[Mip6-firewall] Latest version of the firewall drafts
Suresh Krishnan
suresh.krishnan at ericsson.com
Thu Oct 9 10:55:21 EDT 2008
Hi Ying,
This is because the RO security seems to be based on the HoT and the
HoTI being tunneled ENCRYPTED between the MN and the HA.
In RFC3775
Section 5.2.5 under Home Test
"For improved security, the data passed between the
home agent and the mobile node is made immune to inspection and
passive attacks. Such protection is gained by encrypting the home
keygen token as it is tunneled from the home agent to the mobile
node as specified in Section 10.4.6."
Section 10.4.6
"Therefore, the home agent MUST support tunnel mode
IPsec ESP for the protection of packets belonging to the return
routability procedure. Support for a non-null encryption transform
and authentication algorithm MUST be available."
I was earlier of the same opinion as you to differentiate between null
encrypted and non-null encrypted packets but I feel that in practice
null encryption will not be used on the MN-HA path for the HoTI and HoT
messages as it defeats the purpose for which ESP was required. If you
feel strongly about this we can put this as a question to implementers (
We do support null encryption in our implementation ) after we submit
the drafts.
Cheers
Suresh
QIU Ying wrote:
> Hi, Suresh
>
> Might I know why to delete the pattern for HoTI message in section 4.1
> and 6.1, admin draft? Do we give up the scenarios of null encryption
> algorithm for these ipsec packets?
>
> Regards
> Qiu Ying
>
>
> ----- Original Message ----- From: "Suresh Krishnan"
> <suresh.krishnan at ericsson.com>
> To: <mip6-firewall at zeke.ecotroph.net>
> Sent: Thursday, October 09, 2008 5:55 AM
> Subject: [Mip6-firewall] Latest version of the firewall drafts
>
>
>> Hi Folks,
>> Here is the latest version of the firewall drafts that are to be
>> submitted as version -00 of the mext wg documents. Please let me know if
>> you have any comments.
>>
>> Thanks
>> Suresh
>>
>
>
> --------------------------------------------------------------------------------
>
>
>
>>
>>
>>
>> Network Working Group S. Krishnan
>> Internet-Draft Ericsson
>> Intended status: Informational N. Steinleitner
>> Expires: April 11, 2009 University of Goettingen
>> Y. Qiu
>> Institute for Infocomm Research
>> G. Bajko
>> Nokia
>> October 8, 2008
>>
>>
>> Guidelines for firewall administrators regarding MIPv6 traffic
>> draft-ietf-mext-firewall-admin-00
>>
>> Status of this Memo
>>
>> By submitting this Internet-Draft, each author represents that any
>> applicable patent or other IPR claims of which he or she is aware
>> have been or will be disclosed, and any of which he or she becomes
>> aware will be disclosed, in accordance with Section 6 of BCP 79.
>>
>> Internet-Drafts are working documents of the Internet Engineering
>> Task Force (IETF), its areas, and its working groups. Note that
>> other groups may also distribute working documents as Internet-
>> Drafts.
>>
>> 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."
>>
>> The list of current Internet-Drafts can be accessed at
>> http://www.ietf.org/ietf/1id-abstracts.txt.
>>
>> The list of Internet-Draft Shadow Directories can be accessed at
>> http://www.ietf.org/shadow.html.
>>
>> This Internet-Draft will expire on April 11, 2009.
>>
>> Abstract
>>
>> This document presents some recommendations for firewall
>> administrators to help them configure their existing firewalls in a
>> way that allows in certain deployment scenarios the Mobile IPv6
>> signaling and data messages to pass through. For other scenarios,
>> the support of additional mechanisms to create pinholes required for
>> MIPv6 will be necessary. This document assumes that the firewalls in
>> question include some kind of stateful packet filtering capability.
