< draft-ietf-ospf-security-extension-manual-keying-06.txt		draft-ietf-ospf-security-extension-manual-keying-07.txt >
	OSPF Working Group M. Bhatia		OSPF Working Group M. Bhatia
	Internet-Draft Alcatel-Lucent		Internet-Draft Alcatel-Lucent
	Intended status: Standards Track S. Hartman		Intended status: Standards Track S. Hartman
	Expires: May 29, 2014 Painless Security		Expires: October 10, 2014 Painless Security
	D. Zhang		D. Zhang
	Huawei Technologies co., LTD.		Huawei Technologies co., LTD.
	A. Lindem		A. Lindem
	Ericsson		Ericsson
	November 25, 2013		April 8, 2014
	Security Extension for OSPFv2 when using Manual Key Management		Security Extension for OSPFv2 when using Manual Key Management
	draft-ietf-ospf-security-extension-manual-keying-06		draft-ietf-ospf-security-extension-manual-keying-07
	Abstract		Abstract
	The current OSPFv2 cryptographic authentication mechanism as defined		The current OSPFv2 cryptographic authentication mechanism as defined
	in RFC 2328 and RFC 5709 is vulnerable to both inter-session and		in RFC 2328 and RFC 5709 is vulnerable to both inter-session and
	intra-session replay attacks when using manual keying. Additionally,		intra-session replay attacks when using manual keying. Additionally,
	the existing cryptographic authentication schemes do not cover the IP		the existing cryptographic authentication mechanism does not cover
	header. This omission can be exploited to carry out various types of		the IP header. This omission can be exploited to carry out various
	attacks.		types of attacks.
	This draft proposes changes to the authentication sequence number		This draft proposes changes to the authentication sequence number
	mechanism that will protect OSPFv2 from both inter-session and intra-		mechanism that will protect OSPFv2 from both inter-session and intra-
	session replay attacks when using manual keys for securing OSPFv2		session replay attacks when using manual keys for securing OSPFv2
	protocol packets. Additionally, we also describe some changes in the		protocol packets. Additionally, we also describe some changes in the
	cryptographic hash computation so that we eliminate most attacks that		cryptographic hash computation that will eliminate attacks resulting
	result from OSPFv2 not protecting the IP header.		from OSPFv2 not protecting the IP header.
	Status of this Memo		Status of this Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on May 29, 2014.		This Internet-Draft will expire on October 10, 2014.
	Copyright Notice		Copyright Notice
	Copyright (c) 2013 IETF Trust and the persons identified as the		Copyright (c) 2014 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	skipping to change at page 3, line 10 ¶		skipping to change at page 3, line 10 ¶
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11		9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
	9.1. Normative References . . . . . . . . . . . . . . . . . . . 11		9.1. Normative References . . . . . . . . . . . . . . . . . . . 11
	9.2. Informative References . . . . . . . . . . . . . . . . . . 11		9.2. Informative References . . . . . . . . . . . . . . . . . . 11
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
	1. Introduction		1. Introduction
	The OSPFv2 cryptographic authentication mechanism as described in		The OSPFv2 cryptographic authentication mechanism as described in
	[RFC2328] uses per-packet sequence numbers to provide protection		[RFC2328] uses per-packet sequence numbers to provide protection
	against replay attacks. The sequence numbers increase monotonically		against replay attacks. The sequence numbers increase monotonically
	so that attempts to replay the stale packets can be thwarted. The		so that attempts to replay stale packets can be thwarted. The
	sequence number values are maintained as a part of adjacency states.		sequence number values are maintained as a part of neighbor adjacency
	Therefore, if an adjacency is taken down, the associated sequence		state. Therefore, if an adjacency is taken down, the associated
	numbers get reinitialized and the neighbors start all over again.		sequence numbers get reinitialized and neighbor adjacency formation
	Additionally, the cryptographic authentication mechanism does not		starts over again. Additionally, the cryptographic authentication
	specify how to deal with the rollover of a sequence number when its		mechanism does not specify how to deal with the rollover of a
	value wraps. These omissions can be taken advantage of by attackers		sequence number when its value wraps. These omissions can be
	to implement various replay attacks ([RFC6039]). In order to address		exploited by attackers to implement various replay attacks
	these issues, we propose extensions to the authentication sequence		([RFC6039]). In order to address these issues, we propose extensions
	number mechanism.		to the authentication sequence number mechanism.
