draft-ietf-hip-dns-03.txt   draft-ietf-hip-dns-04.txt 
Network Working Group P. Nikander Network Working Group P. Nikander
Internet-Draft Ericsson Research Nomadic Lab Internet-Draft Ericsson Research Nomadic Lab
Expires: April 13, 2006 J. Laganier Expires: June 19, 2006 J. Laganier
DoCoMo Euro-Labs DoCoMo Euro-Labs
October 10, 2005 December 16, 2005
Host Identity Protocol (HIP) Domain Name System (DNS) Extensions Host Identity Protocol (HIP) Domain Name System (DNS) Extensions
draft-ietf-hip-dns-03 draft-ietf-hip-dns-04
Status of this Memo Status of this Memo
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This Internet-Draft will expire on April 13, 2006. This Internet-Draft will expire on June 19, 2006.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2005).
Abstract Abstract
This document specifies two new resource records (RRs) for the Domain This document specifies a new resource record (RR) for the Domain
Name System (DNS), and how to use them with the Host Identity Name System (DNS), and how to use it with the Host Identity Protocol
Protocol (HIP). These RRs allow a HIP node to store in the DNS its (HIP.) This RR allows a HIP node to store in the DNS its Host
Host Identity (HI, the public component of the node public-private Identity (HI, the public component of the node public-private key
key pair), Host Identity Tag (HIT, a truncated hash of its public pair), Host Identity Tag (HIT, a truncated hash of its public key),
key), and the Domain Name or IP addresses of its rendezvous servers and the Domain Names of its rendezvous servers (RVS.)
(RVS).
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 6 2. Conventions used in this document . . . . . . . . . . . . . . 4
3. Usage Scenarios . . . . . . . . . . . . . . . . . . . . . . . 7 3. Usage Scenarios . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Simple static singly homed end-host . . . . . . . . . . . 8 3.1. Simple static singly homed end-host . . . . . . . . . . . 6
3.2. Mobile end-host . . . . . . . . . . . . . . . . . . . . . 9 3.2. Mobile end-host . . . . . . . . . . . . . . . . . . . . . 7
3.3. Mixed Scenario . . . . . . . . . . . . . . . . . . . . . . 10 3.3. Mixed Scenario . . . . . . . . . . . . . . . . . . . . . . 8
4. Overview of using the DNS with HIP . . . . . . . . . . . . . . 12 4. Overview of using the DNS with HIP . . . . . . . . . . . . . . 11
4.1. Storing HI and HIT in DNS . . . . . . . . . . . . . . . . 12 4.1. Storing HI, HIT and RVS in DNS . . . . . . . . . . . . . . 11
4.1.1. HI and HIT Verification . . . . . . . . . . . . . . . 12 4.2. Initiating connections based on DNS names . . . . . . . . 11
4.2. Storing Rendezvous Servers in the DNS . . . . . . . . . . 12 5. HIP RR Storage Format . . . . . . . . . . . . . . . . . . . . 12
4.3. Initiating connections based on DNS names . . . . . . . . 12 5.1. HIT length format . . . . . . . . . . . . . . . . . . . . 12
5. Storage Format . . . . . . . . . . . . . . . . . . . . . . . . 13 5.2. PK algorithm format . . . . . . . . . . . . . . . . . . . 12
5.1. HIPHI RDATA format . . . . . . . . . . . . . . . . . . . . 13 5.3. PK length format . . . . . . . . . . . . . . . . . . . . . 13
5.1.1. PK algorithm format . . . . . . . . . . . . . . . . . 13 5.4. HIT format . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1.2. HIT length format . . . . . . . . . . . . . . . . . . 13 5.5. Public key format . . . . . . . . . . . . . . . . . . . . 13
5.1.3. HIT format . . . . . . . . . . . . . . . . . . . . . . 13 5.6. Rendezvous servers format . . . . . . . . . . . . . . . . 13
5.1.4. Public key format . . . . . . . . . . . . . . . . . . 13 6. HIP RR Presentation Format . . . . . . . . . . . . . . . . . . 14
5.2. HIPRVS RDATA format . . . . . . . . . . . . . . . . . . . 14 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.2.1. Preference format . . . . . . . . . . . . . . . . . . 14 8. Security Considerations . . . . . . . . . . . . . . . . . . . 16
5.2.2. Rendezvous server type format . . . . . . . . . . . . 14 8.1. Attacker tampering with an insecure HIP RR . . . . . . . . 16
5.2.3. Rendezvous server format . . . . . . . . . . . . . . . 15 8.2. Hash and HITs Collisions . . . . . . . . . . . . . . . . . 17
6. Presentation Format . . . . . . . . . . . . . . . . . . . . . 16 8.3. DNSSEC . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.1. HIPHI Representation . . . . . . . . . . . . . . . . . . . 16 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
6.2. HIPRVS Representation . . . . . . . . . . . . . . . . . . 16 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
6.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 16 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7. Retrieving Multiple HITs and IPs from the DNS . . . . . . . . 18 11.1. Normative references . . . . . . . . . . . . . . . . . . . 20
8. Security Considerations . . . . . . . . . . . . . . . . . . . 19 11.2. Informative references . . . . . . . . . . . . . . . . . . 21
8.1. Attacker tampering with an insecure HIPHI RR . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
8.2. Attacker tampering with an insecure HIPRVS RR . . . . . . 19 Intellectual Property and Copyright Statements . . . . . . . . . . 23
8.3. Opportunistic HIP . . . . . . . . . . . . . . . . . . . . 20
8.4. Unpublished Initiator HI . . . . . . . . . . . . . . . . . 20
8.5. Hash and HITs Collisions . . . . . . . . . . . . . . . . . 20
8.6. DNSSEC . . . . . . . . . . . . . . . . . . . . . . . . . . 20
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23
11.1. Normative references . . . . . . . . . . . . . . . . . . . 23
11.2. Informative references . . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25