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 1]
>>
>> Internet-Draft MIPv6 Firewall Administrator guidelines October 2008
>>
>>
>> Table of Contents
>>
>> 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
>> 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
>> 3. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . 3
>> 4. Home Agent behind a firewall . . . . . . . . . . . . . . . . . 4
>> 4.1. Signaling between the MN and the HA . . . . . . . . . . . 5
>> 4.2. IKEv2 signaling between MN and HA for establishing SAs . . 5
>> 5. Correspondent Node behind a firewall . . . . . . . . . . . . . 5
>> 5.1. Route optimization signaling between MN and CN through
>> HA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
>> 5.2. Route optimization signaling between MN and CN . . . . . . 6
>> 5.3. Binding Update from MN to CN . . . . . . . . . . . . . . . 7
>> 5.4. Route Optimization data traffic from MN . . . . . . . . . 7
>> 6. Mobile Node behind a firewall . . . . . . . . . . . . . . . . 7
>> 6.1. Signaling between MN and HA . . . . . . . . . . . . . . . 8
>> 6.2. Signaling between MN and CN . . . . . . . . . . . . . . . 9
>> 6.3. IKEv2 signaling between MN and HA for establishing SAs . . 9
>> 7. Related documents . . . . . . . . . . . . . . . . . . . . . . 9
>> 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
>> 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
>> 10. Security Considerations . . . . . . . . . . . . . . . . . . . 10
>> 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
>> 11.1. Normative References . . . . . . . . . . . . . . . . . . . 10
>> 11.2. Informative References . . . . . . . . . . . . . . . . . . 10
>> Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
>> Intellectual Property and Copyright Statements . . . . . . . . . . 12
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 2]
>>
>> Internet-Draft MIPv6 Firewall Administrator guidelines October 2008
>>
>>
>> 1. Requirements notation
>>
>> 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 [RFC2119].
>>
>>
>> 2. Introduction
>>
>> Network elements such as firewalls are an integral aspect of a
>> majority of IP networks today, given the state of security in the
>> Internet, threats, and vulnerabilities to data networks. MIPv6
>> [RFC3775] defines mobility support for IPv6 nodes. Firewalls will
>> interfere with the smooth operation of the MIPv6 protocol unless
>> specific steps are taken to allow Mobile IPv6 signaling and data
>> messages to pass through the firewall. The problems caused by
>> firewalls to Mobile IPv6 are documented in [RFC4487].
>>
>> This document presents some recommendations for firewall
>> administrators to help them configure their firewalls in a way that
>> allows the Mobile IPv6 signaling and data messages to pass through.
>> This document assumes that the firewalls in question include some
>> kind of stateful packet filtering capability. The static rules that
>> need to be configured are described in this document. In some
>> scenarios, the support of additional mechanisms to create pinholes
>> required for MIPv6 signalling and data traffic to pass through will
>> be necessary. A possible solution, describing the dynamic
>> capabilities needed for the firewalls to create pinholes based on
>> MIPv6 signalling traffic is described in a companion document
>> [MIP6FWVENDOR]. Other solutions may also be possible.
>>
>> Some Mobile IPv6 signalling messages require the use of encryption to
>> protect the confidentiality of the payload (e.g. the HoTI and HoT
>> messages between the MN and the HA). The other signalling messages
>> allow the use of encryption. If encryption is being used, it is not
>> possible to inspect the contents of the signalling packets. For
>> these messages to get through, a generic rule needs to be added in
>> the firewall to let ESP packets through without further inspection.
>>
>>
>> 3. Abbreviations
>>
>> This document uses the following abbreviations:
>>
>> o CN: Correspondent Node
>>
>> o CoA: Care of Address
>>
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 3]
>>
>> Internet-Draft MIPv6 Firewall Administrator guidelines October 2008
>>
>>
>> o CoTI: Care of Test Init
>>
>> o HA: Home Agent
>>
>> o HoA: Home Address
>>
>> o HoTI: Home Test Init
>>
>> o HoT: Home Test
>>
>> o MN: Mobile Node
>>
>> o RO: Route Optimization
>>
>> o RRT: Return Routability Test
>>
>>
>> 4. Home Agent behind a firewall
>>
>> This section presents the recommendations for configuring a firewall
>> that protects a home agent.
>>
>> +----------------+ +---+
>> | | | A |
>> | | +---+
>> | +----+ | External
>> | | HA | +----+ MN
>> | +----+ | FW | +---+
>> | Home Agent +----+ | B |
>> | of A | +---+
>> | | External
>> | | Node
>> +----------------+
>> Network protected
>> by a firewall
>>
>> Figure 1: HA behind a firewall
>>
>> For each type of traffic that needs to pass through this firewall,
>> recommendations are presented on how to identify that traffic. The
>> following types of traffic are considered
>>
>> o Signaling between the MN and the HA
>>
>> o IKEv2 signaling between MN and HA for establishing SAs
>>
>>
>>
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 4]
>>
>> Internet-Draft MIPv6 Firewall Administrator guidelines October 2008
>>
>>
>> 4.1. Signaling between the MN and the HA
>>
>> The signaling between the MN and HA is protected using IPSec ESP.