	The cryptographic authentication as described in [RFC2328] and later		The cryptographic authentication as described in [RFC2328] and later
	updated in [RFC5709] does not include the IP header. This also can		updated in [RFC5709] does not include the IP header. This omission
	be exploited to launch several attacks as the source address in the		can be exploited to launch several attacks as the source address in
	IP header is no longer protected. The OSPF specification, for		the IP header is not protected. The OSPF specification, for
	broadcast and NBMA (Non-Broadcast Multi-Access Networks), requires		broadcast and NBMA (Non-Broadcast Multi-Access Networks), requires
	implementations to look at the source address in the IP header to		implementations to use the source address in the IP header to
	determine the neighbor from which the packet was received. Changing		determine the neighbor from which the packet was received. Changing
	the IP source address of a packet that confuses the receiver and can		the IP source address of a packet to a conflicting IP address can be
	be exploited to produce a number of denial of service attacks		exploited to produce a number of denial of service attacks [RFC6039].
	[RFC6039]. If the packet is interpreted as coming from a different		If the packet is interpreted as coming from a different neighbor, the
	neighbor, the sequence number received from the neighbor may be		received sequence number state for that neighbor may be incorrectly
	updated. This may disrupt communication with the legitimate		updated. This attack may disrupt communication with a legitimate
	neighbor. Hello packets may be reflected to cause a neighbor to		neighbor. Hello packets may be reflected to cause a neighbor to
	appear to have one-way communication. Additionally, Database		appear to have one-way communication. Additionally, Database
	Description packets may be reflected in cases where the per-packet		Description packets may be reflected in cases where the per-packet
	sequence numbers are sufficiently divergent in order to disrupt an		sequence numbers are sufficiently divergent in order to disrupt an
	adjacency [RFC6863]. This is referred to as the IP layer issue in		adjacency [RFC6863]. This is referred to as the IP layer issue in
	[RFC6862].		[RFC6862].
	[RFC2328] states that implementations MUST offer keyed MD5		[RFC2328] states that implementations MUST offer keyed MD5
	authentication. It is likely that this will be deprecated in favor		authentication. It is likely that this will be deprecated in favor
	of the stronger algorithms described in [RFC5709] and required in		of the stronger algorithms described in [RFC5709] and required in
	skipping to change at page 6, line 8 ¶		skipping to change at page 6, line 8 ¶
	Additionally, the 64-bit sequence number is moved to the first 64-		Additionally, the 64-bit sequence number is moved to the first 64-
	bits following the OSPFv2 packet and is protected by the		bits following the OSPFv2 packet and is protected by the
	authentication digest. These additional 64 bits or 8 octets are		authentication digest. These additional 64 bits or 8 octets are
	included in the IP header length but not the OSPF header packet		included in the IP header length but not the OSPF header packet
	length.		length.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Version # | Type | Packet length |		| Version # | Type | Packet length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Router ID |		| Router ID |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Area ID |		| Area ID |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Checksum | AuType |		| Checksum | AuType |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| 0 | Auth Data Len |		| 0 | Auth Data Len |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Key ID |		| Key ID |
	skipping to change at page 7, line 13 ¶		skipping to change at page 7, line 13 ¶
	time.		time.
	o The key must be valid for the desired security algorithm.		o The key must be valid for the desired security algorithm.
	In the remainder of this section, additional requirements for keys		In the remainder of this section, additional requirements for keys
	are enumerated for different scenarios.		are enumerated for different scenarios.
