide Slide 3838

LISP Internet DraftsLISP Internet Draftsdraft-farinacci-lisp-10.txtdraft-fuller-lisp-alt-03.txtdraft-lewis-lisp-interworking-01.txtdraft-farinacci-lisp-multicast-01.txtdraft-meyer-lisp-eid-block-01.txt

draft-mathy-lisp-dht-00.txtdraft-iannone-openlisp-implementation-01.txtdraft-brim-lisp-analysis-00.txt

draft-meyer-lisp-cons-04.txtdraft-lear-lisp-nerd-04.txtdraft-curran-lisp-emacs-00.txt


Slide Slide 3939

Questions/Comments?Questions/Comments?

Slide Slide 3939

Thanks!

Discussion: [email protected]: http://www.lisp4.netOpenLISP: http://inl.info.ucl.ac.be

http://www.lisp4.net/

http://inl.info.ucl.ac.be/

http://inl.info.ucl.ac.be/

1 eu sp security forum, december, 2008 vince fuller (for the lisp crew) introduction to lisp

Documents

pi eidprefix

provider b11

lisp crewhttp

network topology changes

provider x12

locators aggregation

global internet

lisp core team