draft-ietf-hip-via-01.txt   draft-ietf-hip-via-02.txt 
HIP Working Group G. Camarillo HIP Working Group G. Camarillo
Internet-Draft A. Keranen Internet-Draft A. Keranen
Intended status: Experimental Ericsson Intended status: Experimental Ericsson
Expires: September 9, 2010 March 8, 2010 Expires: December 24, 2010 June 22, 2010
Host Identity Protocol (HIP) Multi-hop Routing Extension Host Identity Protocol (HIP) Multi-hop Routing Extension
draft-ietf-hip-via-01.txt draft-ietf-hip-via-02.txt
Abstract Abstract
This document specifies two extensions to HIP to implement multi-hop This document specifies two extensions to HIP to implement multi-hop
routing. The first extension allows implementing source routing in routing. The first extension allows implementing source routing in
HIP. That is, a host sending a HIP packet can define a set of hosts HIP. That is, a node sending a HIP packet can define a set of nodes
that the HIP packet should traverse. The second extension allows a that the HIP packet should traverse. The second extension allows a
HIP packet to carry and record the list of hosts that forwarded it. HIP packet to carry and record the list of nodes that forwarded it.
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF 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), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
skipping to change at page 1, line 40 skipping to change at page 1, line 40
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."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on September 9, 2010. This Internet-Draft will expire on December 24, 2010.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 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
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3 2.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3
2.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Protocol Definitions . . . . . . . . . . . . . . . . . . . . . 4 3. Protocol Definitions . . . . . . . . . . . . . . . . . . . . . 4
3.1. Creating and Processing Via Lists . . . . . . . . . . . . . 4 3.1. Creating and Processing Via Lists . . . . . . . . . . . . . 4
3.2. Creating Destination Lists . . . . . . . . . . . . . . . . 4 3.2. Creating Destination Lists . . . . . . . . . . . . . . . . 4
3.3. Processing Destination Lists . . . . . . . . . . . . . . . 5 3.3. Processing Destination Lists . . . . . . . . . . . . . . . 5
3.4. Fragmentation Considerations . . . . . . . . . . . . . . . 5
4. Packet Formats . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Packet Formats . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Source and Destination Route List Parameters . . . . . . . 6 4.1. Source and Destination Route List Parameters . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 8 6.1. Forged Destination and Via Lists . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 6.2. Forwarding Loops . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . . 8 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 8.1. Normative References . . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
When HIP [RFC5201] is used in certain contexts, hosts need the When HIP [RFC5201] is used in certain contexts, nodes need the
ability to perform source routing. That is, a host needs the ability ability to perform source routing. That is, a node needs the ability
to send a HIP packet that will traverse a set of hosts before to send a HIP signaling packet that will traverse a set of nodes
reaching its destination. Such features are needed, e.g., in HIP before reaching its destination. Such features are needed, e.g., in
BONE [I-D.ietf-hip-bone] overlay networks or if two hosts wish to HIP BONE [I-D.ietf-hip-bone] overlay networks or if two nodes wish to
keep a third, or more, HIP hosts on the signaling path. This keep a third, or more, HIP nodes on the signaling path. This
document defines an extension that provides HIP with this document defines an extension that provides HIP with this
functionality. functionality.
Additionally, when HIP packets are routed through multiple hosts, Additionally, when HIP signaling packets are routed through multiple
some of these hosts (e.g., the destination host) need the ability to nodes, some of these nodes (e.g., the destination node) need the
know the hosts a particular packet traversed. This document defines ability to know the nodes a particular packet traversed. This
another extension that provides HIP with this functionality. document defines another extension that provides HIP with this
functionality.
These two extensions enable multi-hop routing in HIP. Before these These two extensions enable multi-hop routing in HIP. Before these
extensions were specified, there were standardized ways for extensions were specified, there were standardized ways for
supporting only a single intermediate host (e.g., a rendezvous server supporting only a single intermediate node (e.g., a rendezvous server
[RFC5204]) between the source of a HIP packet and its destination. [RFC5204]) between the source of a HIP packet and its destination.
2. Terminology 2. Terminology
2.1. Requirements Language 2.1. Requirements Language
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 RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2.2. Definitions 2.2. Definitions
The following terms used in this document are similar to those The following terms used in this document are similar to those
defined by RELOAD [I-D.ietf-p2psip-base] but used here in context of defined by RELOAD [I-D.ietf-p2psip-base] but used here in context of
HIP. HIP.
Destination list: A list of HITs of the hosts that a HIP packet Destination list: A list of HITs of the nodes that a HIP packet
should traverse. should traverse.