	4.1. Key Selection for Unicast OSPF Packet Transmission		4.1. Key Selection for Unicast OSPF Packet Transmission
	Assume that a router R1 tries to send a unicast OSPF packet from its		Assume that a router R1 tries to send a unicast OSPF packet from its
	interface I1 to the interface R2 of a remote router R2 using security		interface I1 to the interface I2 of a remote router R2 using security
	protocol P via interface I at time T. First, consider the		protocol P via interface I at time T. First, consider the
	circumstances where R1 and R2 are not connected with a virtual link.		circumstances where R1 and R2 are not connected with a virtual link.
	R1 then needs to select a long long-lived symmetric key from its key		R1 then needs to select a long long-lived symmetric key from its key
	table. Because the key should be shared by the by both R1 and R2 to		table. Because the key should be shared by both R1 and R2 to protect
	protect the communication between I1 and I2, the key should satisfy		the communication between I1 and I2, the key should satisfy the
	the following requirements:		following requirements:
	o The Peers field is unused. OSPF authentication is interface		o The Peers field is unused. OSPF authentication is interface
	based.		based.
	o The Interfaces field includes the local IP address of the		o The Interfaces field includes the local IP address of the
	interface for numbered interfaces or the MIB-II [RFC1213], ifIndex		interface for numbered interfaces or the MIB-II [RFC1213] ifIndex
	for unnumbered interfaces.		for unnumbered interfaces.
	o The Direction field is either "out" or "both".		o The Direction field is either "out" or "both".
	o If multiple keys match the Interface, the key with the most recent		o If multiple keys match the Interfaces field, the key with the most
	SendLifetimeStart time will be selected. This will facilitate		recent SendLifetimeStart time will be selected. This will
	graceful key rollover.		facilitate graceful key rollover.
	o The Key ID field in the OSPFv2 header (refer to figure 1) will be		o The Key ID field in the OSPFv2 header (refer to figure 1) will be
	set to the selected key's LocalKeyName.		set to the selected key's LocalKeyName.
	When R1 and R2 are connected to a virtual link, the interfaces field		When R1 and R2 are connected to a virtual link, the Interfaces field
	must identify the virtual endpoint rather than the virtual link.		must identify the virtual endpoint rather than the virtual link.
	Since there may be virtual links to the same router, the transit area		Since there may be virtual links to the same router, the transit area
	ID must be part of the identifier. Hence, the key should satisfy the		ID must be part of the identifier. Hence, the key should satisfy the
	following requirements:		following requirements:
	o The Peers field is unused. OSPF authentication is interface		o The Peers field is unused. OSPF authentication is interface
	based.		based.
	o The Interfaces field includes both the virtual endpoint's OSPF		o The Interfaces field includes both the virtual endpoint's OSPF
	router ID and the transit area ID for the virtual link.		router ID and the transit area ID for the virtual link.
	o The Direction field is either "out" or "both".		o The Direction field is either "out" or "both".
	o If multiple keys match the Interface, the key with the most recent		o If multiple keys match the Interfaces field, the key with the most
	SendLifetimeStart time will be selected. This will facilitate		recent SendLifetimeStart time will be selected. This will
	graceful key rollover.		facilitate graceful key rollover.
	o The Key ID field in the OSPFv2 header (refer to figure 1) will be		o The Key ID field in the OSPFv2 header (refer to figure 1) will be
	set to the selected key's LocalKeyName.		set to the selected key's LocalKeyName.
