draft-ietf-hip-dns-00.txt   draft-ietf-hip-dns-01.txt 
HIP Working Group P. Nikander HIP Working Group P. Nikander
Internet-Draft Ericsson Research Nomadic Lab Internet-Draft Ericsson Research Nomadic Lab
Expires: April 18, 2005 J. Laganier Expires: August 21, 2005 J. Laganier
LIP / Sun Microsystems LIP / Sun Microsystems
October 18, 2004 February 20, 2005
Host Identity Protocol (HIP) Domain Name System (DNS) Extensions Host Identity Protocol (HIP) Domain Name System (DNS) Extensions
draft-ietf-hip-dns-00 draft-ietf-hip-dns-01
Status of this Memo Status of this Memo
This document is an Internet-Draft and is subject to all provisions This document is an Internet-Draft and is subject to all provisions
of section 3 of RFC 3667. By submitting this Internet-Draft, each of section 3 of RFC 3667. By submitting this Internet-Draft, each
author represents that any applicable patent or other IPR claims of author represents that any applicable patent or other IPR claims of
which he or she is aware have been or will be disclosed, and any of which he or she is aware have been or will be disclosed, and any of
which he or she become aware will be disclosed, in accordance with which he or she become aware will be disclosed, in accordance with
RFC 3668. RFC 3668.
skipping to change at page 1, line 37 skipping to change at page 1, line 37
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 April 18, 2005. This Internet-Draft will expire on August 21, 2005.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2004). Copyright (C) The Internet Society (2005).
Abstract Abstract
This document specifies two new resource records for the Domain Name This document specifies two new resource records (RRs) for the Domain
System (DNS), and how to use them with the Host Identity Protocol Name System (DNS), and how to use them with the Host Identity
(HIP). These records allow a HIP node to store in the DNS its Host Protocol (HIP). These RRs allow a HIP node to store in the DNS its
Identity (its public key), Host Identity Tag (a truncated hash of its Host Identity (HI, the public component of the node public-private
public key), and Rendezvous Servers (RVS). key pair), Host Identity Tag (HIT, a truncated hash of its public
key), and the Domain Name or IP addresses of its Rendezvous Servers
(RVS).
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 5 2. Conventions used in this document . . . . . . . . . . . . . . 5
3. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Usage Scenarios . . . . . . . . . . . . . . . . . . . . . . . 6
3.1 Simple static singly homed end-host . . . . . . . . . . . 7 3.1 Simple static singly homed end-host . . . . . . . . . . . 7
3.2 Mobile end-host . . . . . . . . . . . . . . . . . . . . . 7 3.2 Mobile end-host . . . . . . . . . . . . . . . . . . . . . 8
3.3 Multi-homed Site or End-host . . . . . . . . . . . . . . . 7 3.3 Mixed Scenario . . . . . . . . . . . . . . . . . . . . . . 9
4. Overview of using the DNS with HIP . . . . . . . . . . . . . . 8 4. Overview of using the DNS with HIP . . . . . . . . . . . . . . 10
4.1 Different types of HITs . . . . . . . . . . . . . . . . . 8 4.1 Storing HI and HIT in DNS . . . . . . . . . . . . . . . . 10
4.1.1 Host Assigning Authority (HAA) field . . . . . . . . . 8 4.1.1 Different types of HITs . . . . . . . . . . . . . . . 10
4.2 Storing HI and HIT in DNS . . . . . . . . . . . . . . . . 8 4.2 Storing Rendezvous Servers in the DNS . . . . . . . . . . 11
4.3 Storing HAA in DNS . . . . . . . . . . . . . . . . . . . . 8 4.3 Initiating connections based on DNS names . . . . . . . . 11
4.4 Providing multiple IP addresses . . . . . . . . . . . . . 9 5. Storage Format . . . . . . . . . . . . . . . . . . . . . . . . 12
4.4.1 Storing Rendezvous Servers in the DNS . . . . . . . . 9 5.1 HIPHI RDATA format . . . . . . . . . . . . . . . . . . . . 12
4.5 Initiating connections based on DNS names . . . . . . . . 9 5.1.1 HIT type format . . . . . . . . . . . . . . . . . . . 12
4.6 HI and HIT verification . . . . . . . . . . . . . . . . . 9 5.1.2 HIT algorithm format . . . . . . . . . . . . . . . . . 12
5. Storage Format . . . . . . . . . . . . . . . . . . . . . . . . 10 5.1.3 PK algorithm format . . . . . . . . . . . . . . . . . 12
5.1 HIPHI RDATA format . . . . . . . . . . . . . . . . . . . . 10 5.1.4 HIT format . . . . . . . . . . . . . . . . . . . . . . 13
5.1.1 HIT type format . . . . . . . . . . . . . . . . . . . 10 5.1.5 Public key format . . . . . . . . . . . . . . . . . . 13
5.1.2 HIT algorithm format . . . . . . . . . . . . . . . . . 10 5.2 HIPRVS RDATA format . . . . . . . . . . . . . . . . . . . 13
5.1.3 PK algorithm type format . . . . . . . . . . . . . . . 10 5.2.1 Preference format . . . . . . . . . . . . . . . . . . 14
5.1.4 HIT format . . . . . . . . . . . . . . . . . . . . . . 11 5.2.2 Rendezvous server type format . . . . . . . . . . . . 14
5.1.5 Public key format . . . . . . . . . . . . . . . . . . 11 5.2.3 Rendezvous server format . . . . . . . . . . . . . . . 14
5.2 HIPRVS RDATA format . . . . . . . . . . . . . . . . . . . 11 6. Presentation Format . . . . . . . . . . . . . . . . . . . . . 16
5.2.1 Preference format . . . . . . . . . . . . . . . . . . 12 6.1 HIPHI Representation . . . . . . . . . . . . . . . . . . . 16
5.2.2 Rendezvous server type format . . . . . . . . . . . . 12 6.2 HIPRVS Representation . . . . . . . . . . . . . . . . . . 16
5.2.3 Rendezvous server format . . . . . . . . . . . . . . . 12 6.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . . 17
6. Transition mechanisms . . . . . . . . . . . . . . . . . . . . 14 7. Retrieving Multiple HITs and IPs from the DNS . . . . . . . . 18
7. Security Considerations . . . . . . . . . . . . . . . . . . . 15 8. Transition mechanisms . . . . . . . . . . . . . . . . . . . . 19
7.1 Attacker tampering with an unsecure HIPHI RR . . . . . . . 15 9. Security Considerations . . . . . . . . . . . . . . . . . . . 20
7.2 Attacker tampering with an unsecure HIPRVS RR . . . . . . 15 9.1 Attacker tampering with an unsecure HIPHI RR . . . . . . . 20
7.3 Opportunistic HIP . . . . . . . . . . . . . . . . . . . . 16 9.2 Attacker tampering with an unsecure HIPRVS RR . . . . . . 20
7.4 Anonymous Initiator . . . . . . . . . . . . . . . . . . . 16 9.3 Opportunistic HIP . . . . . . . . . . . . . . . . . . . . 21
7.5 Hash and HITs Collisions . . . . . . . . . . . . . . . . . 16 9.4 Unpublished Initiator HI . . . . . . . . . . . . . . . . . 21
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 9.5 Hash and HITs Collisions . . . . . . . . . . . . . . . . . 21
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . 22
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 23
10.1 Normative references . . . . . . . . . . . . . . . . . . . . 19 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 24
10.2 Informative references . . . . . . . . . . . . . . . . . . . 20 12.1 Normative references . . . . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 20 12.2 Informative references . . . . . . . . . . . . . . . . . . . 25
A. Using multiple HIs with multiple IPs . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 25
B. Document Revision History . . . . . . . . . . . . . . . . . . 23 A. Document Revision History . . . . . . . . . . . . . . . . . . 26
Intellectual Property and Copyright Statements . . . . . . . . 24 Intellectual Property and Copyright Statements . . . . . . . . 27
1. Introduction 1. Introduction
This document specifies two new resource records (RRs) for the Domain This document specifies two new resource records (RRs) for the Domain
Name System (DNS) [7], and how to use them with the Host Identity Name System (DNS) [1], and how to use them with the Host Identity
Protocol (HIP) [9]. These records allow a HIP node to store in the Protocol (HIP) [10]. These RRs allow a HIP node to store in the DNS
DNS its Host Identity (its public key), Host Identity Tag (a its Host Identity (HI, the public component of the node
truncated hash of its public key), and Rendezvous Servers (RVS) [12]. public-private key pair), Host Identity Tag (HIT, a truncated hash of
its HI), and the Domain Name or IP addresses of its Rendezvous
Servers (RVS) [13].
