draft-ietf-hip-rfc5206-bis-13.txt   draft-ietf-hip-rfc5206-bis-14.txt 
Network Working Group T. Henderson, Ed. Network Working Group T. Henderson, Ed.
Internet-Draft University of Washington Internet-Draft University of Washington
Obsoletes: 5206 (if approved) C. Vogt Obsoletes: 5206 (if approved) C. Vogt
Intended status: Standards Track Independent Intended status: Standards Track Independent
Expires: March 13, 2017 J. Arkko Expires: April 13, 2017 J. Arkko
Ericsson Ericsson
September 9, 2016 October 10, 2016
Host Mobility with the Host Identity Protocol Host Mobility with the Host Identity Protocol
draft-ietf-hip-rfc5206-bis-13 draft-ietf-hip-rfc5206-bis-14
Abstract Abstract
This document defines a mobility extension to the Host Identity This document defines a mobility extension to the Host Identity
Protocol (HIP). Specifically, this document defines a "LOCATOR_SET" Protocol (HIP). Specifically, this document defines a "LOCATOR_SET"
parameter for HIP messages that allows for a HIP host to notify peers parameter for HIP messages that allows for a HIP host to notify peers
about alternate addresses at which it may be reached. This document about alternate addresses at which it may be reached. This document
also defines how the parameter can be used to preserve communications also defines how the parameter can be used to preserve communications
across a change to the IP address used by one or both peer hosts. across a change to the IP address used by one or both peer hosts.
The same LOCATOR_SET parameter can also be used to support end-host The same LOCATOR_SET parameter can also be used to support end-host
multihoming, but the procedures are out of scope for this document multihoming (specified in RFC[Replace with the RFC number for draft-
and are specified elsewhere. This document obsoletes RFC 5206. ietf-hip-multihoming]). This document obsoletes RFC 5206.
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 March 13, 2017. This Internet-Draft will expire on April 13, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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
skipping to change at page 2, line 21 skipping to change at page 2, line 21
Table of Contents Table of Contents
1. Introduction and Scope . . . . . . . . . . . . . . . . . . . 3 1. Introduction and Scope . . . . . . . . . . . . . . . . . . . 3
2. Terminology and Conventions . . . . . . . . . . . . . . . . . 4 2. Terminology and Conventions . . . . . . . . . . . . . . . . . 4
3. Protocol Model . . . . . . . . . . . . . . . . . . . . . . . 5 3. Protocol Model . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Operating Environment . . . . . . . . . . . . . . . . . . 5 3.1. Operating Environment . . . . . . . . . . . . . . . . . . 5
3.1.1. Locator . . . . . . . . . . . . . . . . . . . . . . . 7 3.1.1. Locator . . . . . . . . . . . . . . . . . . . . . . . 7
3.1.2. Mobility Overview . . . . . . . . . . . . . . . . . . 7 3.1.2. Mobility Overview . . . . . . . . . . . . . . . . . . 7
3.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 8 3.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 8
3.2.1. Mobility with a Single SA Pair (No Rekeying) . . . . 8 3.2.1. Mobility with a Single SA Pair (No Rekeying) . . . . 9
3.2.2. Mobility with a Single SA Pair (Mobile-Initiated 3.2.2. Mobility with a Single SA Pair (Mobile-Initiated
Rekey) . . . . . . . . . . . . . . . . . . . . . . . 10 Rekey) . . . . . . . . . . . . . . . . . . . . . . . 10
3.2.3. Mobility messaging through rendezvous server . . . . 10 3.2.3. Mobility messaging through rendezvous server . . . . 11
3.2.4. Network Renumbering . . . . . . . . . . . . . . . . . 12 3.2.4. Network Renumbering . . . . . . . . . . . . . . . . . 12
3.3. Other Considerations . . . . . . . . . . . . . . . . . . 12 3.3. Other Considerations . . . . . . . . . . . . . . . . . . 12
3.3.1. Address Verification . . . . . . . . . . . . . . . . 12 3.3.1. Address Verification . . . . . . . . . . . . . . . . 12
3.3.2. Credit-Based Authorization . . . . . . . . . . . . . 12 3.3.2. Credit-Based Authorization . . . . . . . . . . . . . 13
3.3.3. Preferred Locator . . . . . . . . . . . . . . . . . . 14 3.3.3. Preferred Locator . . . . . . . . . . . . . . . . . . 14
4. LOCATOR_SET Parameter Format . . . . . . . . . . . . . . . . 14 4. LOCATOR_SET Parameter Format . . . . . . . . . . . . . . . . 15
4.1. Traffic Type and Preferred Locator . . . . . . . . . . . 16 4.1. Traffic Type and Preferred Locator . . . . . . . . . . . 16
4.2. Locator Type and Locator . . . . . . . . . . . . . . . . 16 4.2. Locator Type and Locator . . . . . . . . . . . . . . . . 17
4.3. UPDATE Packet with Included LOCATOR_SET . . . . . . . . . 17 4.3. UPDATE Packet with Included LOCATOR_SET . . . . . . . . . 17
5. Processing Rules . . . . . . . . . . . . . . . . . . . . . . 17 5. Processing Rules . . . . . . . . . . . . . . . . . . . . . . 17
5.1. Locator Data Structure and Status . . . . . . . . . . . . 17 5.1. Locator Data Structure and Status . . . . . . . . . . . . 18
5.2. Sending LOCATOR_SETs . . . . . . . . . . . . . . . . . . 19 5.2. Sending the LOCATOR_SET . . . . . . . . . . . . . . . . . 19
5.3. Handling Received LOCATOR_SETs . . . . . . . . . . . . . 19 5.3. Handling Received LOCATOR_SETs . . . . . . . . . . . . . 20
5.4. Verifying Address Reachability . . . . . . . . . . . . . 22 5.4. Verifying Address Reachability . . . . . . . . . . . . . 22
5.5. Changing the Preferred Locator . . . . . . . . . . . . . 23 5.5. Changing the Preferred Locator . . . . . . . . . . . . . 23
5.6. Credit-Based Authorization . . . . . . . . . . . . . . . 23 5.6. Credit-Based Authorization . . . . . . . . . . . . . . . 24
5.6.1. Handling Payload Packets . . . . . . . . . . . . . . 24 5.6.1. Handling Payload Packets . . . . . . . . . . . . . . 24
5.6.2. Credit Aging . . . . . . . . . . . . . . . . . . . . 25 5.6.2. Credit Aging . . . . . . . . . . . . . . . . . . . . 26
6. Security Considerations . . . . . . . . . . . . . . . . . . . 26 6. Security Considerations . . . . . . . . . . . . . . . . . . . 27
6.1. Impersonation Attacks . . . . . . . . . . . . . . . . . . 27 6.1. Impersonation Attacks . . . . . . . . . . . . . . . . . . 28
6.2. Denial-of-Service Attacks . . . . . . . . . . . . . . . . 28 6.2. Denial-of-Service Attacks . . . . . . . . . . . . . . . . 29
6.2.1. Flooding Attacks . . . . . . . . . . . . . . . . . . 28 6.2.1. Flooding Attacks . . . . . . . . . . . . . . . . . . 29
6.2.2. Memory/Computational-Exhaustion DoS Attacks . . . . . 28 6.2.2. Memory/Computational-Exhaustion DoS Attacks . . . . . 29
6.3. Mixed Deployment Environment . . . . . . . . . . . . . . 29 6.3. Mixed Deployment Environment . . . . . . . . . . . . . . 30
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30 6.4. Privacy Concerns . . . . . . . . . . . . . . . . . . . . 31
8. Authors and Acknowledgments . . . . . . . . . . . . . . . . . 30 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 31
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 30 8. Differences from RFC 5206 . . . . . . . . . . . . . . . . . . 31
9.1. Normative references . . . . . . . . . . . . . . . . . . 30 9. Authors and Acknowledgments . . . . . . . . . . . . . . . . . 32
9.2. Informative references . . . . . . . . . . . . . . . . . 31 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 33
Appendix A. Document Revision History . . . . . . . . . . . . . 32 10.1. Normative references . . . . . . . . . . . . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33 10.2. Informative references . . . . . . . . . . . . . . . . . 34
Appendix A. Document Revision History . . . . . . . . . . . . . 35
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36
1. Introduction and Scope 1. Introduction and Scope
The Host Identity Protocol [RFC7401] (HIP) supports an architecture The Host Identity Protocol [RFC7401] (HIP) supports an architecture
that decouples the transport layer (TCP, UDP, etc.) from the that decouples the transport layer (TCP, UDP, etc.) from the
internetworking layer (IPv4 and IPv6) by using public/private key internetworking layer (IPv4 and IPv6) by using public/private key
pairs, instead of IP addresses, as host identities. When a host uses pairs, instead of IP addresses, as host identities. When a host uses
HIP, the overlying protocol sublayers (e.g., transport layer sockets HIP, the overlying protocol sublayers (e.g., transport layer sockets
and Encapsulating Security Payload (ESP) Security Associations (SAs)) and Encapsulating Security Payload (ESP) Security Associations (SAs))
are instead bound to representations of these host identities, and are instead bound to representations of these host identities, and
the IP addresses are only used for packet forwarding. However, each the IP addresses are only used for packet forwarding. However, each
host must also know at least one IP address at which its peers are host needs to also know at least one IP address at which its peers
reachable. Initially, these IP addresses are the ones used during are reachable. Initially, these IP addresses are the ones used
the HIP base exchange. during the HIP base exchange.