	4.2. Key Selection for Multicast OSPF Packet Transmission		4.2. Key Selection for Multicast OSPF Packet Transmission
	If a router R1 sends an OSPF packet from its interface I1 to a		If a router R1 sends an OSPF packet from its interface I1 to a
	multicast address (e.g., AllSPFRouters, AllDRouters), it needs to		multicast address (i.e., AllSPFRouters or AllDRouters), it needs to
	select a key according to the following requirements:		select a key according to the following requirements:
	o The Peers field is unused. OSPF authentication is interface		o The Peers field is unused. OSPF authentication is interface
	based.		based.
	o The Interfaces field includes the local IP address of the		o The Interfaces field includes the local IP address of the
	interface for numbered interfaces or the MIB-II [RFC1213], ifIndex		interface for numbered interfaces or the MIB-II [RFC1213] ifIndex
	for unnumbered interfaces.		for unnumbered interfaces.
	o The Direction field is either "out" or "both".		o The Direction field is either "out" or "both".
	o If multiple keys match the Interface, the key with the most recent		o If multiple keys match the Interfaces field, the key with the most
	SendLifetimeStart time will be selected. This will facilitate		recent SendLifetimeStart time will be selected. This will
	graceful key rollover.		facilitate graceful key rollover.
	o The Key ID field in the OSPFv2 header (refer to figure 1) will be		o The Key ID field in the OSPFv2 header (refer to figure 1) will be
	set to the selected key's LocalKeyName.		set to the selected key's LocalKeyName.
	4.3. Key Selection for OSPF Packet Reception		4.3. Key Selection for OSPF Packet Reception
	When Cryptographic Authentication is used, the ID of the		When Cryptographic Authentication is used, the ID of the
	authentication key is included in the authentication field of the		authentication key is included in the authentication field of the
	OSPF packet header. Using this key ID, it is relatively easy for a		OSPF packet header. Using this Key ID, it is straight forward for a
	receiver to locate the key. The simple requirements are:		receiver to locate the corresponding key. The simple requirements
			are:
	o The interface on which the key was received is associated with the		o The interface on which the key was received is associated with the
	key's interface.		key's interface.
	o The Key ID obtained from the OSPFv2 packet header corresponds to		o The Key ID obtained from the OSPFv2 packet header corresponds to
	the neighbor's PeerKeyName. Since OSPFv2 keys are symmetric, the		the neighbor's PeerKeyName. Since OSPFv2 keys are symmetric, the
	LocalKeyName and PeerKeyName for OSPFv2 keys will be identical.		LocalKeyName and PeerKeyName for OSPFv2 keys will be identical.
	Hence, the Key ID will be used to select the correct local key.		Hence, the Key ID will be used to select the correct local key.
	o The Direction field is either "in" or "both".		o The Direction field is either "in" or "both".
	5. Securing the IP header		5. Securing the IP header
	This document updates the definition of Apad which is currently a		This document updates the definition of the Apad constant, as it is
	constant defined in [RFC5709] to the source address from the IP		defined in [RFC5709], to include the IP source address from the IP
	header of the OSPFv2 protocol packet. The overall cryptographic		header of the OSPFv2 protocol packet. The overall cryptographic
	authentication process defined in [RFC5709] remains unchanged. To		authentication process defined in [RFC5709] remains unchanged. To
	reduce the potential for confusion, this section minimizes the		reduce the potential for confusion, this section minimizes the
	repetition of text from RFC 5709 and is incorporated here by		repetition of text from RFC 5709 [RFC5709]. The changes are:
	reference [RFC5709].
	RFC 5709, Section 3.3, describes how the cryptographic authentication		RFC 5709, Section 3.3, describes how the cryptographic authentication
	must be computed. It requires OSPFv2 packet's Authentication Trailer		must be computed. It requires the OSPFv2 packet's Authentication
	(which is the appendage described in RFC 2328, Section D.4.3, Page		Trailer (which is the appendage described in RFC 2328, Section D.4.3,
	233, items (6)(a) and (6)(d)) to be filled with the value Apad where		Page 233, items (6)(a) and (6)(d)) to be filled with the value Apad.
	Apad is a hexadecimal constant value 0x878FE1F3 repeated (L/4) times,		Apad is a hexadecimal constant with the value 0x878FE1F3 repeated
	where L is the length of the hash being used and is measured in		(L/4) times, where L is the length of the hash being used and is
	octets rather than bits.		measured in octets rather than bits.
