Network Working Group P. Nikander Internet-Draft Ericsson Research Nomadic Lab Expires: October 30, 2004 J. Laganier LIP / Sun Microsystems May 2004 Host Identity Protocol (HIP) Domain Name System (DNS) Extensions draft-nikander-hip-dns-00 Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on October 30, 2004. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract This document specifies two new resource records for the Domain Name System, and how to use them with the Host Identity Protocol. These records allow a HIP node to store in the DNS its Host Identity (i.e., its public key), Host Identity Tag (i.e., a truncated hash of its public key), and Rendezvous Servers (RVS). Nikander & Laganier Expires October 30, 2004 [Page 1] Internet-Draft HIP DNS Extensions May 2004 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions used in this document . . . . . . . . . . . . . . 5 3. Usage scenarios . . . . . . . . . . . . . . . . . . . . . . . 6 3.1 Simple static singly homed end-host . . . . . . . . . . . 7 3.2 Mobile end-host . . . . . . . . . . . . . . . . . . . . . 7 3.3 Multi-homed end-host . . . . . . . . . . . . . . . . . . . 7 3.4 Multi-homed site . . . . . . . . . . . . . . . . . . . . . 7 3.5 Site with a HAA . . . . . . . . . . . . . . . . . . . . . 7 4. Overview of using the DNS with HIP . . . . . . . . . . . . . . 8 4.1 Different types of HITs . . . . . . . . . . . . . . . . . 8 4.1.1 Host Assigning Authority (HAA) field . . . . . . . . . 8 4.1.2 Reverse lookup based on Type 2 (HAA-based) HITs . . . 9 4.2 Storing HI and HIT in DNS . . . . . . . . . . . . . . . . 9 4.3 Storing HAA in DNS . . . . . . . . . . . . . . . . . . . . 9 4.4 Providing multiple IP addresses . . . . . . . . . . . . . 9 4.4.1 Storing Rendezvous Servers in the DNS . . . . . . . . 10 4.5 Initiating connections based on DNS names . . . . . . . . 10 4.6 Address verification . . . . . . . . . . . . . . . . . . . 10 5. Storage Format . . . . . . . . . . . . . . . . . . . . . . . . 11 5.1 HIPHI RDATA format . . . . . . . . . . . . . . . . . . . . 11 5.1.1 RDATA format HIT type . . . . . . . . . . . . . . . . 11 5.1.2 RDATA format algorithm type . . . . . . . . . . . . . 11 5.1.3 RDATA format HIT . . . . . . . . . . . . . . . . . . . 11 5.1.4 RDATA format public key . . . . . . . . . . . . . . . 12 5.2 HIPRVS RDATA format . . . . . . . . . . . . . . . . . . . 12 5.2.1 RDATA format precedence . . . . . . . . . . . . . . . 13 5.2.2 RDATA format Rendezvous server type . . . . . . . . . 13 5.2.3 RDATA format Rendezvous server . . . . . . . . . . . . 13 6. Policy considerations . . . . . . . . . . . . . . . . . . . . 14 7. Conjunction of multiple HIs with mutiple IPs . . . . . . . . . 15 8. Security Considerations . . . . . . . . . . . . . . . . . . . 16 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 18 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 11.1 Normative references . . . . . . . . . . . . . . . . . . . . 19 11.2 Informative references . . . . . . . . . . . . . . . . . . . 20 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 20 Intellectual Property and Copyright Statements . . . . . . . . 21 Nikander & Laganier Expires October 30, 2004 [Page 2] Internet-Draft HIP DNS Extensions May 2004 1. Introduction This document specifies two new resource records (RRs) for the Domain Name System (DNS) [8], and how to use them with the Host Identity Protocol (HIP) [10]. These records allow a HIP node to store in the DNS its Host Identity (i.e., its public key), Host Identity Tag (i.e., a truncated hash of its public key), and Rendezvous Servers (RVS) [13]. 