>> These messages are critical to the MIPv6 protocol and if these
>> messages are discarded, Mobile IPv6 as specified today will cease to
>> work. In order to permit these messages through, the firewall has to
>> detect the messages using the following patterns.
>>
>> Destination Address: Address of HA
>> Next Header: 50 (ESP)
>> Mobility Header Type: 5 (BU)
>>
>> This pattern will allow the BU messages from MNs to HA to pass
>> through.
>>
>> 4.2. IKEv2 signaling between MN and HA for establishing SAs
>>
>> The MN and HA exchange IKEv2 signaling in order to establish the
>> security associations. The security associations so established will
>> later be used for securing the mobility signaling messages. Hence
>> these messages need to be permitted to pass through the firewalls.
>> The following pattern will detect these messages.
>>
>> Destination Address: Address of HA
>> Transport Protocol: UDP
>> Destination UDP Port: 500
>>
>>
>>
>> 5. Correspondent Node behind a firewall
>>
>> This section presents the recommendations for configuring a firewall
>> if a node behind it should be able to act as Mobile IPv6 CN.
>>
>> +----------------+ +----+
>> | | | HA |
>> | | +----+
>> | | Home Agent
>> | +---+ +----+ of B
>> | |CN | | FW |
>> | | C | +----+
>> | +---+ | +---+
>> | | | B |
>> | | +---+
>> +----------------+ External Mobile
>> Network protected Node
>> by a firewall
>>
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 5]
>>
>> Internet-Draft MIPv6 Firewall Administrator guidelines October 2008
>>
>>
>> Figure 2: CN behind a firewall
>>
>> For each type of traffic that needs to pass through this firewall,
>> recommendations are presented on how to identify that traffic. The
>> following types of traffic are considered
>>
>> o Route optimization signaling between MN and CN through HA
>>
>> o Route optimization signaling between MN and CN
>>
>> o Binding Update from MN to CN
>>
>> o Route Optimization data traffic from MN
>>
>> 5.1. Route optimization signaling between MN and CN through HA
>>
>> Parts of the initial route optimization signaling has to pass through
>> the HA, namely the HoTI and the HoT messages. Without assistance,
>> the HoTI message from the HA to the CN is not able to traverse the
>> firewall. When only a few priviledged nodes (like servers) are
>> allowed to be contacted by outside nodes, then the following pattern
>> will allow the HoTI messages to reach these nodes:
>>
>> Destination Address: CN Address
>>
>> Mobility Header Type: 1 (HoTI)
>>
>> where CN Address describes the address(es) of the priviledged
>> node(s). This pinhole allows the HoTI message from the HA to the CN
>> to traverse the firewall. The HoT message from the CN to the MN
>> through the HA can traverse the firewall without any assistance.
>> Hence no pinhole is required.
>>
>> 5.2. Route optimization signaling between MN and CN
>>
>> Route Optimization allows direct communication of data packets
>> between the MN and a CN without tunnelling it back through the HA.
>> To get route optimization work, the MN has to send a CoTI message
>> directly to the CN, which response with a CoT message. However, a
>> stateful firewall would prevent the CoTI message to pass through as
>> there is no established state on the firewall. When only a few
>> priviledged nodes (like servers) are allowed to be contacted by
>> outside nodes, then the following pattern will allow the CoTI
>> messages to reach these nodes:
>>
>>
>>
>>
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 6]
>>
>> Internet-Draft MIPv6 Firewall Administrator guidelines October 2008
>>
>>
>> Destination Address: CN Address
>>
>> Mobility Header Type: 2 (CoTI)
>>
>> where CN Address describes the address(es) of the priviledged
>> node(s).The CoT message from the CN to the MN can traverse the
>> firewall without any assistance. Hence no pinhole is required.
>>
>> 5.3. Binding Update from MN to CN
>>
>> After successfully performing the return routability procedure, the
>> MN sends the BU to the CN and expects the BA. Since this BU does not
>> match any previous installed pinhole rules, an additional pinhole
>> with the following format is required.When only a few priviledged
>> nodes (like servers) are allowed to be contacted by outside nodes,
>> then the following pattern will allow the BU messages to reach these
>> nodes:
>>
>> Destination Address: CN Address
>>
>> Mobility Header Type: 5
>>
>> where CN Address describes the address(es) of the priviledged
>> node(s).This allows the BU to traverse the firewall and the BA can
>> pass the firewall without any assistance. Therefore, the Binding
>> Update sequence can be performed successfully.