The current Internet architecture defines two global namespaces: IP The current Internet architecture defines two global namespaces: IP
addresses and domain names. The Domain Name System provides a two addresses and domain names. The Domain Name System provides a two
way lookup between these two namespaces. The HIP architecture [10] way lookup between these two namespaces. The HIP architecture [11]
defines a new third namespace, called the Host Identity Namespace. defines a new third namespace, called the Host Identity Namespace.
This namespace is composed of Host Identifiers (HI) of HIP nodes. This namespace is composed of Host Identifiers (HI) of HIP nodes.
The Host Identity Tag (HIT) is one representation of an HI. This The Host Identity Tag (HIT) is one representation of an HI. This
representation is obtained by taking the output of a secure hash representation is obtained by taking the output of a secure hash
function applied to the HI, truncated to the IPv6 address size. HITs function applied to the HI, truncated to the IPv6 address size. HITs
are supposed to be used in the place of IP addresses in some ULPs and are supposed to be used in the place of IP addresses within most ULPs
applications. and applications.
The Host Identity Protocol [9] allows two HIP nodes to establish a +-----+ +-----+
pair of unidirectional IPsec Security Association. These SAs are | |-------I1------>| |
bound to the HI instead of IP addresses. The proposed HIP | I |<------R1-------| R |
multi-homing mechanisms [11] allow a node to dynamically change its | |-------I2------>| |
set of underlying IP addresses while maintaining IPsec SA and | |<------R2-------| |
transport layer session survivability. The HIP rendezvous extensions +-----+ +-----+
[12] proposal allows a HIP node to maintain HIP reachability while
not relying on dynamic DNS updates to make its peers aware of its The Host Identity Protocol [10] allows two HIP nodes to establish
current location (the set of IP address(es)). together a HIP Association. A HIP association is bound to the nodes
HIs rather than to their IP address(es).
Although a HIP node can initiate HIP communication Although a HIP node can initiate HIP communication
"opportunistically" (without a priori knowledge of its peer's HI), "opportunistically", i.e., without a priori knowledge of its peer's
doing so exposes both endpoints to Man-in-the-Middle attacks on the HI, doing so exposes both endpoints to Man-in-the-Middle attacks on
HIP handshake. Hence, there is a desire to gain knowledge of peers' the HIP handshake and its cryptographic protocol. Hence, there is a
HI before applications and ULPs initiate communication. desire to gain knowledge of peers' HI before applications and ULPs
initiate communication. Because many applications use the Domain
Name System [1] to name nodes, DNSSEC [3] is a straightforward way to
provision nodes with the HIP informations (i.e. HI and possibly RVS)
of nodes named in the DNS tree, without introducing or relying on an
additional piece of infrastructure.
+-----+
+--I1--->| RVS |---I1--+
| +-----+ |
| v
+-----+ +-----+
| |<------R1-------| |
| I |-------I2------>| R |
| |<------R2-------| |
+-----+ +-----+
The proposed HIP multi-homing mechanisms [12] allow a node to
dynamically change its set of underlying IP addresses while
maintaining IPsec SA and transport layer session survivability. The
HIP rendezvous extensions [13] proposal allows a HIP node to maintain
HIP reachability while it is changing its current location (the node
IP address(es)). This rendezvous service is provided by a third
party, the node's Rendezvous Server (RVS). An initiator (I) willing
to establish a HIP association with a responder (R) would typically
initiate a HIP exchange by sending an I1 towards the RVS IP address
rather than towards the responder IP address. Then, the RVS,
noticing that the receiver HIT is not its own, but the HIT of a HIP
node registered for the rendezvous Service, would relay the I1 to the
responder. Typically the responder would then complete the exchange
without further assistance from the RVS by sending an R1 directly to
the initiator IP address.
Currently, most of the Internet applications that need to communicate Currently, most of the Internet applications that need to communicate
with a remote host first translate a domain name (often obtained via with a remote host first translate a domain name (often obtained via
user input) into one or more IP address(es). This step occurs prior user input) into one or more IP address(es). This step occurs prior
to communication with the remote host, and relies on a DNS lookup. to communication with the remote host, and relies on a DNS lookup.
With HIP, IP addresses are expected to be used mostly for on-the-wire With HIP, IP addresses are expected to be used mostly for on-the-wire
communication between end hosts, while most ULPs and applications communication between end hosts, while most ULPs and applications
uses HIs or HITs instead (ICMP might be an example of an ULP not uses HIs or HITs instead (ICMP might be an example of an ULP not
using them). Consequently, we need a means to translate a domain using them). Consequently, we need a means to translate a domain
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IPv6-compatible LSIs) into IP addresses and vice versa. IPv6-compatible LSIs) into IP addresses and vice versa.
This draft introduces the following new DNS Resource Records: This draft introduces the following new DNS Resource Records:
- HIPHI, for storing Host Identifiers and Host Identity Tags - HIPHI, for storing Host Identifiers and Host Identity Tags
- HIPRVS, for storing rendezvous server information - HIPRVS, for storing rendezvous server information
2. Conventions used in this document 2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119 [2]. document are to be interpreted as described in RFC2119 [4].
3. Use cases 3. Usage Scenarios
In this section, we briefly introduce a number of use cases where the In this section, we briefly introduce a number of usage scenarios
DNS is useful with the Host Identity Protocol. where the DNS is useful with the Host Identity Protocol.
With HIP, most application and ULPs are unaware of the IP addresses With HIP, most application and ULPs are unaware of the IP addresses
used to carry packets on the wire. Consequently, a HIP node could used to carry packets on the wire. Consequently, a HIP node could
take advantage of having multiple IP addresses for fail-over, take advantage of having multiple IP addresses for fail-over,
redundancy, mobility, or renumbering, in a manner which is redundancy, mobility, or renumbering, in a manner which is
transparent to most ULPs and applications (because they are bound to transparent to most ULPs and applications (because they are bound to
HIs, hence they are agnostic to these IP address changes). HIs, hence they are agnostic to these IP address changes).
In these situations, a node wishing to be reachable by reference to In these situations, a node wishing to be reachable by reference to
its FQDN should store the following informations in the DNS: its FQDN should store the following informations in the DNS:
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architecture introduces Rendezvous Servers (RVS). A HIP host uses a architecture introduces Rendezvous Servers (RVS). A HIP host uses a
Rendezvous Server as a Rendezvous point, to maintain reachability Rendezvous Server as a Rendezvous point, to maintain reachability
with possible HIP initiators. Such a HIP node would publish in the with possible HIP initiators. Such a HIP node would publish in the
DNS its RVS IP address or DNS name in a HIPRVS RR, while keeping its DNS its RVS IP address or DNS name in a HIPRVS RR, while keeping its
RVS up-to-date with its current set of IP addresses. RVS up-to-date with its current set of IP addresses.
