One document matched: draft-bi-savi-wlan-01.txt
Differences from draft-bi-savi-wlan-00.txt
Network Working Group J. Bi
Internet Draft J. Wu
Intended status: Standard Tracks Y. Wang
Expires: APR, 2012 Tsinghua University
T. Lin
Hangzhou H3C Tech. Co., Ltd.
October 4, 2011
A SAVI solution for WLAN
draft-bi-savi-wlan-01.txt
Abstract
This document describes a source address validation solution for WLAN
enabling 802.11i or other security mechanisms. This mechanism snoops
NDP and DHCP to bind IP address with MAC address, and relies on the
security of MAC address guaranteed by 802.11i or other mechanisms to
filter IP spoofing packets. It can work in the special situations
described in the charter of SAVI workgroup, such as multiple MAC
addresses on one interface. This document describes three different
deployment scenarios, with solutions for migration of mapping entries
when hosts move from one access point to another.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 4, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
Bi, et al. Expires Apr 4, 2012 [Page 1]
Internet-Draft SAVI wlan October 2011
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November 10
2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Table of Contents
1. Introduction ................................................ 3
2. Conventions used in this document............................ 3
3. IP-MAC Binding .............................................. 3
3.1. Data Structures......................................... 4
3.1.1. IP-MAC Mapping Table............................... 4
3.1.2. MAC-IP Mapping Table............................... 4
3.2. Pre-conditions for binding.............................. 4
3.3. Binding IP addresses to MAC addresses................... 4
3.4. Clear Binding .......................................... 5
4. Source Address Validation.................................... 5
5. Deployment Scenarios......................................... 5
5.1. Centralized WLAN........................................ 6
5.1.1. AP Filtering....................................... 6
5.1.1.1. Candidate Binding............................. 6
5.1.1.2. CAPWAP Extension.............................. 6
5.1.1.3. Mobility Solution............................. 8
5.1.2. AC Filtering....................................... 8
5.2. Autonomous WLAN......................................... 8
6. Security Considerations...................................... 9
7. IANA Considerations ......................................... 9
8. Conclusions ................................................. 9
Bi, et al. Expires Apr 4, 2012 [Page 2]
Internet-Draft SAVI wlan October 2011
9. Contributors ................................................ 9
10. Acknowledgments ............................................ 9
11. References ................................................. 9
11.1. Normative References
................................... 9
11.2. Informative References................................ 11
1. Introduction
This document describes a mechanism to perform per packet IP source
address validation in WLAN. This mechanism performs ND snooping or
DHCP snooping to bind allocated IP address with authenticated MAC
address. Static addresses are bound to the MAC addresses of
corresponding stations manually. Then the mechanism can check
validity of source IP address in local packets according to the
binding association. The security of MAC address is assured by
802.11i or other mechanisms, thus the binding association is secure.
The situation that one interfaces with multiple MAC addresses is a
special case mentioned in the charter of SAVI. And this situation is
the only special case that challenges MAC-IP binding. The mechanism
to handle this situation is specified in the document.
There are three deployment scenarios specified in this document. The
mechanism is deployed on different devices in different scenarios.
The deployment detail is described in the document.
When hosts move from one access point to another, the migration of
mapping entries may be triggered according to the specific mobility
scenario. The mechanism to handle host mobility is specified in the
document according to different deployment scenarios.
2. Conventions used in this document
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].
3. IP-MAC Binding
This section specifies the operations of binding IP addresses to MAC
addresses, and the clear of binding.
Bi, et al. Expires Apr 4, 2012 [Page 3]
Internet-Draft SAVI wlan October 2011
3.1. Data Structures
3.1.1. IP-MAC Mapping Table
This table maps IP addresses to corresponding MAC addresses. IP
address is the index of the table. One IP address can only have one
corresponding MAC address, while different IP addresses can be mapped
to the same MAC address.
This table is used in control process. Before creating new IP-MAC
bindings, this table must first be consulted in case of conflict in
binding entries. This table must be synchronized with the MAC-IP
table specified in Section 3.1.2.
The address allocated by DHCP has a limited lifetime, so the related
entry has a limited lifetime, too. According to [RFC4862], stateless
address also has a limited lifetime, the stations set this lifetime
by itself.
3.1.2. MAC-IP Mapping Table
This table maps MAC addresses to corresponding IP addresses. MAC
address is the index of the table. It is a one-to-many mapping table,
which means a MAC address can be mapped to multiple IP addresses.
Though multiple MAC addresses may exist on one interface, these MAC
addresses must be mapped to different IP addresses.
This table is used for filtering and we will specify the details in
Section 4. This table must be synchronized with the IP-MAC table
specified in Section 3.1.1.