>>
>> 5.4. Route Optimization data traffic from MN
>>
>> Also the Route Optimization data traffic from MN directly to the CN
>> can not traverse the firewall without assistance. A dynamically
>> created pinhole such as the one specified in [MIP6FWVENDOR] will
>> allow this traffic to pass.
>>
>>
>> 6. Mobile Node behind a firewall
>>
>> This section presents the recommendations for configuring a firewall
>> that protects the network a mobile node visiting.
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 7]
>>
>> Internet-Draft MIPv6 Firewall Administrator guidelines October 2008
>>
>>
>> +----------------+ +----+
>> | | | HA |
>> | | +----+
>> | | Home Agent
>> | +---+ +----+ of A +---+
>> | | A | | FW | | B |
>> | +---+ +----+ +---+
>> |Internal | External
>> | MN | Node
>> | |
>> +----------------+
>> Network protected
>> by a firewall
>>
>> Figure 3: MN behind a firewall
>>
>> For each type of traffic that needs to pass through this firewall,
>> recommendations are presented on how to identify that traffic. The
>> following types of traffic are considered
>>
>> o Signaling between MN and HA
>>
>> o Route Optimization Signaling between MN and CN
>>
>> o IKEv2 signaling between MN and HA for establishing SAs
>>
>> 6.1. Signaling between MN and HA
>>
>> As described in Section 4.1, the signaling between the MN and HA is
>> protected using IPSec ESP. Currently, a lot of firewalls are
>> configured to block the incoming ESP packets. Moreover, from the
>> view of the firewall, both source and destination addresses of these
>> messages from/to mobile node are variable. Fortunately, for a
>> stateful firewall, if the initial traffic is allowed through the
>> firewall, then the return traffic is also allowed. A mobile node is
>> always the initiator for the BU. Since MN's CoA is not able to be
>> known in advance, the firewall can use following patterns to permit
>> these messages through.
>>
>> Source Address: Visited subnet prefix
>>
>> Destination Address: Address of HA
>> Next Header: 50 (ESP)
>> Mobility Header Type: 5 (BU)
>>
>> This pattern will allow the Binding Update packets to pass through
>> the firewall. Then the return packets (BA from HA to MN) will also
>> able to pass through accordingly.
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 8]
>>
>> Internet-Draft MIPv6 Firewall Administrator guidelines October 2008
>>
>>
>> 6.2. Signaling between MN and CN
>>
>> Route Optimization allows direct communication of data packets
>> between the MN and a CN without tunneling it back through the HA. It
>> includes 3 pairs of messages: HoTI/HoT, CoTI/CoT and BU/BA. The
>> first pair can pass through the firewall using the pattern described
>> in section 5.1. Here we discuss CoTI/CoT and BU/BA messages.
>> Following pattern permits these messages through the firewall.
>>
>> Source Address: Visited subnet prefix
>> Mobility Header Type: 2 (CoTI)
>>
>> Source Address: Visited subnet prefix
>> Mobility Header Type: 5 (BU)
>>
>> This pattern allows the initial messages (CoTI and BU) from the MN to
>> the CN pass through the firewall. The return messages (CoT and BA)
>> from the CN to the MN can also passes through the firewall
>> accordingly.
>>
>> 6.3. IKEv2 signaling between MN and HA for establishing SAs
>>
>> The MN and HA exchange IKEv2 signaling in order to establish the
>> security associations. The security associations so established will
>> later be used for securing the mobility signaling messages. Due to
>> variable source/destination IP addresses and MN always as initiator,
>> the following pattern will let the negotiation pass.
>>
>> Source Address: Visited subnet prefix
>> Transport Protocol: UDP
>> Destination UDP Port: 500
>>
>>
>>
>> 7. Related documents
>>
>> There are other IETF published documents that provide recommendations
>> for firewall configuration that can affect Mobile IPv6 messages.
>> [RFC4890] that provides recommendations for filtering ICMPv6 messages
>> (especially Section 4.3.2). [RFC4942] describes security issues
>> present in IPv6 and related protocols (especially Sections 2.1.2 and
>> 2.1.15).
>>
>>
>> 8. Acknowledgements
>>
>> The authors would like to thank the following members of the MIPv6
>> firewall design team for contributing to this document: Hannes
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 9]
>>
>> Internet-Draft MIPv6 Firewall Administrator guidelines October 2008
>>
>>
>> Tschofenig, Hesham Soliman, Yaron Sheffer, and Vijay Devarapalli.