Intellectual Property and Copyright Statements . . . . . . . . . . 26
1. Introduction 1. Introduction
This document specifies two new resource records (RRs) for the Domain This document specifies a new resource record (RR) for the Domain
Name System (DNS) [RFC1034], and how to use them with the Host Name System (DNS) [RFC1034], and how to use it with the Host Identity
Identity Protocol (HIP) [I-D.ietf-hip-base]. These RRs allow a HIP Protocol (HIP) [I-D.ietf-hip-base]. This RR allows a HIP node to
node to store in the DNS its Host Identity (HI, the public component store in the DNS its Host Identity (HI, the public component of the
of the node public-private key pair), Host Identity Tag (HIT, a node public-private key pair), Host Identity Tag (HIT, a truncated
truncated hash of its HI), and the Domain Name or IP addresses of its hash of its HI), and the Domain Names of its rendezvous servers
rendezvous servers (RVS) [I-D.ietf-hip-rvs]. (RVS.) [I-D.ietf-hip-rvs]
The current Internet architecture defines two global namespaces: IP
addresses and domain names. The Domain Name System provides a two
way lookup between these two namespaces. The HIP architecture
[I-D.ietf-hip-arch] defines a new third namespace, called the Host
Identity Namespace. This namespace is composed of Host Identifiers
(HI) of HIP nodes. The Host Identity Tag (HIT) is one representation
of an HI. This representation is obtained by taking the output of a
secure hash function applied to the HI, truncated to the IPv6 address
size. HITs are supposed to be used in the place of IP addresses
within most ULPs and applications.
The Host Identity Protocol [I-D.ietf-hip-base] allows two HIP nodes
to establish together a HIP Association. A HIP association is bound
to the nodes HIs rather than to their IP address(es).
A HIP node establish a HIP association by initiating a 4 way
handshake where two parties, the initiator and responder, exchange
the I1, I2, R1 and R2 HIP packets (see section 5.3 of [I-D.ietf-hip-
base])
+-----+ +-----+
| |-------I1------>| |
| I |<------R1-------| R |
| |-------I2------>| |
| |<------R2-------| |
+-----+ +-----+
Although a HIP node can initiate HIP communication
"opportunistically", i.e., without prior knowledge of its peer's HI,
doing so exposes both endpoints to Man-in-the-Middle attacks on the
HIP handshake and its cryptographic protocol. Hence, there is a
desire to gain knowledge of peers' HI before applications and ULPs
initiate communication. Because many applications use the Domain
Name System [RFC1034] to name nodes, DNS is a straightforward way to
provision nodes with the HIP information (i.e. HI, HIT and possibly
RVS) of nodes named in the DNS tree, without introducing or relying
on an additional piece of infrastructure. Note that in the absence
of DNSSEC [RFC2065], the DNS name resolution is vulnerable to Man-in-
the-Middle attack (See Section 8), and hence the HIP handshake is
also vulnerable to a Man-in-the-Middle attack.
The proposed HIP multi-homing mechanisms [I-D.ietf-hip-mm] 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 [I-D.ietf-hip-rvs] 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).
+-----+
+--I1--->| RVS |---I1--+
| +-----+ |
| v
+-----+ +-----+
| |<------R1-------| |
| I |-------I2------>| R |
| |<------R2-------| |
+-----+ +-----+
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 intended to be used mostly for on-the-wire
communication between end hosts, while most ULPs and applications use communication between end hosts, while most ULPs and applications use
HIs or HITs instead (ICMP might be an example of an ULP not using HIs or HITs instead (ICMP might be an example of an ULP not using
them). Consequently, we need a means to translate a domain name into them.) Consequently, we need a means to translate a domain name into
an HI. Using the DNS for this translation is pretty straightforward: an HI. Using the DNS for this translation is pretty straightforward:
We define a new HIPHI (HIP HI) resource record. Upon query by an We define a new HIP resource record. Upon query by an application or
application or ULP for a FQDN -> IP lookup, the resolver would then ULP for a FQDN -> IP lookup, the resolver would then additionally
additionally perform an FQDN -> HI lookup, and use it to construct perform an FQDN -> HI lookup, and use it to construct the resulting
the resulting HI -> IP mapping (which is internal to the HIP layer). HI -> IP mapping (which is internal to the HIP layer.) The HIP layer
The HIP layer uses the HI -> IP mapping to translate HIs and their uses the HI -> IP mapping to translate HIs and HITs into IP addresses
local representations (HITs, IPv4 and IPv6-compatible LSIs) into IP and vice versa.
addresses and vice versa.
This draft introduces the following new DNS Resource Records:
- HIPHI, for storing Host Identifiers and Host Identity Tags The HIP rendezvous extensions [I-D.ietf-hip-rvs] proposal allows a
HIP node to be reached via the IP address(es) of a third party, the
node's rendezvous server (RVS.) An initiator willing to establish a
HIP association with a responder served by a RVS would typically
initiate a HIP exchange by sending an I1 towards the RVS IP address
rather than towards the responder IP address. Consequently, we need
a means to translate a domain name into the rendezvous server's
domain name.
- HIPRVS, for storing rendezvous server information This draft introduces the new HIP DNS Resource Record to store
Rendezvous Server (RVS), Host Identity (HI) and Host Identity Tag
(HIT) 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 [RFC2119]. document are to be interpreted as described in RFC2119 [RFC2119].