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 [11] defines a new third namespace called Host Identity Namespace. This namespace is composed of the Host Identity (HI) of HIP nodes. The Host Identity Tag (HIT) is one local representation of a HI (the others being the IPv4-compatible and IPv6-compatible Local Scope Identifiers - LSIs). This local 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 instead of IP addresses in some ULPs and applications. The Host Identity Protocol [10] allows two HIP nodes to establish a pair of unidirectional IPsec Security Association. These SAs are bound to HI instead of regular IP addresses. The proposed HIP multi-homing mechanisms [12] allow a node to dynamically change its set of underlying IP addresses while maintaining transport layer session survivability. The HIP rendezvous extensions [13] proposal allows a HIP node to maintain HIP reachability while not relying on dynamic DNS updates to make its peers aware of its current location (i.e., its set of IP address(es)). Although a HIP node can initiate a HIP communication "opportunistically" (i.e., without a priori knowledge of its peer's HI), doing so expose both endpoints to Man-in-the-Middle attacks on the HIP handshake. Hence, there is a desire to gain knowledge of peers' HI before applications and ULPs initiate communication. Currently, most of the Internet applications which need to communicate 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 to communication with the remote host, and relies on a DNS lookup. Nikander & Laganier Expires October 30, 2004 [Page 3] Internet-Draft HIP DNS Extensions May 2004 With HIP, IP addresses are expected to be used mostly for on-the-wire communication between end hosts, while most ULPs and applications 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 name into an HI. Using the DNS for this translation is pretty straightforward: We define a new HIPHI (HIP HI) resource record. Upon query by an application or ULP for a FQDN -> IP lookup, the resolver would then additionaly perform an FQDN -> HI lookup, and use it to construct the resulting HI -> IP mapping (which is internal to the HIP layer). The HIP layer uses the HI -> IP mapping to translate HIs and their local representations (HITs, IPv4 and IPv6-compatible LSIs) into IP addresses and vice versa. Nikander & Laganier Expires October 30, 2004 [Page 4] Internet-Draft HIP DNS Extensions May 2004 2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC2119 [2]. Nikander & Laganier Expires October 30, 2004 [Page 5] Internet-Draft HIP DNS Extensions May 2004 3. Usage scenarios In this section we briefly introduce a number of usage scenarios where the DNS is useful with the Host Identity Protocol. With HIP, most application and ULPs are unaware of the IP addresses used to carry packets on the wire. Consequently, a HIP node could take advantage of having multiple IP addresses for fail-over, redundancy, mobility or renumbering, in a manner which is transparent to most ULPs and applications (because they are bound to HIs, hence they are agnostic to these IP address(es) changes). In these situations, a node wishing to be reachable by reference to its FQDN MAY store the following informations in the DNS: o Its set of IP address(es). o Its Host Identity (HI) and/or Host Identity Tag (HIT). o Its Host Assigning Authority (HAA). o The IP address(es) or DNS name(s) of its Rendezvous Server(s) (RVS). 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 association towards its peer. Although such an exchange can be initiated opportunistically, i.e., without a priori knowledge of 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 recommended that the initiator first obtain the HI of the responder, and then initiate the exchange. This can be done through manual configuration, or DNS lookups, hence the introduction of the new HIPHI RR. When a HIP node is frequently changing its IP address(es), the dynamic DNS update latency may prevent it from publishing globally its new IP address(es). For solving this problem, the HIP architecture introduce Rendezvous Servers (RVS). A HIP responder uses a Rendezvous Server as a Rendezvous point, to maintain reachability 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 RVS up-to-date with its current set of IP addresses. Then, when some HIP node wants to initiate an HIP exchange with such a responder, it retrieves its RVS IP address by looking up a HIPRVS 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 then complete the HIP exchange, either directly or via the RVS [13]. Note that storing HIP RR informations in the DNS at a FQDN which is Nikander & Laganier Expires October 30, 2004 [Page 6] Internet-Draft HIP DNS Extensions May 2004 assigned to a non-HIP node might have very bad effects on its reachability by HIP nodes. 