draft-krishnan-mip6-firewall-admin-03.txt		draft-krishnan-mip6-firewall-admin-04.txt
	Network Working Group S. Krishnan		Network Working Group S. Krishnan
	Internet-Draft Ericsson		Internet-Draft Ericsson
	Intended status: Informational N. Steinleitner		Intended status: Informational N. Steinleitner
	Expires: August 27, 2008 University of Goettingen		Expires: November 1, 2008 University of Goettingen
	Y. Qiu		Y. Qiu
	Institute for Infocomm Research		Institute for Infocomm Research
	G. Bajko		G. Bajko
	Nokia		Nokia
	February 24, 2008		April 30, 2008
	Guidelines for firewall administrators regarding MIPv6 traffic		Guidelines for firewall administrators regarding MIPv6 traffic
	draft-krishnan-mip6-firewall-admin-03		draft-krishnan-mip6-firewall-admin-04
	Status of this Memo		Status of this Memo
	By submitting this Internet-Draft, each author represents that any		By submitting this Internet-Draft, each author represents that any
	applicable patent or other IPR claims of which he or she is aware		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		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.		aware will be disclosed, in accordance with Section 6 of BCP 79.
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	skipping to change at page 1, line 39		skipping to change at page 1, line 39
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
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	This Internet-Draft will expire on August 27, 2008.		This Internet-Draft will expire on November 1, 2008.
	Copyright Notice		Copyright Notice
	Copyright (C) The IETF Trust (2008).		Copyright (C) The IETF Trust (2008).
	Abstract		Abstract
	This document presents some recommendations for firewall		This document presents some recommendations for firewall
	administrators to help them configure their existing firewalls in a		administrators to help them configure their existing firewalls in a
	way that allows in certain deployment scenarios the Mobile IPv6		way that allows in certain deployment scenarios the Mobile IPv6
	skipping to change at page 2, line 17		skipping to change at page 2, line 17
	question include some kind of stateful packet filtering capability.		question include some kind of stateful packet filtering capability.
	Table of Contents		Table of Contents
	1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3		1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
	2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . 3		3. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . 3
	4. Home Agent behind a firewall . . . . . . . . . . . . . . . . . 4		4. Home Agent behind a firewall . . . . . . . . . . . . . . . . . 4
	4.1. Signaling between the MN and the HA . . . . . . . . . . . 4		4.1. Signaling between the MN and the HA . . . . . . . . . . . 4
	4.2. IKEv2 signaling between MN and HA for establishing SAs . . 5		4.2. IKEv2 signaling between MN and HA for establishing SAs . . 5
	4.3. Data traffic from and to MN passing through the HA . . . . 5
	5. Correspondent Node behind a firewall . . . . . . . . . . . . . 5		5. Correspondent Node behind a firewall . . . . . . . . . . . . . 5
	5.1. Route optimization signaling between MN and CN through		5.1. Route optimization signaling between MN and CN through
	HA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6		HA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
	5.2. Route optimization signaling between MN and CN . . . . . . 7		5.2. Route optimization signaling between MN and CN . . . . . . 6
	5.3. Binding Update from MN to CN . . . . . . . . . . . . . . . 7		5.3. Binding Update from MN to CN . . . . . . . . . . . . . . . 7
	5.4. Route Optimization data traffic from MN . . . . . . . . . 7		5.4. Route Optimization data traffic from MN . . . . . . . . . 7
	5.5. Bi-directional tunnelled data traffic from the MN to		6. Mobile Node behind a firewall . . . . . . . . . . . . . . . . 7
	the CN through HA . . . . . . . . . . . . . . . . . . . . 7		6.1. Signaling between MN and HA . . . . . . . . . . . . . . . 8
	6. Mobile Node behind a firewall . . . . . . . . . . . . . . . . 8		6.2. Signaling between MN and CN . . . . . . . . . . . . . . . 8
	6.1. Signaling between MN and HA . . . . . . . . . . . . . . . 9		6.3. IKEv2 signaling between MN and HA for establishing SAs . . 9
	6.2. Signaling between MN and CN . . . . . . . . . . . . . . . 9		7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
	6.3. IKEv2 signaling between MN and HA for establishing SAs . . 10		8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
	7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 10		9. Security Considerations . . . . . . . . . . . . . . . . . . . 9
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10		10. Normative References . . . . . . . . . . . . . . . . . . . . . 10
	9. Security Considerations . . . . . . . . . . . . . . . . . . . 10		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
	10. Normative References . . . . . . . . . . . . . . . . . . . . . 11		Intellectual Property and Copyright Statements . . . . . . . . . . 12
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
	Intellectual Property and Copyright Statements . . . . . . . . . . 13
	1. Requirements notation		1. Requirements notation
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in [RFC2119].		document are to be interpreted as described in [RFC2119].