Via list: A list of HITs of the hosts that a HIP packet has Via list: A list of HITs of the nodes that a HIP packet has
traversed. traversed.
Symmetric routing: A response to a message is routed back using the Symmetric routing: A response to a message is routed back using the
same set of intermediary nodes as the original message used, same set of intermediary nodes as the original message used,
except in reversed order. Also known as symmetric recursive except in reversed order. Also known as symmetric recursive
routing. routing.
3. Protocol Definitions 3. Protocol Definitions
The multi-hop routing extensions may be used in different contexts The multi-hop routing extensions may be used in different contexts
and whether a new HIP packet should, for example, include a Via list and whether a new HIP signaling packet should, for example, include a
or have different options enabled, can depend on the particular use Via list or have different options enabled, can depend on the
case, local policies, and different protocols using the extension. particular use case, local policies, and different protocols using
This section defines how the new parameters are handled, but when to the extension. This section defines how the new parameters are
use these extensions is out of scope for this document. handled, but when to use these extensions, or how to configure them,
is out of scope for this document.
3.1. Creating and Processing Via Lists 3.1. Creating and Processing Via Lists
When a host sending a HIP packet needs to record the hosts that are When a node sending a HIP packet needs to record the nodes that are
on the path that the HIP packet traverses, it includes an empty on the path that the HIP packet traverses, it includes an empty
ROUTE_VIA parameter to the packet. ROUTE_VIA parameter to the packet.
A host that receives a packet with a ROUTE_VIA parameter SHOULD add A node that receives a packet with a ROUTE_VIA parameter SHOULD add
its own HIT to the end of the ROUTE_VIA parameter, unless it is the its own HIT to the end of the ROUTE_VIA parameter, unless it is the
receiver of the packet. If the host uses a different HIT on the HIP final recipient of the packet. If the node uses a different HIT on
association it used for receiving the packet than for sending it the HIP association it used for receiving the packet than for sending
forward, it SHOULD also add the receiving HIT to the route list it forward, it SHOULD also add the receiving HIT to the route list
before the sending HIT. before the sending HIT.
If the host is the receiver of the packet, and the received packet If the node is the final recipient of the packet, and the received
generates a response HIP packet, the host checks the SYMMETRIC flag packet generates a response HIP packet, the node checks the SYMMETRIC
from the ROUTE_VIA parameter. If the SYMMETRIC flag is set, the host flag from the ROUTE_VIA parameter. If the SYMMETRIC flag is set, the
MUST create a ROUTE_DST parameter from the ROUTE_VIA parameter, as node MUST create a ROUTE_DST parameter from the ROUTE_VIA parameter,
described in Section 3.2, and include it in the response packet. as described in Section 3.2, and include it in the response packet.
Also, if an intermediary host generates a new HIP packet (e.g., an Also, if an intermediary node generates a new HIP packet (e.g., an
error NOTIFY packet) due to a HIP packet that had a ROUTE_VIA error NOTIFY packet) due to a HIP packet that had a ROUTE_VIA
parameter with SYMMETRIC flag set, and the new packet is intended for parameter with SYMMETRIC flag set, and the new packet is intended for
the sender of the original HIP packet, the host SHOULD construct and the sender of the original HIP packet, the node SHOULD construct and
add a ROUTE_DST parameter into the new packet as in the previous add a ROUTE_DST parameter into the new packet as in the previous
case. case.
3.2. Creating Destination Lists 3.2. Creating Destination Lists
A host that needs to define the other hosts that should be on the A node that needs to define the other nodes that should be on the
path a HIP packet traverses adds a ROUTE_DST parameter to the HIP path a HIP packet traverses adds a ROUTE_DST parameter to the HIP
packet. The host may either decide the path independently, or it may packet. The node may either decide the path independently, or it may
create the path based on a ROUTE_VIA parameter. Only the originator create the path based on a ROUTE_VIA parameter. Only the originator
of a signed HIP packet can add a ROUTE_DST parameter to the HIP of a signed HIP packet can add a ROUTE_DST parameter to the HIP
packet since the parameter is covered by the signature. packet, and none of the nodes on path can modify it, since the
parameter is covered by the signature.
When a host creates a ROUTE_DST parameter due to receiving a packet When a node creates a ROUTE_DST parameter due to receiving a packet
with a ROUTE_VIA parameter, it copies all the HITs in the ROUTE_VIA with a ROUTE_VIA parameter, it copies all the HITs in the ROUTE_VIA
parameter to the ROUTE_DST parameter, but in reversed order. This parameter to the ROUTE_DST parameter, but in reversed order. This
results in HIP response packet being forwarded using the same set of results in HIP response packet being forwarded using the same path as
hosts as the packet for which the response was generated for. the packet for which the response was generated for. If the exact
same set of nodes should be traversed by the response packet, also
the MUST_FOLLOW flag (see Table 1) SHOULD be set in the ROUTE_VIA
parameter (and eventually copied to the ROUTE_DST parameter) to
prevent the response packet possibly skipping some nodes on the list.
