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RFC 7620
INTAREA Working Group M. Boucadair
Internet-Draft D. Binet
Intended status: Informational S. Durel
Expires: April 14, 2013 France Telecom
October 11, 2012
HOST_ID: Use Cases
draft-boucadair-intarea-host-identifier-scenarios-00
Abstract
This document describes a set of scenarios in which host
identification is required.
Status of this Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 14, 2013.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Use Case 1: CGN . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Use Case 2: A+P . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Use Case 3: Application Proxies . . . . . . . . . . . . . . . . 5
6. Use Case 4: Open Wi-Fi or Provider Wi-Fi . . . . . . . . . . . 5
7. Use Case 5: Policy and Charging Control Architecture . . . . . 7
8. Use Case 6: Cellular Networks . . . . . . . . . . . . . . . . . 8
9. Security Considerations . . . . . . . . . . . . . . . . . . . . 8
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
11. Informative References . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
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1. Introduction
The ultimate goal of this document is to enumerate scenarios which
encounter the issue of uniquely identifying a host among those
sharing the same IP address. Examples of encountered issues are:
o Blacklist a misbehaving host without impacting all hosts sharing
the same IP address.
o If a remote server enforces a policy to limit access to the
service (based on some counters), the policy will have impact on
all hosts sharing the same IP address.
o If access to a service has failed (e.g., wrong login/passwd), all
hosts sharing the same IP address may not be able to access that
service.
It is out of scope of this document to list all the encountered
issues as this is already covered in [RFC6269].
The generic concept of host identifier, denoted as HOST_ID, is
defined in [I-D.ietf-intarea-nat-reveal-analysis].
2. Scope
It is out of scope of this document to argue in favor or against the
use cases listed in the following sub-sections. The goal is to
identify scenarios the authors are aware of and which share the same
issue of host identification.
This document does not include any solution-specific discussion.
This document can be used as a tool to design solution(s) mitigating
the encountered issues. Having a generic solution which would solve
the issues encountered in these use cases is preferred over designing
a solution for each use case. Describing the use case allows to
identify what is common between the use cases and then would help
during the solution design phase.
The first version of the document does not elaborate whether explicit
authentication is enabled or not.
3. Use Case 1: CGN
Several flavors of stateful CGN have been defined. A non-exhaustive
list is provided below:
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1. NAT44
2. DS-Lite NAT44 [RFC6333]
3. NAT64 [RFC6146]
4. NPTv6 [RFC6296]
As discussed in [I-D.ietf-intarea-nat-reveal-analysis], remote
servers are not able to distinguish between hosts sharing the same IP
address (Figure 1).
+-----------+
| HOST_1 |----+
+-----------+ | +--------------------+ +------------+
| | |------| server 1 |
+-----------+ +-----+ | | +------------+
| HOST_2 |--| CGN |----| INTERNET | ::
+-----------+ +-----+ | | +------------+
| | |------| server n |
+-----------+ | +--------------------+ +------------+
| HOST_3 |-----+
+-----------+
Figure 1
4. Use Case 2: A+P
A+P [RFC6346] denotes a flavor of address sharing solutions which
does not require any additional NAT function be enabled in the
service provider's network. A+P assumes subscribers are assigned
with the same IPv4 address together with a port set. Subscribers
assigned with the same IPv4 address should be assigned non
overlapping port sets. Devices connected to an A+P-enabled network
should be able to restrict the IPv4 source port to be within a
configure range of ports. To forward incoming packets to the
appropriate host, a dedicated entity called PRR (Port Range Router,
[RFC6346]) is needed (Figure 2).
Similar to the CGN case, the same issue to identify hosts sharing the
same IP address is encountered by remote servers.
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+-----------+
| HOST_1 |----+
+-----------+ | +--------------------+ +------------+
| | |------| server 1 |
+-----------+ +-----+ | | +------------+
| HOST_2 |--| PRR |----| INTERNET | ::
+-----------+ +-----+ | | +------------+
| | |------| server n |
+-----------+ | +--------------------+ +------------+
| HOST_3 |-----+
+-----------+
Figure 2
5. Use Case 3: Application Proxies
This scenario is similar to the CGN scenario. Remote servers are not
able to distinguish hosts located behind the PROXY. Applying
policies on the perceived external IP address as received from the
PROXY will impact all hosts connected to that PROXY.
Figure 3 illustrates a simple configuration involving a proxy. Note
several (per-application) proxies may be deployed.
+-----------+
| HOST_1 |----+
+-----------+ | +--------------------+ +------------+
| | |------| server 1 |
+-----------+ +-----+ | | +------------+
| HOST_2 |--|PROXY|----| INTERNET | ::
+-----------+ +-----+ | | +------------+
| | |------| server n |
+-----------+ | +--------------------+ +------------+
| HOST_3 |-----+
+-----------+
Figure 3
6. Use Case 4: Open Wi-Fi or Provider Wi-Fi
In the context of Provider Wi-Fi (also called Open Wi-Fi or FMC
scenario), a dedicated SSID can be configured and advertised by a CPE
for visiting terminals. These visiting terminals can be mobile
terminals, PCs, etc.