>> The authors would also like to thank William Ivancic, Ryuji Wakikawa,
>> Jari Arkko, Henrik Levkowetz, Pasi Eronen and Noriaki Takamiya for
>> their thorough reviews of the document and for providing comments to
>> improve the quality of the document.
>>
>>
>> 9. IANA Considerations
>>
>> This document does not require any IANA action.
>>
>>
>> 10. Security Considerations
>>
>> This document specifies recommendations for firewall administrators
>> to allow Mobile IPv6 traffic to pass through unhindered. Since some
>> of this traffic is encrypted it is not possible for firewalls to
>> discern whether it is safe or not. This document recommends a
>> liberal setting so that all legitimate traffic can pass. This means
>> that some malicious traffic may be permitted by these rules. These
>> rules may allow the initiation of Denial of Service attacks against
>> Mobile IPv6 capable nodes (the MNs, CNs and the HAs).
>>
>>
>> 11. References
>>
>> 11.1. Normative References
>>
>> [MIP6FWVENDOR]
>> Krishnan, S., Sheffer, Y., Steinleitner, N., and G. Bajko,
>> "Guidelines for firewall vendors regarding MIPv6 traffic",
>> draft-ietf-mext-firewall-vendor-0 (work in progress),
>> October 2008.
>>
>> [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
>> Requirement Levels", BCP 14, RFC 2119, March 1997.
>>
>> [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
>> in IPv6", RFC 3775, June 2004.
>>
>> [RFC4487] Le, F., Faccin, S., Patil, B., and H. Tschofenig, "Mobile
>> IPv6 and Firewalls: Problem Statement", RFC 4487,
>> May 2006.
>>
>> 11.2. Informative References
>>
>> [RFC4890] Davies, E. and J. Mohacsi, "Recommendations for Filtering
>> ICMPv6 Messages in Firewalls", RFC 4890, May 2007.
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 10]
>>
>> Internet-Draft MIPv6 Firewall Administrator guidelines October 2008
>>
>>
>> [RFC4942] Davies, E., Krishnan, S., and P. Savola, "IPv6 Transition/
>> Co-existence Security Considerations", RFC 4942,
>> September 2007.
>>
>>
>> Authors' Addresses
>>
>> Suresh Krishnan
>> Ericsson
>> 8400 Decarie Blvd.
>> Town of Mount Royal, QC
>> Canada
>>
>> Phone: +1 514 345 7900 x42871
>> Email: suresh.krishnan at ericsson.com
>>
>>
>> Niklas Steinleitner
>> University of Goettingen
>> Lotzestr. 16-18
>> Goettingen
>> Germany
>>
>> Email: steinleitner at cs.uni-goettingen.de
>>
>>
>> Ying Qiu
>> Institute for Infocomm Research
>> 21 Heng Mui Keng Terrace
>> Singapore
>>
>> Phone: +65-6874-6742
>> Email: qiuying at i2r.a-star.edu.sg
>>
>>
>> Gabor Bajko
>> Nokia
>>
>> Email: gabor.bajko at nokia.com
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 11]
>>
>> Internet-Draft MIPv6 Firewall Administrator guidelines October 2008
>>
>>
>> Full Copyright Statement
>>
>> Copyright (C) The IETF Trust (2008).
>>
>> This document is subject to the rights, licenses and restrictions
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>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 12]
>>
>>
>
>
> --------------------------------------------------------------------------------
>
>
>
>>
>>
>>
>> Network Working Group S. Krishnan
>> Internet-Draft Ericsson
>> Intended status: Standards Track Y. Sheffer
>> Expires: April 11, 2009 Check Point
>> N. Steinleitner
>> University of Goettingen
>> G. Bajko
>> Nokia
>> October 8, 2008
>>
>>
>> Guidelines for firewall vendors regarding MIPv6 traffic
>> draft-ietf-mext-firewall-vendor-00
>>
>> Status of this Memo
>>
>> By submitting this Internet-Draft, each author represents that any
>> applicable patent or other IPR claims of which he or she is aware
>> have been or will be disclosed, and any of which he or she becomes
>> aware will be disclosed, in accordance with Section 6 of BCP 79.
>>
>> Internet-Drafts are working documents of the Internet Engineering
>> Task Force (IETF), its areas, and its working groups. Note that
>> other groups may also distribute working documents as Internet-
>> Drafts.