One consequence of such a decoupling is that new solutions to One consequence of such a decoupling is that new solutions to
network-layer mobility and host multihoming are possible. There are network-layer mobility and host multihoming are possible. There are
potentially many variations of mobility and multihoming possible. potentially many variations of mobility and multihoming possible.
The scope of this document encompasses messaging and elements of The scope of this document encompasses messaging and elements of
procedure for basic network-level host mobility, leaving more procedure for basic network-level host mobility, leaving more
complicated mobility scenarios, multihoming, and other variations for complicated mobility scenarios, multihoming, and other variations for
further study. More specifically, the following are in scope: further study. More specifically, the following are in scope:
This document defines a LOCATOR_SET parameter for use in HIP This document defines a LOCATOR_SET parameter for use in HIP
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signaling the correspondent node); this document is concerned with signaling the correspondent node); this document is concerned with
end-to-end mobility. end-to-end mobility.
Finally, making underlying IP mobility transparent to the Finally, making underlying IP mobility transparent to the
transport layer has implications on the proper response of transport layer has implications on the proper response of
transport congestion control, path MTU selection, and Quality of transport congestion control, path MTU selection, and Quality of
Service (QoS). Transport-layer mobility triggers, and the proper Service (QoS). Transport-layer mobility triggers, and the proper
transport response to a HIP mobility or multihoming address transport response to a HIP mobility or multihoming address
change, are outside the scope of this document. change, are outside the scope of this document.
The main sections of this document are organized as follows.
Section 3 provides a summary overview of operations, scenarios, and
other considerations. Section 4 specifies the messaging parameter
syntax. Section 5 specifies the processing rules for messages.
Section 6 describes security considerations for this specification.
2. Terminology and Conventions 2. Terminology and Conventions
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].
LOCATOR_SET. A HIP parameter containing zero or more Locator fields. LOCATOR_SET. A HIP parameter containing zero or more Locator fields.
Locator. A name that controls how the packet is routed through the Locator. A name that controls how the packet is routed through the
network and demultiplexed by the end host. It may include a network and demultiplexed by the end host. It may include a
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to use for ESP, and the IP addresses (used in both the HIP signaling to use for ESP, and the IP addresses (used in both the HIP signaling
packets and ESP data packets). Note that there can only be one such packets and ESP data packets). Note that there can only be one such
set of bindings in the outbound direction for any given packet, and set of bindings in the outbound direction for any given packet, and
the only fields used for the binding at the HIP layer are the fields the only fields used for the binding at the HIP layer are the fields
exposed by ESP (the SPI and HITs). For the inbound direction, the exposed by ESP (the SPI and HITs). For the inbound direction, the
SPI is all that is required to find the right host context. ESP SPI is all that is required to find the right host context. ESP
rekeying events change the mapping between the HIT pair and SPI, but rekeying events change the mapping between the HIT pair and SPI, but
do not change the IP addresses. do not change the IP addresses.
Consider next a mobility event, in which a host moves to another IP Consider next a mobility event, in which a host moves to another IP
address. Two things must occur in this case. First, the peer must address. Two things need to occur in this case. First, the peer
be notified of the address change using a HIP UPDATE message. needs to be notified of the address change using a HIP UPDATE
Second, each host must change its local bindings at the HIP sublayer message. Second, each host needs to change its local bindings at the
(new IP addresses). It may be that both the SPIs and IP addresses HIP sublayer (new IP addresses). It may be that both the SPIs and IP
are changed simultaneously in a single UPDATE; the protocol described addresses are changed simultaneously in a single UPDATE; the protocol
herein supports this. Although internal notification of transport described herein supports this. Although internal notification of
layer protocols regarding the path change (e.g. to reset congestion transport layer protocols regarding the path change (e.g. to reset
control variables) may be desired, this specification does not congestion control variables) may be desired, this specification does
address such internal notification. In addition, elements of not address such internal notification. In addition, elements of
procedure for traversing middleboxes, including network address procedure for traversing network address translators (NATs) and
translators, may complicate the above basic scenario and are not firewalls, including NATs and firewalls that may understand the HIP
covered by this document. protocol, may complicate the above basic scenario and are not covered
by this document.
3.1.1. Locator 3.1.1. Locator
This document defines a generalization of an address called a This document defines a generalization of an address called a
"locator". A locator specifies a point-of-attachment to the network "locator". A locator specifies a point-of-attachment to the network
but may also include additional end-to-end tunneling or per-host but may also include additional end-to-end tunneling or per-host
demultiplexing context that affects how packets are handled below the demultiplexing context that affects how packets are handled below the
logical HIP sublayer of the stack. This generalization is useful logical HIP sublayer of the stack. This generalization is useful
because IP addresses alone may not be sufficient to describe how because IP addresses alone may not be sufficient to describe how
packets should be handled below HIP. For example, in a host packets should be handled below HIP. For example, in a host
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pair of IP addresses, which are the ones used in the base exchange. pair of IP addresses, which are the ones used in the base exchange.
The readdressing protocol is an asymmetric protocol where a mobile The readdressing protocol is an asymmetric protocol where a mobile
host informs a peer host about changes of IP addresses on affected host informs a peer host about changes of IP addresses on affected
SPIs. The readdressing exchange is designed to be piggybacked on SPIs. The readdressing exchange is designed to be piggybacked on
existing HIP exchanges. In support of mobility, the LOCATOR_SET existing HIP exchanges. In support of mobility, the LOCATOR_SET
parameter is carried in UPDATE packets. parameter is carried in UPDATE packets.
The scenarios below at times describe addresses as being in either an The scenarios below at times describe addresses as being in either an
ACTIVE, UNVERIFIED, or DEPRECATED state. From the perspective of a ACTIVE, UNVERIFIED, or DEPRECATED state. From the perspective of a
host, newly-learned addresses of the peer must be verified before put host, newly-learned addresses of the peer needs to be verified before
into active service, and addresses removed by the peer are put into a put into active service, and addresses removed by the peer are put
deprecated state. Under limited conditions described below into a deprecated state. Under limited conditions described below
(Section 5.6), an UNVERIFIED address may be used. The addressing (Section 5.6), an UNVERIFIED address may be used. The addressing
states are defined more formally in Section 5.1. states are defined more formally in Section 5.1.
Hosts that use link-local addresses as source addresses in their HIP Hosts that use link-local addresses as source addresses in their HIP
handshakes may not be reachable by a mobile peer. Such hosts SHOULD handshakes may not be reachable by a mobile peer. Such hosts SHOULD
provide a globally routable address either in the initial handshake provide a globally routable address either in the initial handshake
or via the LOCATOR_SET parameter. or via the LOCATOR_SET parameter.
3.2.1. Mobility with a Single SA Pair (No Rekeying) 3.2.1. Mobility with a Single SA Pair (No Rekeying)
A mobile host must sometimes change an IP address bound to an A mobile host sometimes needs to change an IP address bound to an
interface. The change of an IP address might be needed due to a interface. The change of an IP address might be needed due to a
change in the advertised IPv6 prefixes on the link, a reconnected PPP change in the advertised IPv6 prefixes on the link, a reconnected PPP
link, a new DHCP lease, or an actual movement to another subnet. In link, a new DHCP lease, or an actual movement to another subnet. In
order to maintain its communication context, the host must inform its order to maintain its communication context, the host needs to inform
peers about the new IP address. This first example considers the its peers about the new IP address. This first example considers the
case in which the mobile host has only one interface, one IP address case in which the mobile host has only one interface, one IP address
in use within the HIP session, a single pair of SAs (one inbound, one in use within the HIP session, a single pair of SAs (one inbound, one
outbound), and no rekeying occurs on the SAs. We also assume that outbound), and no rekeying occurs on the SAs. We also assume that
the new IP addresses are within the same address family (IPv4 or the new IP addresses are within the same address family (IPv4 or
IPv6) as the previous address. This is the simplest scenario, IPv6) as the previous address. This is the simplest scenario,
depicted in Figure 3. depicted in Figure 3. Note that the conventions for message
parameter notations in figures (use of parentheses and brackets) is
defined in Section 2.2 of [RFC7401].