3. Usage Scenarios 3. Usage Scenarios
In this section, we briefly introduce a number of usage scenarios In this section, we briefly introduce a number of usage scenarios
where the 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 information in the DNS: its FQDN should store the following information in the DNS:
o A set of IP address(es) through A and AAAA RRs. o A set of IP address(es) through A and AAAA RRs.
o A Host Identity (HI) and/or Host Identity Tag (HIT) through HIPHI o A Host Identity (HI), Host Identity Tag (HIT) and possibly a set
RRs. of rendezvous server(s) (RVS) through HIP RRs.
o An IP address or DNS name of its rendezvous server(s) (RVS)
through HIPRVS RRs.
When a HIP node wants to initiate a communication with another HIP When a HIP node wants to initiate a communication with another HIP
node, it first needs to perform a HIP base exchange to set-up a HIP node, it first needs to perform a HIP base exchange to set-up a HIP
association towards its peer. Although such an exchange can be association towards its peer. Although such an exchange can be
initiated opportunistically, i.e., without prior knowledge of the initiated opportunistically, i.e., without prior knowledge of the
responder's HI, by doing so both nodes knowingly risk man-in-the- responder's HI, by doing so both nodes knowingly risk man-in-the-
middle attacks on the HIP exchange. To prevent these attacks, it is middle attacks on the HIP exchange. To prevent these attacks, it is
recommended that the initiator first obtain the HI of the responder, recommended that the initiator first obtain the HI of the responder,
and then initiate the exchange. This can be done, for example, and then initiate the exchange. This can be done, for example,
through manual configuration or DNS lookups. Hence, a new HIPHI RR through manual configuration or DNS lookups. Hence, a new HIP RR is
is introduced. introduced.
When a HIP node is frequently changing its IP address(es), the When a HIP node is frequently changing its IP address(es), the
dynamic DNS update latency may prevent it from publishing its new IP dynamic DNS update latency may prevent it from publishing its new IP
address(es) in the DNS. For solving this problem, the HIP address(es) in the DNS. For solving this problem, the HIP
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 domain name(s) in a HIP RR, while keeping its RVS up-to-
RVS up-to-date with its current set of IP addresses. date with its current set of IP addresses.
When a HIP node wants to initiate a HIP exchange with a responder it When a HIP node wants to initiate a HIP exchange with a responder it
will perform a number of DNS lookups. Depending on the type of the will perform a number of DNS lookups. Depending on the type of the
implementation, the order in which those lookups will be issued may implementation, the order in which those lookups will be issued may
vary. For instance, implementations using IP address in APIs may vary. For instance, implementations using IP address in APIs may
typically first query for A and/or AAAA records at the responder typically first query for A and/or AAAA records at the responder
FQDN, while those using HIT in APIS may typically first query for FQDN, while those using HIT in APIS may typically first query for HIP
HIPHI records. RRs.
In the following we assume that the initiator first queries for A In the following we assume that the initiator first queries for A
and/or AAAA records at the responder FQDN. and/or AAAA records at the responder FQDN.
If the query for the A and/or AAAA was responded to with a DNS answer If the query for the A and/or AAAA was responded to with a DNS answer
with RCODE=3 (Name Error), then the responder's information is not with RCODE=3 (Name Error), then the responder's information is not
present in the DNS and further queries SHOULD NOT be made. present in the DNS and further queries SHOULD NOT be made.
In case the query for the address records returned a DNS answer with In case the query for the address records returned a DNS answer with
RCODE=0 (No Error), then the initiator sends out two queries: One for RCODE=0 (No Error), then the initiator sends out one more query for
the HIPHI type and one for the HIPRVS type at the responder's FQDN. for the HIP type at the responder's FQDN.
Depending on the combinations of answer the situations described in Depending on the combinations of answer the situations described in
Section 3.1, Section 3.2 and Section 3.3 can occur. Section 3.1, Section 3.2 and Section 3.3 can occur.
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 (R) with a single static network attachment, wishing to be 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 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 the DNS, in addition to its IP address(es) (IP-R), its Host Identity
(HI-R) in a HIPHI resource record. (HI-R) and Host Identity Tag (HIT-R) in a HIP resource record.
An initiator willing to associate with a node would typically issue An initiator willing to associate with a node would typically issue
the following queries: the following queries:
QNAME=www.example.com, QTYPE=A QNAME=www.example.com, QTYPE=A
(QCLASS=IN is assumed and omitted from the examples) (QCLASS=IN is assumed and omitted from the examples)
Which returns a DNS packet with RCODE=0 and one or more A RRs A with Which returns a DNS packet with RCODE=0 and one or more A RRs A with
the address of the responder (e.g. IP-R) in the answer section. the address of the responder (e.g. IP-R) in the answer section.
QNAME=www.example.com, QTYPE=HIPHI QNAME=www.example.com, QTYPE=HIP
Which returns a DNS packet with RCODE=0 and one or more HIPHI RRs
with the HIT and HI (e.g. HIT-R and HI-R) of the responder in the
answer section.
QNAME=www.example.com, QTYPE=HIPRVS
Which returns a DNS packet with RCODE=0 and an empty answer section. Which returns a DNS packet with RCODE=0 and one or more HIP RRs with
the HIT and HI (e.g. HIT-R and HI-R) of the responder in the answer
section, but no RVS.
Caption: In the remainder of this document, for the sake of keeping Caption: In the remainder of this document, for the sake of keeping
diagrams simple and concise, several DNS queries and answers diagrams simple and concise, several DNS queries and answers
are represented as one single transaction, while in fact are represented as one single transaction, while in fact
there are several queries and answers flowing back and there are several queries and answers flowing back and
forth, as described in the textual examples. forth, as described in the textual examples.