>>
>> 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."
>>
>> The list of current Internet-Drafts can be accessed at
>> http://www.ietf.org/ietf/1id-abstracts.txt.
>>
>> The list of Internet-Draft Shadow Directories can be accessed at
>> http://www.ietf.org/shadow.html.
>>
>> This Internet-Draft will expire on April 11, 2009.
>>
>> Abstract
>>
>> This document presents some recommendations for firewall vendors to
>> help them implement their firewalls in a way that allows Mobile IPv6
>> signaling and data messages to pass through. This document describes
>> how to implement stateful packet filtering capability for MIPv6.
>>
>>
>>
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 1]
>>
>> Internet-Draft MIPv6 Firewall Vendor guidelines October 2008
>>
>>
>> Table of Contents
>>
>> 1. Requirements notation . . . . . . . . . . . . . . . . . . . . . 3
>> 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
>> 3. MIPv6 Firewall Primitives . . . . . . . . . . . . . . . . . . . 3
>> 3.1. Requirements . . . . . . . . . . . . . . . . . . . . . . . 3
>> 3.2. Detecting and parsing the Mobility Header . . . . . . . . . 3
>> 3.3. Parsing Mobility Options . . . . . . . . . . . . . . . . . 4
>> 4. Allowing signaling response packets . . . . . . . . . . . . . . 4
>> 5. Allowing data packets based on signaling . . . . . . . . . . . 5
>> 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
>> 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
>> 8. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
>> 9. Normative References . . . . . . . . . . . . . . . . . . . . . 7
>> Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
>> Intellectual Property and Copyright Statements . . . . . . . . . . 9
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>> Krishnan, et al. Expires April 11, 2009 [Page 2]
>>
>> Internet-Draft MIPv6 Firewall Vendor guidelines October 2008
>>
>>
>> 1. Requirements notation
>>
>> 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 [RFC2119].
>>
>>
>> 2. Introduction
>>
>> Network elements such as firewalls are an integral aspect of a
>> majority of IP networks today, given the state of security in the
>> Internet, threats, and vulnerabilities to data networks. MIPv6
>> [RFC3775] defines mobility support for IPv6 nodes. Since firewalls
>> are not aware of MIPv6 protocol details, they will probably interfere
>> with the smooth operation of the protocol. The problems caused by
>> firewalls to Mobile IPv6 are documented in [RFC4487].
>>
>> This document presents some recommendations for firewall vendors to
>> help them implement their firewalls in a way that allows Mobile IPv6
>> signaling and data messags to pass through. This document describes
>> how to implement stateful packet filtering capability for MIPv6.
>>
>> Some Mobile IPv6 signalling messages require the use of encryption to
>> protect the confidentiality of the payload (e.g. the HoTI and HoT
>> messages between the MN and the HA). The other signalling messages
>> allow the use of encryption. If encryption is being used, it is not
>> possible to inspect the contents of the signalling packets. For
>> these messages to get through, a generic rule needs to be added in
>> the firewall to let ESP packets through without further inspection.
>>
>>
>> 3. MIPv6 Firewall Primitives
>>
>> 3.1. Requirements
>>
>> This document assumes that the firewalls are capable of deep packet
>> inspection at least until the mobility header. It also assumes that
>> the firewalls are capable of creating filters based on arbitrary
>> fields based on the contents of a signaling packet.
>>
>> 3.2. Detecting and parsing the Mobility Header
>>
>> The Mobility Header is the basic primitive in all MIPv6 signaling
>> messages. Thus the firewalls need to be able to recognize the
>> presence of the mobility header and be able to parse the contents of
>> the Mobility Header. The MH is described in section 6.1 of [RFC3775]
>> and the format of the same is scribed in section 6.1.1 of [RFC3775].
>> Firewalls need to be able to at least understand the contents of the
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 3]
>>
>> Internet-Draft MIPv6 Firewall Vendor guidelines October 2008
>>
>>
>> MH Type field that describes the type of signaling message carried.
>>
>> 3.3. Parsing Mobility Options
>>
>> The Mobility Header can carry additional information in the form of
>> mobility options as described in section 6.2 of [RFC3775]. Some of
>> these mobility options need to be understood for proper creation of
>> state on the firewalls. Hence firewalls must be able to parse the
>> mobility options defined in [RFC3775].