	2. Introduction		2. Introduction
	Network elements such as firewalls are an integral aspect of a		Network elements such as firewalls are an integral aspect of a
	skipping to change at page 4, line 41		skipping to change at page 4, line 41
	Figure 1: HA behind a firewall		Figure 1: HA behind a firewall
	For each type of traffic that needs to pass through this firewall,		For each type of traffic that needs to pass through this firewall,
	recommendations are presented on how to identify that traffic. The		recommendations are presented on how to identify that traffic. The
	following types of traffic are considered		following types of traffic are considered
	o Signaling between the MN and the HA		o Signaling between the MN and the HA
	o IKEv2 signaling between MN and HA for establishing SAs		o IKEv2 signaling between MN and HA for establishing SAs
	o Data traffic from and to MN passing through the HA
	4.1. Signaling between the MN and the HA		4.1. Signaling between the MN and the HA
	The signaling between the MN and HA is protected using IPSec ESP.		The signaling between the MN and HA is protected using IPSec ESP.
	These messages are critical to the MIPv6 protocol and if these		These messages are critical to the MIPv6 protocol and if these
	messages are discarded, Mobile IPv6 as specified today will cease to		messages are discarded, Mobile IPv6 as specified today will cease to
	work. In order to permit these messages through, the firewall has to		work. In order to permit these messages through, the firewall has to
	detect the messages using the following patterns.		detect the messages using the following patterns.
	Destination Address: Address of HA		Destination Address: Address of HA
	Next Header: 50 (ESP)		Next Header: 50 (ESP)
	skipping to change at page 5, line 29		skipping to change at page 5, line 26
	The MN and HA exchange IKEv2 signaling in order to establish the		The MN and HA exchange IKEv2 signaling in order to establish the
	security associations. The security associations so established will		security associations. The security associations so established will
	later be used for securing the mobility signaling messages. Hence		later be used for securing the mobility signaling messages. Hence
	these messages need to be permitted to pass through the firewalls.		these messages need to be permitted to pass through the firewalls.
	The following pattern will detect these messages.		The following pattern will detect these messages.
	Destination Address: Address of HA		Destination Address: Address of HA
	Transport Protocol: UDP		Transport Protocol: UDP
	Destination UDP Port: 500		Destination UDP Port: 500
	4.3. 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. 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 would
	expose the MN to any type of possibly malicious traffic, resulting in
	a denial of service or exploitation of known security
	vulnerabilities. This practice is NOT RECOMMENDED.
	5. Correspondent Node behind a firewall		5. Correspondent Node behind a firewall
	This section presents the recommendations for configuring 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.		if a node behind it should be able to act as Mobile IPv6 CN.