Mobile Host Peer Host Mobile Host Peer Host
UPDATE(ESP_INFO, LOCATOR_SET, SEQ) UPDATE(ESP_INFO, LOCATOR_SET, SEQ)
-----------------------------------> ----------------------------------->
UPDATE(ESP_INFO, SEQ, ACK, ECHO_REQUEST) UPDATE(ESP_INFO, SEQ, ACK, ECHO_REQUEST)
<----------------------------------- <-----------------------------------
UPDATE(ACK, ECHO_RESPONSE) UPDATE(ACK, ECHO_RESPONSE)
-----------------------------------> ----------------------------------->
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another; this case is sometimes referred to in the literature as another; this case is sometimes referred to in the literature as
a "break-before-make" case. The host may also obtain its new IP a "break-before-make" case. The host may also obtain its new IP
address before loosing the old one ("make-before-break" case). address before loosing the old one ("make-before-break" case).
In either case, upon obtaining a new IP address, the mobile host In either case, upon obtaining a new IP address, the mobile host
sends a LOCATOR_SET parameter to the peer host in an UPDATE sends a LOCATOR_SET parameter to the peer host in an UPDATE
message. The UPDATE message also contains an ESP_INFO parameter message. The UPDATE message also contains an ESP_INFO parameter
containing the values of the old and new SPIs for a security containing the values of the old and new SPIs for a security
association. In this case, the OLD SPI and NEW SPI parameters association. In this case, the OLD SPI and NEW SPI parameters
both are set to the value of the preexisting incoming SPI; this both are set to the value of the preexisting incoming SPI; this
ESP_INFO does not trigger a rekeying event but is instead ESP_INFO does not trigger a rekeying event but is instead
included for possible parameter-inspecting middleboxes on the included for possible parameter-inspecting firewalls on the path
path. The LOCATOR_SET parameter contains the new IP address ([RFC5207] specifies some such firewall scenarios in which the
(Locator Type of "1", defined below) and a locator lifetime. The HIP-aware firewall may want to associate ESP flows to host
mobile host waits for this UPDATE to be acknowledged, and identities). The LOCATOR_SET parameter contains the new IP
retransmits if necessary, as specified in the base specification address (Locator Type of "1", defined below) and a locator
[RFC7401]. lifetime. The mobile host waits for this UPDATE to be
acknowledged, and retransmits if necessary, as specified in the
base specification [RFC7401].
2. The peer host receives the UPDATE, validates it, and updates any 2. The peer host receives the UPDATE, validates it, and updates any
local bindings between the HIP association and the mobile host's local bindings between the HIP association and the mobile host's
destination address. The peer host MUST perform an address destination address. The peer host MUST perform an address
verification by placing a nonce in the ECHO_REQUEST parameter of verification by placing a nonce in the ECHO_REQUEST parameter of
the UPDATE message sent back to the mobile host. It also the UPDATE message sent back to the mobile host. It also
includes an ESP_INFO parameter with the OLD SPI and NEW SPI includes an ESP_INFO parameter with the OLD SPI and NEW SPI
parameters both set to the value of the preexisting incoming SPI, parameters both set to the value of the preexisting incoming SPI,
and sends this UPDATE (with piggybacked acknowledgment) to the and sends this UPDATE (with piggybacked acknowledgment) to the
mobile host at its new address. The peer MAY use the new address mobile host at its new address. This UPDATE also acknowledges
immediately, but it MUST limit the amount of data it sends to the the mobile host's UPDATE that triggered the exchange. The peer
address until address verification completes. host waits for its UPDATE to be acknowledged, and retransmits if
necessary, as specified in the base specification [RFC7401]. The
peer MAY use the new address immediately, but it MUST limit the
amount of data it sends to the address until address verification
completes.
3. The mobile host completes the readdress by processing the UPDATE 3. The mobile host completes the readdress by processing the UPDATE
ACK and echoing the nonce in an ECHO_RESPONSE. Once the peer ACK and echoing the nonce in an ECHO_RESPONSE, containing the ACK
host receives this ECHO_RESPONSE, it considers the new address to of the peer's UPDATE. This UPDATE is not protected by a
be verified and can put the address into full use. retransmission timer because it does not contain a SEQ parameter
requesting acknowledgment. Once the peer host receives this
ECHO_RESPONSE, it considers the new address to be verified and
can put the address into full use.
While the peer host is verifying the new address, the new address is While the peer host is verifying the new address, the new address is
marked as UNVERIFIED in the interim, and the old address is marked as UNVERIFIED in the interim, and the old address is
DEPRECATED. Once the peer host has received a correct reply to its DEPRECATED. Once the peer host has received a correct reply to its
UPDATE challenge, it marks the new address as ACTIVE and removes the UPDATE challenge, it marks the new address as ACTIVE and removes the
old address. old address.
3.2.2. Mobility with a Single SA Pair (Mobile-Initiated Rekey) 3.2.2. Mobility with a Single SA Pair (Mobile-Initiated Rekey)
The mobile host may decide to rekey the SAs at the same time that it The mobile host may decide to rekey the SAs at the same time that it
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The HIP Rendezvous Extension [I-D.ietf-hip-rfc5204-bis] specifies a The HIP Rendezvous Extension [I-D.ietf-hip-rfc5204-bis] specifies a
rendezvous service that permits the I1 packet from the base exchange rendezvous service that permits the I1 packet from the base exchange
to be relayed from a stable or well-known public IP address location to be relayed from a stable or well-known public IP address location
to the current IP address of the host. It is possible to support to the current IP address of the host. It is possible to support
double-jump mobility with this rendezvous service if the following double-jump mobility with this rendezvous service if the following
extensions to the specifications of [I-D.ietf-hip-rfc5204-bis] and extensions to the specifications of [I-D.ietf-hip-rfc5204-bis] and
[RFC7401] are followed. [RFC7401] are followed.
1. The mobile host sending an UPDATE to the peer, and not receiving 1. The mobile host sending an UPDATE to the peer, and not receiving
an ACK, MAY resend the UPDATE to a rendezvous server (RVS) of the an ACK, MAY resend the UPDATE to a rendezvous server (RVS) of the
peer, if such a server is known. The host may try the RVS of the peer, if such a server is known. The host MAY try the RVS of the
peer up to UPDATE_RETRY_MAX times as specified in [RFC7401]. The peer up to UPDATE_RETRY_MAX times as specified in [RFC7401]. The
host may try to use the peer's RVS before it has tried host MAY try to use the peer's RVS before it has tried
UPDATE_RETRY_MAX times to the last working address (i.e. the RVS UPDATE_RETRY_MAX times to the last working address (i.e. the RVS
may be tried in parallel with retries to the last working MAY be tried in parallel with retries to the last working
address). address). The aggressiveness of a host replicating its UPDATEs
to multiple destinations, to try candidates in parallel instead
of serially, is a policy choice outside of this specification.
2. A rendezvous server supporting the UPDATE forwarding extensions 2. A rendezvous server supporting the UPDATE forwarding extensions
specified herein MUST modify the UPDATE in the same manner as it specified herein MUST modify the UPDATE in the same manner as it
modifies the I1 packet before forwarding. Specifically, it MUST modifies the I1 packet before forwarding. Specifically, it MUST
rewrite the IP header source and destination addresses, recompute rewrite the IP header source and destination addresses, recompute
the IP header checksum, and include the FROM and RVS_HMAC the IP header checksum, and include the FROM and RVS_HMAC
parameters. parameters.
3. A host receiving an UPDATE packet MUST be prepared to process the 3. A host receiving an UPDATE packet MUST be prepared to process the
FROM and RVS_HMAC parameters, and MUST include a VIA_RVS FROM and RVS_HMAC parameters, and MUST include a VIA_RVS
skipping to change at page 12, line 23 skipping to change at page 12, line 47
3.3. Other Considerations 3.3. Other Considerations
3.3.1. Address Verification 3.3.1. Address Verification
When a HIP host receives a set of locators from another HIP host in a When a HIP host receives a set of locators from another HIP host in a
LOCATOR_SET, it does not necessarily know whether the other host is LOCATOR_SET, it does not necessarily know whether the other host is
actually reachable at the claimed addresses. In fact, a malicious actually reachable at the claimed addresses. In fact, a malicious
peer host may be intentionally giving bogus addresses in order to peer host may be intentionally giving bogus addresses in order to
cause a packet flood towards the target addresses [RFC4225]. cause a packet flood towards the target addresses [RFC4225].
Therefore, the HIP host must first check that the peer is reachable Therefore, the HIP host needs to first check that the peer is
at the new address. reachable at the new address.