Then, when some other node wants to initiate a HIP exchange with such Then, when some other node wants to initiate a HIP exchange with such
a responder, it retrieves the RVS IP address by looking up a HIPRVS a responder, it retrieves the RVS IP address by looking up a HIPRVS
RR at the FQDN of the responder, and sends an I1 to this IP address. RR at the FQDN of the responder, and sends an I1 to this IP address.
The I1 will then be relayed by the RVS to the responder, which will The I1 will then be relayed by the RVS to the responder, which will
then complete the HIP exchange, either directly or via the RVS [12]. then complete the HIP exchange, either directly or via the RVS [13].
Note that storing HIP RR information in the DNS at a FQDN which is Note that storing HIP RR information in the DNS at a FQDN which is
assigned to a non-HIP node might have ill effects on its reachability assigned to a non-HIP node might have ill effects on its reachability
by HIP nodes. by HIP nodes.
3.1 Simple static singly homed end-host 3.1 Simple static singly homed end-host
A HIP node having a single static network attachment, wishing to be [A? HIPRVS? HIPHI?]
reachable by reference to its FQDN, would store in the DNS, in [www.example.com ] +-----+
addition to its IP address(es), its Host Identity (HI) in a HIPHI +-------------------------------->| |
resource record. | | DNS |
| +-------------------------------| |
| | [A? HIPRVS? HIPHI? ] +-----+
| | [www.example.com ]
| | [A IP-R ]
| | [HIPHI 10 3 2 HIT-R HI-R]
| v
+-----+ +-----+
| |--------------I1------------->| |
| I |<-------------R1--------------| R |
| |--------------I2------------->| |
| |<-------------R2--------------| |
+-----+ +-----+
A HIP node (R) with a single static network attachment, wishing to be
reachable by reference to its FQDN (www.example.com), would store in
the DNS, in addition to its IP address(es) (IP-R), its Host Identity
(HI-R) in a HIPHI resource record.
3.2 Mobile end-host 3.2 Mobile end-host
A mobile HIP node wishing to be reachable by reference to its FQDN [A? HIPRVS? HIPHI?]
would store in the DNS, instead of its IP address(es), its HI in a [www.example.com ] +-----+
HIPHI RR, and the IP address(es) of its Rendezvous Server(s) in +--------------------------------->| |
HIPRVS resource record(s). The mobile HIP node also need to notify | | DNS |
its Rendezvous Servers of any change in its set of IP address(es). | +--------------------------------| |
| | [A? HIPRVS? HIPHI? ] +-----+
| | [www.example.com ]
| | [HIPRVS 1 2 IP-RVS ]
| | [HIPHI 10 3 2 HIT-R HI-R]
| |
| | +-----+
| | +------I1----->| RVS |-----I1------+
| | | +-----+ |
| | | |
| | | |
| v | v
+-----+ +-----+
| |<---------------R1------------| |
| I |----------------I2----------->| R |
| |<---------------R2------------| |
+-----+ +-----+
A mobile HIP node (R) wishing to be reachable by reference to its
FQDN (www.example.com) would store in the DNS, possibly in addition
to its IP address(es) (IP-R), its HI (HI-R) in a HIPHI RR, and the IP
address(es) of its Rendezvous Server(s) (IP-RVS) in HIPRVS resource
record(s). The mobile HIP node also need to notify its Rendezvous
Servers of any change in its set of IP address(es).
A host wanting to reach this mobile host would then send an I1 to one A host wanting to reach this mobile host would then send an I1 to one
of its RVS. Following, the RVS will relay the I1 up to the mobile of its RVS. Following, the RVS will relay the I1 up to the mobile
node, which will complete the HIP exchange. node, which will complete the HIP exchange.
3.3 Multi-homed Site or End-host 3.3 Mixed Scenario
A HIP node with several distinct network attachments is multi-homed. [A? HIPRVS? HIPHI?]
A HIP node attached to a network with multiple ISPs is in a [www.example.com ] +-----+
multi-homed site will possibly have multiple prefixes and addresses. +--------------------------------->| |
Such HIP node might also be reachable via several distinct Rendezvous | | DNS |
Servers. In addition to its set of IP address(es), a multi-homed | +--------------------------------| |
end-host would store in the DNS its HI in a HIPHI RR, and possibly | | [A? HIPRVS? HIPHI? ] +-----+
the IP address(es) of its RVS(s) in HIPRVS RRs. | | [www.example.com ]
| | [A IP-R1 ]
| | [A IP-R2 ]
| | [HIPRVS 1 2 IP-RVS1 ]
| | [HIPRVS 1 2 IP-RVS2 ]
| | [HIPHI 10 3 2 HIT-R HI-R]
| |
| | +------+
| | +-----I1----->| RVS1 |------I1------+
| | | +------+ |
| v | v
+-----+ +-----+
| |---------------I1------------->| |
| | | |
| I |<--------------R1--------------| R |
| |---------------I2------------->| |
| |<--------------R2--------------| |
+-----+ +-----+
| ^
| +------+ |
+-----I1----->| RVS2 |------I1------+
+------+
A HIP node might be configured with more than one IP address
(multi-homed), or Rendezvous Server (multi-reachable). In these
cases, it is possible that the DNS returns multiples A or AAAA RRs,
as well as HIPRVS containing one or multiple Rendezvous Servers. In
addition to its set of IP address(es) (IP-R1, IP-R2), a multi-homed
end-host would store in the DNS its HI (HI-R) in a HIPHI RR, and
possibly the IP address(es) of its RVS(s) (IP-RVS1, IP-RVS2) in
HIPRVS RRs.
4. Overview of using the DNS with HIP 4. Overview of using the DNS with HIP
4.1 Different types of HITs 4.1 Storing HI and HIT in DNS
Any conforming implementation may store Host Identifiers in a DNS
HIPHI RDATA format. An implementation may also store a HIT along
with its associated HI. If a particular form of an HI or HIT does
not already have a specified RDATA format, a new RDATA-like format
SHOULD be defined for the HI or HIT.
4.1.1 Different types of HITs
There are _currently_ two types of HITs. HITs of the first type There are _currently_ two types of HITs. HITs of the first type
consists just of the least significant bits of the hash of the public consists just of the least significant bits of the hash of the public
key. HITs of the second type consist of a binary prefix Host key. HITs of the second type consist of a binary prefix Host
Assigning Authority (HAA) field, and only the last bits come from a Assigning Authority (HAA) field, and only the last bits come from a
hash of the Host Identity. This latter format for HIT is recommended hash of the Host Identity. This latter format for HIT is recommended
for 'well known' systems. It is possible to support a resolution for 'well known' systems. It is possible to support a resolution
mechanism for these names in directories like DNS. mechanism for these names in directories like DNS.
Note that the format how HITs are stored in the DNS may be different Note that the format how HITs are stored in the DNS may be different
form the format actually used in protocols, the HIP base exchange [9] form the format actually used in protocols, the HIP base exchange
included. This is because the DNS RR explicitly contains the HIT [10] included. This is because the DNS RR explicitly contains the
type and algorithm, while some protocols may prefer to use a prefix HIT type and algorithm, while some protocols may prefer to use a
to indicate the HIT type. The implementations are expected to use prefix to indicate the HIT type. The implementations are expected to
the actual HI when comparing Host Identities. use the actual HI when comparing Host Identities.
4.1.1 Host Assigning Authority (HAA) field 4.1.1.1 Host Assigning Authority (HAA) field
The 64 bits of HAA supports two levels of delegation. The first is a The 64 bits of HAA supports two levels of delegation. The first is a
registered assigning authority (RAA). The second is a registered registered assigning authority (RAA). The second is a registered
identity (RI, commonly a company). The RAA is 24 bits with values identity (RI, commonly a company). The RAA is 24 bits with values
assign sequentially by ICANN. The RI is 40 bits, also assigned assign sequentially by ICANN. The RI is 40 bits, also assigned
sequentially but by the RAA. sequentially but by the RAA.
