--- 1/draft-ietf-hip-rfc4423-bis-05.txt 2013-11-07 14:14:46.451556011 -0800 +++ 2/draft-ietf-hip-rfc4423-bis-06.txt 2013-11-07 14:14:46.535558136 -0800 @@ -1,54 +1,54 @@ -Network Working Group R. Moskowitz +Network Working Group R. Moskowitz, Ed. Internet-Draft Verizon -Obsoletes: 4423 (if approved) September 28, 2012 -Intended status: Standards Track -Expires: April 1, 2013 +Obsoletes: 4423 (if approved) M. Komu +Intended status: Informational Aalto +Expires: May 11, 2014 November 7, 2013 Host Identity Protocol Architecture - draft-ietf-hip-rfc4423-bis-05 + draft-ietf-hip-rfc4423-bis-06 Abstract This memo describes a new namespace, the Host Identity namespace, and a new protocol layer, the Host Identity Protocol, between the internetworking and transport layers. Herein are presented the basics of the current namespaces, their strengths and weaknesses, and how a new namespace will add completeness to them. The roles of this new namespace in the protocols are defined. This document obsoletes RFC 4423 and addresses the concerns raised by the IESG, particularly that of crypto agility. It incorporates lessons learned from the implementations of RFC 5201 and goes further - to explain how HIP works as a secure signalling channel. + to explain how HIP works as a secure signaling channel. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." - This Internet-Draft will expire on April 1, 2013. + This Internet-Draft will expire on May 11, 2014. Copyright Notice - Copyright (c) 2012 IETF Trust and the persons identified as the + Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as @@ -61,55 +61,64 @@ modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 - 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 5 - 2.1. Terms common to other documents . . . . . . . . . . . . . . 5 - 2.2. Terms specific to this and other HIP documents . . . . . . . 5 - 3. Background . . . . . . . . . . . . . . . . . . . . . . . . . 7 - 3.1. A desire for a namespace for computing platforms . . . . . . 7 - 4. Host Identity namespace . . . . . . . . . . . . . . . . . . 9 - 4.1. Host Identifiers . . . . . . . . . . . . . . . . . . . . . . 10 - 4.2. Host Identity Hash (HIH) . . . . . . . . . . . . . . . . . . 10 - 4.3. Host Identity Tag (HIT) . . . . . . . . . . . . . . . . . . 11 - 4.4. Local Scope Identifier (LSI) . . . . . . . . . . . . . . . . 11 - 4.5. Storing Host Identifiers in Directories . . . . . . . . . . 12 - 5. New stack architecture . . . . . . . . . . . . . . . . . . . 12 - 5.1. Transport associations and end-points . . . . . . . . . . . 13 - 6. End-host mobility and multi-homing . . . . . . . . . . . . . 13 - 6.1. Rendezvous mechanism . . . . . . . . . . . . . . . . . . . . 14 - 6.2. Protection against flooding attacks . . . . . . . . . . . . 14 - 7. HIP and ESP . . . . . . . . . . . . . . . . . . . . . . . . 15 - 8. HIP and MAC Security . . . . . . . . . . . . . . . . . . . . 16 - 9. HIP and NATs . . . . . . . . . . . . . . . . . . . . . . . . 17 - 9.1. HIP and Upper-layer checksums . . . . . . . . . . . . . . . 17 - 10. Multicast . . . . . . . . . . . . . . . . . . . . . . . . . 18 - 11. HIP policies . . . . . . . . . . . . . . . . . . . . . . . . 18 - 12. Benefits of HIP . . . . . . . . . . . . . . . . . . . . . . 18 - 12.1. HIP's answers to NSRG questions . . . . . . . . . . . . . . 19 - 13. Changes from RFC 4423 . . . . . . . . . . . . . . . . . . . 21 - 14. Security considerations . . . . . . . . . . . . . . . . . . 21 - 14.1. HITs used in ACLs . . . . . . . . . . . . . . . . . . . . . 23 - 14.2. Alternative HI considerations . . . . . . . . . . . . . . . 24 - 15. IANA considerations . . . . . . . . . . . . . . . . . . . . 24 - 16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 24 - 17. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 - 17.1. Normative References . . . . . . . . . . . . . . . . . . . . 25 - 17.2. Informative references . . . . . . . . . . . . . . . . . . . 26 - Author's Address . . . . . . . . . . . . . . . . . . . . . . 27 + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . 4 + 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 + 2.1. Terms common to other documents . . . . . . . . . . . . . 5 + 2.2. Terms specific to this and other HIP documents . . . . . 5 + 3. Background . . . . . . . . . . . . . . . . . . . . . . . 7 + 3.1. A desire for a namespace for computing platforms . . . . 7 + 4. Host Identity namespace . . . . . . . . . . . . . . . . . 9 + 4.1. Host Identifiers . . . . . . . . . . . . . . . . . . . . 10 + 4.2. Host Identity Hash (HIH) . . . . . . . . . . . . . . . . 11 + 4.3. Host Identity Tag (HIT) . . . . . . . . . . . . . . . . . 11 + 4.4. Local Scope Identifier (LSI) . . . . . . . . . . . . . . 11 + 4.5. Storing Host Identifiers in directories . . . . . . . . . 12 + 5. New stack architecture . . . . . . . . . . . . . . . . . 13 + 5.1. On the multiplicity of identities . . . . . . . . . . . . 14 + 6. Control plane . . . . . . . . . . . . . . . . . . . . . . 15 + 6.1. Base exchange . . . . . . . . . . . . . . . . . . . . . . 15 + 6.2. End-host mobility and multi-homing . . . . . . . . . . . 16 + 6.3. Rendezvous mechanism . . . . . . . . . . . . . . . . . . 16 + 6.4. Relay mechanism . . . . . . . . . . . . . . . . . . . . . 17 + 6.5. Termination of the control plane . . . . . . . . . . . . 17 + 7. Data plane . . . . . . . . . . . . . . . . . . . . . . . 17 + 8. HIP and NATs . . . . . . . . . . . . . . . . . . . . . . 18 + 8.1. HIP and Upper-layer checksums . . . . . . . . . . . . . . 19 + 9. Multicast . . . . . . . . . . . . . . . . . . . . . . . . 19 + 10. HIP policies . . . . . . . . . . . . . . . . . . . . . . 20 + 11. Design considerations . . . . . . . . . . . . . . . . . . 20 + 11.1. Benefits of HIP . . . . . . . . . . . . . . . . . . . . . 20 + 11.2. Drawbacks of HIP . . . . . . . . . . . . . . . . . . . . 23 + 11.3. Deployment and adoption considerations . . . . . . . . . 24 + 11.3.1. Deployment analysis . . . . . . . . . . . . . . . . . . . 25 + 11.3.2. HIP in 802.15.4 networks . . . . . . . . . . . . . . . . 26 + 11.4. Answers to NSRG questions . . . . . . . . . . . . . . . . 26 + 12. Security considerations . . . . . . . . . . . . . . . . . 28 + 12.1. MiTM Attacks . . . . . . . . . . . . . . . . . . . . . . 28 + 12.2. Protection against flooding attacks . . . . . . . . . . . 29 + 12.3. HITs used in ACLs . . . . . . . . . . . . . . . . . . . . 30 + 12.4. Alternative HI considerations . . . . . . . . . . . . . . 31 + 13. IANA considerations . . . . . . . . . . . . . . . . . . . 32 + 14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . 32 + 15. Changes from RFC 4423 . . . . . . . . . . . . . . . . . . 33 + 16. References . . . . . . . . . . . . . . . . . . . . . . . 33 + 16.1. Normative References . . . . . . . . . . . . . . . . . . 33 + 16.2. Informative references . . . . . . . . . . . . . . . . . 34 + Authors' Addresses . . . . . . . . . . . . . . . . . . . 40 1. Introduction The Internet has two important global namespaces: Internet Protocol (IP) addresses and Domain Name Service (DNS) names. These two namespaces have a set of features and abstractions that have powered the Internet to what it is today. They also have a number of weaknesses. Basically, since they are all we have, we try and do too much with them. Semantic overloading and functionality extensions have greatly complicated these namespaces. @@ -134,37 +143,38 @@ There is a subtle but important difference between Host Identities and Host Identifiers. An Identity refers to the abstract entity that is identified. An Identifier, on the other hand, refers to the concrete bit pattern that is used in the identification process. Although the Host Identifiers could be used in many authentication systems, such as IKEv2 [RFC4306], the presented architecture introduces a new protocol, called the Host Identity Protocol (HIP), and a cryptographic exchange, called the HIP base exchange; see also - Section 7. The HIP protocols provide for limited forms of trust - between systems, enhance mobility, multi-homing and dynamic IP - renumbering, aid in protocol translation / transition, and reduce - certain types of denial-of-service (DoS) attacks. + Section 7. HIP provides for limited forms of trust between systems, + enhance mobility, multi-homing and dynamic IP renumbering, aid in + protocol translation / transition, and reduce certain types of + denial-of-service (DoS) attacks. When HIP is used, the actual payload traffic between two HIP hosts is typically, but not necessarily, protected with ESP. The Host Identities are used to create the needed ESP Security Associations (SAs) and to authenticate the hosts. When ESP is used, the actual payload IP packets do not differ in any way from standard ESP protected IP packets. - Much has been learned about HIP since [RFC4423] was published. This - document expands Host Identities beyond use to enable IP connectivity - and security to general interhost secure signalling at any protocol - layer. The signal may establish a security association between the - hosts, or simply pass information within the channel. + Much has been learned about HIP [RFC6538] since [RFC4423] was + published. This document expands Host Identities beyond use to + enable IP connectivity and security to general interhost secure + signalling at any protocol layer. The signal may establish a + security association between the hosts, or simply pass information + within the channel. 