Transcript PANA threat analysis and security requirements

PANA enabling IPsec based
Access control
draft-mohanp-pana-ipsec-00.txt
Mohan Parthasarathy
Tahoe Networks
- Presented by Hannes Tschofenig
7/14/2003
IETF57
Enabling IPsec Access control
• PANA protocol - used to authenticate the client.
• PANA protocol - also capable of sending
Protection-capability-AVP (with PANA-BindRequest) asking (enforcing) the client to use L2 or
L3 cipher.
• But PANA protocol does not specify the details on
how the L2/L3 SAs are established etc.
• This draft essentially discusses the details of using
IPsec as the L3 cipher.
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Pre-requisites for using IPsec
• PANA client (PaC) should learn the IP
address of the enforcement point (EP)
during the PANA exchange.
• PaC learns that the network uses IPsec for
securing the PaC-EP link.
• PaC has already acquired an IP address and
PAA knows about the IP address of the PaC
before the exchange starts.
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IKE/IPsec details
• At the end of a successful authentication, a PANA
SA is established between PaC and PAA
(assuming the underlying EAP method is capable
of generating a Master Key (MK)).
• IKE pre-shared key is derived from the PANA SA
(TBD).
• EP securely receives the following from PAA:
- IKE pre-shared key
- IP address of PaC
- PANA session id
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IKE/IPsec details (contd..)
• Manual keying not supported. IKE is used to
establish IPsec SAs.
• Both Aggressive mode and Main mode is easy to
support.
• In main mode, PaC and EP uses the IP address as
the client identifier.
• In Aggressive mode, PaC and EP use the PANA
session id as identifier - part of ID_KEY_ID
payload.
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IKE/IPsec details (contd..)
• After Phase I SA is established, quick mode
exchange is performed to setup an IPsec
SA.
• Quick mode IPsec SA is an ESP transport
mode SA used in conjunction with IP-IP
tunnel interface (IP-IP transport mode SA).
• IPsec tunnel mode SA also can be used.
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IPv4/IPv6 Details
• Draft has specific examples on SPD entries, IPsec
processing details for both IPv4 and IPv6.
• In IPv4, the SPD entries are very simple. All of
the traffic is tunneled to the security gateway (EP).
• In IPv6, there are a few exceptions.
• EP is the security gateway – a router. Implies hop
count is decremented by 1.
• This won’t work for RD/ND messages which
assume nhop count = 255.
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IPv4/IPv6 details (contd..)
• As IPsec selectors are not capable of expressing
bypass rules for ND/RD messages:
- Use just fe80::/10 as the on-link prefix
i.e., all other packets are sent to the
default router.
- Bypass IPsec for packets destined to
fe80::/10.
• All packets are tunneled to the link-local address
of the EP.
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Double IPsec
• If the PaC uses IPsec for secure remote
access, there will be separate SPD entries
for protecting the remote network traffic.
• Packets will be protected twice. Once for
the remote network and once for the local
network.
• This case of iterated tunneling is discussed
in RFC2401 (IPsec).
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Open Issues
• IKE pre-shared key derivation from PANA
SA.
• Use IPsec tunnel mode to describe the IPsec
details instead of IP-IP transport mode.
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Question to WG
• Should we make this a WG I-D?
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