As IPv6 "global site-local" addresses were proposed in the IPv6 WG to 4.1.1.2 Storing HAA in DNS
replace IPv6 site-local address, it is questionable if HIP needs a
kind of "global site-local" HAA, which would be generated by a given
site by setting the RAA field to 0 while the RI field is filled by
either random or EUI-48 bits.
4.2 Storing HI and HIT in DNS
Any conforming implementation may store Host Identifiers in a DNS
HIPHI RDATA format. An implementation may also store a HIT along
with its associated HI. If a particular form of an HI or HIT does
not already have a specified RDATA format, a new RDATA-like format
SHOULD be defined for the HI or HIT.
4.3 Storing HAA in DNS
Any conforming implementation may store a site's Host Assigning Any conforming implementation may store a domain name Host Assigning
Authority in a DNS HIPHI RDATA format. A HAA MUST be stored Authority (HAA) in a DNS HIPHI RDATA format. A HAA MUST be stored
similarly to a Type 2 HIT, while the least significant bits are set like a Type 2 HIT, while the least significant bits of the HIT
to 0. If a particular form of a HAA does not already have an extracted from the HI hash output are set to zero, the Host Identity
associated HIT specified RDATA format, a new RDATA-like format SHOULD Length is set zero, and the Host Identity field is omitted. If a
be defined for the HIT/HAA. particular form of a HAA does not already have an associated HIT
specified RDATA format, a new RDATA-like format SHOULD be defined for
the HIT/HAA.
4.4 Providing multiple IP addresses 4.1.1.3 HI and HIT verification
With HIP, ULPs doesn't see which IP address is indeed used to carry Upon return of a HIPHI RR, a host MUST always calculate the
packets on the wire. Consequently, a HIP node could take advantage HI-derivative HIT to be used in the HIP exchange, as specified in the
of having multiple IP addresses for ULPs and applications fail over, HIP architecture [11], while the HIT possibly embedded along SHOULD
redundancy, etc. This can be achieved either by storing multiple only be used as an optimization (e.g. table lookup).
addresses in the DNS, while these addresses might be those of
different IP interfaces or Rendezvous servers.
4.4.1 Storing Rendezvous Servers in the DNS 4.2 Storing Rendezvous Servers in the DNS
The HIP Rendezvous server (HIPRVS) resource record indicates an The HIP Rendezvous server (HIPRVS) resource record indicates an
address (or a FQDN resolvable into an address) towards which a HIP I1 address or a domain name of a RendezVous Server, towards which a HIP
packet might be sent to trigger the establishment of an association I1 packet might be sent to trigger the establishment of an
with the entity named by this resource record. association with the entity named by this resource record [13].
An RVS receiving such an I1 would then forward it to the appropriate An RVS receiving such an I1 would then relay it to the appropriate
responder (the owner of the destination HIT in this I1). The responder (the owner of the I1 receiver HIT). The responder will
responder will then complete the exchange with the initiator, then complete the exchange with the initiator, typically without
possibly without ongoing help from the RVS. ongoing help from the RVS.
Any conforming implementation may store Rendezvous Server's IP Any conforming implementation may store Rendezvous Server's IP
address(es) or DNS name in a DNS HIPRVS RDATA format. If a address(es) or DNS name in a DNS HIPRVS RDATA format. If a
particular form of a RVS reference does not already have a specified particular form of a RVS reference does not already have a specified
RDATA format, a new RDATA-like format SHOULD be defined for the RVS. RDATA format, a new RDATA-like format SHOULD be defined for the RVS.
4.5 Initiating connections based on DNS names 4.3 Initiating connections based on DNS names
A Host Identity Protocol exchange SHOULD be initiated whenever the
DNS lookup returns HIPHI resource records. Furthermore, if the DNS
lookups also returns HIPRVS resource records, the addresses of these
RVS SHOULD be put in the destination IP addresses list while
initiating the afore mentioned HIP exchange. Since some hosts may
choose not to have HIPHI information in DNS, hosts MAY implement
support opportunistic HIP.
4.6 HI and HIT verification
Upon return of a HIPHI RR, a host MUST always calculate the On a HIP node, a Host Identity Protocol exchange SHOULD be initiated
HI-derivative HIT to be used in the HIP exchange, as specified in the whenever an Upper Layer Protocol attempt to communicate with an
HIP architecture [10], while the HIT possibly embedded along SHOULD entity and the DNS lookup returns HIPHI and/or HIPRVS resource
only be used as an optimization (e.g., table lookup). records. If a DNS lookup returns one or more HIPRVS RRs and no A nor
AAAA RRs, the afore mentioned HIP exchange SHOULD be initiated
towards one of these RVS [10]. Since some hosts may choose not to
have HIPHI information in DNS, hosts MAY implement support for
opportunistic HIP.
5. Storage Format 5. Storage Format
5.1 HIPHI RDATA format 5.1 HIPHI RDATA format
The RDATA for a HIPHI RR consists of a HIT type, an algorithm type, a The RDATA for a HIPHI RR consists of a HIT type, an algorithm type, a
HIT, and a public key. HIT, and a public key.
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
skipping to change at page 10, line 31 skipping to change at page 12, line 31
/ / / /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
5.1.1 HIT type format 5.1.1 HIT type format
The HIT type field indicates the Host Identity Tag (HIT) type and the The HIT type field indicates the Host Identity Tag (HIT) type and the
implied HIT format. implied HIT format.
The following values are defined: The following values are defined:
0 No HIT is present. 0 No HIT is present
1 A Type 1 HIT is present. 1 A Type 1 HIT is present
2 A Type 2 HIT is present. 2 A Type 2 HIT is present
3-6 Unassigned 3-6 Unassigned
7 A HAA is present. 7 A HAA is present
5.1.2 HIT algorithm format 5.1.2 HIT algorithm format
The HIT algorithm indicates the hash algorithm used to generate the The HIT algorithm indicates the hash algorithm used to generate the
Host Identity Tag (HIT) from the HI. Host Identity Tag (HIT) from the HI.
The following values are defined: The following values are defined:
0 Reserved. 0 Reserved
1 SHA1 1 SHA1
2-255 Unassigned 2-255 Unassigned
5.1.3 PK algorithm type format 5.1.3 PK algorithm format
The algorithm type indicates the public key cryptographic algorithm The PK algorithm field indicates the public key cryptographic
and the implied public key field format. This document reuse the algorithm and the implied public key field format. This document
values defined for the 'algorithm type' of the IPSECKEY RR [13] reuse the values defined for the 'algorithm type' of the IPSECKEY RR
'gateway type' field. [14] 'gateway type' field.
The presently defined values are given only informally: The presently defined values are given only informally:
0 No key is present. 1 A DSA key is present, in the format defined in RFC2536 [5].
1 A DSA key is present, in the format defined in RFC2536 [3]. 2 A RSA key is present, in the format defined in RFC3110 [6].