2. Terminology 2.1. Terms common to other documents +---------------+---------------------------------------------------+ | Term | Explanation | +---------------+---------------------------------------------------+ | Public key | The public key of an asymmetric cryptographic key | | | pair. Used as a publicly known identifier for | @@ -173,35 +183,36 @@ | | only to known to the World. | | | | | Private key | The private or secret key of an asymmetric | | | cryptographic key pair. Assumed to be known only | | | to the party identified by the corresponding | | | public key. Used by the identified party to | | | authenticate its identity to other parties. | | | | | Public key | An asymmetric cryptographic key pair consisting | | pair | of public and private keys. For example, | - | | Rivest-Shamir-Adelman (RSA) and Digital Signature | - | | Algorithm (DSA) key pairs are such key pairs. | + | | Rivest-Shamir-Adelman (RSA), Digital Signature | + | | Algorithm (DSA) and Elliptic Curve DSA (ECDSA) | + | | key pairs are such key pairs. | | | | | End-point | A communicating entity. For historical reasons, | | | the term 'computing platform' is used in this | | | document as a (rough) synonym for end-point. | +---------------+---------------------------------------------------+ 2.2. Terms specific to this and other HIP documents It should be noted that many of the terms defined herein are tautologous, self-referential or defined through circular reference to other terms. This is due to the succinct nature of the definitions. See the text elsewhere in this document and in RFC 5201 - [RFC5201-bis] for more elaborate explanations. + [I-D.ietf-hip-rfc5201-bis] for more elaborate explanations. +---------------+---------------------------------------------------+ | Term | Explanation | +---------------+---------------------------------------------------+ | Computing | An entity capable of communicating and computing, | | platform | for example, a computer. See the definition of | | | 'End-point', above. | | | | | HIP base | A cryptographic protocol; see also Section 7. | | exchange | | @@ -211,54 +222,54 @@ | | | | Host Identity | An abstract concept assigned to a 'computing | | | platform'. See 'Host Identifier', below. | | | | | Host Identity | A name space formed by all possible Host | | namespace | Identifiers. | | | | | Host Identity | A protocol used to carry and authenticate Host | | Protocol | Identifiers and other information. | | | | - | Host Identity | The cryptograhic hash used in creating the Host | + | Host Identity | The cryptographic hash used in creating the Host | | Hash | Identity Tag from the Host Identity. | | | | | Host Identity | A 128-bit datum created by taking a cryptographic | | Tag | hash over a Host Identifier plus bits to identify | | | which hash used. | | | | | Host | A public key used as a name for a Host Identity. | | Identifier | | | | | | Local Scope | A 32-bit datum denoting a Host Identity. | | Identifier | | | | | - | Public Host | A published or publicly known Host Identfier used | - | Identifier | as a public name for a Host Identity, and the | - | and Identity | corresponding Identity. | + | Public Host | A published or publicly known Host Identifier | + | Identifier | used as a public name for a Host Identity, and | + | and Identity | the corresponding Identity. | | | | | Unpublished | A Host Identifier that is not placed in any | | Host | public directory, and the corresponding Host | | Identifier | Identity. Unpublished Host Identities are | | and Identity | typically short lived in nature, being often | | | replaced and possibly used just once. | | | | | Rendezvous | A mechanism used to locate mobile hosts based on | | Mechanism | their HIT. | +---------------+---------------------------------------------------+ 3. Background The Internet is built from three principal components: computing platforms (end-points), packet transport (i.e., internetworking) infrastructure, and services (applications). The Internet exists to service two principal components: people and robotic services - (silicon based people, if you will). All these components need to be + (silicon-based people, if you will). All these components need to be named in order to interact in a scalable manner. Here we concentrate on naming computing platforms and packet transport elements. There are two principal namespaces in use in the Internet for these components: IP addresses, and Domain Names. Domain Names provide hierarchically assigned names for some computing platforms and some services. Each hierarchy is delegated from the level above; there is no anonymity in Domain Names. Email, HTTP, and SIP addresses all reference Domain Names. @@ -275,21 +286,21 @@ That is, every time an interface is connected to the network, it is assigned an IP address. In the current Internet, the transport layers are coupled to the IP addresses. Neither can evolve separately from the other. IPng deliberations were strongly shaped by the decision that a corresponding TCPng would not be created. There are three critical deficiencies with the current namespaces. Firstly, dynamic readdressing cannot be directly managed. Secondly, - anonymity is not provided in a consistent, trustable manner. + confidentiality is not provided in a consistent, trustable manner. Finally, authentication for systems and datagrams is not provided. All of these deficiencies arise because computing platforms are not well named with the current namespaces. 3.1. A desire for a namespace for computing platforms An independent namespace for computing platforms could be used in end-to-end operations independent of the evolution of the internetworking layer and across the many internetworking layers. This could support rapid readdressing of the internetworking layer @@ -303,22 +314,25 @@ Such a namespace (for computing platforms) and the names in it should have the following characteristics: o The namespace should be applied to the IP 'kernel' or stack. The IP stack is the 'component' between applications and the packet transport infrastructure. o The namespace should fully decouple the internetworking layer from the higher layers. The names should replace all occurrences of IP addresses within applications (like in the Transport Control - Block, TCB). This may require changes to the current APIs. In - the long run, it is probable that some new APIs are needed. + Block, TCB). This replacement can be handled transparently for + legacy applications as the LSIs and HITs are compatible with IPv4 + and IPv6 addresses [RFC5338]. However, HIP-aware applications + require some modifications from the developers, who may employ + networking API extensions for HIP [RFC6317]. o The introduction of the namespace should not mandate any administrative infrastructure. Deployment must come from the bottom up, in a pairwise deployment. o The names should have a fixed length representation, for easy inclusion in datagram headers and existing programming interfaces (e.g the TCB). o Using the namespace should be affordable when used in protocols. @@ -337,23 +351,20 @@ expect a collision until approximately 2**50 (1 quadrillion) hashes were generated. o The names should have a localized abstraction so that it can be used in existing protocols and APIs. o It must be possible to create names locally. When such names are not published, this can provide anonymity at the cost of making resolvability very difficult. - * Sometimes the names may contain a delegation component. This - is the cost of resolvability. - o The namespace should provide authentication services. o The names should be long lived, but replaceable at any time. This impacts access control lists; short lifetimes will tend to result in tedious list maintenance or require a namespace infrastructure for central control of access lists. In this document, a new namespace approaching these ideas is called the Host Identity namespace. Using Host Identities requires its own protocol layer, the Host Identity Protocol, between the @@ -368,37 +379,39 @@ with an IP stack. This identity is normally associated with, but not limited to, an IP stack. A system can have multiple identities, some 'well known', some unpublished or 'anonymous'. A system may self- assert its own identity, or may use a third-party authenticator like DNSSEC [RFC2535], PGP, or X.509 to 'notarize' the identity assertion to another namespace. It is expected that the Host Identifiers will initially be authenticated with DNSSEC and that all implementations will support DNSSEC as a minimal baseline. In theory, any name that can claim to be 'statistically globally - unique' may serve as a Host Identifier. However, in the authors' - opinion, a public key of a 'public key pair' makes the best Host - Identifier. As specified in the Host Identity Protocol [RFC5201-bis] - specification, a public-key-based HI can authenticate the HIP packets - and protect them for man-in-the-middle attacks. Since authenticated - datagrams are mandatory to provide much of HIP's denial-of-service - protection, the Diffie-Hellman exchange in HIP BEX has to be - authenticated. Thus, only public-key HI and authenticated HIP - messages are supported in practice. + unique' may serve as a Host Identifier. In the HIP architecture, the + public key of a private-public key pair has been chosen as the Host + Identifier because it can be self managed and it is computationally + difficult to forge. As specified in the Host Identity Protocol + [I-D.ietf-hip-rfc5201-bis] specification, a public-key-based HI can + authenticate the HIP packets and protect them for man-in-the-middle + attacks. Since authenticated datagrams are mandatory to provide much + of HIP's denial-of-service protection, the Diffie-Hellman exchange in + HIP BEX has to be authenticated. Thus, only public-key HI and + authenticated HIP messages are supported in practice. In this document, the non-cryptographic forms of HI and HIP are presented to complete the theory of HI, but they should not be implemented as they could produce worse denial-of-service attacks - than the Internet has without Host Identity. There is on-going - research in challenge puzzles to use non-cryptographic HI, like - RFIDs, in an HIP exchange tailored to the workings of such - challenges. + than the Internet has without Host Identity. There has been past + research in challenge puzzles to use non-cryptographic HI, for Radio + Frequency IDentification (RFID), in an HIP exchange tailored to the + workings of such challenges (as described further in [urien-rfid] and + [urien-rfid-draft]). 