[A? HIPRVS? HIPHI?] [A? HIP? ]
[www.example.com ] +-----+ [www.example.com ] +-----+
+-------------------------------->| | +-------------------------------->| |
| | DNS | | | DNS |
| +-------------------------------| | | +-------------------------------| |
| | [A? HIPRVS? HIPHI? ] +-----+ | | [A? HIP? ] +-----+
| | [www.example.com ] | | [www.example.com ]
| | [A IP-R ] | | [A IP-R ]
| | [HIPHI 10 3 2 HIT-R HI-R] | | [HIP HIT-R HI-R ]
| v | v
+-----+ +-----+ +-----+ +-----+
| |--------------I1------------->| | | |--------------I1------------->| |
| I |<-------------R1--------------| R | | I |<-------------R1--------------| R |
| |--------------I2------------->| | | |--------------I2------------->| |
| |<-------------R2--------------| | | |<-------------R2--------------| |
+-----+ +-----+ +-----+ +-----+
The initiator would then send an I1 to the responder's IP addresses
(IP-R.)
3.2. Mobile end-host 3.2. Mobile end-host
A mobile HIP node (R) wishing to be reachable by reference to its 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 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 to its IP address(es) (IP-R), its HI (HI-R), HIT (HIT-R) and the
address(es) of its rendezvous server(s) (IP-RVS) in HIPRVS resource domain name(s) of its rendezvous server(s) (rvs.example.com) in HIP
record(s). The mobile HIP node also needs to notify its rendezvous resource record(s). The mobile HIP node also needs to notify its
servers of any change in its set of IP address(es). rendezvous servers of any change in its set of IP address(es).
An initiator willing to associate with such mobile node would An initiator willing to associate with such mobile node would
typically issue the following queries: typically issue the following queries:
QNAME=www.example.com, QTYPE=A QNAME=www.example.com, QTYPE=A
Which returns a DNS packet with RCODE=0 and an empty answer section. Which returns a DNS packet with RCODE=0 and an empty answer section.
QNAME=www.example.com, QTYPE=HIPHI QNAME=www.example.com, QTYPE=HIP
Which returns a DNS packet with RCODE=0 and one or more HIPHI RRs Which returns a DNS packet with RCODE=0 and one or more HIP RRs with
with the HIT and HI (e.g. HIT-R and HI-R) of the responder in the the HIT, HI and RVS domain name(s) (e.g. HIT-R, HI-R, and
answer section. rvs.example.com) of the responder in the answer section.
QNAME=www.example.com, QTYPE=HIPRVS QNAME=rvs.example.com, QTYPE=A
Which returns a DNS packet with RCODE=0 and one or more HIPRVS RRs
containing IP address(es) (e.g. IP-RVS) or FQDN(s) of RVS(s).
[A? HIPRVS? HIPHI?] [A? HIP? ]
[www.example.com ] +-----+ [www.example.com]
+--------------------------------->| |
[A? ]
[RVS.example.com] +-----+
+----------------------------------------->| |
| | DNS | | | DNS |
| +--------------------------------| | | +----------------------------------------| |
| | [A? HIPRVS? HIPHI? ] +-----+ | | [A? HIP? ] +-----+
| | [www.example.com ] | | [www.example.com ]
| | [HIPRVS 1 2 IP-RVS ] | | [HIP HIT-R HI-R rvs.example.com]
| | [HIPHI 10 3 2 HIT-R HI-R] | |
| | [A? ]
| | [rvs.example.com]
| | [A IP-RVS ]
| | | |
| | +-----+ | | +-----+
| | +------I1----->| RVS |-----I1------+ | | +------I1----->| RVS |-----I1------+
| | | +-----+ | | | | +-----+ |
| | | | | | | |
| | | | | | | |
| v | v | v | v
+-----+ +-----+ +-----+ +-----+
| |<---------------R1------------| | | |<---------------R1------------| |
| I |----------------I2----------->| R | | I |----------------I2----------->| R |
| |<---------------R2------------| | | |<---------------R2------------| |
+-----+ +-----+ +-----+ +-----+
The initiator would then send an I1 to one of its RVS. Following, The initiator would then send an I1 to the RVS IP address (IP-RVS.)
the RVS will relay the I1 up to the mobile node, which will complete Following, the RVS will relay the I1 up to the mobile node's IP
the HIP exchange. address (IP-R), which will complete the HIP exchange.
3.3. Mixed Scenario 3.3. Mixed Scenario
A HIP node might be configured with more than one IP address (multi- A HIP node might be configured with more than one IP address (multi-
homed), or rendezvous server (multi-reachable). In these cases, it homed), or rendezvous server (multi-reachable.) In these cases, it
is possible that the DNS returns multiple A or AAAA RRs, as well as is possible that the DNS returns multiple A or AAAA RRs, as well as
HIPRVS containing one or multiple rendezvous servers. In addition to HIP RRs containing one or multiple rendezvous servers. In addition
its set of IP address(es) (IP-R1, IP-R2), a multi-homed end-host 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 would store in the DNS its HI (HI-R), HIT (HIT-R) and domain name(s)
IP address(es) of its RVS(s) (IP-RVS1, IP-RVS2) in HIPRVS RRs. of its RVS(s) (rvs.example.com) in HIP RRs.
An initiator willing to associate with such a node would typically An initiator willing to associate with such mobile node would
issue the following queries: typically issue the following queries:
QNAME=www.example.com, QTYPE=A QNAME=www.example.com, QTYPE=A
Which returns a DNS packet with RCODE=0 and one or more A or AAAA RRs Which returns a DNS packet with RCODE=0 and one or more A or AAAA RRs
containing IP address(es) (e.g. IP-R1 and IP-R2) in the answer containing IP address(es) (e.g. IP-R1 and IP-R2) in the answer
section. section.