	Routers at the sending side must initialize Apad to a value of the		OSPF routers sending OSPF packets must initialize Apad to the value
	source address that would be used when sending out the OSPFv2 packet,		of the IP source address that would be used when sending an OSPFv2
	repeated L/4 times, where L is the length of the hash, measured in		packet, repeated L/4 times, where L is the length of the hash,
	octets. The basic idea is to incorporate the source address from the		measured in octets. The basic idea is to incorporate the IP source
	IP header in the cryptographic authentication computation so that any		address from the IP header in the cryptographic authentication
	change of IP source address in a replayed packet can be detected.		computation so that any change of IP source address in a replayed
			packet can be detected.
	At the receiving end, implementations MUST initialize Apad as the		When an OSPF packet is received, implementations MUST initialize Apad
	source address from IP Header of the incoming OSPFv2 packet, repeated		as the IP source address from the IP Header of the incoming OSPFv2
	L/4 times, instead of the constant that's currently defined in		packet, repeated L/4 times, instead of the constant that's currently
	[RFC5709]. Besides changing the value of Apad, this document does		defined in [RFC5709]. Besides changing the value of Apad, this
	not introduce any other changes to the authentication mechanism		document does not introduce any other changes to the authentication
	described in [RFC5709]. This would prevent all attacks where a rogue		mechanism described in [RFC5709]. This would prevent all attacks
	OSPF router changes the IP source address of an OSPFv2 packet and		where a rogue OSPF router changes the IP source address of an OSPFv2
	replays it on the same multi-access interface or another interface		packet and replays it on the same multi-access interface or another
	since the IP source address is now protected and modification would		interface since the IP source address is now included in the
	result in the OSPFv2 packet being dropped due to an authentication		cryptographic hash computation and modification would result in the
	failure.		OSPFv2 packet being dropped due to an authentication failure.
	6. Mitigating Cross-Protocol Attacks		6. Mitigating Cross-Protocol Attacks
	In order to prevent cross protocol replay attacks for protocols		In order to prevent cross-protocol replay attacks for protocols
	sharing common keys, the two octet OSPFv2 Cryptographic Protocol ID		sharing common keys, the two octet OSPFv2 Cryptographic Protocol ID
	is appended to the authentication key prior to use. Refer to IANA		is appended to the authentication key prior to use. Refer to IANA
	Considerations (Section 8).		Considerations (Section 8).
	[RFC5709], Section 3.3 describes the mechanism to prepare the key		[RFC5709], Section 3.3 describes the mechanism to prepare the key
	used in the hash computation. This document updates the sub section		used in the hash computation. This document updates the sub section
	"PREPARATION OF KEY" as follows:		"PREPARATION OF KEY" as follows:
	The OSPFv2 Cryptographic Protocol ID is appended to the		The OSPFv2 Cryptographic Protocol ID is appended to the
	Authentication Key (K) yielding a Protocol-Specific Authentication		Authentication Key (K) yielding a Protocol-Specific Authentication
	skipping to change at page 10, line 39 ¶		skipping to change at page 10, line 39 ¶
	7. Security Considerations		7. Security Considerations
	This document rectifies the manual key management procedure that		This document rectifies the manual key management procedure that
	currently exists within OSPFv2, as part of the Phase 1 of the KARP		currently exists within OSPFv2, as part of the Phase 1 of the KARP
	Working Group. Therefore, only the OSPFv2 manual key management		Working Group. Therefore, only the OSPFv2 manual key management
	mechanism is considered. Any solution that takes advantage of the		mechanism is considered. Any solution that takes advantage of the
	automatic key management mechanism is beyond the scope of this		automatic key management mechanism is beyond the scope of this
	document.		document.