3.2. Pre-conditions for binding
In the binding based mechanism, the security of IP address is based
on the security of the binding anchor. In WLAN, a number of security
mechanisms on link layer make MAC address a strong enough binding
anchor, for instance, 802.11i, WAPI, WEP.
If MAC address has no protection, attackers can spoof MAC address to
succeed in validation. However, in general cases, if MAC address is
not protected, more serious attack can be launched than IP spoofing
attack.
3.3. Binding IP addresses to MAC addresses
All the static IP-MAC address pairs are configured into the IP-MAC
Mapping Table with the mechanism enabled.
Bi, et al. Expires Apr 4, 2012 [Page 4]
Internet-Draft SAVI wlan October 2011
An individual procedure handles binding DHCP addresses to MAC
addresses. This procedure snoops the DHCP address assignment
procedure between attached hosts and DHCP server. DHCP snooping in
WLAN is the same as wired network.
An individual procedure handles binding stateless addresses to MAC
addresses. This procedure snoops Duplicate Address Detection
procedure. ND snooping in WLAN is the same as wired network.
3.4. Clear Binding
Three kinds of events will trigger clearing binding:
1. The lifetime of an IP address in one entry has expired. This IP
entry MUST be cleared.
2. A station leaves this access point. The entries for all the
related MAC addresses MUST be deleted.
3. A DHCP RELEASE message is received from the owner of corresponding
IP address. This IP entry MUST be deleted.
4. Source Address Validation
This section describes source address validation procedure on packet.
In this procedure, all the frames are assumed to have passed the
verifications of 802.11i or other security mechanisms.
This procedure has the following steps:
1. Extract the IP source and MAC source from the frame. Lookup the
MAC address in the MAC-IP Mapping Table and check if the MAC-IP pair
exists. If yes, forward the packet. Or else go to next step.
2. Lookup the IP address in the IP-MAC Mapping Table and check if the
IP address exists. If no, insert a new entry into the IP-MAC Mapping
Table and forward the packet. If yes, check whether The MAC address
in the entry is the same as that in the frame. If yes, forward the
packet. Else drop the packet.
5. Deployment Scenarios
This section specifies three deployment scenarios including two under
centralized WLAN and one under autonomous WLAN. The deployment
details and solutions for host mobility between access points are
described respectively in each scenario.
Bi, et al. Expires Apr 4, 2012 [Page 5]
Internet-Draft SAVI wlan October 2011
5.1. Centralized WLAN
Centralized WLAN is comprised of FIT Access Points (AP) and Access
Controllers (AC). In this scenario, this document proposes the
following two deployment solutions.
5.1.1. AP Filtering
In this scenario, AC maintains IP-MAC Mapping Table while AP
maintains MAC-IP Mapping Table. Packet filtering will be performed on
each AP as specified in Section 4.
5.1.1.1. Candidate Binding
AP executes the procedure specified in Section 3.3. Candidate binding
is generated after snooping procedure. Candidate binding must be
confirmed by AC to be valid.
After a candidate binding is generated, AC is notified and checks
whether the binding is valid or not. The validity of a candidate
binding is determined if the binding does not violate any existing
bindings in the IP-MAC Mapping Table. Otherwise if an address is not
suitable for a host to use, AC notifies the corresponding AP. If the
candidate binding is valid, AC adds an entry into the IP-MAC Mapping
Table and notifies AP. Afterwards AP also adds an entry into the
local MAC-IP Mapping Table.
5.1.1.2. CAPWAP Extension
CAPWAP protocol is used for communication between AP and AC. A new
CAPWAP protocol message element is introduced, which extends the
[CAPWAP]. The host IP message element is used by both AP and AC to
exchange the binding information of hosts.
The host IP message element MAY be sent by AP. When AP generates a
candidate binding, it reports the MAC address and related IP
addresses to AC using this message, with suggestions of the state and
lifetime of each IP address.
The host IP message element MAY be sent by AC. After AC checks the
validation of a candidate binding, it replies using a message of the
same format to inform AP the validation of each IP address with
suggestions of its state and lifetime.
Bi, et al. Expires Apr 4, 2012 [Page 6]
Internet-Draft SAVI wlan October 2011
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Radio ID | Total Length +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC flag | Length | MAC Address... +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Address... +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 flag | Length | IPv4 Address... +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Address... +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 flag | Length | IPv6 Address... +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 Address... +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Radio ID: An 8-bit value representing the radio, whose value is
between 1 and 31.
Total Length: Total length of the following fields.
MAC flag: An 8-bit value representing that the sub-field's type is
MAC address, whose value is 1.
Length: The length of the MAC Address field. The formats and lengths
specified in [EUI-48] and [EUI-64] are supported.
MAC Address: A MAC address of the host.
IPv4 flag: An 8-bit value representing that the sub-field's type is
IPv4 address, whose value is 2.
Length: The length of the IPv4 Address field.