QNAME=www.example.com, QTYPE=HIPHI QNAME=www.example.com, QTYPE=HIP
Which returns a DNS packet with RCODE=0 and one or more HIPHI RRs Which returns a DNS packet with RCODE=0 and one or more HIP RRs with
with the HIT and HI (e.g. HIT-R and HI-R) of the responder in the the HIT, HI and RVS domain name(s) (e.g. HIT-R, HI-R, and
answer section. rvs.example.com) of the responder in the answer section.
QNAME=www.example.com, QTYPE=HIPRVS QNAME=rvs.example.com, QTYPE=A
Which returns a DNS packet with RCODE=0 and one or more HIPRVS RRs [A? HIP? ]
containing IP address(es) (e.g. IP-RVS1, IP-RVS2) or FQDN(s) of [www.example.com]
RVS(s).
[A? HIPRVS? HIPHI?] [A? ]
[www.example.com ] +-----+ [RVS.example.com] +-----+
+--------------------------------->| | +----------------------------------------->| |
| | DNS | | | DNS |
| +--------------------------------| | | +----------------------------------------| |
| | [A? HIPRVS? HIPHI? ] +-----+ | | [A? HIP? ] +-----+
| | [www.example.com ] | | [www.example.com ]
| | [A IP-R1 ] | | [A IP-R ]
| | [A IP-R2 ] | | [HIP HIT-R HI-R rvs.example.com]
| | [HIPRVS 1 2 IP-RVS1 ]
| | [HIPRVS 1 2 IP-RVS2 ]
| | [HIPHI 10 3 2 HIT-R HI-R]
| | | |
| | +------+ | | [A? ]
| | +-----I1----->| RVS1 |------I1------+ | | [rvs.example.com]
| | | +------+ | | | [A IP-RVS ]
| |
| | +-----+
| | +------I1----->| RVS |-----I1------+
| | | +-----+ |
| | | |
| | | |
| v | v | v | v
+-----+ +-----+ +-----+ +-----+
| |---------------I1------------->| | | |----------------I1----------->| |
| | | | | |<---------------R1------------| |
| I |<--------------R1--------------| R | | I |----------------I2----------->| R |
| |---------------I2------------->| | | |<---------------R2------------| |
| |<--------------R2--------------| |
+-----+ +-----+ +-----+ +-----+
| ^ The initiator would then typically send the same I1 to both the RVS
| +------+ | and the responder's IP addresses (IP-RVS and IP-R.)
+-----I1----->| RVS2 |------I1------+
+------+
4. Overview of using the DNS with HIP 4. Overview of using the DNS with HIP
4.1. Storing HI and HIT in DNS 4.1. Storing HI, HIT and RVS in DNS
Any conforming implementation may store a Host Identity (HI) and its Any conforming implementation may store a Host Identity (HI) and its
associated Host Identity Tag (HIT) in a DNS HIPHI RDATA format. If a associated Host Identity Tag (HIT) in a DNS HIP RDATA format. If a
particular form of an HI does not already have a specified RDATA particular form of an HI does not already have a specified RDATA
format, a new RDATA-like format SHOULD be defined for the HI. HI and format, a new RDATA-like format SHOULD be defined for the HI. HI and
HIT are defined in Section 3 of [I-D.ietf-hip-base]. HIT are defined in Section 3 of [I-D.ietf-hip-base].
4.1.1. HI and HIT Verification Upon return of a HIP RR, a host MUST always calculate the HI-
Upon return of a HIPHI RR, a host MUST always calculate the HI-
derivative HIT to be used in the HIP exchange, as specified in derivative HIT to be used in the HIP exchange, as specified in
Section 3 of the HIP base specification [I-D.ietf-hip-base], while Section 3 of the HIP base specification [I-D.ietf-hip-base], while
the HIT possibly embedded along SHOULD only be used as an the HIT possibly embedded along SHOULD only be used as an
optimization (e.g. table lookup). optimization (e.g. table lookup.)
4.2. Storing Rendezvous Servers in the DNS
The HIP rendezvous server (HIPRVS) resource record indicates an The HIP resource record may also contains one or more domain name(s)
address or a domain name of a rendezvous Server, towards which a HIP of rendezvous server(s) towards which HIP I1 packets might be sent to
I1 packet might be sent to trigger the establishment of an trigger the establishment of an association with the entity named by
association with the entity named by this resource record [I-D.ietf- this resource record [I-D.ietf-hip-rvs].
hip-rvs].
An RVS receiving such an I1 would then relay it to the appropriate An RVS receiving such an I1 would then relay it to the appropriate
responder (the owner of the I1 receiver HIT). The responder will responder (the owner of the I1 receiver HIT.) The responder will
then complete the exchange with the initiator, typically without then complete the exchange with the initiator, typically without
ongoing help from the RVS. ongoing help from the RVS.
Any conforming implementation may store rendezvous server's IP 4.2. Initiating connections based on DNS names
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
RDATA format, a new RDATA-like format SHOULD be defined for the RVS.
4.3. Initiating connections based on DNS names
On a HIP node, a Host Identity Protocol exchange SHOULD be initiated On a HIP node, a Host Identity Protocol exchange SHOULD be initiated
whenever an Upper Layer Protocol attempt to communicate with an whenever an Upper Layer Protocol attempt to communicate with an
entity and the DNS lookup returns HIPHI and/or HIPRVS resource entity and the DNS lookup returns HIP resource records.
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 [I-D.ietf-hip-base]. Since some hosts may
choose not to have HIPHI information in DNS, hosts MAY implement
support for opportunistic HIP.