2 A RSA key is present, in the format defined in RFC3110 [5].
5.1.4 HIT format 5.1.4 HIT format
There's currently two types of HITs, and a single type of HAA. Both There's currently two types of HITs, and a single type of HAA. Both
of them have a variable length and are stored within a single of them are stored in network byte order within a self-describing
<character-string> holding the bits of the HITs or HAA: variable length wire-encoded <character-string> (as per Section 3.3
of [2]):
o A *Type 1* HIT: least significant bits of the hash (e.g., SHA1) of o A *Type 1* HIT: least significant bits of the hash (e.g., SHA1) of
the public key (Host Identity), which is possibly following in the the public key (Host Identity), which is possibly following in the
HIPHI RR. HIPHI RR.
o A *Type 2* HIT: binary prefix (HAA) concatenated with a the least o A *Type 2* HIT: binary prefix (HAA) concatenated with a the least
significant bits of the hash (e.g., SHA1) of the public key (Host significant bits of the hash (e.g., SHA1) of the public key (Host
Identity), which is possibly following in the HIPHI RR. Identity), which is possibly following in the HIPHI RR.
o A HAA: binary prefix (HAA) concatenated with 0, up to the o A HAA: binary prefix (HAA) concatenated with 0, up to the
associated HIT length. associated HIT length.
5.1.5 Public key format 5.1.5 Public key format
Both of the public key types defined in this document (RSA and DSA) Both of the public key types defined in this document (RSA and DSA)
reuse the public key formats defined for the IPSECKEY RR [13] (which reuse the public key formats defined for the IPSECKEY RR [14] (which
in turns contains the algorithm-specific portion of the KEY RR RDATA, in turns contains the algorithm-specific portion of the KEY RR RDATA,
all of the KEY RR DATA after the first four octets, corresponding to all of the KEY RR DATA after the first four octets, corresponding to
the same portion of the KEY RR that must be specified by documents the same portion of the KEY RR that must be specified by documents
that define a DNSSEC algorithm). that define a DNSSEC algorithm).
In the future, if a new algorithm is to be used both by IPSECKEY RR In the future, if a new algorithm is to be used both by IPSECKEY RR
and HIPHI RR, it would probably use the same public key encodings for and HIPHI RR, it would probably use the same public key encodings for
both RRs. Unless specified otherwise, the HIPHI public key field both RRs. Unless specified otherwise, the HIPHI public key field
would use the same public key format as the IPSECKEY RR RDATA for the would use the same public key format as the IPSECKEY RR RDATA for the
corresponding algorithm. corresponding algorithm.
The DSA key format is defined in RFC2536 [3]. The DSA key format is defined in RFC2536 [5].
The RSA key format is defined in RFC3110 [5]. The RSA key format is defined in RFC3110 [6] and the RSA key size
limit (4096 bits) is relaxed in the IPSECKEY RR [14] specification.
5.2 HIPRVS RDATA format 5.2 HIPRVS RDATA format
The RDATA for a HIPRVS RR consists of a preference value, a The RDATA for a HIPRVS RR consists of a preference value, a
Rendezvous server type and either one or more Rendezvous server Rendezvous server type and either one or more Rendezvous server
address, or one Rendezvous server FQDN. address, or one Rendezvous server domain name.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| preference | type | | | preference | type | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Rendezvous server | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Rendezvous server |
~ ~ ~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5.2.1 Preference format 5.2.1 Preference format
This is an 8-bit preference order for this record. This used to This is an unsigned 8-bit value, used to specify the preference given
specify the preference given to this RR amongst others at the same to this RR amongst others at the same owner. Lower values are
owner. Lower values are preferred. If there is a tie with some RRs, preferred. If there is a tie within some RR subset, the server
the server should return a set of RRs ordered in a load balancing should return a permutation (e.g. round robin) of the set of RRs,
manner (e.g., round robin). such that the requester load is fairly balanced amongst all RRs of
the set.
5.2.2 Rendezvous server type format 5.2.2 Rendezvous server type format
The Rendezvous server type indicates the format of the information The Rendezvous server type indicates the format of the information
stored in the Rendezvous server field. stored in the Rendezvous server field.
This document reuses the type values for the 'gateway type' field of This document reuses the type values for the 'gateway type' field of
the IPSECKEY RR [13]. The presently defined values are given only the IPSECKEY RR [14]. The presently defined values are given only
informally: informally:
0 Reserved. 1. One or more 4-byte IPv4 address(es) in network byte order are
1 One or more 4-byte IPv4 address(es) in network byte order are
present. present.
2 One or more 16-byte IPv6 address(es) in network byte order are 2. One or more 16-byte IPv6 address(es) in network byte order are
present. present.
3 One or more variable length wire-encoded domain names as 3. One or more variable length wire-encoded domain names as
described in section 3.3 of RFC1035 [1]. The wire-encoded format described in section 3.3 of RFC1035 [2]. The wire-encoded format
is self-describing, so the length is implicit. The domain names is self-describing, so the length is implicit. The domain names
MUST NOT be compressed. MUST NOT be compressed.
5.2.3 Rendezvous server format 5.2.3 Rendezvous server format
The Rendezvous server field indicates one or more address(es) (or one The Rendezvous server field indicates one or more Rendezvous
or more FQDN(s) resolvable into one or more address(es)) towards Server(s) IP address(es), or domain name(s). A HIP I1 packet sent to
which a HIP I1 packet might be send in order to reach the entity any of these RVS would reach the entity named by this resource
named by this resource record. record.
This document reuses the format used for the 'gateway' field of the This document reuses the format used for the 'gateway' field of the
IPSECKEY RR [13], but allows to concatenate several IP (v4 or v6) IPSECKEY RR [14], but allows to concatenate several IP (v4 or v6)
addresses. The presently defined formats for the data portion of the addresses. The presently defined formats for the data portion of the
Rendezvous server field are given only informally: Rendezvous server field are given only informally:
o One or more 32-bit IPv4 address(es) in network byte order. o One or more 32-bit IPv4 address(es) in network byte order.
o One or more 128-bit IPv6 address(es) in network byte order. o One or more 128-bit IPv6 address(es) in network byte order.
o One or more variable length wire-encoded domain names as described o One or more variable length wire-encoded domain names as described
in section 3.3 of RFC1035 [1]. The wire-encoded format is in section 3.3 of RFC1035 [2]. The wire-encoded format is
self-describing, so the length is implicit. The domain names MUST self-describing, so the length is implicit. The domain names MUST
NOT be compressed. NOT be compressed.
6. Transition mechanisms 6. Presentation Format
During a transition period, instead of storing the HI or HIT in a This section specifies the representation of the HIPHI and HIPRVS RR
HIPHI RR, the HIT MAY be stored in an AAAA RR. If a HIT is stored in in a zone data master file.
an AAAA RR, it MUST be returned as the last item in the set of AAAA
RRs returned to avoid as most as possible conflicts with non-HIP IPv6
nodes.
During a transition period, similarly to what may happen with HITs, 6.1 HIPHI Representation
the RVS's IP address might be stored in an A or AAAA RR instead of a
HIPRVS RR. If a RVS IP address is stored in an A or AAAA RR, it MUST
be returned as the last item in the set of returned RRs to avoid as
most as possible conflicts with non-HIP IPv6 nodes.
7. Security Considerations The HIT Type, HIT algorithm, PK algorithm, and Public Key are
REQUIRED. The HIT field is OPTIONAL.
The HIT Type, HIT algorithm, and PK algorithm are represented as
unsigned integers.
The HIT field is represented as the Base16 encoding [8] (a.k.a. hex
or hexadecimal) of the public key. If no HIT is to be indicated,
then the HIT algorithm MUST be zero and the HIT field must be ".".
The Public Key field is represented as the Base64 encoding [8] of the
public key.
The complete representation of the HPIHI record is:
IN HIPHI ( hit-type hit-algorithm pk-algorithm
base16-encoded-hit
base64-encoded-public-key )
6.2 HIPRVS Representation
The Preference and RVS Type fields are REQUIRED. At least one RVS
field MUST be present.
The HIT Type, HIT algorithm, and PK algorithm are represented as
unsigned integers.