4.1. Host Identifiers Host Identity adds two main features to Internet protocols. The first is a decoupling of the internetworking and transport layers; see Section 5. This decoupling will allow for independent evolution of the two layers. Additionally, it can provide end-to-end services over multiple internetworking realms. The second feature is host authentication. Because the Host Identifier is a public key, this key can be used for authentication in security protocols like ESP. @@ -414,91 +427,148 @@ Architecturally, any other Internet naming convention might form a usable base for Host Identifiers. However, non-cryptographic names should only be used in situations of high trust - low risk. That is any place where host authentication is not needed (no risk of host spoofing) and no use of ESP. However, at least for interconnected networks spanning several operational domains, the set of environments where the risk of host spoofing allowed by non- cryptographic Host Identifiers is acceptable is the null set. Hence, the current HIP documents do not specify how to use any other types - of Host Identifiers but public keys. + of Host Identifiers but public keys. For instance, Back-to-My-Mac + [RFC6281] from Apple comes pretty close to the functionality of HIP, + but unlike HIP, it is based on non-cryptographic identifiers. - The actual Host Identifiers are never directly used in any Internet - protocols. The corresponding Host Identifiers (public keys) may be - stored in various DNS or LDAP directories as identified elsewhere in - this document, and they are passed in the HIP base exchange. A Host - Identity Tag (HIT) is used in other protocols to represent the Host - Identity. Another representation of the Host Identities, the Local - Scope Identifier (LSI), can also be used in protocols and APIs. + The actual Host Identifiers are never directly used at the transport + or network layers. The corresponding Host Identifiers (public keys) + may be stored in various DNS or other directories as identified + elsewhere in this document, and they are passed in the HIP base + exchange. A Host Identity Tag (HIT) is used in other protocols to + represent the Host Identity. Another representation of the Host + Identities, the Local Scope Identifier (LSI), can also be used in + protocols and APIs. 4.2. Host Identity Hash (HIH) - The Host Identity Hash is the cryptographic hash used in producing - the HIT from the HI. It is also the hash used through out the HIP - protocol for consistancy and simplicity. It is possible to for the - two hosts in the HIP exchange to use different hashes. + The Host Identity Hash is the cryptographic hash algorithm used in + producing the HIT from the HI. It is also the hash used through out + the HIP protocol for consistency and simplicity. It is possible to + for the two hosts in the HIP exchange to use different hash + algorithms. Multiple HIHs within HIP are needed to address the moving target of creation and eventual compromise of cryptographic hashes. This significantly complicates HIP and offers an attacker an additional - downgrade attack that is mitigated in the HIP protocol. + downgrade attack that is mitigated in the HIP protocol + [I-D.ietf-hip-rfc5201-bis]. 4.3. Host Identity Tag (HIT) A Host Identity Tag is a 128-bit representation for a Host Identity. It is created from an HIH and other information, like an IPv6 prefix and a hash identifier. There are two advantages of using the HIT over using the Host Identifier in protocols. Firstly, its fixed length makes for easier protocol coding and also better manages the packet size cost of this technology. Secondly, it presents the identity in a consistent format to the protocol independent of the cryptographic algorithms used. - There can be multiple HITs per Host Identifier when multiple hashes - are supported. An Initator may have to initially guess which HIT to - use for the Responder, typically based on what it prefers, until it - learns the appropriate HIT through the HIP exchange. + In essence, the HIT is a hash over the public key. As such, two + algorithms affect the generation of a HIT: the public-key algorithm + of the HI and the used HIH. The two algorithms are encoded in the + bit presentation of the HIT. As the two communicating parties may + support different algorithms, [I-D.ietf-hip-rfc5201-bis] defines the + minimum set for interoperability. For further interoperability, the + responder may store its keys in DNS records, and thus the initiator + may have to couple destination HITs with appropriate source HIts + according to matching HIH. In the HIP packets, the HITs identify the sender and recipient of a packet. Consequently, a HIT should be unique in the whole IP universe as long as it is being used. In the extremely rare case of a single HIT mapping to more than one Host Identity, the Host Identifiers (public keys) will make the final difference. If there is more than one public key for a given node, the HIT acts as a hint for the correct public key to use. 4.4. Local Scope Identifier (LSI) An LSI is a 32-bit localized representation for a Host Identity. The purpose of an LSI is to facilitate using Host Identities in existing - protocols and APIs. LSI's advantage over HIT is its size; its - disadvantage is its local scope. + APIs for IPv4-based applications. Besides facilitating HIP-based + connectivity for legacy IPv4 applications, the LSIs are beneficial in + two other scenarios [RFC6538]. - Examples of how LSIs can be used include: as the address in an FTP - command and as the address in a socket call. Thus, LSIs act as a - bridge for Host Identities into IPv4-based protocols and APIs. LSIs - also make it possible for some IPv4 applications to run over an IPv6 - network. + In the first scenario, two IPv4-only applications are residing on two + separate hosts connected by IPv6-only network. With HIP-based + connectivity, the two applications are able to communicate despite of + the mismatch in the protocol families of the applications and the + underlying network. The reason is that the HIP layer translates the + LSIs originating from the upper layers into routable IPv6 locators + before delivering the packets on the wire. -4.5. Storing Host Identifiers in Directories + The second scenario is the same as the first one, but with the + difference that one of the applications supports only IPv6. Now two + obstacles hinder the communication between the application: the + addressing families of the two applications differ, and the + application residing at the IPv4-only side is again unable to + communicate because of the mismatch between addressing families of + the application (IPv4) and network (IPv6). With HIP-based + connectivity for applications, this scenario works; the HIP layer can + choose whether to translate the locator of an incoming packet into an + LSI or HIT. + + Effectively, LSIs improve IPv6 interoperability at the network layer + as described in the first scenario and at the application layer as + depicted in the second example. The interoperability mechanism + should not be used to avoid transition to IPv6; the authors firmly + believe in IPv6 adoption and encourage developers to port existing + IPv4-only applications to use IPv6. However, some proprietary, + closed-source, IPv4-only applications may never see the daylight of + IPv6, and the LSI mechanism is suitable for extending the lifetime of + such applications even in IPv6-only networks. + + The main disadvantage of an LSI is its local scope. Applications may + violate layering principles and pass LSIs to each other in + application-layer protocols. As the LSIs are valid only in the + context of the local host, they may represent an entirely different + host when passed to another host. However, it should be emphasized + here that the LSI concept is effectively a host-based NAT and does + not introduce any more issues than the prevalent middlebox based NATs + for IPv4. In other words, the applications violating layering + principles are already broken by the NAT boxes that are ubiquitously + deployed. + +4.5. Storing Host Identifiers in directories The public Host Identifiers should be stored in DNS; the unpublished Host Identifiers should not be stored anywhere (besides the communicating hosts themselves). The (public) HI along with the supported HIHs are stored in a new RR type. This RR type is defined in HIP DNS Extension [I-D.ietf-hip-rfc5205-bis]. Alternatively, or in addition to storing Host Identifiers in the DNS, - they may be stored in various other directories (e.g. LDAP, DHT) or - in a Public Key Infrastructure (PKI). Such a practice may allow them - to be used for purposes other than pure host identification. + they may be stored in various other directories. For instance, + Light-weight Directory Access Protocol (LDAP) or in a Public Key + Infrastructure (PKI) [I-D.ietf-hip-rfc6253-bis]. Alternatively, + Distributed Hash Tables (DHTs) [RFC6537] have successfully been + utilized [RFC6538]. Such a practice may allow them to be used for + purposes other than pure host identification. + + Some types of application may cache and use Host Identifiers + directly, while others may indirectly discover them through symbolic + host name (such as FQDN) look up from a directory. Even though Host + Identities can have a substantially longer lifetime associate with + them than routable IP addresses, directories may be a better approach + to manage the lifespan of Host Identities. For example, a LDAP or + DHT can be used for locally published identities whereas DNS can be + more suitable for public advertisement. 