Address verification is implemented by the challenger sending some Address verification is implemented by the challenger sending some
piece of unguessable information to the new address, and waiting for piece of unguessable information to the new address, and waiting for
some acknowledgment from the Responder that indicates reception of some acknowledgment from the Responder that indicates reception of
the information at the new address. This may include the exchange of the information at the new address. This may include the exchange of
a nonce, or the generation of a new SPI and observation of data a nonce, or the generation of a new SPI and observation of data
arriving on the new SPI. arriving on the new SPI. More details are found in Section 5.4 of
this document.
An additional potential benefit of performing address verification is An additional potential benefit of performing address verification is
to allow middleboxes in the network along the new path to obtain the to allow NATs and firewalls in the network along the new path to
peer host's inbound SPI. obtain the peer host's inbound SPI.
3.3.2. Credit-Based Authorization 3.3.2. Credit-Based Authorization
Credit-Based Authorization (CBA) allows a host to securely use a new Credit-Based Authorization (CBA) allows a host to securely use a new
locator even though the peer's reachability at the address embedded locator even though the peer's reachability at the address embedded
in the locator has not yet been verified. This is accomplished based in the locator has not yet been verified. This is accomplished based
on the following three hypotheses: on the following three hypotheses:
1. A flooding attacker typically seeks to somehow multiply the 1. A flooding attacker typically seeks to somehow multiply the
packets it generates for the purpose of its attack because packets it generates for the purpose of its attack because
skipping to change at page 14, line 30 skipping to change at page 14, line 32
|<-------------------------------| credit -= size(packet) |<-------------------------------| credit -= size(packet)
| X credit < size(packet) | X credit < size(packet)
| | => do not send packet! | | => do not send packet!
+ address verification concludes | + address verification concludes |
address | | address | |
ACTIVE |<-------------------------------| do not change credit ACTIVE |<-------------------------------| do not change credit
| | | |
Figure 5: Readdressing Scenario Figure 5: Readdressing Scenario
This document does not specify how to set the credit limit value, but
the goal is to allow data transfers to proceed without much
interruption while the new address is verified. A simple heuristic
to accomplish this, if the sender knows roughly its round-trip time
(RTT) and current sending rate to the host, is to allow enough credit
to support maintaining the sending rate for a duration corresponding
to two or three RTTs.
3.3.3. Preferred Locator 3.3.3. Preferred Locator
When a host has multiple locators, the peer host must decide which to When a host has multiple locators, the peer host needs to decide
use for outbound packets. It may be that a host would prefer to which to use for outbound packets. It may be that a host would
receive data on a particular inbound interface. HIP allows a prefer to receive data on a particular inbound interface. HIP allows
particular locator to be designated as a Preferred locator and a particular locator to be designated as a Preferred locator and
communicated to the peer (see Section 4). communicated to the peer (see Section 4).
4. LOCATOR_SET Parameter Format 4. LOCATOR_SET Parameter Format
The LOCATOR_SET parameter is a critical parameter as defined by The LOCATOR_SET parameter has a type number value that is considered
[RFC7401]. It consists of the standard HIP parameter Type and Length to be a 'critical parameter' as per the definition in [RFC7401]; such
parameter types MUST be recognized and processed by the recipient.
The parameter consists of the standard HIP parameter Type and Length
fields, plus zero or more Locator sub-parameters. Each Locator sub- fields, plus zero or more Locator sub-parameters. Each Locator sub-
parameter contains a Traffic Type, Locator Type, Locator Length, parameter contains a Traffic Type, Locator Type, Locator Length,
Preferred locator bit, Locator Lifetime, and a Locator encoding. A Preferred locator bit, Locator Lifetime, and a Locator encoding. A
LOCATOR_SET containing zero Locator fields is permitted but has the LOCATOR_SET containing zero Locator fields is permitted but has the
effect of deprecating all addresses. effect of deprecating all addresses.
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 |
skipping to change at page 16, line 17 skipping to change at page 16, line 31
Locator: The locator whose semantics and encoding are indicated by Locator: The locator whose semantics and encoding are indicated by
the Locator Type field. All Locator sub-fields are integral the Locator Type field. All Locator sub-fields are integral
multiples of four octets in length. multiples of four octets in length.
The Locator Lifetime indicates how long the following locator is The Locator Lifetime indicates how long the following locator is
expected to be valid. The lifetime is expressed in seconds. Each expected to be valid. The lifetime is expressed in seconds. Each
locator MUST have a non-zero lifetime. The address is expected to locator MUST have a non-zero lifetime. The address is expected to
become deprecated when the specified number of seconds has passed become deprecated when the specified number of seconds has passed
since the reception of the message. A deprecated address SHOULD NOT since the reception of the message. A deprecated address SHOULD NOT
be used as a destination address if an alternate (non-deprecated) is be used as a destination address if an alternate (non-deprecated) is
available and has sufficient scope. available and has sufficient address scope.
4.1. Traffic Type and Preferred Locator 4.1. Traffic Type and Preferred Locator
The following Traffic Type values are defined: The following Traffic Type values are defined:
0: Both signaling (HIP control packets) and user data. 0: Both signaling (HIP control packets) and user data.
1: Signaling packets only. 1: Signaling packets only.
2: Data packets only. 2: Data packets only.
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4.3. UPDATE Packet with Included LOCATOR_SET 4.3. UPDATE Packet with Included LOCATOR_SET
A number of combinations of parameters in an UPDATE packet are A number of combinations of parameters in an UPDATE packet are
possible (e.g., see Section 3.2). In this document, procedures are possible (e.g., see Section 3.2). In this document, procedures are
defined only for the case in which one LOCATOR_SET and one ESP_INFO defined only for the case in which one LOCATOR_SET and one ESP_INFO
parameter is used in any HIP packet. Any UPDATE packet that includes parameter is used in any HIP packet. Any UPDATE packet that includes
a LOCATOR_SET parameter SHOULD include both an HMAC and a a LOCATOR_SET parameter SHOULD include both an HMAC and a
HIP_SIGNATURE parameter. HIP_SIGNATURE parameter.
The UPDATE MAY also include a HOST_ID parameter (which may be useful The UPDATE MAY also include a HOST_ID parameter (which may be useful
for middleboxes inspecting the HIP messages for the first time). If for HIP-aware firewalls inspecting the HIP messages for the first
the UPDATE includes the HOST_ID parameter, the receiving host MUST time). If the UPDATE includes the HOST_ID parameter, the receiving
verify that the HOST_ID corresponds to the HOST_ID that was used to host MUST verify that the HOST_ID corresponds to the HOST_ID that was
establish the HIP association, and the HIP_SIGNATURE must verify with used to establish the HIP association, and the HIP_SIGNATURE MUST
the public key associated with this HOST_ID parameter. verify with the public key associated with this HOST_ID parameter.
The relationship between the announced Locators and any ESP_INFO The relationship between the announced Locators and any ESP_INFO
parameters present in the packet is defined in Section 5.2. This parameters present in the packet is defined in Section 5.2. This
document does not support any elements of procedure for sending more document does not support any elements of procedure for sending more
than one LOCATOR_SET or ESP_INFO parameter in a single UPDATE. than one LOCATOR_SET or ESP_INFO parameter in a single UPDATE.
5. Processing Rules 5. Processing Rules
This section describes rules for sending and receiving the This section describes rules for sending and receiving the
LOCATOR_SET parameter, testing address reachability, and using LOCATOR_SET parameter, testing address reachability, and using
Credit-Based Authorization (CBA) on UNVERIFIED locators. Credit-Based Authorization (CBA) on UNVERIFIED locators.
5.1. Locator Data Structure and Status 5.1. Locator Data Structure and Status
In a typical implementation, each locator announced in a LOCATOR_SET Each locator announced in a LOCATOR_SET parameter is represented by a
parameter is represented by a piece of state that contains the piece of state that contains the following data:
following data:
o the actual bit pattern representing the locator, o the actual bit pattern representing the locator,
o the lifetime (seconds), o the lifetime (seconds),
o the status (UNVERIFIED, ACTIVE, DEPRECATED), o the status (UNVERIFIED, ACTIVE, DEPRECATED),
o the Traffic Type scope of the locator, and o the Traffic Type scope of the locator, and
o whether the locator is preferred for any particular scope. o whether the locator is preferred for any particular scope.
skipping to change at page 18, line 26 skipping to change at page 18, line 44
successfully. successfully.
UNVERIFIED to DEPRECATED The locator lifetime expires while the UNVERIFIED to DEPRECATED The locator lifetime expires while the
locator is UNVERIFIED. locator is UNVERIFIED.
ACTIVE to DEPRECATED The locator lifetime expires while the locator ACTIVE to DEPRECATED The locator lifetime expires while the locator
is ACTIVE. is ACTIVE.
ACTIVE to UNVERIFIED There has been no traffic on the address for ACTIVE to UNVERIFIED There has been no traffic on the address for
some time, and the local policy mandates that the address some time, and the local policy mandates that the address
reachability must be verified again before starting to use it reachability needs to be verified again before starting to use it
again. again.
