Network Working Group J. Wu
Internet-Draft G. Ren
Intended status: Experimental J. Bi
Expires: December 10, 2007 X. Li
CERNET
M. Williams
Juniper Networks
June 8, 2007
A First-Hop Source Address Validation Solution for SAVA
draft-wu-sava-solution-firsthop-eap-00
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Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
This document describes a solution for preventing source address
spoofing in the first hop, local subnet of the Internet. The main
idea of the solution is to get a dynamic binding between IP address
and access switch port.
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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].
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. First-Hop, Local Subnet Source Address Validation . . . . . . . 3
2.1. Problem Description . . . . . . . . . . . . . . . . . . . . 3
2.2. Focus of the Solution . . . . . . . . . . . . . . . . . . . 4
3. An IP Address-Switch Port Binding Solution . . . . . . . . . . 4
3.1. System Architecture . . . . . . . . . . . . . . . . . . . . 4
3.2. Key Mechanisms . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Discussion of Control Protocol . . . . . . . . . . . . . . 6
4. CNGI-CERNET2 Test Experience . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
Intellectual Property and Copyright Statements . . . . . . . . . . 9
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1. Introduction
The problem of source address validation is decomposed hierarchically
into three levels of granularity in [I-D.wu-sava-framework] for
discussion: first-hop, local subnet source validation, intra-AS
source validation, and inter-AS source validation.
The first-hop, local subnet source validation is the crucial level in
the hierarchy when it comes to achieving "strict-validated", SAVA
status, which means the packet can be traced back to an individual
host that is authorized to emit packets with that source address. An
IP address-switch port binding solution is proposed in this document.
It should be stressed that at this early stage, the solutions
proposed in the solution document are not intended to pre-empt other
work carried out by the IETF in the solution space. Indeed,
consensus must be reached on a framework before solution work can be
fully undertaken. Furthermore, it is envisaged that more than one
solution could be devised and deployed for each of the proposed
solution elements required under the framework, in keeping with the
requirement for a loosely-coupled architecture and, as far as
possible, a plug-and-play framework.
The intention of this document is to provide some potential solution
ideas which have been implemented on the testbed described
in[I-D.wu-sava-testbed-experience]. Some other procedures that could
be used as solution elements in the first-hop, local subnet source
validation have been devised and one is introduced and discussed in
[I-D.baker-sava-simple].
2. First-Hop, Local Subnet Source Address Validation
2.1. Problem Description
The deployment of BCP38 typically requires that the source address of
a packet entering the provider network belong to a prefix that is
allocated to or has transit through the attached access network. If
there is no special consideration, one host can still spoof source
address by sending packet with the "legal" IP address of another host
with same IP prefix. The goal of the First-Hop, Local Subnet source
address validation is to solve the source address spoofing problem in
these scenarios. That is, to achieve "strict-validated" SAVA
validation status, which means the packet can be traced back to an
individual host that is authorized to emit packets with that source
address. See detail in [I-D.wu-sava-framework].
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2.2. Focus of the Solution
There are several different first-hop, local subnet scenarios:
enterprise networks with switches, home broadband access, access from
a wireless mobile device etc. The focus of the solution described in
this document is enterprise networks with switches.The source address
may be assigned to the host in a static way or a dynamic way.
The solution tested in the SAVA testbed takes the strongest
requirement for validation in the first-hop, local subnet. That is,
any IPv6 address should have a unique association with an entity that
is specifically authorised to use that IPv6 address. The SAVA
testbed has implemented a solution for IPv6 only. The principles can
be extended to IPv4 without difficulty.
3. An IP Address-Switch Port Binding Solution
3.1. System Architecture
The main idea of the solution described in this document is based on
creating a dynamic binding between a switch port and valid source IP
address, or a binding between MAC address, source IP address and
switch port.
There are four main modules of the system: Source Address Request
Client (SARC) on the host, Source Address Validation Proxy (SAVP) on
the switch, Source Address Management Server (SAMS) and Interface to
the Authentication Server (IAS). The system architecture is shown in
Figure 1.
