[Mip6-firewall] HA Firewall BCP draft v01
Qiu Ying
qiuying at i2r.a-star.edu.sg
Fri Jul 6 08:14:36 EDT 2007
OK. omit 5.4.
________________________________
From: Hannes Tschofenig [mailto:Hannes.Tschofenig at gmx.net]
Sent: Fri 7/6/2007 7:18 PM
To: Qiu Ying
Cc: Suresh Krishnan; mip6-firewall at zeke.ecotroph.net
Subject: Re: [Mip6-firewall] HA Firewall BCP draft v01
Maybe I got the purpose of the document wrong but I thought that this
document will concentrate on the best current practice for configuring
firewall.
The document does not describe ways to dynamically establish rules based
on processing some signaling messages.
Hence, I would suggest to omit Section 5.4 from your text proposal.
QIU Ying wrote:
> Hi, Suresh
>
> The MN part was re-wrote according to your template. Please review and
> attached.
>
> BTW, in section 3.1, the first paragraph, the third sentence,
> duplicated "either"s are displayed.
> In section 4.3, rule pattern: why use "IPv6 Destination Options
> Header", should be " Mobility Header Type: 5"?
>
> Regards and Thanks
> Qiu Ying
>
>
> ----- Original Message ----- From: "Suresh Krishnan"
> <suresh.krishnan at ericsson.com>
> To: <mip6-firewall at zeke.ecotroph.net>
> Sent: Friday, July 06, 2007 6:34 AM
> Subject: [Mip6-firewall] HA Firewall BCP draft v01
>
>
>> Hi Folks,
>> Here is v01 of the draft. Since I have not heard back from Qiu Ying
>> regarding my comments, I have not included the MN part yet. I will try
>> to wait until Sunday to submit this in case there are any comments.
>>
>> Cheers
>> Suresh
>>
>
>
> --------------------------------------------------------------------------------
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>> Network Working Group S. Krishnan
>> Internet-Draft Ericsson
>> Intended status: Informational N. Steinleitner
>> Expires: December 30, 2007 University of Goettingen
>> Q. Ying
>> Institute for Infocomm Research
>> June 28, 2007
>>
>>
>> Firewall Recommendations for MIPv6
>> draft-krishnan-mip6-firewall-01
>>
>> 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 December 30, 2007.
>>
>> Copyright Notice
>>
>> Copyright (C) The IETF Trust (2007).
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>> Krishnan, et al. Expires December 30, 2007 [Page 1]
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>> Internet-Draft MIPv6 Firewall BCP June 2007
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>> Abstract
>>
>> This document presents some recommendations for firewall
>> administrators to help them configure their firewalls in a way that
>> allows Mobile IPv6 signaling and data messags to pass through. This
>> document assumes that the firewalls in question include some kind of
>> stateful packet filtering capability.
>>
>>
>> Table of Contents
>>
>> 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
>> 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
>> 3. Home Agent behind a firewall . . . . . . . . . . . . . . . . . 5
>> 3.1. Signaling between the MN and the HA . . . . . . . . . . . 5
>> 3.2. Route optimization signaling between MN and CN through
>> HA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
>> 3.3. IKEv2 signaling between MN and HA for establishing SAs . . 6
>> 3.4. Data traffic from and to MN passing through the HA . . . . 6
>> 4. Correspondent Node behind a firewall . . . . . . . . . . . . . 7
>> 4.1. RRT signaling between MN and CN through HA . . . . . . . . 7
>> 4.2. Route optimization signaling between MN and CN . . . . . . 7
>> 4.3. Binding Update from MN to CN . . . . . . . . . . . . . . . 8
>> 4.4. Route Optimization data traffic from MN . . . . . . . . . 8
>> 4.5. Bi-directional tunnelled data traffic from the MN to
>> the CN through HA . . . . . . . . . . . . . . . . . . . . 8
>> 5. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 10
>> 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
>> 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
>> 8. Normative References . . . . . . . . . . . . . . . . . . . . . 13
>> Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
>> Intellectual Property and Copyright Statements . . . . . . . . . . 15
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>> Krishnan, et al. Expires December 30, 2007 [Page 2]
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>> Internet-Draft MIPv6 Firewall BCP June 2007
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>> 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].
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>> Krishnan, et al. Expires December 30, 2007 [Page 3]
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>> Internet-Draft MIPv6 Firewall BCP June 2007
>>
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>> 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
>> administrators to help them configure their firewalls in a way that
>> allows Mobile IPv6 signaling and data messags to pass through. This
>> document assumes that the firewalls in question include some kind of
>> stateful packet filtering capability.
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>> Krishnan, et al. Expires December 30, 2007 [Page 4]
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>> Internet-Draft MIPv6 Firewall BCP June 2007
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>> 3. Home Agent behind a firewall
>>
>> This section presents the recommendations for configuring a firewall
>> that is protects a home agent. 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 Route optimization signaling between MN and CN through HA
>>
>> o IKEv2 signaling between MN and HA for establishing SAs
>>
>> o Data traffic from and to MN passing through the HA
>>
>> 3.1. Signaling between the MN and the HA
>>
>> The signaling between the MN and HA is protected using IPSec ESP.
>> These messages are encrypted and hence are not inspectable by
>> firewalls. So the firewall either has to either permit all these
>> messages or discard all of them. But 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 pattern.
>>
>> Destination Address: Address of HA
>> IP payload protocol number: 50 (ESP)
>>
>> This pattern will allow the BU messages from MNs to HA and BA
>> messages from the HA to the MNs to pass through. It will also allow
>> the HoTI and HoT messages (related to route optimization) between the
>> MN and the HA to pass through.
