[Mip6-firewall] HA Firewall BCP draft v01
Yaron Sheffer
yaronf at checkpoint.com
Fri Jul 6 15:42:44 EDT 2007
Hi Hannes,
If the only way you can get reasonable security is by using advanced FW
capabilities, then why not do it. This is the case for VoIP, for
example: you need protocol inspection to open pinholes for RTP.
Thanks,
Yaron
Hannes Tschofenig wrote:
> Hi Yaron,
>
> it is true that firewalls add rules dynamically based on bypassing
> data and signaling packets.
>
> However, the purpose of THIS draft was something different.
>
> Ciao
> Hannes
>
> Qiu Ying wrote:
>> Hi, Yaron
>>
>> Thanks for your comments.
>> The BU there is to correspondent node, which is not encrypted.
>>
>> Regards
>> Qiu Ying
>>
>> ________________________________
>>
>> From: Yaron Sheffer [mailto:yaronf at checkpoint.com]
>> Sent: Sat 7/7/2007 12:49 AM
>> To: Qiu Ying
>> Cc: Hannes Tschofenig; mip6-firewall at zeke.ecotroph.net
>> Subject: Re: [Mip6-firewall] HA Firewall BCP draft v01
>>
>>
>>
>> Actually, firewalls do allow to dynamically add rules based on
>> observed traffic. Or at least to add new instances of rule templates.
>> So I would say 5.4 is in scope.
>>
>>
>>
>>
>> But isn't the BU encrypted? Can the firewall actually see the HoA?
>>
>>
>>
>>
>> Thanks,
>>
>> Yaron
>>
>>
>>
>>
>> Qiu Ying wrote:
>>
>>
>> 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>
>> <mailto:suresh.krishnan at ericsson.com> To:
>> <mip6-firewall at zeke.ecotroph.net>
>> <mailto: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
>>
>>
>>
>> --------------------------------------------------------------------------------
>>
>>
>>
>>
>>
>> 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).
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Krishnan, et al. Expires December 30,
>> 2007 [Page 1]
>>
>> Internet-Draft MIPv6 Firewall
>> BCP June 2007
>>
>>
>> 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]
>>
>> Internet-Draft MIPv6 Firewall
>> BCP June 2007
>>
>>
>> 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]
>>
>> Internet-Draft MIPv6 Firewall
>> BCP June 2007
>>
>>
>> 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]
>>
>> Internet-Draft MIPv6 Firewall
>> BCP June 2007
>>
>>
>> 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
>>
>>
>>
>> Krishnan, et al. Expires December 30,
>> 2007 [Page 5]
>>
>> Internet-Draft MIPv6 Firewall
>> BCP June 2007
>>
>>
>> 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]
>>
>> Internet-Draft MIPv6 Firewall
>> BCP June 2007
>>
>>
>> 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.
>>
>>
>>
>>
>>
>>
>>
>> Krishnan, et al. Expires December 30,
>> 2007 [Page 7]
>>
>> Internet-Draft MIPv6 Firewall
>> BCP June 2007
>>
>>
>> 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
>>
>>
>>
>>
>>
>>
>>
>> Krishnan, et al. Expires December 30,
>> 2007 [Page 8]
>>
>> Internet-Draft MIPv6 Firewall
>> BCP June 2007
>>
>>
>> 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]
>>
>> Internet-Draft MIPv6 Firewall
>> BCP June 2007
>>
>>
>> 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
>>
>>
>> 6. IANA Considerations
>>
>> This document does not require any IANA action.
>>
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>> Krishnan, et al. Expires December 30,
>> 2007 [Page 11]
>>
>> Internet-Draft MIPv6 Firewall
>> BCP June 2007
>>
>>
>> 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
>>
>> _______________________________________________
>> Mip6-firewall mailing list
>> Mip6-firewall at zeke.ecotroph.net
>> https://zeke.ecotroph.net/mailman/listinfo/mip6-firewall
>>
>>
>>
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