The RVS field is represented by one or more:
o IPv4 dotted decimal address(es)
o IPv6 colon hex address(es)
o uncompressed domain name(s)
The complete representation of the HPIRVS record is:
IN HIPRVS ( preference rendezvous-server-type
rendezvous-server[1]
...
rendezvous-server[n] )
6.3 Examples
Example of a node with a HI but no HIT:
www.example.com IN HIPHI ( 0 1 2
.
AB3NzaC1kc3MAAACBAOBhKnTCPOuFBzZQX/N3O9dm9P9ivUIMoId== )
Example of a node with a HI and a HIT:
www.example.com IN HIPHI ( 1 1 2
120cf10ea842e0ba53320f1fe0ba5d3a3
AB3NzaC1kc3MAAACBAOBhKnTCPOuFBzZQX/N3O9dm9P9ivUIMoId== )
Example of a node with an IPv6 RVS:
www.example.com IN HIPRVS ( 10 2 2001:0db8:0200:1:20c:f1ff:fe0b:a533 )
Example of a node with three IPv4 RVS:
www.example.com IN HIPRVS ( 10 1 192.0.2.2 192.0.99.2 192.0.199.2)
Example of a node with two named RVS:
www.example.com IN HIPRVS ( 10 3 rvs.uk.example.com rvs.us.example.com )
7. Retrieving Multiple HITs and IPs from the DNS
If a host receives multiple HITs in a response to a DNS query, those
HITs MUST be considered to denote a single service, and be
semantically equivalent from that point of view. When initiating a
base exchange with the denoted service, the host SHOULD be prepared
to accept any of HITs as the peer's identity. A host MAY implement
this by using the opportunistic mode (destination HIT null in I1), or
by sending multiple I1s, if needed.
In particular, if a host receives multiple HITs and multiple IP
addresses in response to a DNS query, the host cannot know how the
HITs are reachable at the listed IP addresses. The mapping may be
any, i.e., all HITs may be reachable at all of the listed IP
addresses, some of the HITs may be reachable at some of the IP
addresses, or there may even be one-to-one mapping between the HITs
and IP addresses. In general, the host cannot know the mapping and
MUST NOT expect any particular mapping.
It is RECOMMENDED that if a host receives multiple HITs, the host
SHOULD first try to initiate the base exchange by using the
opportunistic mode. If the returned HIT does not match with any of
the expected HITs, the host SHOULD retry by sending further I1s, one
at time, trying out all of the listed HITs. If the host receives an
R1 for any of the I1s, the host SHOULD continue to use the successful
IP address until an R1 with a listed HIT is received, or the host has
tried all HITs, and try the other IP addresses only after that. A
host MAY also send multiple I1s in parallel, but sending such I1s
MUST be rate limited to avoid flooding (as per Section 8.4.1 of
[10]).
8. Transition mechanisms
During a transition period, to allows to store the HIP informations
of a node in a DNS server which does not support the HIPHI and HIPRVS
RRs, A and AAAA RRs MAY be overloaded. A HIT would typically be
stored in a AAAA RR and a RVS in either a A or AAAA RR. If such a
situation occurs, the overloaded RRs MUST be returned as the last
items of the returned RRs set (A or AAAA), to avoid as most as
possible conflicts with non-HIP IPv6 nodes.
9. Security Considerations
Though the security considerations of the HIP DNS extensions still Though the security considerations of the HIP DNS extensions still
need to be more investigated and documented, this section contains a need to be more investigated and documented, this section contains a
description of the known threats involved with the usage of the HIP description of the known threats involved with the usage of the HIP
DNS extensions. DNS extensions.
In a manner similar to the IPSECKEY RR [13], the HIP DNS Extensions In a manner similar to the IPSECKEY RR [14], the HIP DNS Extensions
allows to provision two HIP nodes with the public keying material allows to provision two HIP nodes with the public keying material
(HI) of their peer. These HIs will be subsequently used in a key (HI) of their peer. These HIs will be subsequently used in a key
exchange between the peers. Hence, the HIP DNS Extensions introduce exchange between the peers. Hence, the HIP DNS Extensions introduce
the same kind of threats that IPSECKEY does, plus threats caused by the same kind of threats that IPSECKEY does, plus threats caused by
the possibility of using unpublished initiator and opportunistic mode the possibility given to a HIP node to initiate or accept a HIP
in HIP. exchange using "Opportunistic" or "Unpublished Initiator HI" modes.
A HIP node SHOULD obtain both the HIPHI and HIPRVS RRs from a trusted A HIP node SHOULD obtain both the HIPHI and HIPRVS RRs from a trusted
party trough a secure channel insuring proper data integrity of the party trough a secure channel insuring proper data integrity of the
RRs. This might be DNSSEC, or another secure channel to another RRs. DNSSEC [3] provides such a secure channel.
directory lookup service.
In the absence of a proper secure channel, both parties are In the absence of a proper secure channel, both parties are
vulnerable to MitM and DoS attacks, and unrelated parties might be vulnerable to MitM and DoS attacks, and unrelated parties might be
subject to DoS attacks as well. These threats are described in the subject to DoS attacks as well. These threats are described in the
following sections. following sections.
7.1 Attacker tampering with an unsecure HIPHI RR 9.1 Attacker tampering with an unsecure HIPHI RR
The HIPHI RR contains public keying material in the form of the named The HIPHI RR contains public keying material in the form of the named
peer's public key (the HI) and its secure hash (the HIT). Both of peer's public key (the HI) and its secure hash (the HIT). Both of
these are not sensitive to attacks where an adversary gains knowledge these are not sensitive to attacks where an adversary gains knowledge
of them. However, an attacker that is able to mount an active attack of them. However, an attacker that is able to mount an active attack
on the DNS, i.e., tampers with this HIPHI RR (e.g., using DNS on the DNS, i.e., tampers with this HIPHI RR (e.g., using DNS
spoofing) is able to mount Man-in-the-Middle attacks on the spoofing) is able to mount Man-in-the-Middle attacks on the
cryptographic core of the eventual HIP exchange (responder's HIPHI cryptographic core of the eventual HIP exchange (responder's HIPHI
and HIPRVS rewritten by the attacker). and HIPRVS rewritten by the attacker).
7.2 Attacker tampering with an unsecure HIPRVS RR 9.2 Attacker tampering with an unsecure HIPRVS RR
The HIPRVS RR contains a destination IP address where the named peer The HIPRVS RR contains a destination IP address where the named peer
is reachable by an I1 (HIP Rendezvous Extensions IPSECKEY RR [12] ). is reachable by an I1 (HIP Rendezvous Extensions IPSECKEY RR [13] ).
Thus, an attacker able to tamper with this RRs is able to redirect I1 Thus, an attacker able to tamper with this RRs is able to redirect I1
packets sent to the named peer to a chosen IP address, for DoS or packets sent to the named peer to a chosen IP address, for DoS or
MitM attacks. Note that this kind of attacks are not specific to HIP MitM attacks. Note that this kind of attacks are not specific to HIP
and exist independently to whether or not HIP and the HIPRVS RR are and exist independently to whether or not HIP and the HIPRVS RR are
used. Such an attacker might tamper with A and AAAA RRs as well. used. Such an attacker might tamper with A and AAAA RRs as well.
An attacker might obviously use these two attacks in conjunction: It An attacker might obviously use these two attacks in conjunction: It
will replace the responder's HI and RVS IP address by its owns in a will replace the responder's HI and RVS IP address by its owns in a
spoofed DNS packet sent to the initiator HI, then redirect all spoofed DNS packet sent to the initiator HI, then redirect all
exchanged packets through him and mount a MitM on HIP. In this case exchanged packets through him and mount a MitM on HIP. In this case
HIP won't provide confidentiality nor initiator HI protection from HIP won't provide confidentiality nor initiator HI protection from
eavesdroppers. eavesdroppers.