5. Storage Format
5.1. HIPHI RDATA format 5. HIP RR Storage Format
The RDATA for a HIPHI RR consists of a public key algorithm type, the The RDATA for a HIP RR consists of a public key algorithm type, the
HIT length, a HIT, and a public key. HIT length, a HIT, a public key, and optionnally one or more
rendezvous server(s).
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PK algorithm | HIT length | | | HIT length | PK algorithm | PK length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ HIT | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
~ HIT ~
| |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |
+-+-+-+-+-+-+-+-+-+-+-+ +
| Public Key |
~ ~ ~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |
| / + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Public Key / | | |
/ / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| | |
~ Rendezvous Servers ~
| |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+
The PK algorithm, HIT length, HIT and Public Key field are REQUIRED. The HIT length, PK algorithm, PK length, HIT and Public Key field are
REQUIRED. The Rendezvous Servers field is OPTIONAL.
5.1.1. PK algorithm format 5.1. HIT length format
The HIT length indicates the length in bytes of the HIT field.
5.2. PK algorithm format
The PK algorithm field indicates the public key cryptographic The PK algorithm field indicates the public key cryptographic
algorithm and the implied public key field format. This document algorithm and the implied public key field format. This document
reuse the values defined for the 'algorithm type' of the IPSECKEY RR reuses the values defined for the 'algorithm type' of the IPSECKEY RR
[RFC4025] 'gateway type' field. [RFC4025] 'gateway type' field.
The presently defined values are given only informally: The presently defined values are shown here for reference:
1 A DSA key is present, in the format defined in RFC2536 1 A DSA key is present, in the format defined in RFC2536
[RFC2536]. [RFC2536].
2 A RSA key is present, in the format defined in RFC3110 2 A RSA key is present, in the format defined in RFC3110
[RFC3110]. [RFC3110].
5.1.2. HIT length format 5.3. PK length format
The HIT length indicates the length in bytes of the HIT field. The PK length indicates the length in bytes of the Public key field.
5.1.3. HIT format 5.4. HIT format
The HIT is stored, as a binary value, in network byte order. The HIT is stored, as a binary value, in network byte order.
5.1.4. Public key format 5.5. 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 [RFC4025] reuse the public key formats defined for the IPSECKEY RR [RFC4025]
(which in turns contains the algorithm-specific portion of the KEY RR (which in turns contains the algorithm-specific portion of the KEY RR
RDATA, all of the KEY RR DATA after the first four octets, RDATA, all of the KEY RR DATA after the first four octets,
corresponding to the same portion of the KEY RR that must be corresponding to the same portion of the KEY RR that must be
specified by documents that define a DNSSEC algorithm). specified by documents 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 encoding for and HIP RR, it should use the same public key encoding for both RRs.
both RRs. Unless specified otherwise, the HIPHI public key field Unless specified otherwise, the HIP RR public key field SHOULD use
would use the same public key format as the IPSECKEY RR RDATA for the the same public key format as the IPSECKEY RR RDATA for the
corresponding algorithm. corresponding algorithm.
The DSA key format is defined in RFC2536 [RFC2536]. The DSA key format is defined in RFC2536 [RFC2536].
The RSA key format is defined in RFC3110 [RFC3110] and the RSA key The RSA key format is defined in RFC3110 [RFC3110] and the RSA key
size limit (4096 bits) is relaxed in the IPSECKEY RR [RFC4025] size limit (4096 bits) is relaxed in the IPSECKEY RR [RFC4025]
specification. specification.
5.2. HIPRVS RDATA format 5.6. Rendezvous servers format
The RDATA for a HIPRVS RR consists of a preference value, a
rendezvous server type and either one or more rendezvous server
address, or one rendezvous server domain name.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| preference | type | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ rendezvous server |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Preference and RVS Type fields are REQUIRED. At least one RVS
field MUST be present.
5.2.1. Preference format
This is an unsigned 8-bit value, used to specify the preference given
to the RVS in the HIPRVS RR amongst others at the same owner. RVSs
with lower values are preferred. If there is a tie within some RR
subset, the initiating HIP host should pick one of the RVS randomly
from the set of RRs, such that the requester load is fairly balanced
amongst all RVSs of the set.
5.2.2. Rendezvous server type format
The rendezvous server type indicates the format of the information
stored in the rendezvous server field.
This document reuses the type values for the 'gateway type' field of
the IPSECKEY RR [RFC4025]. The presently defined values are given
only informally:
1. One or more 4-byte IPv4 address(es) in network byte order are
present.
2. One or more 16-byte IPv6 address(es) in network byte order are
present.
3. One or more variable length wire-encoded domain names as
described in section 3.3 of RFC1035 [RFC1035]. The wire-encoded
format is self-describing, so the length is implicit. The domain
names MUST NOT be compressed.
5.2.3. Rendezvous server format
The rendezvous server field indicates one or more rendezvous
server(s) IP address(es), or domain name(s). A HIP I1 packet sent to
any of these RVS would reach the entity named by this resource
record.
This document reuses the format used for the 'gateway' field of the
IPSECKEY RR [RFC4025], but allows to concatenate several IP (v4 or
v6) addresses. The presently defined formats for the data portion of
the rendezvous server field are given only informally:
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 variable length wire-encoded domain names as described The Rendezvous servers field indicates one or more variable length
in Section 3.3 of RFC1035 [RFC1035]. The wire-encoded format is wire-encoded domain names rendezvous server(s), as described in
self-describing, so the length is implicit. The domain names MUST Section 3.3 of RFC1035 [RFC1035]. The wire-encoded format is self-
NOT be compressed. describing, so the length is implicit. The domain names MUST NOT be
compressed. The rendezvous server(s) are listed in order of
preference (i.e. first rendezvous server(s) are preferred).