	+----------------+ +----+		+----------------+ +----+
	| | | HA |		| | | HA |
	| | +----+		| | +----+
	| | Home Agent		| | Home Agent
	| +---+ +----+ of B		| +---+ +----+ of B
	skipping to change at page 6, line 24		skipping to change at page 6, line 4
	| | +---+		| | +---+
	+----------------+ External Mobile		+----------------+ External Mobile
	Network protected Node		Network protected Node
	by a firewall		by a firewall
	Figure 2: CN behind a firewall		Figure 2: CN behind a firewall
	For each type of traffic that needs to pass through this firewall,		For each type of traffic that needs to pass through this firewall,
	recommendations are presented on how to identify that traffic. The		recommendations are presented on how to identify that traffic. The
	following types of traffic are considered		following types of traffic are considered
	o Route optimization signaling between MN and CN through HA		o Route optimization signaling between MN and CN through HA
	o Route optimization signaling between MN and CN		o Route optimization signaling between MN and CN
	o Binding Update from MN to CN		o Binding Update from MN to CN
	o Route Optimization data traffic from MN		o Route Optimization data traffic from MN
	o Bi-directional tunnelled data traffic from the MN to the CN
	through HA
	5.1. Route optimization signaling between MN and CN through HA		5.1. Route optimization signaling between MN and CN through HA
	Parts of the initial route optimization signaling has to pass through		Parts of the initial route optimization signaling has to pass through
	the HA, namely the HoTI and the HoT messages. Without assistance,		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		the HoTI message from the HA to the CN is not able to traverse the
	firewall. The following pattern will allow these messages to		firewall. When only a few priviledged nodes (like servers) are
	traverse.		allowed to be contacted by outside nodes, then the following pattern
			will allow the HoTI messages to reach these nodes:
	Destination Address: CN Address		Destination Address: CN Address
	Mobility Header Type: 1		Mobility Header Type: 1 (HoTI)
	This pinhole allows the HoTI message from the HA to the CN to		where CN Address describes the address(es) of the priviledged
	traverse the firewall. The HoT message from the CN to the MN through		node(s). This pinhole allows the HoTI message from the HA to the CN
	the HA can traverse the firewall without any assistance. Hence no		to traverse the firewall. The HoT message from the CN to the MN
	pinhole is required.		through the HA can traverse the firewall without any assistance.
			Hence no pinhole is required.
	5.2. Route optimization signaling between MN and CN		5.2. Route optimization signaling between MN and CN
	Route Optimization allows direct communication of data packets		Route Optimization allows direct communication of data packets
	between the MN and a CN without tunnelling it back through the HA.		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		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		directly to the CN, which response with a CoT message. However, a
	stateful firewall would prevent the CoTI message to pass through as		stateful firewall would prevent the CoTI message to pass through as
	there is no established state on the firewall. The following pinhole		there is no established state on the firewall. When only a few
	will allow the CoTI message to traverse.		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:
	Destination Address: CN Address		Destination Address: CN Address
	Mobility Header Type: 2		Mobility Header Type: 2 (CoTI)
	The CoT message from the CN to the MN can traverse the firewall		where CN Address describes the address(es) of the priviledged
	without any assistance. Hence no pinhole is required.		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		5.3. Binding Update from MN to CN
	After successfully performing the return routability procedure, the		After successfully performing the return routability procedure, the
	MN sends the BU to the CN and expects the BA. Since this BU does not		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		match any previous installed pinhole rules, an additional pinhole
	with the following format is required.		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		Destination Address: CN Address
	Mobility Header Type: 5		Mobility Header Type: 5
	This allows the BU to traverse the firewall and the BA can pass the		where CN Address describes the address(es) of the priviledged
	firewall without any assistance. Therefore, the Binding Update		node(s).This allows the BU to traverse the firewall and the BA can
	sequence can be performed successfully.		pass the firewall without any assistance. Therefore, the Binding
			Update sequence can be performed successfully.
	5.4. Route Optimization data traffic from MN		5.4. Route Optimization data traffic from MN
	Also the Route Optimization data traffic from MN directly to the CN		Also the Route Optimization data traffic from MN directly to the CN
	can not traverse the firewall without assistance. A dynamically		can not traverse the firewall without assistance. A dynamically
	created pinhole such as the one specified in [MIP6FWVENDOR] will		created pinhole such as the one specified in [MIP6FWVENDOR] will
	allow this traffic to pass.		allow this traffic to pass.
	5.5. 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
	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. Allowing this traffic might allow any kind of traffic,
	including malicious traffic, to pass through unfiltered to the CN.
	This would expose the CN to any type of possibly malicious traffic,
	resulting in a denial of service or exploitation of known security
	vulnerabilities. This practice is NOT RECOMMENDED.
	6. Mobile Node behind a firewall		6. Mobile Node behind a firewall
	This section presents the recommendations for configuring a firewall		This section presents the recommendations for configuring a firewall
	that protects the network a mobile node visiting.		that protects the network a mobile node visiting.