7.3 Opportunistic HIP 9.3 Opportunistic HIP
A HIP initiator may not be aware of its peer's HI, and/or its HIT A HIP initiator may not be aware of its peer's HI, and/or its HIT
(e.g., because the DNS does not contains HIP material, or the (e.g., because the DNS does not contains HIP material, or the
resolver isn't HIP-enabled), and attempt an opportunistic HIP resolver isn't HIP-enabled), and attempt an opportunistic HIP
exchange towards its known IP address, filling the responder HIT exchange towards its known IP address, filling the responder HIT
field with zeros in the I1 header. Such an initiator is vulnerable field with zeros in the I1 header. Such an initiator is vulnerable
to a MitM attack because it can't validate the HI and HIT contained to a MitM attack because it can't validate the HI and HIT contained
in a replied R1. Hence, an implementation MAY choose not to use in a replied R1. Hence, an implementation MAY choose not to use
opportunistic mode. opportunistic mode.
7.4 Anonymous Initiator 9.4 Unpublished Initiator HI
A HIP initiator may choose to use an unpublished HI, which is not A HIP initiator may choose to use an unpublished HI, which is not
stored in the DNS by means of a HIPHI RR. A responder associating stored in the DNS by means of a HIPHI RR. A responder associating
with such an initiator knowingly risks a MitM attack because it with such an initiator knowingly risks a MitM attack because it
cannot validate the initiator's HI. Hence, an implementation MAY cannot validate the initiator's HI. Hence, an implementation MAY
choose not to use unpublished mode. choose not to use unpublished mode.
7.5 Hash and HITs Collisions 9.5 Hash and HITs Collisions
As many cryptographic algorithm, some secure hashes (e.g. SHA1, used As many cryptographic algorithm, some secure hashes (e.g. SHA1, used
by HIP to generate a HIT from an HI) eventually become insecure, by HIP to generate a HIT from an HI) eventually become insecure,
because an exploit has been found in which an attacker with a because an exploit has been found in which an attacker with a
reasonable computation power breaks one of the security features of reasonable computation power breaks one of the security features of
the hash (e.g., its supposed collision resistance). This is why a the hash (e.g., its supposed collision resistance). This is why a
HIP end-node implementation SHOULD NOT authenticate its HIP peers HIP end-node implementation SHOULD NOT authenticate its HIP peers
based solely on a HIT retrieved from DNS, but rather use both the HI based solely on a HIT retrieved from DNS, but SHOULD rather use
and HIT. HI-based authentication.
8. IANA Considerations 10. IANA Considerations
IANA needs to allocate two new RR type code for HIPHI and HIPRVS from IANA needs to allocate two new RR type code for HIPHI and HIPRVS from
the standard RR type space. the standard RR type space.
IANA does not need to open a new registry for the HIPHI RR type for
public key algorithms because the HIPHI RR reuse 'algorithms types'
defined for the IPSECKEY RR [13]. The presently defined numbers are
given here only informally:
0 is reserved
1 is RSA
2 is DSA
IANA needs to open a new registry for the HIPHI RR HIT type. Defined IANA needs to open a new registry for the HIPHI RR HIT type. Defined
types are: types are:
0 No HIT is present 0 No HIT is present
1 A Type 1 HIT is present 1 A Type 1 HIT is present
2 A Type 2 HIT is present 2 A Type 2 HIT is present
3-6 Unassigned 3-6 Unassigned
7 A HAA is present 7 A HAA is present
Adding new reservations requires IETF consensus RFC2434 [14]. Adding new reservations requires IETF consensus RFC2434 [16].
IANA needs to open a new registry for the HIPHI RR HIT algorithm IANA needs to open a new registry for the HIPHI RR HIT algorithm.
type. Defined types are: Defined types are:
0 Reserved 0 Reserved
1 SHA1 1 SHA1
2-255 Unassigned 2-255 Unassigned
Adding new reservations requires IETF consensus RFC2434 [14]. Adding new reservations requires IETF consensus RFC2434 [16].
IANA does not need to open a new registry for the HIPHI RR type for
public key algorithms because the HIPHI RR reuse 'algorithms types'
defined for the IPSECKEY RR [14]. The presently defined numbers are
given here only informally:
0 is reserved
1 is RSA
2 is DSA
IANA does not need to open a new registry for the HIPRVS RR IANA does not need to open a new registry for the HIPRVS RR
Rendezvous server type because the HIPHI RR reuse the 'gateway types' Rendezvous server type because the HIPHI RR reuse the 'gateway types'
defined for the IPSECKEY RR [13]. The presently defined numbers are defined for the IPSECKEY RR [14]. The presently defined numbers are
given here only informally: given here only informally:
0 is reserved 0 is reserved
1 is IPv4 1 is IPv4
2 is IPv6 2 is IPv6
3 is a wire-encoded uncompressed domain name 3 is a wire-encoded uncompressed domain name
9. Acknowledgments 11. Acknowledgments
Some parts of this draft stem from [9]. This work is heavily
influenced by [13], which serves as a model for this document.
The authors would like to thanks the following people, who have As usual in the IETF, this document is the result of a collaboration
between many people. The authors would like to thanks the author
(Michael Richardson), contributors and reviewers of the IPSECKEY RR
[14] specification, which this document was framed after. The
authors would also like to thanks the following people, who have
provided thoughtful and helpful discussions and/or suggestions, that provided thoughtful and helpful discussions and/or suggestions, that
have improved this document: Rob Austein, Hannu Flinck, Tom have helped improving this document: Rob Austein, Hannu Flinck, Tom
Henderson, Miika Komu, Andrew McGregor, Erik Nordmark, and Gabriel Henderson, Miika Komu, Andrew McGregor, Erik Nordmark, and Gabriel
Montenegro. Montenegro. Some parts of this draft stem from [10].
10. References 12. References
10.1 Normative references 12.1 Normative references
[1] Mockapetris, P., "Domain names - implementation and [1] Mockapetris, P., "Domain names - concepts and facilities", STD
13, RFC 1034, November 1987.
[2] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987. specification", STD 13, RFC 1035, November 1987.
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement [3] Eastlake, D. and C. Kaufman, "Domain Name System Security
Extensions", RFC 2065, January 1997.
[4] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[3] Eastlake, D., "DSA KEYs and SIGs in the Domain Name System [5] Eastlake, D., "DSA KEYs and SIGs in the Domain Name System
(DNS)", RFC 2536, March 1999. (DNS)", RFC 2536, March 1999.
[4] Crawford, M., "Binary Labels in the Domain Name System", RFC [6] Eastlake, D., "RSA/SHA-1 SIGs and RSA KEYs in the Domain Name
2673, August 1999.
[5] Eastlake, D., "RSA/SHA-1 SIGs and RSA KEYs in the Domain Name
System (DNS)", RFC 3110, May 2001. System (DNS)", RFC 3110, May 2001.
[6] Bush, R., Durand, A., Fink, B., Gudmundsson, O. and T. Hain, [7] Bush, R., Durand, A., Fink, B., Gudmundsson, O. and T. Hain,
"Representing Internet Protocol version 6 (IPv6) Addresses in "Representing Internet Protocol version 6 (IPv6) Addresses in
the Domain Name System (DNS)", RFC 3363, August 2002. the Domain Name System (DNS)", RFC 3363, August 2002.
[7] Klensin, J., "Role of the Domain Name System (DNS)", RFC 3467, [8] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings",
February 2003. RFC 3548, July 2003.
[8] Thomson, S., Huitema, C., Ksinant, V. and M. Souissi, "DNS [9] Thomson, S., Huitema, C., Ksinant, V. and M. Souissi, "DNS
Extensions to Support IP Version 6", RFC 3596, October 2003. Extensions to Support IP Version 6", RFC 3596, October 2003.