6. Presentation Format 6. HIP RR Presentation Format
This section specifies the representation of the HIPHI and HIPRVS RR This section specifies the representation of the HIP RR in a zone
in a zone data master file. data master file.
6.1. HIPHI Representation The HIT length field is not represented as it is implicitly known
thanks to the HIT field representation.
The PK algorithm field is represented as unsigned integers. The PK algorithm field is represented as unsigned integers.
The HIT length field is not represented as it is implicitly known The PK length field is not represented as it is implicitly known
thanks to the HIT field representation. thanks to the Public key field representation.
The HIT field is represented as the Base16 encoding [RFC3548] (a.k.a. The HIT field is represented as the Base16 encoding [RFC3548] (a.k.a.
hex or hexadecimal) of the HIT. The encoding MUST NOT contains hex or hexadecimal) of the HIT. The encoding MUST NOT contain
whitespace(s). whitespace(s).
The Public Key field is represented as the Base64 encoding [RFC3548] The Public Key field is represented as the Base64 encoding [RFC3548]
of the public key. The encoding MAY contains whitespace(s), and such of the public key. The encoding MAY contain whitespace(s), and such
whitespace(s) MUST be ignored. whitespace(s) MUST be ignored.
The Rendezvous servers field is represented by one or more
uncompressed domain name(s)
The complete representation of the HPIHI record is: The complete representation of the HPIHI record is:
IN HIPHI ( pk-algorithm IN HIP ( pk-algorithm
base16-encoded-hit base16-encoded-hit
base64-encoded-public-key ) base64-encoded-public-key
6.2. HIPRVS Representation
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[1]
... ...
rendezvous-server[n] ) rendezvous-server[n] )
6.3. Examples 7. Examples
Example of a node with a HI and a HIT: Example of a node with HI and HIT but no RVS:
www.example.com IN HIPHI ( 2 2A20E0FF0FE8A52422D059FFFEA938A1 www.example.com IN HIP ( 2 2A20E0FF0FE8A52422D059FFFEA938A1
AB3NzaC1kc3MAAACBAOBhKn AB3NzaC1kc3MAAACBAOBhKn
TCPOuFBzZQX/N3O9dm9P9iv TCPOuFBzZQX/N3O9dm9P9iv
UIMoId== ) UIMoId== )
Example of a node with an IPv6 RVS: Example of a node with a HI, HIT and one RVS:
www.example.com IN HIPRVS (10 2 2001:db8:200:1:20c:f1ff:feb:a533 )
Example of a node with three IPv4 RVS:
www.example.com IN HIPRVS ( 10 1 192.0.1.2 192.0.2.2 192.0.3.2 )
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 www.example.com IN HIP ( 2 2A20E0FF0FE8A52422D059FFFEA938A1
HITs MUST be considered to denote a single service, and be AB3NzaC1kc3MAAACBAOBhKn
semantically equivalent from that point of view. When initiating a TCPOuFBzZQX/N3O9dm9P9iv
base exchange with the denoted service, the host SHOULD be prepared UIMoId==
to accept any of HITs as the peer's identity. A host MAY implement rvs.example.com )
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 Example of a node with a HI, HIT and two RVS:
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 www.example.com IN HIP ( 2 2A20E0FF0FE8A52422D059FFFEA938A1
SHOULD first try to initiate the base exchange by using the AB3NzaC1kc3MAAACBAOBhKn
opportunistic mode. If the returned HIT does not match with any of TCPOuFBzZQX/N3O9dm9P9iv
the expected HITs, the host SHOULD retry by sending further I1s, one UIMoId==
at time, trying out all of the listed HITs. If the host receives an rvs1.example.com
R1 for any of the I1s, the host SHOULD continue to use the successful rvs2.example.com )
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
[I-D.ietf-hip-base]).
8. Security Considerations 8. 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 [RFC4025], the HIP DNS In a manner similar to the IPSECKEY RR [RFC4025], the HIP DNS
Extensions allows to provision two HIP nodes with the public keying Extensions allows to provision two HIP nodes with the public keying
material (HI) of their peer. These HIs will be subsequently used in material (HI) of their peer. These HIs will be subsequently used in
a key exchange between the peers. Hence, the HIP DNS Extensions a key exchange between the peers. Hence, the HIP DNS Extensions
introduce the same kind of threats that IPSECKEY does, plus threats introduce the same kind of threats that IPSECKEY does, plus threats
caused by the possibility given to a HIP node to initiate or accept a caused by the possibility given to a HIP node to initiate or accept a
HIP exchange using "opportunistic" or "unpublished initiator HI" HIP exchange using "opportunistic" or "unpublished initiator HI"
modes. modes.
A HIP node SHOULD obtain both the HIPHI and HIPRVS RRs from a trusted A HIP node SHOULD obtain HIP RRs from a trusted party trough a secure
party trough a secure channel insuring proper data integrity of the channel insuring proper data integrity of the RRs. DNSSEC [RFC2065]
RRs. DNSSEC [RFC2065] provides such a secure channel. provides such a secure channel.
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.
8.1. Attacker tampering with an insecure HIPHI RR 8.1. Attacker tampering with an insecure HIP RR
The HIPHI RR contains public keying material in the form of the named The HIP 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 HIP RR (e.g. using DNS spoofing)
spoofing) is able to mount Man-in-the-Middle attacks on the is able to mount Man-in-the-Middle attacks on the cryptographic core
cryptographic core of the eventual HIP exchange (responder's HIPHI of the eventual HIP exchange (responder's HIP RR rewritten by the
and HIPRVS rewritten by the attacker). attacker.)