IPv4 Address: An IPv4 address of the host. There may exist many
entries, and each entry is comprised of an IPv4 address, an 8-bit
value for address state (only value 1 is used for now), and a 32-bit
value for lifetime.
IPv6 flag: An 8-bit value representing that the sub-field's type is
IPv6 address, whose value is 3.
Bi, et al. Expires Apr 4, 2012 [Page 7]
Internet-Draft SAVI wlan October 2011
Length: The length of the IPv6 Address field.
IPv6 Address: An IPv6 address of the host. There may exist many
entries, and each entry is comprised of an IPv6 address, an 8-bit
value of address state (also one value for now), and a 32-bit value
lifetime.
5.1.1.3. Mobility Solution
When a host moves from one AP to another, layer-2 association happens
before IP packet transfer. Home AP deletes the binding when mobile
host is disconnected, and foreign AP immediately requests the bound
addresses with the associated MAC from AC. After AC tells AP the
addresses should be bound, the binding migration is completed.
In WLAN, a host can move from an AC to another AC while keeping using
the same IP address. To be compatible with such scenario, ACs must
communicate to perform the binding migration.
CAPWAP extensions specified in Section 5.1.1.2 can also be used for
communications between AC. The procedure of binding migration is the
similar to that in the previous scenario. Home AC deletes the binding
when mobile host is disconnected, and foreign AC requests the bound
addresses with the associated MAC from Home AC.
5.1.2. AC Filtering
In this scenario, AC maintains both MAC-IP and IP-MAC Mapping Table
and performs packet filtering. So all the packets must be firstly be
forwarded to AC. AC executes the procedure specified in Section 3.3.
Mobility in one AC does not trigger any binding migration. Mobility
between different ACs triggers binding migration and the procedure is
the same as that in Section 5.1.1.3.
5.2. Autonomous WLAN
Autonomous WLAN is comprised of FAT Access Points. In this scenario,
FAT AP maintains both MAC-IP and IP-MAC Mapping Table and performs
packet filtering and executes the procedure specified in Section 3.3.
Mobility between different FAT APs will trigger binding migration,
and the procedure is the same as that in Section 5.1.1.3.
Bi, et al. Expires Apr 4, 2012 [Page 8]
Internet-Draft SAVI wlan October 2011
6. Security Considerations
The security of address allocation methods matters the security of
this mechanism. Thus it is necessary to improve the security of
stateless auto-configuration and DHCP firstly.
7. IANA Considerations
There is no IANA Consideration currently.
8. Conclusions
This solution can satisfy the requirements of SAVI charter in WLAN
enabling 802.11i or other security mechanisms.
9. Contributors
Guang Yao
Tsinghua University
Network Research Center, Tsinghua University
Beijing 100084
China
EMail: yaog@netarchlab.tsinghua.edu.cn
Yang Shi
Hangzhou H3C Tech. Co., Ltd.
Beijing 100085
China
EMail: rishyang@gmail.com
Hao Wang
Hangzhou H3C Tech. Co., Ltd.
Beijing 100085
China
EMail: hwang@h3c.com
10. Acknowledgments
This document was prepared using 2-Word-v2.0.template.dot.
11. References
11.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
Bi, et al. Expires Apr 4, 2012 [Page 9]
Internet-Draft SAVI wlan October 2011
[2] Crocker, D. and Overell, P.(Editors), "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, Internet Mail Consortium and
Demon Internet Ltd., November 1997.
[3] IEEE 802.11i-2004: Amendment 6: Medium Access Control (MAC)
Security Enhancements
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4862] Thomson, S., Narten, T. and Jinmei, T., "IPv6 Stateless
Autoconfiguration", RFC4862, September, 2007.
[RFC3315] R. Droms, Ed., J. Bound, B. Volz, T. Lemon, C. Perkins, and
M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC3315, July, 2003.
[RFC5415] Control And Provisioning of Wireless Access Points (CAPWAP)
Protocol Specification
Bi, et al. Expires Apr 4, 2012 [Page 10]
Internet-Draft SAVI wlan October 2011
11.2. Informative References
Authors' Addresses
Jun Bi
Tsinghua University
Network Research Center, Tsinghua University
Beijing 100084
China
EMail: junbi@cernet.edu.cn
Jianping Wu
Tsinghua University
Computer Science, Tsinghua University
Beijing 100084
China
EMail: jianping@cernet.edu.cn
You Wang
Tsinghua University
Network Research Center, Tsinghua University
Beijing 100084
China
EMail: wangyou@netarchlab.tsinghua.edu.cn
Tao Lin
Hangzhou H3C Tech. Co., Ltd.
Beijing 100085
China
EMail: lintaog@gmail.com
Bi, et al. Expires Apr 4, 2012 [Page 11]
| PAFTECH AB 2003-2026 | 2026-04-24 04:16:50 |