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---------
| IAS |
------|-
|
----------------
| SERVER |
| ------- |
| | SAMS | |
| -------- |
-----------------
|
|
----------------
| SWITCH |
| ------- |
| | SAVP | |
| -------- |
-----------------
|
|
----------------
| END HOST |
| ------- |
| | SARC | |
| -------- |
-----------------
Key: SARC == Source Address Request Client , SAVP == Source Address
Validation Proxy, SAMS== Source Address Management Server, IAS==
Interface to the Authentication Server
Figure 1: System Architecture
o SARC sends an IP address request to the SAMS.
o SAVP relays the IP address request from SARC to SAMS and the IP
addess response from SAMS to SARC. It maintain a binding table
between switch port and source IP address.
o SAMS receives the request from SARC and generates an address
response to SARC based on the address allocation and management
policy of the local subnet. It can contact to the authentication
server for identification and access control via IAS. The
allocation history of the address is stored in SAMS for future
traceback.
o IAS is the interface between the SAMS and authentication server.
In many cases, the allocation and binding of IP addresses is
performed after a process of identity discovery and application of
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access control policy.
3.2. Key Mechanisms
The solution's principle steps are as follows:
1. The SARC on the end host sends an IP address request. The SAVP
on the switch relays this request to the SAMS. If the address
has been predetermined by the end host, it still needs to put it
in the request datagram for acceptance from SAMS.
2. SAMS receives the IP address request, and generates an address
response to SARC based on the address allocation and management
policy of the local subnet. The allocation of the IP address is
stored in the history database of SAMS for traceback. If the
allocation and binding of IP address is performed process of
identity discovery and application of access control policy, do
the identification via IAS. If authorization is successful, send
the IP address response to the SARC.
3. The SAVP on the access switch receives the response, and binds
the IP address with the switch port on the binding table. In
addition, it forwards the issued address to SARC on the end host.
4. The access switch begins to filter packets sent from the end
host. Packets which do not conform to the tuple (IP address,
Switch Port) are discarded.
3.3. Discussion of Control Protocol
The control protocol for generating binding rules of IP address and
switch port can be an extension of DHCP, or a new protocol. The
allocation and binding of IP address can also performed after a
process of access control and identification. For the implementation
in CNGI-CERNET2 testbed, The communication between SARC and SAVP is
an extension of EAP, and the communication between SAVP and SAMS is
an extension of Radius.
4. CNGI-CERNET2 Test Experience
The solutions outlined above have been implemented on the testbed of
CNGI-CERNET2. An extension of EAP is used for the communication
between SARC and SAVP, and an extension of Radius is used for the
communication between SAVP and SAMS. Successful testing of the
solution has been carried out. A more detailed discussion is
described in [I-D.wu-sava-testbed-experience].
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5. IANA Considerations
This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
6. Security Considerations
7. Acknowledgements
I-D.wu-sava-problem-statement
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
8.2. Informative References
[I-D.baker-sava-simple]
Baker, F., "Simple Source Address Validation",
draft-baker-sava-simple-00 (work in progress), March 2007.
[I-D.wu-sava-framework]
Wu, J., "Source Address Validation Architecture (SAVA)
Framework", draft-wu-sava-framework-00 (work in progress),
February 2007.
[I-D.wu-sava-problem-statement]
Wu, J., Bonica, R., Bi, J., Li, X., Ren, G., and M.
Williams, ""Source Address Validation Architecture (SAVA)
Problem Statement", draft-wu-sava-problem-statement-00
(Work in Progress)", February 2007.
[I-D.wu-sava-testbed-experience]
Wu, J., "SAVA Testbed and Experiences to Date",
draft-wu-sava-testbed-experience-00 (work in progress),
February 2007.
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Authors' Addresses
Jianping Wu
CERNET
Network Center, Tsinghua University
Beijing 100084
China
Email: jianping@cernet.edu.cn
Gang Ren
CERNET
Network Center, Tsinghua University
Beijing 100084
China
Email: rg03@mails.tsinghua.edu.cn
Jun Bi
CERNET
Network Center, Tsinghua University
Beijing 100084
China
Email: junbi@cernet.edu.cn
Xing Li
CERNET
Network Center, Tsinghua University
Beijing 100084
China
Email: xing@cernet.edu.cn
Mark I. Williams
Juniper Networks
Suite 1508, W3 Tower, Oriental Plaza, 1 East Chang'An Ave
Dong Cheng District, Beijing 100738
China
Email: miw@juniper.net
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