Mobile IPv6 Security Arnaud Ebalard - EADS Corporate Research Center - - PowerPoint PPT Presentation

Mobile IPv6 Security

Arnaud Ebalard - EADS Corporate Research Center France Guillaume Valadon - The University of Tokyo / Laboratoire d’Informatique de Paris 6

Summary

• IPv6
• Mobile IPv6
• Security and Mobile IPv6
• Protections by default

2.IPsec

IPv6

Differences With IPv4

Functional changes:

• End-to-End communications
• ARP replacement uses ICMPv6

Structural changes:

• Fixed length header
• Fragmentation at the source; no checksum

6.Extensions/options through header

chaining

The IPv6 Header

Extensions

Routing Header

IPv6 Addresses

• Hierarchical/geogra

phical

• 64 bits prefix
• Interface ID

dynamically generated

Auto-configuration

• Mechanism based on ICMPv6
• Steps:
• Retrieval of the IPv6 prefix advertised by the access

router (RS/RA: Router Solicitation/Advertisement)

• Generation of an unique interface ID
• Generation of the global address: concatenation of the

prefix and the unique interface ID

Mobile IPv6

RFC 3775

Why ?

• Use the same IPv6 address wherever you

are located

• Make changes of mediums transparent for

transport layers

• Keep connections alive while moving

➡use a laptop/PDA the same way that you

do with your cell-phone today

Challenges

• The routing is geographical, and the IP

address have a double functionality:

✓ Identifier: identify the machine ✓ Locator: geographical position in the network

• Architectural constraints:
• Compatible with actual end nodes
• Not modifying the actual routing system

➡

MIPv6 is only implemented in end points

How ?

• The protocol is integrated into the IPv6 stack
• Separate identifier and locator functions

using two IPv6 addresses:

• HoA (Home Address)
• CoA (Care of Address)
• Three new entities:
• Mobile Node, reachable at its HoA, not matter its

CoA

• Home Agent, binds the HoA and current CoA
• Correspondent Node

Behavior

HoA: permanent address of the MN (identifier) CoA: address of the MN in the visiting network (locator)

?

In Details

New Extensions

• Allow packets to pass ingress filtering. IPv6 header

always contains CoA, never HoA.

• Maintain topological correctness
• T

ype 2 Routing Header

• limited version of previously introduced T

ype-0 Routing Header (but carries only a single address)

• provides real destination address (HoA) of packets to MN
• Home Address Option
• provides real source address (HoA) of packets from MN

T ype-2 Routing Header

Home Address Option

Triangular routing

Provide an optimal routing

Challenging Issues

• Optimize MN/CN communications in a

secure way

• Ensure the relation between identifier and

locator using the routing plane

✓ verify the MN is reachable at its HoA and CoA

➡generate a key to sign the Binding Update

sent to the CN

Return Routability Procedure

HoT: Home of Test CoT: Care of Test

RRP in a nutshell

• Goal: avoid triangular routing
• Hypothesis: no trust relationship between

MN/CN

• Lack: provides no data

integrity/confidentiality ➡ Efficiency/Security tradeoff

Security & Mobile IPv6

Possible T argets

• Protecting network infrastructure

➡

Stateless behavior, Careful design

• Protecting communications between MN/HA (signaling and data)

➡

IPsec

• Protecting direct communications between MN/CN (signaling and

data)

➡

Return Routability Procedure

• Signalisation MN <-> HA

1.Tunnel MN<->

• Signalisation MN <-> CN

2.Trafic de données MN <-> CN ➡

Return Routability Procedure

Protecting the infrastructure

Challenges and solutions

• Advice: “Do no harm to the existing

Internet”

• Prevent spoofing
• proof of HoA ownership
• specific extensions: HAO and T

ype-2 Routing Header

• Prevent DoS
• against infrastructure: “One message received,
• ne sent”

4.against CN: stateless exchanges

MN/CN Communications

Return Routability Procedure

• HoT/HoTI, CoT/CoTI and BU/BACK exchanges
• CN : verify that the MN is able to receive/emit

traffic with both its HoA and its CoA

• MN : generate a key to sign BU emitted

towards the CN

• Possible problems (MiTM, eavesdropping)
• attacker on the home network;
• attacker on the foreign network;

5.attacker on both networks

MN/HA Communications

IPsec

• Rationale for IPsec
• Mandatory in IPv6 stacks
• End-to-End communications
• What must be protected
• Signaling messages (i.e. BU et BACK)
• Data traffic (i.e. MN/HA tunnel)
• Return Routability Procedure (i.e. HoTI/HoT)

➡Problems related to MIPv6/IPsec/IKE

interactions

Signaling traffic

Basics

SA2 SA1 BU BACK SA1: BU from HoA to HA@ => ESP in transport mode SA2: BACK from HA@ to HoA=> ESP in transport mode

IPsec/MIPv6 Coordination

• Binding Update:
• Emission: IPsec protection, switch of CoA

and HoA thanks to the HAO option

• Reception : addresses switch before IPsec

processing

• Binding Acknowledgment: same kind of

processing applied to T ype-2 Routing Header

Bootstrapping

• Setup of SA must be performed before sending

BU/BACK

• In Static Keying, no problem
• In dynamic Keying, someone must direct IKE

daemon to use CoA for negotiation of SA associated to the HoA. HoA is not already usable.

• PF_KEY SADB_X_EXT_PACKET extension:
• includes BU packet that triggered the

negotiation

• provides the CoA to IKE daemon

Data traffic

T unnel Mode SA Migration

• Initially, SP/SA in tunnel mode use the MN’s HoA

(CoA is not known at setup time).

• An automatic update of SA tunnel’s endpoints is

performed on MN/HA

• MIPv6 stack emits a PF_KEY MIGRATE

message when MN sends the BU, and when HA receives it

• Message reception triggers:
• SP/SA update by kernel
• [ IKE daemon internal structures update ]

Mobile Mobile IPv6 IPv6 IKE IKE Daemon Daemon SPD SPD SAD SAD

PF_KEY Socket

Userland Kernel

• 1. PF_KEY MIGRATE
• 4. SPD & SAD Update
• 3. SAD Update
• 2. SPD Update

Conclusion

• Separation between identifier and

locator is compatible with today’s Internet

• End of “perimetric security” ?
• Built-in security mechanisms: IPsec

and RRP

Conclusion

Possible deployments

Classic RRP Future ?! ?

Future work

• Leveraging IPsec protection to

MN/MN traffic

• New prerequisites: trust relationship

between MN/MN (ex: PKI environment)

3.IKEv2 integration

Demonstration

MN CN 1 2 3 5 4

Stream to HoA Stream to HoA

Soekris

2001:db8:0:1::/64 2001:db8:0:ccc::/64

CN 1 2 3 5 4

Stream to HoA Stream to HoA

MN 2001:db8:0:1::/64 2001:db8:0:ccc0::/64 IPsec

Soekris

CN 1 2 3 5 4 MN 2001:db8:0:1::/64 2001:db8:0:ccc1::/64

Stream to HoA

IPsec

Soekris

Stream to HoA

Questions ? Coffee ?

NEMO

A whole network moves. Mobile Router