3.3. Processing Destination Lists 3.3. Processing Destination Lists
When a host receives a HIP packet that contains a ROUTE_DST When a node receives a HIP packet that contains a ROUTE_DST
parameter, it first looks up its own HIT from the route list. If parameter, it first looks up its own HIT from the route list. If
host's own HIT is not in the list and the host is not the receiver of node's own HIT is not in the list and the node is not the receiver of
the packet, the packet was incorrectly forwarded and MUST be dropped. the packet, the packet was incorrectly forwarded and MUST be dropped.
If the host's HIT is in the list more than once, the list is invalid If the node's HIT is in the list more than once, the list is invalid
and the packet MUST be dropped to avoid forwarding loops. Next hop and the packet MUST be dropped to avoid forwarding loops. Next hop
for the packet is the HIT after host's own HIT in the list. If the for the packet is the HIT after node's own HIT in the list. If the
host's HIT was the last HIT in the list, the next hop is the node's HIT was the last HIT in the list, the next hop is the
receiver's HIT in the HIP header. receiver's HIT in the HIP header.
If the MUST_FOLLOW flag in the ROUTE_DST parameter is not set, the If the MUST_FOLLOW flag in the ROUTE_DST parameter is not set, the
host SHOULD check whether it has a valid locator for one of the hosts node SHOULD check whether it has a valid locator for one of the nodes
later in the list, or for the receiver of the packet, and it MAY later in the list, or for the receiver of the packet, and it MAY
select such a host as the next hop. If the MUST_FOLLOW flag is set, select such a node as the next hop. If the MUST_FOLLOW flag is set,
the host MUST NOT skip any hosts in the list. the node MUST NOT skip any nodes in the list.
If the host has a valid locator for the next hop, it MUST forward the If the node has a valid locator for the next hop, it MUST forward the
HIP packet to the next hop host. If the host can not determine a HIP packet to the next hop node. If the node can not determine a
valid locator for the next hop host, it SHOULD drop the packet and valid locator for the next hop node, it SHOULD drop the packet and
SHOULD send back a NOTIFY error packet with type UNKNOWN_NEXT_HOP SHOULD send back a NOTIFY error packet with type UNKNOWN_NEXT_HOP
(value [TBD by IANA; 90]). The Notification Data field for the error (value [TBD by IANA; 90]). The Notification Data field for the error
notifications SHOULD contain the HIP header of the rejected packet notifications SHOULD contain the HIP header of the rejected packet
and the ROUTE_DST parameter. and the ROUTE_DST parameter.
3.4. Fragmentation Considerations
Via and Destination lists with multiple HITs can substantially
increase the size of the HIP packets and thus fragmentation issues
(see Section 5.1.3 of [RFC5201]) should be taken into consideration
when these extensions are used. Especially Via lists should be used
with care since the final size of the packet is not known unless the
maximum possible amount of hops is known beforehand. Both parameters
do still have a maximum size based on the maximum number of allowed
HITs (see Section 4.1).
4. Packet Formats 4. Packet Formats
This memo defines two new HIP parameters that are used for recording This memo defines two new HIP parameters that are used for recording
a route via multiple hosts (ROUTE_VIA) and for defining a route a a route via multiple nodes (ROUTE_VIA) and for defining a route a
packet should traverse by the sender of the packet (ROUTE_DST). packet should traverse by the sender of the packet (ROUTE_DST).
The ROUTE_DST parameter is integrity protected with the signature The ROUTE_DST parameter is integrity protected with the signature
(where present) but ROUTE_VIA is not so that intermediary hosts can (where present) but ROUTE_VIA is not so that intermediary nodes can
add their own HITs to the list. Both parameters have critical type add their own HITs to the list. Both parameters have critical type
(as defined in Section 5.2.1 of [RFC5201]) since the packet will not (as defined in Section 5.2.1 of [RFC5201]) since the packet will not
be properly routed unless all hosts on path recognize the parameters. be properly routed unless all nodes on path recognize the parameters.