DEPRECATED to UNVERIFIED The host receives a new lifetime for the DEPRECATED to UNVERIFIED The host receives a new lifetime for the
locator. locator.
A DEPRECATED address MUST NOT be changed to ACTIVE without first A DEPRECATED address MUST NOT be changed to ACTIVE without first
verifying its reachability. verifying its reachability.
Note that the state of whether or not a locator is preferred is not Note that the state of whether or not a locator is preferred is not
necessarily the same as the value of the Preferred bit in the Locator necessarily the same as the value of the Preferred bit in the Locator
sub-parameter received from the peer. Peers may recommend certain sub-parameter received from the peer. Peers may recommend certain
locators to be preferred, but the decision on whether to actually use locators to be preferred, but the decision on whether to actually use
a locator as a preferred locator is a local decision, possibly a locator as a preferred locator is a local decision, possibly
influenced by local policy. influenced by local policy.
In addition to state maintained about status and remaining lifetime In addition to state maintained about status and remaining lifetime
for each locator learned from the peer, an implementation would for each locator learned from the peer, an implementation would
typically maintain similar state about its own locators that have typically maintain similar state about its own locators that have
been offered to the peer. been offered to the peer.
An unbounded locator lifetime can be signified by setting the value
of the lifetime field to the maximum (unsigned) value.
Finally, the locators used to establish the HIP association are by Finally, the locators used to establish the HIP association are by
default assumed to be the initial preferred locators in ACTIVE state, default assumed to be the initial preferred locators in ACTIVE state,
with an unbounded lifetime. with an unbounded lifetime.
5.2. Sending LOCATOR_SETs 5.2. Sending the LOCATOR_SET
The decision of when to send LOCATOR_SETs is basically a local policy The decision of when to send the LOCATOR_SET is a local policy issue.
issue. However, it is RECOMMENDED that a host send a LOCATOR_SET However, it is RECOMMENDED that a host send a LOCATOR_SET whenever it
whenever it recognizes a change of its IP addresses in use on an recognizes a change of its IP addresses in use on an active HIP
active HIP association, and assumes that the change is going to last association, and assumes that the change is going to last at least
at least for a few seconds. Rapidly sending LOCATOR_SETs that force for a few seconds. Rapidly sending LOCATOR_SETs that force the peer
the peer to change the preferred address SHOULD be avoided. to change the preferred address SHOULD be avoided.
The sending of a new LOCATOR_SET parameter replaces the locator
information from any previously sent LOCATOR_SET parameter, and
therefore if a host sends a new LOCATOR_SET parameter, it needs to
continue to include all active locators. Hosts MUST NOT announce
broadcast or multicast addresses in LOCATOR_SETs.
We now describe a few cases introduced in Section 3.2. We assume We now describe a few cases introduced in Section 3.2. We assume
that the Traffic Type for each locator is set to "0" (other values that the Traffic Type for each locator is set to "0" (other values
for Traffic Type may be specified in documents that separate the HIP for Traffic Type may be specified in documents that separate the HIP
control plane from data plane traffic). Other mobility cases are control plane from data plane traffic). Other mobility cases are
possible but are left for further study. possible but are left for further study.
1. Host mobility with no multihoming and no rekeying. The mobile 1. Host mobility with no multihoming and no rekeying. The mobile
host creates a single UPDATE containing a single ESP_INFO with a host creates a single UPDATE containing a single ESP_INFO with a
single LOCATOR_SET parameter. The ESP_INFO contains the current single LOCATOR_SET parameter. The ESP_INFO contains the current
value of the SPI in both the OLD SPI and NEW SPI fields. The value of the SPI in both the OLD SPI and NEW SPI fields. The
LOCATOR_SET contains a single Locator with a "Locator Type" of LOCATOR_SET contains a single Locator with a "Locator Type" of
"1"; the SPI must match that of the ESP_INFO. The Preferred bit "1"; the SPI MUST match that of the ESP_INFO. The Preferred bit
SHOULD be set and the "Locator Lifetime" is set according to SHOULD be set and the "Locator Lifetime" is set according to
local policy. The UPDATE also contains a SEQ parameter as usual. local policy. The UPDATE also contains a SEQ parameter as usual.
This packet is retransmitted as defined in the HIP protocol This packet is retransmitted as defined in the HIP protocol
specification [RFC7401]. The UPDATE should be sent to the peer's specification [RFC7401]. The UPDATE should be sent to the peer's
preferred IP address with an IP source address corresponding to preferred IP address with an IP source address corresponding to
the address in the LOCATOR_SET parameter. the address in the LOCATOR_SET parameter.
2. Host mobility with no multihoming but with rekeying. The mobile 2. Host mobility with no multihoming but with rekeying. The mobile
host creates a single UPDATE containing a single ESP_INFO with a host creates a single UPDATE containing a single ESP_INFO with a
single LOCATOR_SET parameter (with a single address). The single LOCATOR_SET parameter (with a single address). The
ESP_INFO contains the current value of the SPI in the OLD SPI and ESP_INFO contains the current value of the SPI in the OLD SPI and
the new value of the SPI in the NEW SPI, and a KEYMAT Index as the new value of the SPI in the NEW SPI, and a KEYMAT Index as
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the address in the LOCATOR_SET parameter. the address in the LOCATOR_SET parameter.
2. Host mobility with no multihoming but with rekeying. The mobile 2. Host mobility with no multihoming but with rekeying. The mobile
host creates a single UPDATE containing a single ESP_INFO with a host creates a single UPDATE containing a single ESP_INFO with a
single LOCATOR_SET parameter (with a single address). The single LOCATOR_SET parameter (with a single address). The
ESP_INFO contains the current value of the SPI in the OLD SPI and ESP_INFO contains the current value of the SPI in the OLD SPI and
the new value of the SPI in the NEW SPI, and a KEYMAT Index as the new value of the SPI in the NEW SPI, and a KEYMAT Index as
selected by local policy. Optionally, the host may choose to selected by local policy. Optionally, the host may choose to
initiate a Diffie Hellman rekey by including a DIFFIE_HELLMAN initiate a Diffie Hellman rekey by including a DIFFIE_HELLMAN
parameter. The LOCATOR_SET contains a single Locator with parameter. The LOCATOR_SET contains a single Locator with
"Locator Type" of "1"; the SPI must match that of the NEW SPI in "Locator Type" of "1"; the SPI MUST match that of the NEW SPI in
the ESP_INFO. Otherwise, the steps are identical to the case in the ESP_INFO. Otherwise, the steps are identical to the case in
which no rekeying is initiated. which no rekeying is initiated.
5.3. Handling Received LOCATOR_SETs 5.3. Handling Received LOCATOR_SETs
A host SHOULD be prepared to receive a single LOCATOR_SET parameter A host SHOULD be prepared to receive a single LOCATOR_SET parameter
in a HIP UPDATE packet. Reception of multiple LOCATOR_SET parameters in a HIP UPDATE packet. Reception of multiple LOCATOR_SET parameters
in a single packet, or in HIP packets other than UPDATE, is outside in a single packet, or in HIP packets other than UPDATE, is outside
of the scope of this specification. of the scope of this specification.
Because a host sending the LOCATOR_SET may send the same parameter in
different UPDATE messages to different destination addresses,
including possibly the rendezvous server of the host, the host
receiving the LOCATOR_SET MUST be prepared to handle the possibility
of duplicate LOCATOR_SETs sent to more than one of the host's
addresses. As a result, the host MUST detect and avoid reprocessing
a LOCATOR_SET parameter that is redundant with a LOCATOR_SET
parameter that has been recently received and processed.
This document describes sending both ESP_INFO and LOCATOR_SET This document describes sending both ESP_INFO and LOCATOR_SET
parameters in an UPDATE. The ESP_INFO parameter is included when parameters in an UPDATE. The ESP_INFO parameter is included when
there is a need to rekey or key a new SPI, and is otherwise included there is a need to rekey or key a new SPI, and is otherwise included
for the possible benefit of HIP-aware middleboxes. The LOCATOR_SET for the possible benefit of HIP-aware NATs and firewalls. The
parameter contains a complete listing of the locators that the host LOCATOR_SET parameter contains a complete listing of the locators
wishes to make or keep active for the HIP association. that the host wishes to make or keep active for the HIP association.
In general, the processing of a LOCATOR_SET depends upon the packet In general, the processing of a LOCATOR_SET depends upon the packet
type in which it is included. Here, we describe only the case in type in which it is included. Here, we describe only the case in
which ESP_INFO is present and a single LOCATOR_SET and ESP_INFO are which ESP_INFO is present and a single LOCATOR_SET and ESP_INFO are
sent in an UPDATE message; other cases are for further study. The sent in an UPDATE message; other cases are for further study. The
steps below cover each of the cases described in Section 5.2. steps below cover each of the cases described in Section 5.2.