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Several deployment scenarios are envisaged:
1. Deploy a dedicated node in the service provider's network which
will be responsible to intercept all the traffic issued from
visiting terminals (see Figure 4). This node may be co-located
with a CGN function if private IPv4 addresses are assigned to
visiting terminals. Similar to the CGN case discussed in
Section 3, remote servers may not be able to distinguish visiting
hosts sharing the same IP address (see [RFC6269]).
2. Unlike the previous deployment scenario, IPv4 addresses are
managed by the CPE without requiring any additional NAT to be
deployed in the service provider's network for handling traffic
issued from visiting terminals. Concretely, a visiting terminal
is assigned with a private IPv4 address from the pool managed by
the CPE. Packets issued form a visiting terminal are translated
using the public IP address assigned to the CPE (see Figure 5).
This deployment scenario induces the following identification
concerns:
* The provider is not able to distinguish the traffic belonging
to the visiting terminal from the traffic of the subscriber
owning the CPE. This is needed to apply some policies such
as: accounting, DSCP remarking, black list, etc.
* Similar to the CGN case Section 3, a misbehaving visiting
terminal is likely to have some impact on the experienced
service by the customer owning the CPE (e.g., some of the
issues are discussed in [RFC6269]).
+-----------+
| TV |----+
+-----------+ |
| |
+-----------+ +-----+ | +-----------+
| HOST |--| CPE |-|--|Border Node|
+-----------+ +-----+ | +----NAT----+
| |
+-----------+ | | Service Provider
|Visiting UE|-----+
+-----------+
Figure 4
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+-----------+
| TV |----+
+-----------+ |
| |
+-----------+ +-----+ | +-----------+
| HOST |--| CPE |-|--|Border Node|
+-----------+ +-NAT-+ | +-----------+
| |
+-----------+ | | Service Provider
|Visiting UE|-----+
+-----------+
Figure 5
7. Use Case 5: Policy and Charging Control Architecture
This issue is related to the framework defined in [TS.23203] when a
NAT is located between the PCEF (Policy and Charging Enforcement
Function) and the AF (Application Function) as shown in Figure 6.
The main issue is: PCEF, PCRF and AF all receive information bound to
the same UE but without being able to correlate between the piece of
data visible for each entity. Concretely,
o PCEF is aware of the IMSI (International Mobile Subscriber
Identity) and an internal IP address assigned to the UE.
o AF receives an external IP address and port as assigned by the NAT
function.
o PCRF is not able to correlate between the external IP address/port
assigned by the NAT and the internal IP address and IMSI of the
UE.
+------+
| PCRF |-----------------+
+------+ |
| |
+----+ +------+ +-----+ +-----+
| UE |------| PCEF |---| NAT |----| AF |
+----+ +------+ +-----+ +-----+
Figure 6
This scenario can be generalized as follows (Figure 7):
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o Policy Enforcement Point (PEP, [RFC2753])
o Policy Decision Point (PDP, [RFC2753])
+------+
| PDP |-----------------+
+------+ |
| |
+----+ +------+ +-----+ +------+
|Host|------| PEP |---| NAT |----|Server|
+----+ +------+ +-----+ +------+
Figure 7
8. Use Case 6: Cellular Networks
Cellular operators allocate private IPv4 addresses to mobile
customers and deploy NAT44 function, generally co-located with
firewalls, to access to public IP services. The NAT function is
located at the boundaries of the PLMN. IPv6-only strategy,
consisting in allocating IPv6 prefixes only to customers, is
considered by various operators. A NAT64 function is also considered
in order to preserve IPv4 service continuity for these customers.
These NAT44 and NAT64 functions bring some issues very similar to
those mentioned in Figure 1 and Section 7. This issue is
particularly encountered if policies are to be applied on the Gi
interface: a private IP address may be assigned to several UEs, no
correlation between the internal IP address and the address:port
assigned by the NAT function, etc.
9. Security Considerations
This document does not define an architecture nor a protocol; as such
it does not raise any security concern.
10. IANA Considerations
This document does not require any action from IANA.
11. Informative References
[I-D.ietf-intarea-nat-reveal-analysis]
Boucadair, M., Touch, J., Levis, P., and R. Penno,
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"Analysis of Solution Candidates to Reveal a Host
Identifier (HOST_ID) in Shared Address Deployments",
draft-ietf-intarea-nat-reveal-analysis-04 (work in
progress), August 2012.
[RFC2753] Yavatkar, R., Pendarakis, D., and R. Guerin, "A Framework
for Policy-based Admission Control", RFC 2753,
January 2000.
[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.
[RFC6269] Ford, M., Boucadair, M., Durand, A., Levis, P., and P.
Roberts, "Issues with IP Address Sharing", RFC 6269,
June 2011.
[RFC6296] Wasserman, M. and F. Baker, "IPv6-to-IPv6 Network Prefix
Translation", RFC 6296, June 2011.
[RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4
Exhaustion", RFC 6333, August 2011.
[RFC6346] Bush, R., "The Address plus Port (A+P) Approach to the
IPv4 Address Shortage", RFC 6346, August 2011.
[TS.23203]
3GPP, "Policy and charging control architecture",
September 2012.
Authors' Addresses
Mohamed Boucadair
France Telecom
Rennes, 35000
France
Email: mohamed.boucadair@orange.com
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David Binet
France Telecom
Rennes,
France
Email: david.binet@orange.com
Sophie Durel
France Telecom
Rennes
France
Email: sophie.durel@orange.com
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