>>
>>
>> 4. Allowing signaling response packets
>>
>> The MIPv6 signalling messages are usually performed as a request-
>> response pair. The request message is usually allowed by setting up
>> a static firewall rule to allow the traffic to pass through. The
>> response message on the other hand can be dynamically allowed if the
>> firewall can automatically setup a filter for the response packets
>> when the request packet passes through. This is not trivial, but
>> fortunately is straightforward. There are 3 message pairs that are
>> of importance to MIPv6 signaling. They are the BU/BA, HoTI/HoT and
>> CoTI/CoT pairs. When the first message in the pair traverses the
>> firewall in one direction, the firewall must setup a filter rule to
>> allow the second message through in the other direction.
>>
>> Consider a packet that matches a static rule configured on a firewall
>>
>> Destination Address: Address of HA
>> Next Header: 50 (ESP)
>> Mobility Header Type: 5 (BU)
>>
>> This rule allows a binding update message from a MN to pass through
>> to the HA. Once a packet that matches this rule passes through the
>> firewall, the firewall must setup a dynamic filter for the return
>> packet
>>
>> Source Address: Destination Address from Packet
>>
>> Destination Address: Source Address from Packet
>> Next Header: 50 (ESP)
>> Mobility Header Type: 6 (BA)
>>
>> This rule ensures that the return BA packet will pass through
>> unhindered. The rules can be generalized as summarized in the table
>> below.
>>
>>
>>
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 4]
>>
>> Internet-Draft MIPv6 Firewall Vendor guidelines October 2008
>>
>>
>> +---------------------------------+---------------------------------+
>> | Passing packet MH Type | Setup return filter with MH |
>> | | Type |
>> +---------------------------------+---------------------------------+
>> | Mobility Header Type:1(HoTI) | Mobility Header Type:3(HoT) |
>> | Mobility Header Type:2(CoTI) | Mobility Header Type:4(CoT) |
>> | Mobility Header Type:5(BU) | Mobility Header Type:6(BA) |
>> +---------------------------------+---------------------------------+
>>
>> Table 1: Message Pairs in MIPv6
>>
>> Such dynamic rules can be timed out after a configurable period
>> STATEFUL_PINHOLE_LIFETIME, unless renewed by new mobility messages.
>> This document recommends that the default value of
>> STATEFUL_PINHOLE_LIFETIME be set to 30 seconds.
>>
>> These dynamic rules MUST be immediately deleted after the return
>> message passes through. e.g. Once a return HoT message for a HoTI
>> passes through, the pinhole must be immediately removed. The loss of
>> the HoT packet after passing the firewall needs to be handled by the
>> original MN retransmitting the HoTI message.
>>
>>
>> 5. Allowing data packets based on signaling
>>
>> Once the MIPv6 signaling completes, the data traffic can begin to
>> flow. The traffic filters for the data traffic can be inferred from
>> the contents of the signaling messages that setup the session. This
>> section describes how firewalls can intelligently setup filters for
>> data traffic based on signaling traffic.The following example
>> describes how to setup a filter for allowing incoming route optimized
>> messages from a CN to an MN after the MN sent a BU message to a CN.
>>
>> When the BU message from MN to CN (MH Type 5) traverses through the
>> firewall the firewall extracts the home address (HoA) from the Home
>> Address Option (section 6.3 of [RFC3775]) of the packet.
>>
>> The firewall adds the following rule in order to let the return
>> traffic pass.
>>
>> Destination Address: Source Address of the packet (MN CoA)
>> Source Address: Destination Address of packet (CN)
>> Routing Header Type 2 Address: HoA
>>
>> This pattern allows all route optimized traffic coming from the CN to
>> the MN to pass through.
>>
>> Additionally, the firewall adds a second rule in order to let the
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 5]
>>
>> Internet-Draft MIPv6 Firewall Vendor guidelines October 2008
>>
>>
>> data traffic from the MN to the CN pass through.
>>
>> Source Address: Source Address of the packet (MN CoA)
>> Destination Address: Destination Address of packet (CN)
>> Next Header: IPv6 Destination Options Header(60)
>> Home Address Dest. Option: MN HoA
>>
>> This pattern allows all route optimized traffic coming from the MN to
>> the CN to pass through.
>>
>> A firewall protecting the HA can add the following rule on reception
>> of a HA binding update, in order to let the incoming bi-directional
>> tunneled traffic pass.