8.2. Attacker tampering with an insecure HIPRVS RR
The HIPRVS RR contains a destination IP address where the named peer The HIP RR may contain a rendezvous server domain name resolved into
is reachable by an I1 (HIP Rendezvous Extensions IPSECKEY RR a destination IP address where the named peer is reachable by an I1
[I-D.ietf-hip-rvs] ). Thus, an attacker able to tamper with this RR (HIP Rendezvous Extensions IPSECKEY RR [I-D.ietf-hip-rvs].) Thus, an
is able to redirect I1 packets sent to the named peer to a chosen IP attacker able to tamper with this RR is able to redirect I1 packets
address, for DoS or MitM attacks. Note that this kind of attacks is sent to the named peer to a chosen IP address, for DoS or MitM
not specific to HIP and exists independently to whether or not HIP attacks. Note that this kind of attack is not specific to HIP and
and the HIPRVS RR are used. Such an attacker might tamper with A and exists independently to whether or not HIP and the HIP RR are used.
AAAA RRs as well. 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 to him and mount a MitM on HIP. In this case HIP exchanged packets to him and mount a MitM on HIP. In this case HIP
won't provide confidentiality nor initiator HI protection from won't provide confidentiality nor initiator HI protection from
eavesdroppers. eavesdroppers.
8.3. Opportunistic HIP 8.2. Hash and HITs Collisions
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 resolver
isn't HIP-enabled), and attempt an opportunistic HIP exchange towards
its known IP address, filling the responder HIT 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 in a replied R1.
Hence, an implementation MAY choose not to use opportunistic mode.
8.4. Unpublished Initiator HI
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
with such an initiator knowingly risks a MitM attack because it
cannot validate the initiator's HI. Hence, an implementation MAY
choose not to use unpublished mode.
8.5. 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 HIP the hash (e.g. its supposed collision resistance.) This is why a HIP
end-node implementation SHOULD NOT authenticate its HIP peers based end-node implementation SHOULD NOT authenticate its HIP peers based
solely on a HIT retrieved from DNS, but SHOULD rather use HI-based solely on a HIT retrieved from DNS, but SHOULD rather use HI-based
authentication. authentication.
8.6. DNSSEC 8.3. DNSSEC
In the absence of DNSSEC, the HIPHI and HIPRVS RRs are subject to the In the absence of DNSSEC, the HIP RR is subject to the threats
threats described in RFC 3833 [RFC3833]. described in RFC 3833 [RFC3833].
9. IANA Considerations 9. IANA Considerations
IANA needs to allocate two new RR type code for HIPHI and HIPRVS from IANA should allocate one new RR type code for the HIP RR from the
the standard RR type space. standard RR type space.
IANA does not need to open a new registry for the HIPHI RR type for IANA does not need to open a new registry for public key algorithms
public key algorithms because the HIPHI RR reuse 'algorithms types' of the HIP RR because the HIP RR reuses "algorithms types" defined
defined for the IPSECKEY RR [RFC4025]. The presently defined numbers for the IPSECKEY RR [RFC4025]. The presently defined values are
are given here only informally: shown here for reference:
0 is reserved 0 is reserved
1 is RSA 1 is RSA
2 is DSA 2 is DSA
IANA does not need to open a new registry for the HIPRVS RR
rendezvous server type because the HIPHI RR reuse the 'gateway types'
defined for the IPSECKEY RR [RFC4025]. The presently defined numbers
are given here only informally:
0 is reserved
1 is IPv4
2 is IPv6
3 is a wire-encoded uncompressed domain name
10. Acknowledgments 10. Acknowledgments
As usual in the IETF, this document is the result of a collaboration As usual in the IETF, this document is the result of a collaboration
between many people. The authors would like to thanks the author between many people. The authors would like to thanks the author
(Michael Richardson), contributors and reviewers of the IPSECKEY RR (Michael Richardson), contributors and reviewers of the IPSECKEY RR
[RFC4025] specification, which this document was framed after. The [RFC4025] specification, which this document was framed after. The
authors would also like to thanks the following people, who have 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 helped improving this document: Rob Austein, Hannu Flinck, Tom have helped improving this document: Rob Austein, Hannu Flinck, Tom
Henderson, Olaf Kolkman, Miika Komu, Andrew McGregor, Erik Nordmark, Henderson, Olaf Kolkman, Miika Komu, Andrew McGregor, Erik Nordmark,
skipping to change at page 23, line 44 skipping to change at page 20, line 44
[RFC3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi, [RFC3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi,
"DNS Extensions to Support IP Version 6", RFC 3596, "DNS Extensions to Support IP Version 6", RFC 3596,
October 2003. October 2003.
[RFC4025] Richardson, M., "A Method for Storing IPsec Keying [RFC4025] Richardson, M., "A Method for Storing IPsec Keying
Material in DNS", RFC 4025, March 2005. Material in DNS", RFC 4025, March 2005.
[I-D.ietf-hip-base] [I-D.ietf-hip-base]
Moskowitz, R., "Host Identity Protocol", Moskowitz, R., "Host Identity Protocol",
draft-ietf-hip-base-03 (work in progress), June 2005. draft-ietf-hip-base-04 (work in progress), October 2005.
[I-D.ietf-hip-rvs] [I-D.ietf-hip-rvs]
Laganier, J. and L. Eggert, "Host Identity Protocol (HIP) Laganier, J. and L. Eggert, "Host Identity Protocol (HIP)
Rendezvous Extension", draft-ietf-hip-rvs-04 (work in Rendezvous Extension", draft-ietf-hip-rvs-04 (work in
progress), October 2005. progress), October 2005.
11.2. Informative references 11.2. Informative references
[I-D.ietf-hip-arch] [I-D.ietf-hip-arch]
Moskowitz, R. and P. Nikander, "Host Identity Protocol Moskowitz, R. and P. Nikander, "Host Identity Protocol
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