[9] Moskowitz, R., Nikander, P. and P. Jokela, "Host Identity [10] Moskowitz, R., Nikander, P. and P. Jokela, "Host Identity
Protocol", draft-ietf-hip-base-01 (work in progress), October Protocol", draft-ietf-hip-base-01 (work in progress), October
2004. 2004.
[10] Moskowitz, R. and P. Nikander, "Host Identity Protocol [11] Moskowitz, R. and P. Nikander, "Host Identity Protocol
Architecture", draft-ietf-hip-arch-00 (work in progress), Architecture", draft-ietf-hip-arch-00 (work in progress),
October 2004. October 2004.
[11] Nikander, P., "End-Host Mobility and Multi-Homing with Host [12] Nikander, P., "End-Host Mobility and Multi-Homing with Host
Identity Protocol", draft-ietf-hip-mm-00 (work in progress), Identity Protocol", draft-ietf-hip-mm-00 (work in progress),
October 2004. October 2004.
[12] Laganier, J. and L. Eggert, "Host Identity Protocol (HIP) [13] Laganier, J. and L. Eggert, "Host Identity Protocol (HIP)
Rendezvous Extensions", draft-ietf-hip-rvs-00 (work in Rendezvous Extensions", draft-ietf-hip-rvs-00 (work in
progress), October 2004. progress), October 2004.
[13] Richardson, M., "A method for storing IPsec keying material in [14] Richardson, M., "A method for storing IPsec keying material in
DNS", draft-ietf-ipseckey-rr-10 (work in progress), April 2004. DNS", draft-ietf-ipseckey-rr-12 (work in progress), January
2005.
10.2 Informative references 12.2 Informative references
[14] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA [15] Jokela, P., Moskowitz, R. and P. Nikander, "Using ESP transport
format with HIP", draft-jokela-hip-esp-00 (work in progress),
February 2005.
[16] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 2434, October Considerations Section in RFCs", BCP 26, RFC 2434, October
1998. 1998.
[15] Rescorla, E. and B. Korver, "Guidelines for Writing RFC Text on
Security Considerations", BCP 72, RFC 3552, July 2003.
Authors' Addresses Authors' Addresses
Pekka Nikander Pekka Nikander
Ericsson Research Nomadic Lab Ericsson Research Nomadic Lab
JORVAS FIN-02420 JORVAS FIN-02420
FINLAND FINLAND
Phone: +358 9 299 1 Phone: +358 9 299 1
EMail: pekka.nikander@nomadiclab.com EMail: pekka.nikander@nomadiclab.com
Julien Laganier Julien Laganier
LIP (CNRS-INRIA-ENSL-UCBL) & Sun Labs (Sun Microsystems) LIP (CNRS-INRIA-ENSL-UCBL) & Sun Labs (Sun Microsystems)
180, Avenue de l'Europe 180, Avenue de l'Europe
Saint Ismier CEDEX 38334 Saint Ismier CEDEX 38334
France France
Phone: +33 476 188 815 Phone: +33 476 188 815
EMail: ju@sun.com EMail: ju@sun.com
Appendix A. Using multiple HIs with multiple IPs Appendix A. Document Revision History
The RRs defined in this document are "flat", in the sense that the IP
addresses and HIs are associated to an FQDN on an equality basis. In
the case where an FQDN is resolved into multiple HIs (HIPHI RRs) and
IP addresses (A, AAAA or HIPRVS RRs), the requester cannot associate
an IP address with a specific HI, nor the opposite.
Considering the following DNS-IP load balancing model: Multiple
initiators are querying a DNS server with A or AAAA RRs at a given
FQDN. The DNS server replies with a round-robin ordered set of IP
addresses, causing each initiator to connect to a different address
(the first address of the set they received from the DNS). This
model can be extended to HIP by having the DNS returning a
round-robin ordered set of HIs and IP addresses. But then the
problem is that the initiator would need to map each of these HIs to
a subset of the returned set of IP addresses. Hence, perhaps there
is a need for having a "hierarchical" model for these RRs, which will
allows to tie an HI to a specific subset of IP addresses, as
illustrated in the figure below:
FQDN
|
+---+---+
| |
V V
FQDN HI1,HI2 HI3
| | |
+---+---+---+---+---+ +-+-+ |
| | | | | | | | |
V V V V V V V V V
IP1 IP2 IP3 HI1 HI2 HI3 IP1 IP2 IP3
'Flat' DNS model Vs. 'Hierarchical' HI model
However, as HIs and Type 1 HITs are not yet resolvable using the DNS,
implementing such a model would certainly prove to be difficult. The
use of Distributed Hash Tables (DHTs) might help to resolve HIs, but
at this point the whole story isn't known. In the absence of HI
resolvability, there is two solutions: index IP addresses and
HIs/HITs used by HIP with a common key (e.g., the IP address, the
HIT, a 8-bit int, etc.), or use a per-HI DNS name, pointed to by the
FQDN global to the set of HIs, and pointing to the HIs, and IP
addresses associated with this particular set of HIs. to map to
specific HIs, in a manner similar to what is done with NS RRs.
In the first solution (indexing), each HIPHI, HIPRVS, and HIPLOC (a
new to-be-defined RR carrying the IP address of a HIP node, to be
used by HIP instead of A and AAAA RRs, if present) would contain an
additional HI index field allowing to link an HI with a subset of IP
addresses and vice versa. This solution is neither space-efficient,
nor it is architecturally clean.
In the second solution (parallel DNS names and bindings), the PTR RR
is used to alias the name of a group of node into multiple FQDNs,
which are then bound to set of HIs and IP addresses, as shown in the
figure below. These additional FQDNs are kind of HIP sub-FQDNs; an
easy way to generate them is to suffix, or prefix the unqualified
name with a sufficient number of bits of the HIT to prevent
collisions local to a FQDN (e.g., foo.bar.com might haves multiple
HIP sub-FQDNs: foo_2fa6.bar.com, foo_8cc4.bar.com, etc.).
FQDN
|
+---+---+
| |
V V
FQDN_1<--FQDN-->FQDN_2 HI1,HI2 HI3
| | | |
+---+---+---+ +-+-+ +-+-+ |
| | | | | | | | |
V V V V V V V V V
HI1 HI2 IP1 IP2 HI3 IP3 IP1 IP2 IP3
The 'Hierarchical' HIP model fitting in a 'Flat' DNS model
The current plan is to use the second solution unless HIP WG members
express desire to have the first solution implemented.
Appendix B. Document Revision History
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
| Revision | Comments | | Revision | Comments |
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
| 00 | Compared to draft-nikander-hip-dns-00: Merge | | 01 | Compared to draft-ietf-hip-dns-01: Removed HIP |
| | multihomed site and end-host use cases. Remove HAA | | | rendezvous registration protocol. Removed references |
| | related text not required for Type 2 HIT definition. | | | to DNS. Added figures. Added text discussing multiple |
| | Remove IPv6 LSIs definitions. Replace fixed length | | | HITs and IP. |
| | and algorithm Type 1 and Type 2 HITs by variable | | | |
| | length, type and algorithm HITs. Remove 'Policy | | 00 | Initial version as a HIP WG item. |
| | Considerations' section. Fill-in 'Security |
| | Considerations' section. Allow for several IP |
| | addresses in the same HIPRVS RR. Reuse the type |
| | values and IANA registries of IPSECKEY RR. Add Annex |
| | discussing alternatives for storing multiple |
| | parallels FQDN-to-HI and HI-to-IP at a single FQDN. |
| | Minor fixes to figures and their descriptive text. |
| | Update references. |
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
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