3.1 Simple static singly homed end-host A HIP node having a single static network attachment, wishing to be reachable by reference to its FQDN, would store in the DNS, in addition to its IP address(es), its Host Identity (HI) in a HIPHI resource record. 3.2 Mobile end-host A mobile HIP node wishing to be reachable by reference to its FQDN would store in the DNS, instead of its IP address(es), its HI in a 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 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 of its RVS. Following, the RVS will relay the I1 up to the mobile node, which will complete the HIP exchange. 3.3 Multi-homed end-host A HIP node having several distinct network attachments is multi-homed. Such a HIP node might also be reachable via several distinct Rendezvous 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 the IP address(es) of its RVS(s) in HIPRVS RRs. 3.4 Multi-homed site A HIP node being attached to the network of a multi-homed site will possibly have multiple prefixes and addresses. This site might also be reachable via several distinct Rendezvous 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 the IP address(es) of its site RVS(s) in HIPRVS RRs. 3.5 Site with a HAA A site which has an assigned HAA might store this HAA in a HIPHI RR. This might be useful to verify that a HIP node with a given "Type 2" HIT belongs to a site referenced by a given HAA. Nikander & Laganier Expires October 30, 2004 [Page 7] Internet-Draft HIP DNS Extensions May 2004 4. Overview of using the DNS with HIP 4.1 Different types of HITs There are _currently_ two types of HITs. HITs of the first type consists just of the SHA-1 hash of the public key. HITs of the second type consist of a 63 bits Host Assigning Authority (HAA) field, and only the last 64 bits come from a SHA-1 hash of the Host Identity. This latter format for HIT is recommended for 'well known' systems. It is possible to support a resolution mechanism for these names in directories like DNS. Another use of HAA is in policy controls, see Section 6. The first bit of a HIT is used to differentiate between Type 1 and Type 2 format. If the first bit is 0 then the rest of a HIT is the 127 upper bits of a SHA-1 hash of the Host Identity. If the first bit is 1 then the next 63 bits is the HAA field, and only the last 64 bits come from the hash of the Host Identity. Additionnaly, this document defines an internal IPv6-compatible LSI representation format, to be used within the legacy IPv6-compatible API (e.g., socket over AF_INET6). The format of these IPv6-compatible LSIs is designed to avoid the most commonly occurring IPv6 addresses in RFC3596 [9]. An IPv6-compatible LSI representation is easily computed by replacing in the corresponding HIT the Bit 1 with NOT(Bit 0). That way if Bit 0 is zero and Bit 1 is one, then the rest of the LSI is a 126 bits of a SHA-1 hash of the Host Identity. If Bit 0 is one and Bit 1 is zero, then the next 62 bits come from the HAA field, and only the last 64 bits come from the hash of the Host Identity. The figure belows shows how the specified IPv6-compatible LSI format tries to avoid collision: Allocation Prefix Fraction of IPv6 (binary) Address Space ------------------------ -------- ------------- IPv6 Address space 00 1/4 Type 1 IPv6-compatible LSI 01 1/4 Type 2 IPv6-compatible LSI 10 1/4 IPv6 Address space 11 1/4 4.1.1 Host Assigning Authority (HAA) field The 63 bits of HAA supports two levels of delegation. The first is a registered assigning authority (RAA). The second is a registered identity (RI, commonly a company). The RAA is 23 bits with values assign sequentially by ICANN. The RI is 40 bits, also assigned Nikander & Laganier Expires October 30, 2004 [Page 8] Internet-Draft HIP DNS Extensions May 2004 sequentially but by the RAA. As IPv6 "global site-local" addresses were proposed in the IPv6 WG to 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. 4.1.2 Reverse lookup based on Type 2 (HAA-based) HITs This can be used to create a resolution mechanism in the DNS. For example if FOO is RAA number 100 and BAR is FOO's 50th registered identity, and if 1385D17FC63961F5 is the hash of the Host Identity for www.bar.com, then by using DNS Binary Labels [5] there could be a reverse lookup record like: \[x1385D17FC63961F5/64].