PCP Working Group M. Boucadair
Internet-Draft France Telecom
Intended status: Standards Track T. Reddy
Expires: April 14, 2013 Cisco
October 11, 2012
Retrieving the Capabilities of a PCP-controlled Device
draft-boucadair-pcp-capability-01
Abstract
This document extends Port Control Protocol (PCP) with the ability to
retrieve the capabilities of PCP-controlled device: CAPABILITY
Option.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 14, 2013.
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carefully, as they describe your rights and restrictions with respect
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. CAPABILITY . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. PCP Client/Server Behaviour . . . . . . . . . . . . . . . . . . 4
4. Option Usage . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Firewall . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
This document extends the base PCP [I-D.ietf-pcp-base] with a new
feature to discover the capabilities of a PCP-controlled device.
Retrieving the capabilities of a PCP-controlled device would allow to
avoid error, provide a hint why some applications fails, help select
the OpCode to issue, etc.
This option can be elected to be defined as a new OpCode.
This option has been defined first in [I-D.boucadair-pcp-extensions].
2. CAPABILITY
The CAPABILITY option (Code: TBA, Figure 1) is used by a PCP Server
to indicate to a requesting PCP Client the capabilities it supports
with regards to port forwarding operations.
One single Capability option is conveyed in the same PCP response
message even if several functions are co-located in the same PCP-
controlled device (e.g., NAT44 and NAT64, NAT44 and ports set
assignment capability, etc.).
This option, when received from a PCP Server, is used by a PCP Client
to constraint the content of its requests and therefore avoid errors.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CAPABILITY | Reserved | Length=16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A| Capability |
+-+ |
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This Option:
Option Name: PCP Capabilities Option (CAPABILITY)
Number: TBA (IANA)
Purpose: Retrieve the capabilities of a PCP-controlled device
Valid for Opcodes: ANNOUNCE, MAP, PEER
Length: 16
May appear in: both request and response
Maximum occurrences: None
Figure 1: Capability option
A-bit when set (i.e., 1) indicates the PCP Server supports
authentication. If this bit is set to 0, is indicates plain PCP is
supported.
The Capability Field is encoded in 127 bits. Each bit in the
Capability bit mask is used to represent the PCP-controlled device
capability. Several bits can be set if several functions are co-
located in the same device. The following values for the Capability
field are:
Bit #: Description
1: NAT44
2: Stateless NAT64 [RFC6145].
4: Stateful NAT64 [RFC6146].
8: A+P Port Range Router [RFC6346].
16: IPv4 firewall Section 5
32: IPv6 Firewall [RFC6092].
64: NPTv6 [RFC6296].
127: ILNP Translator [I-D.irtf-rrg-ilnp-arch]
3. PCP Client/Server Behaviour
This section specifies the behavior of the PCP Client and the PCP
Server to handle the CAPABILITY Option.
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Once the PCP Client is configured with its PCP Server(s), it MAY
issue an ANNOUNCE OpCode which enclose a CAPABILITY Option. Sending
the ANNOUNCE OpCode and the CAPABILITY Option allows the PCP Client
to determine whether the PCP Server is alive and also to retrieve its
capabilities. Based on the received capabilities, the PCP Client may
decide to tune its requests (e.g., Section 4) and decide whether all
PCP Servers need to be contacted in parallel or only a subset of them
should be contacted.
Upon receipt of a PCP request from a PCP Client requiring the PCP
Server to enforce an operation beyond its capabilities, the PCP
Server MAY return an error code together with the CAPABILITY option.
When a new PCP Server joins the network then it MAY send an ANNOUNCE
OpCode with its capabilities (i.e., CAPABILITY Option).
4. Option Usage
Below are provided examples of the CAPABILITY Option usage:
o In an IPv6 network with NPTv6 [RFC6296], Firewalls implementing
the PCP Server are on different devices: the PCP Client learns of
the available PCP Servers by using DHCP [I-D.ietf-pcp-dhcp] or any
other PCP Server discovery technique defined in future
specifications. PCP Client learns the PCP Server capabilities
using CAPABILITY Option. The PCP Client sends MAP PCP request to
PCP-controlled NPTv6 device with Internal Port=0 and Protocol=0
(which means 'all ports for all protocols') to find the external
IP address. This PCP request has to be sent only once since NPTv6
is stateless and provides a 1:1 relationship between addresses in
the "inside" and "outside" prefixes. The PCP Client will send PCP
re-request to NTPv6 only before the Assigned Lifetime of the MAP
response expires or when the host embedding the PCP Client
acquires a new IPv6 address using "inside" prefix. However PCP
Client will send MAP/PEER requests to Firewall to create/delete
dynamic outbound mapping or use PCP instead of its default
application keep-alives to maintain the Firewall state alive.