4.1. Source and Destination Route List Parameters 4.1. Source and Destination Route List Parameters
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Reserved | | Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type [ TBD by IANA Type [ TBD by IANA
ROUTE_DST: 971 ROUTE_DST: 971
ROUTE_VIA: 65525 ] ROUTE_VIA: 65525 ]
Length length in octets, excluding Type and Length Length length in octets, excluding Type and Length
(i.e., number-of-HITs * 16 + 4) (i.e., number-of-HITs * 16 + 4)
Flags bit flags that can be used for requesting special Flags bit flags that can be used for requesting special
handling of the parameter handling of the parameter
Reserved reserved for future use Reserved reserved for future use
HIT Host Identity Tag of one of the hosts on the path HIT Host Identity Tag of one of the nodes on the path
Figure 1: Format of the ROUTE_VIA and ROUTE_DST Parameters Figure 1: Format of the ROUTE_VIA and ROUTE_DST Parameters
Figure 1 shows the format of both ROUTE_VIA and ROUTE_DST parameters. Figure 1 shows the format of both ROUTE_VIA and ROUTE_DST parameters.
The ROUTE_DST parameter, if present, MUST have at least one HIT, but The ROUTE_DST parameter, if present, MUST have at least one HIT, but
the ROUTE_VIA parameter can also have zero HITs. Both can contain at the ROUTE_VIA parameter can also have zero HITs. Neither of the
most 32 HITs. The Flags field is used for requesting special parameters SHALL NOT contain more than 32 HITs. The Flags field is
handling for via and destination lists. The flags defined in this used for requesting special handling for Via and Destination lists.
document are shown in Table 1. The Reserved field can be used by The flags defined in this document are shown in Table 1. The
future extensions; it MUST be zero when sending and ignored when Reserved field can be used by future extensions; it MUST be zero when
receiving this parameter. sending and ignored when receiving this parameter.
+-----+-------------+-----------------------------------------------+ +-----+-------------+-----------------------------------------------+
| Pos | Name | Purpose | | Pos | Name | Purpose |
+-----+-------------+-----------------------------------------------+ +-----+-------------+-----------------------------------------------+
| 0 | SYMMETRIC | The response packet MUST be sent with a | | 0 | SYMMETRIC | The response packet MUST be sent with a |
| | | ROUTE_DST list made from the ROUTE_VIA list | | | | ROUTE_DST list made from the ROUTE_VIA list |
| | | containing this flag, i.e., using symmetric | | | | containing this flag, i.e., using symmetric |
| | | routing. | | | | routing. |
| 1 | MUST_FOLLOW | All the hosts in a ROUTE_DST list MUST be | | 1 | MUST_FOLLOW | All the nodes in a ROUTE_DST list MUST be |
| | | traversed, i.e., even if a host would have a | | | | traversed, i.e., even if a node would have a |
| | | valid locator for a host beyond the next hop, | | | | valid locator for a node beyond the next hop, |
| | | it MUST NOT forward the packet there but to | | | | it MUST NOT forward the packet there but to |
| | | the next hop host. | | | | the next hop node. |
+-----+-------------+-----------------------------------------------+ +-----+-------------+-----------------------------------------------+
Table 1: Bit Flags in ROUTE_VIA and ROUTE_DST Parameters Table 1: Bit Flags in ROUTE_VIA and ROUTE_DST Parameters
The "Pos" column in Table 1 shows the bit position of the flag (as in The "Pos" column in Table 1 shows the bit position of the flag (as in
Figure 1) in the Flags field, "Name" gives the name of the flag used Figure 1) in the Flags field, "Name" gives the name of the flag used
in this document, and "Purpose" gives brief description of the in this document, and "Purpose" gives brief description of the
meaning of that flag. meaning of that flag.
The flags apply to both ROUTE_VIA and ROUTE_DST parameters and when a The flags apply to both ROUTE_VIA and ROUTE_DST parameters and when a
skipping to change at page 7, line 40 skipping to change at page 7, line 45
5. IANA Considerations 5. IANA Considerations
This section is to be interpreted according to [RFC5226]. This section is to be interpreted according to [RFC5226].
This document updates the IANA Registry for HIP Parameter Types This document updates the IANA Registry for HIP Parameter Types
[RFC5201] by assigning new HIP Parameter Type values for the new HIP [RFC5201] by assigning new HIP Parameter Type values for the new HIP
Parameters: ROUTE_VIA and ROUTE_DST (defined in Section 4). This Parameters: ROUTE_VIA and ROUTE_DST (defined in Section 4). This
document also defines a new Notify Packet Type [RFC5201] document also defines a new Notify Packet Type [RFC5201]
UNKNOWN_NEXT_HOP in Section 3.3. UNKNOWN_NEXT_HOP in Section 3.3.