\[x32/40].\[x64/23].HIT.int IN PTR www.bar.com. (Note that RFC2673 [5] is Experimental, and that there are some bad experiences with binary DNS labels. [7]) 4.2 Storing HI and HIT in DNS Any conforming implementation might 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 a HI or HIT does not already have a specified RDATA format, a new RDATA-like format SHOULD be defined for the HI or HIT. During a transition period, instead of storing the HI or HIT in a HIPHI RR, the HIT MAY be stored in an AAAA RR. If a HIT is stored in 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. 4.3 Storing HAA in DNS Any conforming implementation might store a site's Host Assigning Authority in a DNS HIPHI RDATA format. A HAA MUST be stored similarly to a Type 2 HIT, while the least significant 64-bit are set to 0. If a 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 Nikander & Laganier Expires October 30, 2004 [Page 9] Internet-Draft HIP DNS Extensions May 2004 4.4.1 Storing Rendezvous Servers in the DNS The Rendezvous server (RVS) resource record indicates an address (or a FQDN resolvable into an address) towards which a HIP I1 packet might be sent to trigger the establishment of an association with the entity named by this resource record. An RVS receiving such an I1 would then forward it to the appropriate responder (i.e., the owner of the destination HIT in this I1). The responder will then complete the exchange with the initiator, possibly without ongoing help from the RVS. Any conforming implementation may store Rendezvous Server's IP 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. During a transition period, similarly to what may happen with HITs, 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. 4.5 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 Address verification Upon return of an HIPHI RR, a host MUST always calculate the HI-derivative HIT to be used in the HIP exchange, as specified in the HIP architecture [11], while the HIT possibly embedded along SHOULD only be used as an optimisation (e.g., table lookup). Nikander & Laganier Expires October 30, 2004 [Page 10] Internet-Draft HIP DNS Extensions May 2004 5. Storage Format 5.1 HIPHI RDATA format The RDATA for a HIPHI RR consists of a HIT type, an algorithm type, a HIT and a public key. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | HIT type | algorithm | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ HIT | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | / / public key / / / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| 5.1.1 RDATA format HIT type The algorithm type indicates the Host Identity Tag (HIT) type and the implied HIT format. The following values are defined: 0 No HIT is present. 1 A 128-bit Type 1 HIT is present. 2 A 128-bit Type 2 HIT is present. 3 A 128-bit HAA is present. 5.1.2 RDATA format algorithm type The algorithm type indicates the public key cryptographic algorithm and the implied public key field format. The following values are defined: 0 No key is present. 1 A DSA key is present, in the format defined in RFC2536 [4]. 2 A RSA key is present, in the format defined in RFC3110 [6]. 5.1.3 RDATA format HIT There's currently two types of HITs, both 128-bit long, and a single type of HAA. Both of them are stored within a a single RDATA format. Nikander & Laganier Expires October 30, 2004 [Page 11] Internet-Draft HIP DNS Extensions May 2004 This Field contain either: o A *Type 1* HIT: binary prefix 0 concatenated with least significant 127-bit of the hash (e.g., SHA1) of the public key (Host Identity), which is possibly following in the HIPHI RR. o A *Type 2* HIT: binary prefix 1 concatenated with a 63-bit HAA, and the least significant 64-bit of the hash (e.g., SHA1) of the public key (Host Identity), which is possibly following in the HIPHI RR. o A HAA: binary prefix 1 concatenated with a 63-bit HAA, and the remaining 64-bit are set to 0. 