	+----------------+ +----+		+----------------+ +----+
	| | | HA |		| | | HA |
	| | +----+		| | +----+
	| | Home Agent		| | Home Agent
	| +---+ +----+ of A +---+		| +---+ +----+ of A +---+
	skipping to change at page 10, line 19		skipping to change at page 9, line 28
	The MN and HA exchange IKEv2 signaling in order to establish the		The MN and HA exchange IKEv2 signaling in order to establish the
	security associations. The security associations so established will		security associations. The security associations so established will
	later be used for securing the mobility signaling messages. Due to		later be used for securing the mobility signaling messages. Due to
	variable source/destination IP addresses and MN always as initiator,		variable source/destination IP addresses and MN always as initiator,
	the following pattern will let the negotiation pass.		the following pattern will let the negotiation pass.
	Source Address: Visited subnet prefix		Source Address: Visited subnet prefix
	Transport Protocol: UDP		Transport Protocol: UDP
	Destination UDP Port: 500		Destination UDP Port: 500
	7. Contributors		7. Acknowledgements
	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@gmx.net
	Gabor Bajko Gabor.Bajko@nokia.com
	Suresh Krishnan suresh.krishnan@ericsson.com
	Hesham Soliman solimanhs@gmail.com
	Yaron Sheffer yaronf@checkpoint.com
	Qiu Ying qiuying@i2r.a-star.edu.sg
	Niklas Steinleitner steinleitner@cs.uni-goettingen.de
	Vijay Devarapalli vijay.devarapalli@AzaireNet.com		The authors would like to thank the following members of the MIPv6
			firewall design team for contributing to this document: Hannes
			Tschofenig, Hesham Soliman, Yaron Sheffer, and Vijay Devarapalli.
			The authors would also like to thank William Ivancic, Ryuji Wakikawa,
			Jari Arkko and Henrik Levkowetz for their thorough reviews of the
			document and for providing comments to improve the quality of the
			document.
	8. IANA Considerations		8. IANA Considerations
	This document does not require any IANA action.		This document does not require any IANA action.
	9. Security Considerations		9. Security Considerations
	This document specifies recommendations for firewall administrators		This document specifies recommendations for firewall administrators
	to allow Mobile IPv6 traffic to pass through unhindered. Since some		to allow Mobile IPv6 traffic to pass through unhindered. Since some
	of this traffic is encrypted it is not possible for firewalls to		of this traffic is encrypted it is not possible for firewalls to
	discern whether it is safe or not. This document recommends a		discern whether it is safe or not. This document recommends a
	liberal setting so that all legitimate traffic can pass. This means		liberal setting so that all legitimate traffic can pass. This means
	that some malicious traffic may be permitted by these rules. These		that some malicious traffic may be permitted by these rules. These
	rules may allow the initiation of Denial of Service attacks against		rules may allow the initiation of Denial of Service attacks against
	Mobile IPv6 capable nodes (the MNs, CNs and the HAs). Especially the		Mobile IPv6 capable nodes (the MNs, CNs and the HAs).
	rules specified in Section 4.3 and Section 5.5 are broadly defined
	and hence possess the most potential for abuse. Hence, if these
	rules are implemented, the firewalls SHOULD be configured to rate-
	limit such traffic on a per-destination basis. This would allow the
	firewall to mitigate possible denial of service attacks on the
	endpoints. Please note that such measures would not mitigate other
	potential security issues.
	10. Normative References		10. Normative References
	[MIP6FWVENDOR]		[MIP6FWVENDOR]
	Krishnan, S., "Guidelines for firewall vendors regarding		Krishnan, S., Sheffer, Y., Steinleitner, N., and G. Bajko,
	MIPv6 traffic", draft-krishnan-mip6-firewall-vendor-01		"Guidelines for firewall vendors regarding MIPv6 traffic",
	(work in progress), November 2007.		draft-krishnan-mip6-firewall-vendor-03 (work in progress),
			February 2008.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
	[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support		[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
	in IPv6", RFC 3775, June 2004.		in IPv6", RFC 3775, June 2004.
	[RFC4487] Le, F., Faccin, S., Patil, B., and H. Tschofenig, "Mobile		[RFC4487] Le, F., Faccin, S., Patil, B., and H. Tschofenig, "Mobile
	IPv6 and Firewalls: Problem Statement", RFC 4487,		IPv6 and Firewalls: Problem Statement", RFC 4487,
	May 2006.		May 2006.
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