5. New stack architecture One way to characterize Host Identity is to compare the proposed new architecture with the current one. As discussed above, the IP addresses can be seen to be a confounding of routing direction vectors and interface names. Using the terminology from the IRTF Name Space Research Group Report [nsrg-report] and, e.g., the unpublished Internet-Draft Endpoints and Endpoint Names [chiappa-endpoints], the IP addresses currently embody the dual role @@ -509,83 +579,158 @@ point-of-attachment, thereby acting as a end-point name. In the HIP architecture, the end-point names and locators are separated from each other. IP addresses continue to act as locators. The Host Identifiers take the role of end-point identifiers. It is important to understand that the end-point names based on Host Identities are slightly different from interface names; a Host Identity can be simultaneously reachable through several interfaces. The difference between the bindings of the logical entities are - illustrated in Figure 1. + illustrated in Figure 1. Left side illustrates the current TCP/IP + architecture and right side the HIP-based architecture. Transport ---- Socket Transport ------ Socket association | association | | | | | | | End-point | End-point --- Host Identity \ | | \ | | \ | | \ | | Location --- IP address Location --- IP address Figure 1 -5.1. Transport associations and end-points - Architecturally, HIP provides for a different binding of transport- layer protocols. That is, the transport-layer associations, i.e., TCP connections and UDP associations, are no longer bound to IP - addresses but to Host Identities. + addresses but rather to Host Identities. In practice, the Host + Identities are exposed as LSIs and HITs for legacy applications and + the transport layer to facilitate backward compatibility with + existing networking APIs and stacks. - It is possible that a single physical computer hosts several logical - end-points. With HIP, each of these end-points would have a distinct - Host Identity. Furthermore, since the transport associations are - bound to Host Identities, HIP provides for process migration and - clustered servers. That is, if a Host Identity is moved from one - physical computer to another, it is also possible to simultaneously - move all the transport associations without breaking them. - Similarly, if it is possible to distribute the processing of a single - Host Identity over several physical computers, HIP provides for - cluster based services without any changes at the client end-point. +5.1. On the multiplicity of identities -6. End-host mobility and multi-homing + For security reasons, it may be a bad idea to duplicate the same Host + Identity on multiple hosts because the compromise of a single host + taints the identities of the other hosts. Management of machines + with identical Host Identities may also present other challenges and, + therefore, it is advisable to have a unique identity for each host. + + Instead of duplicating identities, HIP opportunistic mode can be + employed, where the initiator leaves out the identifier of the + responder when initiating the key exchange and learns it upon the + completion of the exchange. The tradeoffs are related to lowered + security guarantees, but a benefit of the approach is to avoid + publishing of Host Identifiers in any directories [komu-leap]. The + approach could also be used for load balancing purposes at the HIP + layer because the identity of the responder can be decided + dynamically during the key exchange. Thus, the approach has the + potential to be used as a HIP-layer "anycast", either directly + between two hosts or indirectly through the rendezvous service + [komu-diss]. + + At the client side, a host may have multiple Host Identities, for + instance, for privacy purposes. Another reason can be that the + person utilizing the host employs different identities for different + administrative domains as an extra security measure. If a HIP-aware + middlebox, such as a HIP-based firewall, is on the path between the + client and server, the user or the underlying system should carefully + choose the correct identity to avoid the firewall to unnecessarily + drop HIP-base connectivity [komu-diss]. + + Similarly, a server may have multiple Host Identities. For instance, + a single web server may serve multiple different administrative + domains. Typically, the distinction is accomplished based on the DNS + name, but also the Host Identity could be used for this purpose. + However, a more compelling reason to employ multiple identities are + HIP-aware firewalls that are unable see the HTTP traffic inside the + encrypted IPsec tunnel. In such a case, each service could be + configured with a separate identity, thus allowing the firewall to + segregate the different services of the single web server from each + other [lindqvist-enterprise]. + +6. Control plane + + HIP decouples control and data plane from each other. The control + plane between two end-hosts is initialized using a key exchange + procedure called the base exchange. The procedure can be assisted by + new infrastructural intermediaries called rendezvous or relay + servers. In the event of IP address changes, the end-hosts sustain + control plane connectivity with mobility and multihoming extensions. + Eventually, the end-hosts terminate the control plane and remove the + associated state. + +6.1. Base exchange + + The base exchange is key exchange procedure that authenticates the + initiator and responder to each other using their public keys. + Typically, the initiator is the client-side host and the responder is + the server-side host. The roles are used by the state machine of a + HIP implementation, but discarded upon successful completion. + + The exchange consists of four messages during which the hosts also + create symmetric keys to protect the control plane with Hash-based + message authentication codes (HMACs). The keys can be also used to + protect the data plane, and IPsec ESP [I-D.ietf-hip-rfc5202-bis] is + typically used as the data-plane protocol, albeit HIP can also + accommodate others. Both the control and data plane are terminated + using a closing procedure consisting of two messages. + + The base exchange also includes a computational puzzle + [I-D.ietf-hip-rfc5201-bis] that the initiator must solve. The + responder chooses the difficulty of the puzzle which allows the + responder to delay new incoming initiators according to local + policies, for instance, when the responder is under heavy load. The + puzzle can offer some resiliency against DoS attacks because the + design of the puzzle mechanism allows the responder to remain + stateless until the very end of the base exchange [aura-dos]. HIP + puzzles have also been researched under steady-state DDoS attacks + [beal-dos], multiple adversary models with varying puzzle + difficulties [tritilanunt-dos] and ephemeral Host Identities + [komu-mitigation]. + +6.2. End-host mobility and multi-homing HIP decouples the transport from the internetworking layer, and binds the transport associations to the Host Identities (through actually - either the HIT or LSI). Consequently, HIP can provide for a degree - of internetworking mobility and multi-homing at a low infrastructure - cost. HIP mobility includes IP address changes (via any method) to - either party. Thus, a system is considered mobile if its IP address - can change dynamically for any reason like PPP, DHCP, IPv6 prefix - reassignments, or a NAT device remapping its translation. Likewise, - a system is considered multi-homed if it has more than one globally - routable IP address at the same time. HIP links IP addresses - together, when multiple IP addresses correspond to the same Host - Identity, and if one address becomes unusable, or a more preferred - address becomes available, existing transport associations can easily - be moved to another address. + either the HIT or LSI). After the initial key exchange, the HIP + layer maintains transport-layer connectivity and data flows using its + mobility [I-D.ietf-hip-rfc5206-bis] and multihoming + [I-D.ietf-hip-multihoming] extensions. Consequently, HIP can provide + for a degree of internetworking mobility and multi-homing at a low + infrastructure cost. HIP mobility includes IP address changes (via + any method) to either party. Thus, a system is considered mobile if + its IP address can change dynamically for any reason like PPP, DHCP, + IPv6 prefix reassignments, or a NAT device remapping its translation. + Likewise, a system is considered multi-homed if it has more than one + globally routable IP address at the same time. HIP links IP + addresses together, when multiple IP addresses correspond to the same + Host Identity, and if one address becomes unusable, or a more + preferred address becomes available, existing transport associations + can easily be moved to another address. When a node moves while communication is already on-going, address changes are rather straightforward. The peer of the mobile node can just accept a HIP or an integrity protected ESP packet from any address and ignore the source address. However, as discussed in - Section 6.2 below, a mobile node must send a HIP readdress packet to + Section 12.2 below, a mobile node must send a HIP UPDATE packet to inform the peer of the new address(es), and the peer must verify that the mobile node is reachable through these addresses. This is especially helpful for those situations where the peer node is sending data periodically to the mobile node (that is re-starting a connection after the initial connection). -6.1. Rendezvous mechanism +6.3. Rendezvous mechanism Making a contact to a mobile node is slightly more involved. In order to start the HIP exchange, the initiator node has to know how to reach the mobile node. Although infrequently moving HIP nodes could use Dynamic DNS [RFC2136] to update their reachability information in the DNS, an alternative to using DNS in this fashion is to use a piece of new static infrastructure