5.1.4 RDATA format public key Both of the public key types defined in this document (RSA and DSA) inherit their public key formats from the corresponding KEY RR formats. The public key field contains the algorithm-specific portion of the KEY RR RDATA (i.e., 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 that define a DNSSEC algorithm). In the future, if a new algorithm is to be used both by DNSSEC's KEY RR and HIPHI RR, it would probably use the same public key encodings for both RRs. Unless specified otherwise, the HIPHI public key field would contain the algorithm-specific portion of the KEY RR RDATA for the corresponding algorithm. Such an algorithm must still be designated for use with the HIP protocol and an algorithm type number must be assigned to it. Similarly to what happened with public key encodings, this algorithm type number is likely to be the same than the one used in DNSSEC, though it might not always be the case. The DSA key format is defined in RFC2536 [4]. The RSA key format is defined in RFC3110 [6]. 5.2 HIPRVS RDATA format The RDATA for a HIPRVS RR consists of a preference value, a Rendezvous server type and a Rendezvous server address. 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 | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Nikander & Laganier Expires October 30, 2004 [Page 12] Internet-Draft HIP DNS Extensions May 2004 5.2.1 RDATA format precedence This is an 8-bit preference order for this record. This used to specify the preference given to this RR amongst others at the same owner. Lower values are preferred, and if there is a tie with some RRs, the order should be non-deterministic (e.g., round-robin). 5.2.2 RDATA format Rendezvous server type The Rendezvous server type indicates the format of the information stored in the Rendezvous server field. The following values are defined: 0 Reserved. 1 A 4-byte IPv4 address in network byte order is present. 2 A 16-byte IPv6 address in network byte order is present. 3 A variable length wire-encoded domain name as described in section 3.3 of RFC1035 [1]. The domain name MUST NOT be compressed. 5.2.3 RDATA format Rendezvous server The Rendezvous server field indicates an address (or a FQDN resolvable into an address) towards which a HIP I1 packet might be send in order to reach the entity named by this resource record. There are three different formats for the data portion of the Rendezvous server field: o A 32-bit IPv4 address in network byte order. o A 128-bit IPv6 address in network byte order. o A variable length wire-encoded domain name as described in section 3.3 of RFC1035 [1]. The domain name MUST NOT be compressed. Nikander & Laganier Expires October 30, 2004 [Page 13] Internet-Draft HIP DNS Extensions May 2004 6. Policy considerations There are a number of variables that will influence the HIP exchanges that each host must support. All HIP implementations MUST support at least 2 HIs, one to publish in the DNS and one for anonymous usage. Although anonymous HIs will be rarely used as responder HIs, they will be common for initiators. Support for multiple HIs is RECOMMENDED. Nikander & Laganier Expires October 30, 2004 [Page 14] Internet-Draft HIP DNS Extensions May 2004 7. Conjunction of multiple HIs with mutiple IPs 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 FQDN | / \ +-----+-----+-----+ HI1 HI2 / / \ \ \ / \ \ IP1 IP2 IP3 HI1 HI2 IP1 IP2 IP3 "Flat" model Vs. "Hierarchical" 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, a solution might be to index each IP addresses and HIs with a descriptor. This descriptor might be the HIT, or more efficiently, an additional 8-bit field. That way each HIPHI, HIPRVS, and HIPLOC (a new to-be-defined RR carrying the IP address of a HIP node) would contain an additionnal HI index field allowing to link a HI with a subset of IP addresses and vice versa. Nikander & Laganier Expires October 30, 2004 [Page 15] Internet-Draft HIP DNS Extensions May 2004 8. Security Considerations The security considerations of the HIP DNS extensions still need to be investigated and documented. Man-in-the-middle attacks are difficult to defend against, without third-party authentication. A skillful MitM could easily handle all parts of HIP; but HIP indirectly provides the following protection from a MitM attack. If the responder's HI is retrieved from a signed DNS zone by the initiator, the initiator can use this to validate the R1 HIP packet. Likewise, if the