The processing of ESP_INFO and LOCATOR_SET parameters is intended to The processing of ESP_INFO and LOCATOR_SET parameters is intended to
be modular and support future generalization to the inclusion of be modular and support future generalization to the inclusion of
multiple ESP_INFO and/or multiple LOCATOR_SET parameters. A host multiple ESP_INFO and/or multiple LOCATOR_SET parameters. A host
SHOULD first process the ESP_INFO before the LOCATOR_SET, since the SHOULD first process the ESP_INFO before the LOCATOR_SET, since the
ESP_INFO may contain a new SPI value mapped to an existing SPI, while ESP_INFO may contain a new SPI value mapped to an existing SPI, while
a Type "1" locator will only contain a reference to the new SPI. a Type "1" locator will only contain a reference to the new SPI.
When a host receives a validated HIP UPDATE with a LOCATOR_SET and When a host receives a validated HIP UPDATE with a LOCATOR_SET and
ESP_INFO parameter, it processes the ESP_INFO as follows. The ESP_INFO parameter, it processes the ESP_INFO as follows. The
ESP_INFO parameter indicates whether an SA is being rekeyed, created, ESP_INFO parameter indicates whether an SA is being rekeyed, created,
deprecated, or just identified for the benefit of middleboxes. The deprecated, or just identified for the benefit of HIP-aware NATs and
host examines the OLD SPI and NEW SPI values in the ESP_INFO firewalls. The host examines the OLD SPI and NEW SPI values in the
parameter: ESP_INFO parameter:
1. (no rekeying) If the OLD SPI is equal to the NEW SPI and both 1. (no rekeying) If the OLD SPI is equal to the NEW SPI and both
correspond to an existing SPI, the ESP_INFO is gratuitous correspond to an existing SPI, the ESP_INFO is gratuitous
(provided for middleboxes) and no rekeying is necessary. (provided for HIP-aware NATs and firewalls) and no rekeying is
necessary.
2. (rekeying) If the OLD SPI indicates an existing SPI and the NEW 2. (rekeying) If the OLD SPI indicates an existing SPI and the NEW
SPI is a different non-zero value, the existing SA is being SPI is a different non-zero value, the existing SA is being
rekeyed and the host follows HIP ESP rekeying procedures by rekeyed and the host follows HIP ESP rekeying procedures by
creating a new outbound SA with an SPI corresponding to the NEW creating a new outbound SA with an SPI corresponding to the NEW
SPI, with no addresses bound to this SPI. Note that locators in SPI, with no addresses bound to this SPI. Note that locators in
the LOCATOR_SET parameter will reference this new SPI instead of the LOCATOR_SET parameter will reference this new SPI instead of
the old SPI. the old SPI.
3. (new SA) If the OLD SPI value is zero and the NEW SPI is a new 3. (new SA) If the OLD SPI value is zero and the NEW SPI is a new
non-zero value, then a new SA is being requested by the peer. non-zero value, then a new SA is being requested by the peer.
This case is also treated like a rekeying event; the receiving This case is also treated like a rekeying event; the receiving
host must create a new SA and respond with an UPDATE ACK. host MUST create a new SA and respond with an UPDATE ACK.
4. (deprecating the SA) If the OLD SPI indicates an existing SPI and 4. (deprecating the SA) If the OLD SPI indicates an existing SPI and
the NEW SPI is zero, the SA is being deprecated and all locators the NEW SPI is zero, the SA is being deprecated and all locators
uniquely bound to the SPI are put into the DEPRECATED state. uniquely bound to the SPI are put into the DEPRECATED state.
If none of the above cases apply, a protocol error has occurred and If none of the above cases apply, a protocol error has occurred and
the processing of the UPDATE is stopped. the processing of the UPDATE is stopped.
Next, the locators in the LOCATOR_SET parameter are processed. For Next, the locators in the LOCATOR_SET parameter are processed. For
each locator listed in the LOCATOR_SET parameter, check that the each locator listed in the LOCATOR_SET parameter, check that the
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LOCATOR_SET. LOCATOR_SET.
5.4. Verifying Address Reachability 5.4. Verifying Address Reachability
A host MUST verify the reachability of an UNVERIFIED address. The A host MUST verify the reachability of an UNVERIFIED address. The
status of a newly learned address MUST initially be set to UNVERIFIED status of a newly learned address MUST initially be set to UNVERIFIED
unless the new address is advertised in a R1 packet as a new unless the new address is advertised in a R1 packet as a new
Preferred locator. A host MAY also want to verify the reachability Preferred locator. A host MAY also want to verify the reachability
of an ACTIVE address again after some time, in which case it would of an ACTIVE address again after some time, in which case it would
set the status of the address to UNVERIFIED and reinitiate address set the status of the address to UNVERIFIED and reinitiate address
verification. verification. A typical verification that is protected by
retransmission timers is to include an ECHO REQUEST within an UPDATE
sent to the new address.
A host typically starts the address-verification procedure by sending A host typically starts the address-verification procedure by sending
a nonce to the new address. A host MAY choose from different message a nonce to the new address. A host MAY choose from different message
exchanges or different nonce values so long as it establishes that exchanges or different nonce values so long as it establishes that
the peer has received and replied to the nonce at the new address. the peer has received and replied to the nonce at the new address.
For example, when the host is changing its SPI and sending an For example, when the host is changing its SPI and sending an
ESP_INFO to the peer, the NEW SPI value SHOULD be random and the ESP_INFO to the peer, the NEW SPI value SHOULD be random and the
random value MAY be copied into an ECHO_REQUEST sent in the rekeying random value MAY be copied into an ECHO_REQUEST sent in the rekeying
UPDATE. However, if the host is not changing its SPI, it MAY still UPDATE. However, if the host is not changing its SPI, it MAY still
use the ECHO_REQUEST parameter for verification but with some other use the ECHO_REQUEST parameter for verification but with some other
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In some cases, it MAY be sufficient to use the arrival of data on a In some cases, it MAY be sufficient to use the arrival of data on a
newly advertised SA as implicit address reachability verification as newly advertised SA as implicit address reachability verification as
depicted in Figure 7, instead of waiting for the confirmation via a depicted in Figure 7, instead of waiting for the confirmation via a
HIP packet. In this case, a host advertising a new SPI as part of HIP packet. In this case, a host advertising a new SPI as part of
its address reachability check SHOULD be prepared to receive traffic its address reachability check SHOULD be prepared to receive traffic
on the new SA. on the new SA.
Mobile host Peer host Mobile host Peer host
UPDATE(ESP_INFO, LOCATOR_SET, ...)
---------------------------------->
prepare incoming SA prepare incoming SA
NEW SPI in ESP_INFO (UPDATE) UPDATE(ESP_INFO, ...) with new SPI
<----------------------------------- <-----------------------------------
switch to new outgoing SA switch to new outgoing SA
data on new SA data on new SA
-----------------------------------> ----------------------------------->
mark address ACTIVE mark address ACTIVE
UPDATE(ACK, ECHO_RESPONSE) later arrives
----------------------------------->
Figure 7: Address Activation Via Use of a New SA Figure 7: Address Activation Via Use of a New SA
When address verification is in progress for a new Preferred locator, When address verification is in progress for a new Preferred locator,
the host SHOULD select a different locator listed as ACTIVE, if one the host SHOULD select a different locator listed as ACTIVE, if one
such locator is available, to continue communications until address such locator is available, to continue communications until address
verification completes. Alternatively, the host MAY use the new verification completes. Alternatively, the host MAY use the new
Preferred locator while in UNVERIFIED status to the extent Credit- Preferred locator while in UNVERIFIED status to the extent Credit-
Based Authorization permits. Credit-Based Authorization is explained Based Authorization permits. Credit-Based Authorization is explained
in Section 5.6. Once address verification succeeds, the status of in Section 5.6. Once address verification succeeds, the status of
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4. If the new Preferred locator has DEPRECATED status and there is 4. If the new Preferred locator has DEPRECATED status and there is
at least one non-deprecated address, the host selects one of the at least one non-deprecated address, the host selects one of the
non-deprecated addresses as a new Preferred locator and non-deprecated addresses as a new Preferred locator and
continues. If the selected address is UNVERIFIED, the address continues. If the selected address is UNVERIFIED, the address
verification procedure described above will apply. verification procedure described above will apply.