to facilitate rendezvous between HIP nodes. The mobile node keeps the rendezvous infrastructure continuously @@ -594,259 +739,462 @@ address mappings. The rendezvous mechanism is also needed if both of the nodes happen to change their address at the same time, either because they are mobile and happen to move at the same time, because one of them is off-line for a while, or because of some other reason. In such a case, the HIP UPDATE packets will cross each other in the network and never reach the peer node. The HIP rendezvous mechanism is defined in HIP Rendezvous - [I-D.ietf-hip-rfc5204-bis]. - -6.2. Protection against flooding attacks - - Although the idea of informing about address changes by simply - sending packets with a new source address appears appealing, it is - not secure enough. That is, even if HIP does not rely on the source - address for anything (once the base exchange has been completed), it - appears to be necessary to check a mobile node's reachability at the - new address before actually sending any larger amounts of traffic to - the new address. - - Blindly accepting new addresses would potentially lead to flooding - Denial-of-Service attacks against third parties [RFC4225]. In a - distributed flooding attack an attacker opens high volume HIP - connections with a large number of hosts (using unpublished HIs), and - then claims to all of these hosts that it has moved to a target - node's IP address. If the peer hosts were to simply accept the move, - the result would be a packet flood to the target node's address. To - prevent this type of attack, HIP includes an address check mechanism - where the reachability of a node is separately checked at each - address before using the address for larger amounts of traffic. + specifications [I-D.ietf-hip-rfc5204-bis]. - A credit-based authorization approach Host Mobility with the Host - Identity Protocol [I-D.ietf-hip-rfc5206-bis] can be used between - hosts for sending data prior to completing the address tests. - Otherwise, if HIP is used between two hosts that fully trust each - other, the hosts may optionally decide to skip the address tests. - However, such performance optimization must be restricted to peers - that are known to be trustworthy and capable of protecting themselves - from malicious software. +6.4. Relay mechanism -7. HIP and ESP + The HIP relay mechanism [I-D.ietf-hip-native-nat-traversal] is an + alternative to the HIP rendezvous mechanism. The HIP relay mechanism + is more suitable for IPv4 networks with NATs because a HIP relay can + forward all control and data plane communications in order to + guarantee successful NAT traversal. - The preferred way of implementing HIP is to use ESP to carry the - actual data traffic. As of today, the only completely defined method - is to use ESP Encapsulated Security Payload (ESP) to carry the data - packets [I-D.ietf-hip-rfc5202-bis]. In the future, other ways of - transporting payload data may be developed, including ones that do - not use cryptographic protection. +6.5. Termination of the control plane - In practice, the HIP base exchange uses the cryptographic Host - Identifiers to set up a pair of ESP Security Associations (SAs) to - enable ESP in an end-to-end manner. This is implemented in a way - that can span addressing realms. + The control plane between two hosts can be terminated using a secure + two message procotol as specified in (XX FIXME). The related state + (i.e. host associations) should be removed upon successful + termination. - While it would be possible, at least in theory, to use some existing - cryptographic protocol, such as IKEv2 together with Host Identifiers, - to establish the needed SAs, HIP defines a new protocol. There are a - number of historical reasons for this, and there are also a few - architectural reasons. First, IKE (and IKEv2) were not designed with - middle boxes in mind. As adding a new naming layer allows one to - potentially add a new forwarding layer (see Section 9, below), it is - very important that the HIP provides mechanisms for middlebox - authentication. +7. Data plane - Second, from a conceptual point of view, the IPsec Security Parameter - Index (SPI) in ESP provides a simple compression of the HITs. This - does require per-HIT-pair SAs (and SPIs), and a decrease of policy - granularity over other Key Management Protocols, such as IKE and - IKEv2. In other words, from an architectural point of view, HIP only - supports host-to-host (or endpoint-to-endpoint) Security - Associations. + The control and data plane are decoupled in the HIP architecture. + This means that the encapsulation format for data plane used for + carrying the application-layer traffic is changeable and can is + dynamically negotiated during the key exchange. For instance, + HICCUPS extensions [RFC6078] define a way to transport application- + layer datagrams directly over the HIP control plane, protected by + asymmetric key cryptography. Also, S-RTP has been considered as the + data encapsulation protocol [hip-srtp]. However, the most widely + implemented method is the Encapsulated Security Payload (ESP) + [I-D.ietf-hip-rfc5202-bis] that is protected by symmetric keys + derived during the key exchange. ESP Security Associations (SAs) + offer both confidentiality and integrity protection, of which the + former can be disabled during the key exchange. In the future, other + ways of transporting application-layer data may be defined. - Originally, as HIP is designed for host usage, not for gateways or so - called Bump-in-the-Wire (BITW) implementations, only ESP transport - mode is supported. An ESP SA pair is indexed by the SPIs and the two - HITs (both HITs since a system can have more than one HIT). The SAs - need not to be bound to IP addresses; all internal control of the SA - is by the HITs. Thus, a host can easily change its address using - Mobile IP, DHCP, PPP, or IPv6 readdressing and still maintain the - SAs. Since the transports are bound to the SA (via an LSI or a HIT), - any active transport is also maintained. Thus, real-world conditions - like loss of a PPP connection and its re-establishment or a mobile - handover will not require a HIP negotiation or disruption of - transport services [Bel1998]. + The ESP SAs are established and terminated between the initiator and + the responder hosts. Usually, the hosts create at least two SAs, one + in each direction (initiator-to-responder SA and responder-to- + initiator SA). If the IP addresses of either host are changed, the + HIP mobility extensions can be used to re-negotiate the corresponding + SAs. - It should be noted that there are already BITW implementations of HIP - providing virtual private network (VPN) services. This is still - consistent to the SA bindings above. + On the wire, the difference in the use of identifiers between the HIP + control and data plane is that the HITs are included in all control + packets, but not in the data plane when ESP is employed. Instead, + the ESP employs SPI numbers that act as compressed HITs. Any HIP- + aware middlebox (for instance, a HIP-aware firewall) interested in + the ESP based data plane should keep track between the control and + data plane identifiers in order to associate them with each other. Since HIP does not negotiate any SA lifetimes, all lifetimes are local policy. The only lifetimes a HIP implementation must support are sequence number rollover (for replay protection), and SA timeout. An SA times out if no packets are received using that SA. - Implementations may support lifetimes for the various ESP transforms. - -8. HIP and MAC Security - - The IEEE 802 standards have been defining MAC layered security. Many - of these standards use EAP [RFC3748] as a Key Management System (KMS) - transport, but some like IEEE 802.15.4 [IEEE.802-15-4.2011] leave the - KMS and its transport as "Out of Scope". - - HIP is well suited as a KMS in these environments. - - o HIP is independent of IP addressing and can be directly - transported over any network protocol. - - o Master Keys in 802 protocols are strictly pair-based with group - keys transported from the group controller using pair-wise keys. - - o AdHoc 802 networks can be better served by a peer-to-peer KMS than - the EAP client/server model. - - o Some devices are very memory constrained and a common KMS for both - MAC and IP security represents a considerable code savings. + Implementations may support lifetimes for the various ESP transforms + and other data-plane protocols. -9. HIP and NATs +8. HIP and NATs Passing packets between different IP addressing realms requires - changing IP addresses in the packet header. This may happen, for + changing IP addresses in the packet header. This may occur, for example, when a packet is passed between the public Internet and a private address space, or between IPv4 and IPv6 networks. The address translation is usually implemented as Network Address Translation (NAT) [RFC3022] or NAT Protocol translation (NAT-PT) [RFC2766]. In a network environment where identification is based on the IP - addresses, identifying the communicating nodes is difficult when NAT - is used. With HIP, the transport-layer end-points are bound to the - Host Identities. Thus, a connection between two hosts can traverse - many addressing realm boundaries. The IP addresses are used only for - routing purposes; they may be changed freely during packet traversal. - - For a HIP-based flow, a HIP-aware NAT or NAT-PT system tracks the - mapping of HITs, and the corresponding ESP SPIs, to an IP address. - The NAT system has to learn mappings both from HITs and from SPIs to - IP addresses. Many HITs (and SPIs) can map to a single IP address on - a NAT, simplifying connections on address poor NAT interfaces. The - NAT can gain much of its knowledge from the HIP packets themselves; - however, some NAT configuration may be necessary. + addresses, identifying the