>>
>> Destination Address: Source Address of the packet (MN HoA)
>> Source Address: Destination Address of packet (CN)
>>
>>
>>
>> 6. Acknowledgements
>>
>> The authors would like to thank the following members of the MIPv6
>> firewall design team for contributing to this document: Hannes
>> Tschofenig, Hesham Soliman, Qiu Ying, and Vijay Devarapalli. The
>> authors would also like to thank William Ivancic, Ryuji Wakikawa,
>> Jari Arkko, Henrik Levkowetz, Pasi Eronen and Noriaki Takamiya for
>> their thorough reviews of the document and for providing comments to
>> improve the quality of the document.
>>
>>
>> 7. IANA Considerations
>>
>> This document does not require any IANA action.
>>
>>
>> 8. Security Considerations
>>
>> This document specifies recommendations for firewall vendors to allow
>> Mobile IPv6 traffic to pass through unhindered. This document
>> recommends a liberal setting of firewall rules so that all legitimate
>> traffic may be allowed to pass. This means that some malicious
>> traffic may be permitted by these rules. These rules may allow the
>> initiation of Denial of Service attacks against Mobile IPv6 capable
>> nodes (the MNs, CNs and the HAs).
>>
>> One of the main goals of any firewall is to prevent unsolicited
>> traffic from entering the network. The proposed solution allows such
>> traffic into the network, albeit with a number of restrictions.
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 6]
>>
>> Internet-Draft MIPv6 Firewall Vendor guidelines October 2008
>>
>>
>> In a typical enterprise environment, an administrator cannot
>> distinguish Mobile IPv6 capable nodes from other nodes. In such a
>> situation any node in the protected network may end up receiving
>> unsolicited packets from outside the firewall. The risk in this case
>> is that such packets could trigger unknown vulnerabilities in any of
>> these nodes, causing denial-of-service or worse attacks. This issue
>> is compounded in a mobile service provider environment by the risks
>> specific to such environments like endpoint battery exhaustion and
>> spectrum misuse.
>>
>>
>> 9. Normative References
>>
>> [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
>> Requirement Levels", BCP 14, RFC 2119, March 1997.
>>
>> [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
>> in IPv6", RFC 3775, June 2004.
>>
>> [RFC4487] Le, F., Faccin, S., Patil, B., and H. Tschofenig, "Mobile
>> IPv6 and Firewalls: Problem Statement", RFC 4487,
>> May 2006.
>>
>>
>> Authors' Addresses
>>
>> Suresh Krishnan
>> Ericsson
>> 8400 Decarie Blvd.
>> Town of Mount Royal, QC
>> Canada
>>
>> Phone: +1 514 345 7900 x42871
>> Email: suresh.krishnan at ericsson.com
>>
>>
>> Yaron Sheffer
>> Check Point
>> 5 Hasolelim St.
>> Tel Aviv 67897
>> Israel
>>
>> Email: yaronf at checkpoint.com
>>
>>
>>
>>
>>
>>
>>
>>
>> Krishnan, et al. Expires April 11, 2009 [Page 7]
>>
>> Internet-Draft MIPv6 Firewall Vendor guidelines October 2008
>>
>>
>> Niklas Steinleitner
>> University of Goettingen
>> Lotzestr. 16-18
>> Goettingen
>> Germany
>>
>> Email: steinleitner at cs.uni-goettingen.de
>>
>>
>> Gabor Bajko
>> Nokia
>>
>> Email: gabor.bajko at nokia.com
>>
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>> Krishnan, et al. Expires April 11, 2009 [Page 8]
>>
>> Internet-Draft MIPv6 Firewall Vendor guidelines October 2008
>>
>>
>> Full Copyright Statement
>>
>> Copyright (C) The IETF Trust (2008).
>>
>> This document is subject to the rights, licenses and restrictions
>> contained in BCP 78, and except as set forth therein, the authors
>> retain all their rights.
>>
>> This document and the information contained herein are provided on an
>> "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
>> OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
>> THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
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>> THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
>> WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
>>
>>
>> Intellectual Property
>>
>> The IETF takes no position regarding the validity or scope of any
>> Intellectual Property Rights or other rights that might be claimed to
>> pertain to the implementation or use of the technology described in
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>> Copies of IPR disclosures made to the IETF Secretariat and any
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>> The IETF invites any interested party to bring to its attention any
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>>
>>
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>>
>> Krishnan, et al. Expires April 11, 2009 [Page 9]
>>
>>
>
>
> --------------------------------------------------------------------------------
>
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