initiator's HI is in a secure DNS zone, the responder can retrieve it after it gets the I2 HIP packet and validate that. However, since an initiator may choose to use an anonymous HI, it knowingly risks a MitM attack. The responder may choose not to accept a HIP exchange with an anonymous initiator. Nikander & Laganier Expires October 30, 2004 [Page 16] Internet-Draft HIP DNS Extensions May 2004 9. IANA Considerations IANA needs to allocate two new RR type code for HIPHI and HIPRVS from the standard RR type space. IANA needs to open a new registry for the HIPHI RR type for public key algorithms. Defined types are: 0 is reserved 1 is RSA 2 is DSA Adding new reservations requires IETF consensus RFC2434 [1]. IANA needs to open a new registry for the HIPHI RR HIT type. Defined types are: 0 No HIT is present 1 A 128-bit Type 1 HIT is present 2 A 128-bit Type 2 HIT is present 3 A 128-bit HAA is present Adding new reservations requires IETF consensus RFC2434 [1]. IANA needs to open a new registry for the HIPRVS RR Rendezvous server type. Defined types are: 0 is reserved 1 is IPv4 2 is IPv6 3 is a wire-encoded uncompressed domain name Adding new reservations requires IETF consensus RFC2434 [1]. Nikander & Laganier Expires October 30, 2004 [Page 17] Internet-Draft HIP DNS Extensions May 2004 10. Acknowledgments Some parts of this draft stem from [10]. This work is heavily influenced by [15], which serves as a model for this document. The authors would like to thanks the following people, who have provided thoughtful and helpful discussions and/or suggestions, that have improved this document: Rob Austein, Hannu Flinck, Miika Komu, Gabriel Montenegro. Nikander & Laganier Expires October 30, 2004 [Page 18] Internet-Draft HIP DNS Extensions May 2004 11. References 11.1 Normative references [1] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [3] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. [4] Eastlake, D., "DSA KEYs and SIGs in the Domain Name System (DNS)", RFC 2536, March 1999. [5] Crawford, M., "Binary Labels in the Domain Name System", RFC 2673, August 1999. [6] Eastlake, D., "RSA/SHA-1 SIGs and RSA KEYs in the Domain Name System (DNS)", RFC 3110, May 2001. [7] Bush, R., Durand, A., Fink, B., Gudmundsson, O. and T. Hain, "Representing Internet Protocol version 6 (IPv6) Addresses in the Domain Name System (DNS)", RFC 3363, August 2002. [8] Klensin, J., "Role of the Domain Name System (DNS)", RFC 3467, February 2003. [9] Thomson, S., Huitema, C., Ksinant, V. and M. Souissi, "DNS Extensions to Support IP Version 6", RFC 3596, October 2003. [10] Moskowitz, R., Nikander, P. and P. Jokela, "Host Identity Protocol", draft-moskowitz-hip-09 (work in progress), February 2004. [11] Moskowitz, R., "Host Identity Protocol Architecture", draft-moskowitz-hip-arch-05 (work in progress), October 2003. [12] Nikander, P., "End-Host Mobility and Multi-Homing with Host Identity Protocol", draft-nikander-hip-mm-01 (work in progress), January 2004. [13] Eggert, L. and J. Laganier, "Host Identity Protocol (HIP) Rendezvous Extensions", draft-eggert-hip-rvs-00 (work in progress), July 2004. Nikander & Laganier Expires October 30, 2004 [Page 19] Internet-Draft HIP DNS Extensions May 2004 11.2 Informative references [14] Rescorla, E. and B. Korver, "Guidelines for Writing RFC Text on Security Considerations", draft-iab-sec-cons-00 (work in progress), August 2002. [15] Richardson, M., "A method for storing IPsec keying material in DNS", draft-ietf-ipseckey-rr-09 (work in progress), February 2004. Authors' Addresses Pekka Nikander Ericsson Research Nomadic Lab JORVAS FIN-02420 FINLAND Phone: +358 9 299 1 EMail: pekka.nikander@nomadiclab.com Julien Laganier LIP (CNRS-INRIA-ENSL-UCBL) & Sun Labs (Sun Microsystems) 180, Avenue de l'Europe Saint Ismier CEDEX 38334 France Phone: +33 476 188 815 EMail: ju@sun.com Nikander & Laganier Expires October 30, 2004 [Page 20] Internet-Draft HIP DNS Extensions May 2004 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the IETF's procedures with respect to rights in IETF Documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2004). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Nikander & Laganier Expires October 30, 2004 [Page 21]