communicating nodes is difficult when NATs + are employed because the private address spaces introduced by NATs + are overlapping. In other words, two hosts cannot distinguished from + each other solely based on their IP address. With HIP, the + transport-layer end-points (i.e. applications) are bound to unique + Host Identities rather than overlapping private addresses. This + makes it possible for two end-points to distinguish one other even + when they are located in private address realms. Thus, the IP + addresses used only for routing purposes; they may be changed freely + during when a packet between two hosts traverses possibly multiple + addressing realm boundaries. - NAT systems cannot touch the datagrams within the ESP envelope, thus - application-specific address translation must be done in the end - systems. HIP provides for 'Distributed NAT', and uses the HIT or the - LSI as a placeholder for embedded IP addresses. + NAT traversal extensions for HIP [I-D.ietf-hip-native-nat-traversal] + can be used to realize the actual end-to-end connectivity through NAT + devices. To support basic backward compatibility with legacy NATs, + the extensions encapsulated both HIP control and data plane in UDP. + The extensions define mechanisms for forwarding the two planes + through an intermediary host called HIP relay and procedures to + establish direct end-to-end connectivity by penetrating NATs. + Besides this "native" NAT traversal mode for HIP, other NAT traversal + mechanisms have been successfully utilized, such as Teredo + [varjonen-split]. - An experimental HIP and NAT traversal is defined in [RFC5770]. + Besides legacy NATs, a HIP-aware NAT has been designed and + implemented [ylitalo-spinat]. For a HIP-based flow, a HIP-aware NAT + or NAT-PT system tracks the mapping of HITs, and the corresponding + ESP SPIs, to an IP address. The NAT system has to learn mappings + both from HITs and from SPIs to IP addresses. Many HITs (and SPIs) + can map to a single IP address on a NAT, simplifying connections on + address poor NAT interfaces. The NAT can gain much of its knowledge + from the HIP packets themselves; however, some NAT configuration may + be necessary. -9.1. HIP and Upper-layer checksums +8.1. HIP and Upper-layer checksums There is no way for a host to know if any of the IP addresses in an IP header are the addresses used to calculate the TCP checksum. That is, it is not feasible to calculate the TCP checksum using the actual IP addresses in the pseudo header; the addresses received in the incoming packet are not necessarily the same as they were on the sending host. Furthermore, it is not possible to recompute the upper-layer checksums in the NAT/NAT-PT system, since the traffic is ESP protected. Consequently, the TCP and UDP checksums are calculated using the HITs in the place of the IP addresses in the pseudo header. Furthermore, only the IPv6 pseudo header format is used. This provides for IPv4 / IPv6 protocol translation. -10. Multicast +9. Multicast - Since its inception, a few studies have looked at how HIP might - affect IP-layer or application-layer multicast. + A number of studies have intestigating HIP-based multicast have been + published (including [shields-hip], [xueyong-hip], [xueyong-hip], + [amir-hip], [kovacshazi-host] and [xueyong-secure]). Particularly, + so called bloom filters, that allow to compressing of multiple labels + into small datastructures, may be a promising way forward + [sarela-bloom]. However, the different schemes have not been adopted + by HIP working group (nor the HIP research group in IRTF), so the + details are not further elaborated here. -11. HIP policies +10. HIP policies There are a number of variables that will influence the HIP exchanges that each host must support. All HIP implementations should support at least 2 HIs, one to publish in DNS or similar directory service and an unpublished one for anonymous usage. Although unpublished HIs will be rarely used as responder HIs, they are likely be common for initiators. Support for multiple HIs is recommended. This provides new challenges for systems or users to decide which type of HI to expose when they start a new session. - Opportunistic mode (where the initator starts a HIP exchange without - prior knowledge of the responder's HI) presents a policy tradeoff. - It provides some security benefits but may be subject to MITM. + Opportunistic mode (where the initiator starts a HIP exchange without + prior knowledge of the responder's HI) presents a security tradeoff. + At the expense of being subject to MITM attacks, the opportunistic + mode allows the initiator learn the the identity of the responder + during communications rather than from an external directory. + Opportunistic mode can be used for registering to HIP-based services + [I-D.ietf-hip-rfc5203-bis] (i.e. utilized by HIP for its own internal + purposes) or by the application layer [komu-leap]. For security + reasons, especially the latter requires some involvement from the + user to accept the identity of the responder in a similar vain as SSH + prompts the user when connecting to a server for the first time + [pham-leap]. In practice, this can be realized for with end-host + based firewalls in the case of legacy applications [karvonen-usable] + or with native APIs for HIP APIs [RFC6317] in the case of HIP-aware + applications. Many initiators would want to use a different HI for different responders. The implementations should provide for a policy of initiator HIT to responder HIT. This policy should also include preferred transforms and local lifetimes. Responders would need a similar policy, describing the hosts allowed to participate in HIP exchanges, and the preferred transforms and local lifetimes. -12. Benefits of HIP +11. Design considerations + +11.1. Benefits of HIP In the beginning, the network layer protocol (i.e., IP) had the following four "classic" invariants: - o Non-mutable: The address sent is the address received. + 1. Non-mutable: The address sent is the address received. - o Non-mobile: The address doesn't change during the course of an + 2. Non-mobile: The address doesn't change during the course of an "association". - o Reversible: A return header can always be formed by reversing the + 3. Reversible: A return header can always be formed by reversing the source and destination addresses. - o Omniscient: Each host knows what address a partner host can use to - send packets to it. + 4. Omniscient: Each host knows what address a partner host can use + to send packets to it. Actually, the fourth can be inferred from 1 and 3, but it is worth mentioning for reasons that will be obvious soon if not already. In the current "post-classic" world, we are intentionally trying to get rid of the second invariant (both for mobility and for multi- homing), and we have been forced to give up the first and the fourth. Realm Specific IP [RFC3102] is an attempt to reinstate the fourth invariant without the first invariant. IPv6 is an attempt to reinstate the first invariant. - Few systems on the Internet have DNS names that are meaningful. That - is, if they have a Fully Qualified Domain Name (FQDN), that name - typically belongs to a NAT device or a dial-up server, and does not - really identify the system itself but its current connectivity. - FQDNs (and their extensions as email names) are application-layer - names; more frequently naming services than a particular system. - This is why many systems on the Internet are not registered in the - DNS; they do not have services of interest to other Internet hosts. + Few client-side systems on the Internet have DNS names that are + meaningful. That is, if they have a Fully Qualified Domain Name + (FQDN), that name typically belongs to a NAT device or a dial-up + server, and does not really identify the system itself but its + current connectivity. FQDNs (and their extensions as email names) + are application-layer names; more frequently naming services than a + particular system. This is why many systems on the Internet are not + registered in the DNS; they do not have services of interest to other + Internet hosts. DNS names are references to IP addresses. This only demonstrates the interrelationship of the networking and application layers. DNS, as the Internet's only deployed, distributed database is also the repository of other namespaces, due in part to DNSSEC and application specific key records. Although each namespace can be stretched (IP with v6, DNS with KEY records), neither can adequately provide for host authentication or act as a separation between internetworking and transport layers. The Host Identity (HI) namespace fills an important gap between the IP and DNS namespaces. An interesting thing about the HI is that it actually allows one to give up all but the 3rd network-layer invariant. That is to say, as long as the source and destination addresses in the network-layer protocol are reversible, then things work ok because HIP takes care of host identification, and - reversibility allows one to get a packet back to one's partner host. - You do not care if the network-layer address changes in transit - (mutable) and you don't care what network-layer address the partner - is using (non-omniscient). + reversibility allows one to receive a packet back to one's partner + host. You do not care if the network-layer address changes in + transit (mutable) and you don't care what network-layer address the + partner is using (non-omniscient). -12.1. HIP's answers to NSRG questions + The Host Identity (HI) namespace fills an important gap between the + IP and DNS namespaces. An interesting thing about the HI is that it + actually allows one to give up all but the 3rd network-layer + invariant. That is to say, as long as the source and destination + addresses in the network-layer protocol are reversible, then things + work ok because HIP takes care of host