The ROUTE_DST and ROUTE_VIA parameters utilize bit flags, for which
IANA is to create and maintain a new sub-registry entitled "HIP Via
Flags" under the "Host Identity Protocol (HIP) Parameters" registry.
Initial values for the registry are given in Table 1; future
assignments are to be made through IETF Review [RFC5226].
Assignments consist of the bit position and the name of the flag.
6. Security Considerations 6. Security Considerations
A malicious host could craft a destination route list that contains The standard HIP mechanisms (e.g., using signatures, puzzles, and the
ENCRYPTED parameter [RFC5201]) provide protection against
eavesdropping, replay, message insertion, deletion, modification, and
man-in-the-middle attacks. Yet, the extensions described in this
document allow nodes to route HIP messages via other nodes and hence
possibly try to mount Denial of Service (DoS) attacks against them.
The following sections describe possible attacks and means to
mitigate them.
6.1. Forged Destination and Via Lists
The Destination list is protected by the HIP signature so that the
receiver of the message can check that the list was indeed created by
the sender of the message and not modified on path. Also the nodes
forwarding the message MAY check the signature of the forwarded
packets if they have the Host Identity (HI) of the sender (e.g., from
a I2 or R1 message) and drop packets whose signature check fails.
With forwarding nodes checking the signature and allowing messages to
be forwarded only from nodes for which there is an active HIP
association, it is also possible to reliably identify attacking
nodes.
The limited amount of HITs allowed in a Destination list limits the
impact of attacks using a forged Destination list and the attacker
also needs to know a set of HIP nodes that are able to route the
message hop-by-hop for the attack to be effective.
A forged Via list results in a similar attack as with the Destination
list and with similar limitations. However, in this attack the
Destination list generated from the Via list is validly signed by the
responding node. To limit the effect of this kind of attacks a
responding node may further decrease the maximum acceptable number of
nodes in the Via lists or allow only certain HITs in the lists.
However, using these mechanisms require either good knowledge of the
overlay network (i.e., maximum realistic amount of hops) or knowing
the HITs of all potential nodes forwarding the messages.
6.2. Forwarding Loops
A malicious node could craft a destination route list that contains
the same HIT more than once and thus create a forwarding loop. The the same HIT more than once and thus create a forwarding loop. The
check described in Section 3.3 should break such loops but hosts MAY check described in Section 3.3 should break such loops but nodes MAY
in addition utilize the OVERLAY_TTL [I-D.ietf-hip-bone] parameter for in addition utilize the OVERLAY_TTL [I-D.ietf-hip-bone] parameter for
additional protection against forwarding loops. additional protection against forwarding loops.
7. Acknowledgments 7. Acknowledgments
Tom Henderson provided valuable comments and improvement suggestions Tom Henderson provided valuable comments and improvement suggestions
for this document. for this document.
8. References 8. References
skipping to change at page 8, line 33 skipping to change at page 9, line 33
Rendezvous Extension", RFC 5204, April 2008. Rendezvous Extension", RFC 5204, April 2008.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. May 2008.
[I-D.ietf-hip-bone] [I-D.ietf-hip-bone]
Camarillo, G., Nikander, P., Hautakorpi, J., Keranen, A., Camarillo, G., Nikander, P., Hautakorpi, J., Keranen, A.,
and A. Johnston, "HIP BONE: Host Identity Protocol (HIP) and A. Johnston, "HIP BONE: Host Identity Protocol (HIP)
Based Overlay Networking Environment", Based Overlay Networking Environment",
draft-ietf-hip-bone-04 (work in progress), January 2010. draft-ietf-hip-bone-06 (work in progress), April 2010.
[I-D.ietf-p2psip-base] [I-D.ietf-p2psip-base]
Jennings, C., Lowekamp, B., Rescorla, E., Baset, S., and Jennings, C., Lowekamp, B., Rescorla, E., Baset, S., and
H. Schulzrinne, "REsource LOcation And Discovery (RELOAD) H. Schulzrinne, "REsource LOcation And Discovery (RELOAD)
Base Protocol", draft-ietf-p2psip-base-07 (work in Base Protocol", draft-ietf-p2psip-base-08 (work in
progress), February 2010. progress), March 2010.
Authors' Addresses Authors' Addresses
Gonzalo Camarillo Gonzalo Camarillo
Ericsson Ericsson
Hirsalantie 11 Hirsalantie 11
02420 Jorvas 02420 Jorvas
Finland Finland
Email: Gonzalo.Camarillo@ericsson.com Email: Gonzalo.Camarillo@ericsson.com
 End of changes. 43 change blocks. 
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