5.6. Credit-Based Authorization 5.6. Credit-Based Authorization
To prevent redirection-based flooding attacks, the use of a Credit- To prevent redirection-based flooding attacks, the use of a Credit-
Based Authorization (CBA) approach MUST be used when a host sends Based Authorization (CBA) approach MUST be used when a host sends
data to an UNVERIFIED locator. The following algorithm meets the data to an UNVERIFIED locator. The following algorithm addresses the
security considerations for prevention of amplification and time- security considerations for prevention of amplification and time-
shifting attacks. Other forms of credit aging, and other values for shifting attacks. Other forms of credit aging, and other values for
the CreditAgingFactor and CreditAgingInterval parameters in the CreditAgingFactor and CreditAgingInterval parameters in
particular, are for further study, and so are the advanced CBA particular, are for further study, and so are the advanced CBA
techniques specified in [CBA-MIPv6]. techniques specified in [CBA-MIPv6].
5.6.1. Handling Payload Packets 5.6.1. Handling Payload Packets
A host maintains a "credit counter" for each of its peers. Whenever A host maintains a "credit counter" for each of its peers. Whenever
a packet arrives from a peer, the host SHOULD increase that peer's a packet arrives from a peer, the host SHOULD increase that peer's
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The HIP mobility mechanism provides a secure means of updating a The HIP mobility mechanism provides a secure means of updating a
host's IP address via HIP UPDATE packets. Upon receipt, a HIP host host's IP address via HIP UPDATE packets. Upon receipt, a HIP host
cryptographically verifies the sender of an UPDATE, so forging or cryptographically verifies the sender of an UPDATE, so forging or
replaying a HIP UPDATE packet is very difficult (see [RFC7401]). replaying a HIP UPDATE packet is very difficult (see [RFC7401]).
Therefore, security issues reside in other attack domains. The two Therefore, security issues reside in other attack domains. The two
we consider are malicious redirection of legitimate connections as we consider are malicious redirection of legitimate connections as
well as redirection-based flooding attacks using this protocol. This well as redirection-based flooding attacks using this protocol. This
can be broken down into the following: can be broken down into the following:
Impersonation attacks 1) Impersonation attacks
- direct conversation with the misled victim - direct conversation with the misled victim
- man-in-the-middle attack - man-in-the-middle attack
DoS attacks 2) DoS attacks
- flooding attacks (== bandwidth-exhaustion attacks) - flooding attacks (== bandwidth-exhaustion attacks)
* tool 1: direct flooding * tool 1: direct flooding
* tool 2: flooding by botnets * tool 2: flooding by botnets
* tool 3: redirection-based flooding * tool 3: redirection-based flooding
- memory-exhaustion attacks - memory-exhaustion attacks
- computational-exhaustion attacks - computational-exhaustion attacks
3) Privacy concerns
We consider these in more detail in the following sections. We consider these in more detail in the following sections.
In Section 6.1 and Section 6.2, we assume that all users are using In Section 6.1 and Section 6.2, we assume that all users are using
HIP. In Section 6.3 we consider the security ramifications when we HIP. In Section 6.3 we consider the security ramifications when we
have both HIP and non-HIP hosts. have both HIP and non-HIP hosts.
6.1. Impersonation Attacks 6.1. Impersonation Attacks
An attacker wishing to impersonate another host will try to mislead An attacker wishing to impersonate another host will try to mislead
its victim into directly communicating with them, or carry out a man- its victim into directly communicating with them, or carry out a man-
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6.2.1. Flooding Attacks 6.2.1. Flooding Attacks
The purpose of a denial-of-service attack is to exhaust some resource The purpose of a denial-of-service attack is to exhaust some resource
of the victim such that the victim ceases to operate correctly. A of the victim such that the victim ceases to operate correctly. A
denial-of-service attack can aim at the victim's network attachment denial-of-service attack can aim at the victim's network attachment
(flooding attack), its memory, or its processing capacity. In a (flooding attack), its memory, or its processing capacity. In a
flooding attack, the attacker causes an excessive number of bogus or flooding attack, the attacker causes an excessive number of bogus or
unwanted packets to be sent to the victim, which fills their unwanted packets to be sent to the victim, which fills their
available bandwidth. Note that the victim does not necessarily need available bandwidth. Note that the victim does not necessarily need
to be a node; it can also be an entire network. The attack basically to be a node; it can also be an entire network. The attack functions
functions the same way in either case. the same way in either case.
An effective DoS strategy is distributed denial of service (DDoS). An effective DoS strategy is distributed denial of service (DDoS).
Here, the attacker conventionally distributes some viral software to Here, the attacker conventionally distributes some viral software to
as many nodes as possible. Under the control of the attacker, the as many nodes as possible. Under the control of the attacker, the
infected nodes (e.g. nodes in a botnet), jointly send packets to the infected nodes (e.g. nodes in a botnet), jointly send packets to the
victim. With such an 'army', an attacker can take down even very victim. With such an 'army', an attacker can take down even very
high bandwidth networks/victims. high bandwidth networks/victims.
With the ability to redirect connections, an attacker could realize a With the ability to redirect connections, an attacker could realize a
DDoS attack without having to distribute viral code. Here, the DDoS attack without having to distribute viral code. Here, the
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4. A HIP host attempts to steal a non-HIP host's session. A HIP 4. A HIP host attempts to steal a non-HIP host's session. A HIP
host could spoof the non-HIP host's IP address during the base host could spoof the non-HIP host's IP address during the base
exchange or set the non-HIP host's IP address as its preferred exchange or set the non-HIP host's IP address as its preferred
address via an UPDATE. Other possibilities exist, but a solution address via an UPDATE. Other possibilities exist, but a solution
is to prevent the local redirection of sessions that were is to prevent the local redirection of sessions that were
previously using an unverified address, but outside of the previously using an unverified address, but outside of the
existing HIP context, into the HIP SAs until the address change existing HIP context, into the HIP SAs until the address change
can be verified. can be verified.
6.4. Privacy Concerns
The exposure of a host's IP addresses through HIP mobility extensions
may raise privacy concerns. The administrator of a host may be
trying to hide its location in some context through the use of a VPN
or other virtual interfaces. Similar privacy issues also arise in
other frameworks such as WebRTC and are not specific to HIP.
Implementations SHOULD provide a mechanism to allow the host
administrator to block the exposure of selected addresses or address
ranges. While this issue may be more relevant in a host multihoming
scenario in which multiple IP addresses might be exposed
([I-D.ietf-hip-multihoming]), it is worth noting also here that
mobility events might cause an implementation to try to inadvertently
use a locator that the adminstrator would rather avoid exposing to
the peer host.
7. IANA Considerations 7. IANA Considerations
RFC5206, obsoleted by this document, specified an allocation for a [RFC5206], obsoleted by this document, specified an allocation for a
LOCATOR parameter in the HIP Parameters registry. This document LOCATOR parameter in the HIP Parameters registry, with a type value
requests IANA to rename the parameter to 'LOCATOR_SET' and to update of 193. This document requests IANA to rename the parameter to
the reference from RFC5206 to this specification. 'LOCATOR_SET' and to update the reference from [RFC5206] to this
specification.
RFC5206, obsoleted by this document, specified an allocation a [RFC5206], obsoleted by this document, specified an allocation a
LOCATOR_TYPE_UNSUPPORTED type in the Notify Message Type registry. LOCATOR_TYPE_UNSUPPORTED type in the Notify Message Type registry,
This document requests IANA to update the reference from RFC5206 to with a type value of 46. This document requests IANA to update the
this specification. reference from [RFC5206] to this specification.
8. Authors and Acknowledgments 8. Differences from RFC 5206
This section summarizes the technical changes made from [RFC5206].
This section is informational, intended to help implementors of the
previous protocol version. If any text in this section contradicts
text in other portions of this specification, the text found outside
of this section should be considered normative.
This document specifies extensions to the HIP Version 2 protocol,
while [RFC5206] specifies extensions to the HIP Version 1 protocol.
[RFC7401] documents the differences between these two protocol
versions.
[RFC5206] included procedures for both HIP host mobility and basic
host multihoming. In this document, only host mobility procedures
are included; host multihoming procedures are now specified in
[I-D.ietf-hip-multihoming]. In particular, multihoming-related
procedures related to the exposure of multiple locators in the base
exchange packets, the transmission, reception, and processing of
multiple locators in a single UPDATE packet, handovers across IP
address families, and other multihoming-related specification has
been removed.
The following additional changes have been made:
o The LOCATOR parameter in [RFC5206] has been renamed to
LOCATOR_SET.
o Specification text regarding the handling of mobility when both
hosts change IP addresses at nearly the same time (a 'double-jump'
mobility scenario) has been added.
o Specification text regarding the mobility event in which the host
briefly has an active new locator and old locator at the same time
(a 'make-before-break' mobility scenario) has been added.
o Specification text has been added to note that a host may add the
source IP address of a received HIP packet as a candidate locator
for the peer even if it is not listed in the peer's LOCATOR_SET,
but that it should prefer locators explicitly listed in the
LOCATOR_SET.
o This document clarifies that the HOST_ID parameter may be included
in UPDATE messages containing LOCATOR_SET parameters, for the
possible benefit of HIP-aware firewalls.
o The previous specification mentioned that it may be possible to
include multiple LOCATOR_SET and ESP_INFO parameters in an UPDATE.