PCP
Client __________
+-----------+ +------+ +------+ / \ +-----------+
|Application|___| NPTv6|___| FW |____| Internet |___|Application|
| Client | | | | | | | | Server |
+-----------+ +------+ +------+ \__________/ +-----------+
Figure 2: NPTv6 and FW not collocated with PCP server Capability
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o In a network with NAT64 [RFC6146], Firewall implementing PCP
servers are on different devices: IPv6-only PCP Client can send
PREFIX64 PCP Option [I-D.boucadair-pcp-nat64-prefix64-option] only
to the PCP-controlled NAT64 device to learn the Prefix64(s) used
to build IPv4-embedded IPv6 addresses.
o Multiple PCP-controlled devices: See Figure 3 the example of a
network deploying several techniques to ensure interconnection
with IPv4, provide IPv6-only connectivity, etc. Of course, one
can argue this configuration is no realistic.
+-----+
______|NPTv6|___________
/ +-----+ \
| |
| +-----+
+-----------+ +------+ | | PRR |
|Application|___| IPv6 |______| SP Network +-----+
|PCP Client| | FW | | |
+-----------+ +------+ | +------+
| | NAT64|
+-----------+ +-------+ | | + |
|PCP Client |___|A+P NAT|_____| | FW |
+-----------+ +-------+ | +-----+ +------+
\______|NPTv6|___________/
+-----+
Figure 3: Multiple PCP-controlled devoce
o In a IPv6 network with ILNP translator [I-D.irtf-rrg-ilnp-arch],
Firewall implementing PCP servers are on different devices. PCP
client needs to send PCP request only to the PCP-controlled ILNP
translator to find Global Locators associated with Internal
Locators.
o When the PCP-controlled device is a PRR, the PCP Client should use
MAP_PORT_SET [I-D.tsou-pcp-natcoord] instead of MAP OpCode.
5. Firewall
There are various kinds of firewalls:
o Context or Zone-based firewalls, that protect systems within a
perimeter from systems outside it.
o Pervasive routing-based measures, which protect intermingled
systems from each other by enforcing role-based policies,
o Systems that analyze application behavior and trigger on events
that are unusual, match a signature, or involve an untrusted peer.
These firewalls types are explained in [I-D.ietf-opsawg-firewalls]
and PCP server SHOULD be implemented on Context or Zone-based
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firewalls and not on other kinds of firewalls.
6. Security Considerations
Security considerations discussed in [I-D.ietf-pcp-base] must be
considered.
7. IANA Considerations
The following PCP Option Code are to be allocated:
CAPABILITY
8. References
8.1. Normative References
[I-D.boucadair-pcp-nat64-prefix64-option]
Boucadair, M., "Learn NAT64 PREFIX64s using PCP",
draft-boucadair-pcp-nat64-prefix64-option-02 (work in
progress), September 2012.
[I-D.ietf-pcp-base]
Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
Selkirk, "Port Control Protocol (PCP)",
draft-ietf-pcp-base-28 (work in progress), October 2012.
[I-D.ietf-pcp-dhcp]
Boucadair, M., Penno, R., and D. Wing, "DHCP Options for
the Port Control Protocol (PCP)", draft-ietf-pcp-dhcp-05
(work in progress), September 2012.
[I-D.irtf-rrg-ilnp-arch]
Atkinson, R. and S. Bhatti, "ILNP Architectural
Description", draft-irtf-rrg-ilnp-arch-06 (work in
progress), July 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation
Algorithm", RFC 6145, April 2011.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, April 2011.
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8.2. Informative References
[I-D.boucadair-pcp-extensions]
Boucadair, M., Penno, R., and D. Wing, "Some Extensions to
Port Control Protocol (PCP)",
draft-boucadair-pcp-extensions-03 (work in progress),
April 2012.
[I-D.ietf-opsawg-firewalls]
Baker, F., "On Firewalls in Internet Security",
draft-ietf-opsawg-firewalls-00 (work in progress),
June 2012.
[I-D.tsou-pcp-natcoord]
Sun, Q., Boucadair, M., Deng, X., Zhou, C., and T. Tsou,
"Lightweight 4over6 Port-set Allocation: Using PCP To
Coordinate Between the CGN and Home Gateway",
draft-tsou-pcp-natcoord-07 (work in progress), July 2012.
[RFC6092] Woodyatt, J., "Recommended Simple Security Capabilities in
Customer Premises Equipment (CPE) for Providing
Residential IPv6 Internet Service", RFC 6092,
January 2011.
[RFC6296] Wasserman, M. and F. Baker, "IPv6-to-IPv6 Network Prefix
Translation", RFC 6296, June 2011.
[RFC6346] Bush, R., "The Address plus Port (A+P) Approach to the
IPv4 Address Shortage", RFC 6346, August 2011.
Authors' Addresses
Mohamed Boucadair
France Telecom
Rennes, 35000
France
Email: mohamed.boucadair@orange.com
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Tirumaleswar Reddy
Cisco Systems, Inc.
Cessna Business Park, Varthur Hobli
Sarjapur Marathalli Outer Ring Road
Bangalore, Karnataka 560103
India
Email: tireddy@cisco.com
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