	The proposed sequence number extension offers most of the benefits of		The proposed sequence number extension offers most of the benefits of
	more complicated mechanisms involving challenges. There are,		more complicated mechanisms without their attendant challenges.
	however, a couple drawbacks to this approach. First, it requires the		There are, however, a couple drawbacks to this approach. First, it
	OSPF implementation to be able to save its boot count in non-volatile		requires the OSPF implementation to be able to save its boot count in
	storage. If the non-volatile storage is ever repaired or upgraded		non-volatile storage. If the non-volatile storage is ever repaired
	such that the contents are lost or the OSPFv2 router is replaced, the		or upgraded such that the contents are lost or the OSPFv2 router is
	keys MUST be changed to prevent replay attacks.		replaced, the authentication keys MUST be changed to prevent replay
			attacks.
	Second, if a router is taken out of service completely (either		Second, if a router is taken out of service completely (either
	intentionally or due to a persistent failure), the potential exists		intentionally or due to a persistent failure), the potential exists
	for reestablishment of an OSPFv2 adjacency by replaying the entire		for reestablishment of an OSPFv2 adjacency by replaying the entire
	OSPFv2 session establishment. This scenario is however, extremely		OSPFv2 session establishment. However, this scenario is extremely
	unlikely, since it would imply an identical OSPFv2 adjacency		unlikely, since it would imply an identical OSPFv2 adjacency
	formation packet exchange. Without adjacency formation, the replay		formation packet exchange. Without adjacency formation, the replay
	of OSPFv2 hello packets alone for an OSPFv2 router that has been		of OSPFv2 hello packets alone for an OSPFv2 router that has been
	taken out of service should not result in any serious attack as the		taken out of service should not result in any serious attack as the
	only consequence is superfluous processing. Of course, this attack		only consequence is superfluous processing. Of course, this attack
	could also be thwarted by changing the relevant manual keys.		could also be thwarted by changing the relevant manual keys.
	This document also provides a solution to prevent certain denial of		This document also provides a solution to prevent certain denial of
	service attacks that can be launched by changing the source address		service attacks that can be launched by changing the source address
	in the IP header of an OSPFv2 protocol packet.		in the IP header of an OSPFv2 protocol packet.
	skipping to change at page 11, line 49 ¶		skipping to change at page 12, line 4 ¶
	9.2. Informative References		9.2. Informative References
	[FIPS-198]		[FIPS-198]
	US National Institute of Standards & Technology, "The		US National Institute of Standards & Technology, "The
	Keyed-Hash Message Authentication Code (HMAC)", FIPS PUB		Keyed-Hash Message Authentication Code (HMAC)", FIPS PUB
	198 , March 2002.		198 , March 2002.
	[I-D.ietf-karp-crypto-key-table]		[I-D.ietf-karp-crypto-key-table]
	Housley, R., Polk, T., Hartman, S., and D. Zhang,		Housley, R., Polk, T., Hartman, S., and D. Zhang,
	"Database of Long-Lived Symmetric Cryptographic Keys",		"Database of Long-Lived Symmetric Cryptographic Keys",
	draft-ietf-karp-crypto-key-table-07 (work in progress),		draft-ietf-karp-crypto-key-table-10 (work in progress),
	March 2013.		December 2013.
	[RFC1213] McCloghrie, K. and M. Rose, "Management Information Base		[RFC1213] McCloghrie, K. and M. Rose, "Management Information Base
	for Network Management of TCP/IP-based internets:MIB-II",		for Network Management of TCP/IP-based internets:MIB-II",
	STD 17, RFC 1213, March 1991.		STD 17, RFC 1213, March 1991.
	[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-		[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
	Hashing for Message Authentication", RFC 2104,		Hashing for Message Authentication", RFC 2104,
	February 1997.		February 1997.
	[RFC3414] Blumenthal, U. and B. Wijnen, "User-based Security Model		[RFC3414] Blumenthal, U. and B. Wijnen, "User-based Security Model
End of changes. 31 change blocks.
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