>>
>> 3.2. Route optimization signaling between MN and CN through HA
>>
>> Route Optimization allows direct communication of data packets
>> between the MN and a CN without tunneling it back through the HA. In
>> order for route optimization to work, part of the initial signaling
>> has to pass through the HA. The following pattern will allow these
>> messages to pass through.
>>
>> Destination Address: HoA of MN
>> Mobility Header Type: 3
>>
>> This pattern allows the HoT message from the CN to the MN's HoA to
>> pass through the firewall. The HoTI message from the MN to the CN
>> through the HA usually passes through the firewall without any
>>
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>> Krishnan, et al. Expires December 30, 2007 [Page 5]
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>> Internet-Draft MIPv6 Firewall BCP June 2007
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>> problems. Hence no specific pattern is recommended.
>>
>> 3.3. 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. 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
>>
>>
>> 3.4. Data traffic from and to MN passing through the HA
>>
>> If a CN tries to initiate traffic to an MN, a stateful firewall would
>> prevent these connection requests to pass through as there is no
>> established state on the firewall. Since MNs do not usually provide
>> services, this is not usually a problem. But if this is necessary to
>> do, the pattern to look for is
>>
>> Destination Address: MN HoA
>>
>> Allowing this traffic might allow any kind of traffic, including
>> malicious traffic, to pass through unfiltered to the MN. This might
>> cause a Denial of Service at the MN.
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>> Krishnan, et al. Expires December 30, 2007 [Page 6]
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>> Internet-Draft MIPv6 Firewall BCP June 2007
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>> 4. 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. 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 RRT 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
>>
>> o Bi-directional tunnelled data traffic from the MN to the CN
>> through HA
>>
>> 4.1. RRT signaling between MN and CN through HA
>>
>> Parts of the initial RRT 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. The
>> following pattern will allow these messages to traverse.
>>
>> Destination Address: CN Address
>>
>> Mobility Header Type: 1
>>
>> 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.
>>
>> 4.2. 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. The following pinhole
>> will allow the CoTI message to traverse.
>>
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>> Krishnan, et al. Expires December 30, 2007 [Page 7]
>>
>> Internet-Draft MIPv6 Firewall BCP June 2007
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>> Destination Address: CN Address
>>
>> Mobility Header Type: 2
>>
>> The CoT message from the CN to the MN can traverse the firewall
>> without any assistance. Hence no pinhole is required.
>>
>> 4.3. Binding Update from MN to CN
>>
>> After successfully performing the RRT, 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.
>>
>> Destination Address: CN Address
>>
>> IPv6 Destination Options Header
>>
>> 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.
>>
>> 4.4. 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. But as we have
>> configured the firewall to allow the BU message from MN to the CN to
>> traverse the firewall, the Route Optimization data traffic is able to
>> pass through as it also matches the pinhole installed for the BU.
>>
>> Therefore, no additional pinhole rules are required.
>>
>> 4.5. Bi-directional tunnelled data traffic from the MN to the CN
>> through HA
>>
>> If a MN tries to initiate traffic to a CN through the HA using bi-
>> directional tunnelling, a stateful firewall would prevent these
>> connection requests to pass through as there is no established state
>> on the firewall. This is usually a problem as CNs often provide
>> services. A solution is to static configure the firewall to let this
>> traffic pass through. However, this is only an acceptable option if
>> it is not necessary to open an all-embracing pinhole, e.g. if the
>> destination ports are well-known. In this case, the pinhole has to
>> look like
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>> Krishnan, et al. Expires December 30, 2007 [Page 8]
>>
>> Internet-Draft MIPv6 Firewall BCP June 2007
>>
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>> Destination Address: CN Address
>>
>> Destination Port: Application Ports
>>
>> If the ports are unknown, it is necessary to install a pinhole with
>> only the Destination Address as pattern. Allowing this traffic might
>> allow any kind of traffic, including malicious traffic, to traverse
>> to the CN. This might cause a Denial of Service at the CN.
>>
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>> Krishnan, et al. Expires December 30, 2007 [Page 9]
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>> Internet-Draft MIPv6 Firewall BCP June 2007
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>> 5. Contributors
>>
>> This document is one of the deliverables of the MIPv6 firewall
>> design. The following members of the team were involved in the
>> creation of this document.
>>
>> Hannes Tschofenig Hannes.Tschofenig at gmx.net
>>
>> Gabor Bajko Gabor.Bajko at nokia.com
>>
>> Suresh Krishnan suresh.krishnan at ericsson.com
>>
>> Hesham Soliman solimanhs at gmail.com
>>
>> Yaron Sheffer yaronf at checkpoint.com
>>
>> Qiu Ying qiuying at i2r.a-star.edu.sg
>>
>> Ram Vishnu vishnu at motorola.com
>>
>> Niklas Steinleitner steinleitner at cs.uni-goettingen.de
>>
>> Vijay Devarapalli vijay.devarapalli at AzaireNet.com
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>> Krishnan, et al. Expires December 30, 2007 [Page 10]
>>
>> Internet-Draft MIPv6 Firewall BCP June 2007
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>> 6. IANA Considerations
>>
>> This document does not require any IANA action.
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>> Krishnan, et al. Expires December 30, 2007 [Page 11]
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>> Internet-Draft MIPv6 Firewall BCP June 2007
>>
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>> 7. 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 such as a home agent
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