This document only specifies the case of a single LOCATOR_SET and
ESP_INFO parameter in an UPDATE.
o The previous specification mentioned that it may be possible to
send LOCATOR_SET parameters in packets other than the UPDATE.
This document only specifies the use of the UPDATE packet.
o This document describes a simple heuristic for setting the credit
value for Credit-Based Authorization.
o This specification mandates that a host must be able to receive
and avoid reprocessing redundant LOCATOR_SET parameters that may
have been sent in parallel to multiple addresses of the host.
9. Authors and Acknowledgments
Pekka Nikander and Jari Arkko originated this document, and Christian Pekka Nikander and Jari Arkko originated this document, and Christian
Vogt and Thomas Henderson (editor) later joined as co-authors. Greg Vogt and Thomas Henderson (editor) later joined as co-authors. Greg
Perkins contributed the initial draft of the security section. Petri Perkins contributed the initial draft of the security section. Petri
Jokela was a co-author of the initial individual submission. Jokela was a co-author of the initial individual submission.
Credit-Based Authorization was originally introduced in [SIMPLE-CBA], Credit-Based Authorization was originally introduced in [SIMPLE-CBA],
and portions of this document have been adopted from that earlier and portions of this document have been adopted from that earlier
draft. draft.
The authors thank Jeff Ahrenholz, Baris Boyvat, Rene Hummen, Miika The authors thank Jeff Ahrenholz, Baris Boyvat, Rene Hummen, Miika
Komu, Mika Kousa, Jan Melen, and Samu Varjonen for improvements to Komu, Mika Kousa, Jan Melen, and Samu Varjonen for improvements to
the document. the document.
9. References 10. References
9.1. Normative references 10.1. Normative references
[I-D.ietf-hip-rfc5203-bis] [I-D.ietf-hip-rfc5203-bis]
Laganier, J. and L. Eggert, "Host Identity Protocol (HIP) Laganier, J. and L. Eggert, "Host Identity Protocol (HIP)
Registration Extension", draft-ietf-hip-rfc5203-bis-11 Registration Extension", draft-ietf-hip-rfc5203-bis-11
(work in progress), August 2016. (work in progress), August 2016.
[I-D.ietf-hip-rfc5204-bis] [I-D.ietf-hip-rfc5204-bis]
Laganier, J. and L. Eggert, "Host Identity Protocol (HIP) Laganier, J. and L. Eggert, "Host Identity Protocol (HIP)
Rendezvous Extension", draft-ietf-hip-rfc5204-bis-08 (work Rendezvous Extension", draft-ietf-hip-rfc5204-bis-08 (work
in progress), August 2016. in progress), August 2016.
skipping to change at page 31, line 20 skipping to change at page 34, line 5
Henderson, "Host Identity Protocol Version 2 (HIPv2)", Henderson, "Host Identity Protocol Version 2 (HIPv2)",
RFC 7401, DOI 10.17487/RFC7401, April 2015, RFC 7401, DOI 10.17487/RFC7401, April 2015,
<http://www.rfc-editor.org/info/rfc7401>. <http://www.rfc-editor.org/info/rfc7401>.
[RFC7402] Jokela, P., Moskowitz, R., and J. Melen, "Using the [RFC7402] Jokela, P., Moskowitz, R., and J. Melen, "Using the
Encapsulating Security Payload (ESP) Transport Format with Encapsulating Security Payload (ESP) Transport Format with
the Host Identity Protocol (HIP)", RFC 7402, the Host Identity Protocol (HIP)", RFC 7402,
DOI 10.17487/RFC7402, April 2015, DOI 10.17487/RFC7402, April 2015,
<http://www.rfc-editor.org/info/rfc7402>. <http://www.rfc-editor.org/info/rfc7402>.
9.2. Informative references 10.2. Informative references
[CBA-MIPv6] [CBA-MIPv6]
Vogt, C. and J. Arkko, "Credit-Based Authorization for Vogt, C. and J. Arkko, "Credit-Based Authorization for
Mobile IPv6 Early Binding Updates", February 2005. Mobile IPv6 Early Binding Updates", February 2005.
[I-D.ietf-hip-multihoming] [I-D.ietf-hip-multihoming]
Henderson, T., Vogt, C., and J. Arkko, "Host Multihoming Henderson, T., Vogt, C., and J. Arkko, "Host Multihoming
with the Host Identity Protocol", draft-ietf-hip- with the Host Identity Protocol", draft-ietf-hip-
multihoming-10 (work in progress), July 2016. multihoming-11 (work in progress), September 2016.
[RFC4225] Nikander, P., Arkko, J., Aura, T., Montenegro, G., and E. [RFC4225] Nikander, P., Arkko, J., Aura, T., Montenegro, G., and E.
Nordmark, "Mobile IP Version 6 Route Optimization Security Nordmark, "Mobile IP Version 6 Route Optimization Security
Design Background", RFC 4225, DOI 10.17487/RFC4225, Design Background", RFC 4225, DOI 10.17487/RFC4225,
December 2005, <http://www.rfc-editor.org/info/rfc4225>. December 2005, <http://www.rfc-editor.org/info/rfc4225>.
[RFC5206] Nikander, P., Henderson, T., Ed., Vogt, C., and J. Arkko,
"End-Host Mobility and Multihoming with the Host Identity
Protocol", RFC 5206, DOI 10.17487/RFC5206, April 2008,
<http://www.rfc-editor.org/info/rfc5206>.
[RFC5207] Stiemerling, M., Quittek, J., and L. Eggert, "NAT and
Firewall Traversal Issues of Host Identity Protocol (HIP)
Communication", RFC 5207, DOI 10.17487/RFC5207, April
2008, <http://www.rfc-editor.org/info/rfc5207>.
[SIMPLE-CBA] [SIMPLE-CBA]
Vogt, C. and J. Arkko, "Credit-Based Authorization for Vogt, C. and J. Arkko, "Credit-Based Authorization for
Concurrent Reachability Verification", February 2006. Concurrent Reachability Verification", February 2006.
Appendix A. Document Revision History Appendix A. Document Revision History
To be removed upon publication To be removed upon publication
+----------+--------------------------------------------------------+ +----------+--------------------------------------------------------+
| Revision | Comments | | Revision | Comments |
skipping to change at page 33, line 19 skipping to change at page 36, line 19
| | parameters in packets other than UPDATE (per previous | | | parameters in packets other than UPDATE (per previous |
| | mailing list discussion) | | | mailing list discussion) |
| | | | | |
| draft-11 | Editorial improvements from WGLC | | draft-11 | Editorial improvements from WGLC |
| | | | | |
| draft-12 | Update author affiliations and IPR boilerplate to | | draft-12 | Update author affiliations and IPR boilerplate to |
| | trust200902 | | | trust200902 |
| | | | | |
| draft-13 | Editorial improvements to IANA considerations section. | | draft-13 | Editorial improvements to IANA considerations section. |
| | | | | |
| | Moved citation of [SIMPLE-CBA] to Section 8 and | | | Moved citation of [SIMPLE-CBA] to Section 9 and |
| | slightly updated text for redirection-based flooding | | | slightly updated text for redirection-based flooding |
| | attacks in the Security Considerations section. | | | attacks in the Security Considerations section. |
| | | | | |
| | Editorial improvements based on last call comments. | | | Editorial improvements based on last call comments. |
| | |
| draft-14 | Added section to summarize changes from RFC5206. |
| | |
| | Replace references to 'middleboxes' with more specific |
| | 'NATs and firewalls'. |
| | |
| | Describe a simple heuristic for setting the credit |
| | value based on sending rate and RTT. |
| | |
| | Add subsection about privacy concerns of locator |
| | exposure to the Security Considerations section. |
| | |
| | Clarify that a host must be able to receive and avoid |
| | reprocessing redundant LOCATOR_SET parameters that may |
| | have been sent in parallel to multiple addresses of |
| | the host. |
| | |
| | Clarify that multicast or broadcast addresses must not |
| | be announced in a LOCATOR_SET. |
| | |
| | Editorial improvements based on last call comments. |
+----------+--------------------------------------------------------+ +----------+--------------------------------------------------------+
Authors' Addresses Authors' Addresses
Thomas R. Henderson (editor) Thomas R. Henderson (editor)
University of Washington University of Washington
Campus Box 352500 Campus Box 352500
Seattle, WA Seattle, WA
USA USA
EMail: tomhend@u.washington.edu EMail: tomhend@u.washington.edu
Christian Vogt Christian Vogt
Independent Independent
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