identification, and + reversibility allows one to receive a packet back to one's partner + host. You do not care if the network-layer address changes in + transit (mutable) and you don't care what network-layer address the + partner is using (non-omniscient). + + The Sockets API is the de-facto API for utilize the TCP/IP stack. + Application use the Sockets API either directly or indirectly through + some libraries or frameworks. However, the Sockets API was based on + the assumption of static IP addresses and DNS with its lifetime + values was invented at later stages during the evolution of the + Internet. Hence, the Sockets API does not deal with the lifetime of + addresses [RFC6250]. As majority of the end-user equipment is mobile + today, their addresses are effectively ephemeral, but the Sockets API + still gives a fallacious illusion of persistent IP addresses to the + unwary developer. HIP can be used to solidify this illusion because + HIP provides persistent surrogate addresses to the application layer + in the form of LSIs and HITs. + + The persistent identifiers as provided by HIP are useful in multiple + scenarios (as described in more detail in e.g. [ylitalo-diss] or + [komu-diss]): + + o When a mobile host moves physically between two different WLAN + networks and obtains a new address, an application using the + identifiers remains isolated of the topology changes while the + underlying HIP layer re-establishes connectivity (i.e. a + horizontal handoff). + + o Similarly, the application utilizing the identifiers remains again + unaware of the topological changes when the underlying host + equipped with WLAN and cellular network interfaces switches + between the two different access technologies (i.e. a vertical + handoff). + + o Even when hosts are located in private address realms, + applications can uniquely distinguish different hosts from each + other based on their identifier. In other words, it can be stated + that HIP improves Internet transparency for the application layer + [komu-diss]. + + o Site renumbering events for services can occur due to corporate + mergers or acquisitions, or by changes in Internet Service + Provider. They can involve changing the entire network prefix of + an organization, which is problematic due to hard-coded addresses + in service configuration files or cached IP addresses at the + client side [RFC5887]. Considering such human errors, a site + employing location-independent identifiers as promoted by HIP may + experience less problems while renumbering their network. + + o More agile IPv6 interoperability as discussed in section + Section 4.4. IPv6-based applications can communicate using HITs + with IPv4-based applications that are using LSIs. Also, the + underlying network type (IPv4 or IPv6) becomes independent of the + addressing family of the application. + + o HITs (or LSIs) can be used in IP-based access control lists as a + more secure replacement for IPv6 addresses. Besides security, HIT + based access control has two other benefits. First, the use of + HITs halves the size of access control lists as separate rules for + IPv4 are not needed [komu-diss]. Second, HIT-based configuration + rules in HIP-aware middleboxes remain static and independent of + topology changes, thus simplifying administrative efforts + particularly for mobile environments. For instance, the benefits + of HIT based access control have been harnessed in the case of + HIP-aware firewalls, but can be utilized directly at the end-hosts + as well [RFC6538]. + + While some of these benefits could be and have been redundantly + implemented by individual applications, providing such generic + functionality at the lower layers is useful because it reduces + software development efforts and networking software bugs (as the + layer is tested with multiple applications). It also allows the + developer to focus on building the application itself rather than + delving into the intricacies of mobile networking, thus facilitating + separation of concerns. + + HIP could also be realized by combining a number of different + protocols, but the complexity of the resulting software may become + substantially larger, and the interaction multiple possibly layered + protocols may have adverse effects on latency and throughput. It is + also worth noting that virtually nothing prevents realizing the HIP + architecture, for instance, as an application-layer library, which + has been actually implemented in the past [xin-hip-lib]. However, + the tradeoff in moving the HIP layer to the application layer is that + legacy applications may not be supported. + +11.2. Drawbacks of HIP + + In computer science, many problems can be solved with an extra layer + of indirection. However, the indirection always involves some costs + as there no such thing as "free lunch". In the case of HIP, the main + costs could be stated as follows: + + o In general, a new layer and a new namespace involves always some + initial effort in terms implementation, deployment and + maintenance. Some education of people may also be needed. + However, the HIP community at the IETF have spent years in + experimenting, exploring, testing, documenting and implementing + HIP curb the amount of efforts required. + + o HIP decouples identifier and locator roles of IP addresses. + Consequently, a mapping mechanism is needed to associate them + together. A failure to map a HIT to its corresponding locator may + result in failed connectivity because a HIT is "flat" by its + nature and cannot be looked up from the hierarchically organized + DNS. HITs are flat by design due to a security tradeoff. The + more bits are allocated for the hash in the HIT, the less likely + there will be (malicious) collisions. + + o From performance viewpoint, HIP control and data plane processing + introduces some overhead in terms throughput and latency as + elaborated below. + + The key exchange introduces some extra latency (two round trips) in + connection establishment. This can further affect TCP traffic + particularly when a TCP application triggers the key exchange and the + triggering SYN packet is dropped instead of being cached. Similarly + as with the key exchange, a similar performance penalty may incur for + TCP during HIP handoff procedures. The penalty can be constrained + with caching TCP packets. Also, TCP user timeout [RFC5482] is + another way to optimize TCP behavior during handoffs + [scultz-intermittent]. + + The most CPU-intensive operations involve the use of the asymmetric + keys and Diffie-Hellman key derivation at the control plane, but this + occurs only during the key exchange, its maintenance (handoffs, + refreshing of key material) and tear down procedures of HIP + associations. The data plane is typically implemented with ESP has a + smaller overhead due to symmetric key encryption. Naturally, even + ESP involves some overhead in terms latency (processing costs) and + throughput (tunneling) (see e.g. [ylitalo-diss] for a performance + evaluation). + +11.3. Deployment and adoption considerations + + This section describes some deployment and adoption considerations + related to HIP from a technical perspective. + +11.3.1. Deployment analysis + + HIP has commercially been utilized at Boeing airplane factory for + their internal purposes[paine-hip]. It has been included in a + security product called Tofino to support layer-two Virtual Private + Networks [henderson-vpls] to facilitate, e.g, supervisory control and + data acquisition (SCADA) security. However, HIP has not been a "wild + success" [RFC5218] in the Internet as argued by Levae et al + [leva-barriers]. Here, we briefly highligt some of their findings + based on interviews with 19 experts from the industry and academia. + + From a marketing perspective, the demand for HIP has been low and + substitute technologies have been favored. Another identified reason + has been that some technical misconceptions related to the early + stages of HIP specifications still persist. Two identified + misconceptions are that HIP does not support NAT traversal, and HIP + must be implemented in the OS kernel. Both of these claims are + untrue; HIP does have NAT traversal extensions + [I-D.ietf-hip-native-nat-traversal], and kernel modifications can be + avoided with modern operating systems by diverting packets for + userspace processing. + + The analysis clarifies infrastructural requirements for HIP. In a + minimal set up, a client and server machine have to run HIP software. + However, to avoid manual configurations, usually DNS records for HIP + are set up. For instance, the popular DNS server software Bind9 does + not require any changes to accomodate DNS records for HIP because + they can be supported in binary format in its configuration files + [RFC6538]. HIP rendezvous servers and firewalls are optional. No + changes are required to network address points, NATs, edge routers or + core networks. HIP may require holes in legacy firewalls. + + The analysis also clarifies the requirements for the host components + that consist of three parts. First, a HIP control plane component is + required, typically implemented as as userspace daemon. Second, a + data plane component is needed. Most HIP implementations utilize the + so called BEET mode of ESP that has been available since Linux kernel + 2.6.27, but is included also as a userspace component in HIPL and + OpenHIP implementations. Third, HIP systems usually provide a DNS + proxy for the local host that translates HIP DNS records to LSIs and + HITs, and communicates the corresponding locators to HIP userspace + daemon. While the third component is not strictly speaking + mandatory, it is very useful for avoiding manual configurations. The + three components are further described in the HIP experiment report + [RFC6538]. + + Based on the interviews, Levae et al suggest further directions to + facilitate HIP deployment. Transitioning the HIP specifications to + the standards track may help, but other measures could be taken. As + a more radical measure, the authors suggest to implement HIP as a + purely application-layer library [xin-hip-lib] or other kind of + middleware. On the other hand, more conservative measures include + focusing on private deployments controlled by a single stakeholder. + As an a more concrete example of such a scenario, HIP could be used + by a single service provider to provide interconnectivity between its + servers [komu-cloud]. + +11.3.2. HIP in 802.15.4 networks + + The IEEE 802 standards have been defining MAC layered security. Many + of these standards use EAP [RFC3748] as a Key Management System (KMS) + transport, but some like IEEE 802.15.4 [IEEE.802-15-4.2011] leave the + KMS and its transport as "Out of Scope". + + HIP is well suited as a KMS in these environments: + + o HIP is independent of IP addressing and can be directly + transported over any network protocol. + + o Master Keys in 802 protocols are strictly pair-based with group + keys transported from the group controller using pair-wise keys. + + o AdHoc 802 networks can be better served by a peer-to-peer KMS than + the EAP client/server model. + + o Some devices are very memory constrained and a common KMS for both + MAC and IP security represents a considerable code savings. + +11.4. Answers to NSRG questions The IRTF Name Space Research Group has posed a number of evaluating questions in their report [nsrg-report]. In this section, we provide answers to these questions. 1. How would a stack name improve the overall functionality of the Internet? HIP decouples the internetworking layer from the transport layer, allowing each to evolve separately. The decoupling @@ -911,240 +1259,331 @@ of a resolution mechanisms would be required? For most purposes, an approach where DNS names are resolved simultaneously to HIs and IP addresses is sufficient. However, if it becomes necessary to resolve HIs into IP addresses or back to DNS names, a flat resolution infrastructure is needed. Such an infrastructure could be based on the ideas of Distributed Hash Tables, but would require significant new development and deployment. -13. Changes from RFC 4423 +12. Security considerations - This section summarizes the changes made from [RFC4423]. + This section includes discussion on some issues and solutions related + to security in the HIP architecture. -14. Security considerations +12.1. MiTM Attacks HIP takes advantage of the new Host Identity paradigm to provide secure authentication of hosts and to provide a fast key exchange for ESP. HIP also attempts to limit the exposure of the host to various denial-of-service (DoS) and man-in-the-middle (MitM) attacks. In so doing, HIP itself is subject to its own DoS and MitM attacks that potentially could be more damaging to a host's ability to conduct business as usual. Resource exhausting denial-of-service attacks take advantage of the cost of setting up a state for a protocol on the responder compared to the 'cheapness' on the initiator. HIP allows a responder to increase the cost of the start of state on the initiator and makes an effort to reduce the cost to the responder. This is done by having the responder start the authenticated Diffie-Hellman exchange instead - of the initiator, making the HIP base exchange 4 packets long. There - are more details on this process in the Host Identity Protocol. + of the initiator, making the HIP base exchange 4 packets long. The + first packet sent by the responder can be prebuilt to further + mitigate the costs. This packet also includes a computational puzzle + that can optionally be used to further delay the initiator, for + instance, when the responder is overloaded. The details are + explained in the base exchange specification + [I-D.ietf-hip-rfc5201-bis]. - HIP optionally supports opportunistic negotiation. That is, if a - host receives a start of transport without a HIP negotiation, it can - attempt to force a HIP exchange before accepting the connection. - This has the potential for DoS attacks against both hosts. If the - method to force the start of HIP is expensive on either host, the - attacker need only spoof a TCP SYN. This would put both systems into - the expensive operations. HIP avoids this attack by having the - responder send a simple HIP packet that it can pre-build. Since this - packet is fixed and easily replayed, the initiator only reacts to it - if it has just started a connection to the responder. + Man-in-the-middle (MitM) attacks are difficult to defend against, + without third-party authentication. A skillful MitM could easily + handle all parts of the HIP base exchange, but HIP indirectly + provides the following protection from a MitM attack. If the + responder's HI is retrieved from a signed DNS zone or securely + obtained by some other means, the initiator can use this to + authenticate the signed HIP packets. Likewise, if the initiator's HI + is in a secure DNS zone, the responder can retrieve it and validate + the signed HIP packets. However, since an initiator may choose to + use an unpublished HI, it knowingly risks a MitM attack. The + responder may choose not to accept a HIP exchange with an initiator + using an unknown HI. - Man-in-the-middle attacks are difficult to defend against, without - third-party authentication. A skillful MitM could easily handle all - parts of the HIP base exchange, but HIP indirectly provides the - following protection from a MitM attack. If the responder's HI is - retrieved from a signed DNS zone or secured by some other means, the - initiator can use this to authenticate the signed HIP packets. - Likewise, if the initiator's HI is in a secure DNS zone, the - responder can retrieve it and validate the signed HIP packets. - However, since an initiator may choose to use an unpublished HI, it - knowingly risks a MitM attack. The responder may choose not to - accept a HIP exchange with an initiator using an unknown HI. + Other types of MitM attacks against HIP can be mounted using ICMP + messages that can be used to signal about problems. As a overall + guideline, the ICMP messages should be considered as unreliable + "hints" and should be acted upon only after timeouts. The exact + attack scenarios and countermeasures are described in full detail the + base exchange specification [I-D.ietf-hip-rfc5201-bis]. The need to support multiple hashes for generating the HIT from the - HI affords the MitM a potentially powerful downgrade attack due to - the a-priori need of the HIT in the HIP base exchange. The base - exchange has been augmented to deal with such an attack by restarting - on detecting the attack. At worst this would only lead to a - situation in which the base exchange would never finish (or would be - aborted after some retries). As a drawback, this leads to an 6-way - base exchange which may seem bad at first. However, since this only - happens in an attack scenario and since the attack can be handled (so - it is not interesting to mount anymore), we assume the additional - messages are not a problem at all. Since the MitM cannot be - successful with a downgrade attack, these sorts of attacks will only - occur as 'nuisance' attacks. So, the base exchange would still be - usually just four packets even though implementations must be + HI affords the MitM to mount a potentially powerful downgrade attack + due to the a-priori need of the HIT in the HIP base exchange. The + base exchange has been augmented to deal with such an attack by + restarting on detecting the attack. At worst this would only lead to + a situation in which the base exchange would never finish (or would + be aborted after some retries). As a drawback, this leads to an + 6-way base exchange which may seem bad at first. However, since this + only occurs in an attack scenario and since the attack can be handled + (so it is not interesting to mount anymore), we assume the subsequent + messages do not represent a security threat. Since the MitM cannot + be successful with a downgrade attack, these sorts of attacks will + only occur as 'nuisance' attacks. So, the base exchange would still + be usually just four packets even though implementations must be prepared to protect themselves against the downgrade attack. In HIP, the Security Association for ESP is indexed by the SPI; the source address is always ignored, and the destination address may be ignored as well. Therefore, HIP-enabled Encapsulated Security - Payload (ESP) is IP address independent. This might seem to make it - easier for an attacker, but ESP with replay protection is already as - well protected as possible, and the removal of the IP address as a - check should not increase the exposure of ESP to DoS attacks. + Payload (ESP) is IP address independent. This might seem to make + attacking easier, but ESP with replay protection is already as well + protected as possible, and the removal of the IP address as a check + should not increase the exposure of ESP to DoS attacks. - Since not all hosts will ever support HIP, ICMPv4 'Destination - Unreachable, Protocol Unreachable' and ICMPv6 'Parameter Problem, - Unrecognized Next Header' messages are to be expected and present a - DoS attack. Against an initiator, the attack would look like the - responder does not support HIP, but shortly after receiving the ICMP - message, the initiator would receive a valid HIP packet. Thus, to - protect against this attack, an initiator should not react to an ICMP - message until a reasonable time has passed, allowing it to get the - real responder's HIP packet. A similar attack against the responder - is more involved. +12.2. Protection against flooding attacks - Another MitM attack is simulating a responder's administrative - rejection of a HIP initiation. This is a simple ICMP 'Destination - Unreachable, Administratively Prohibited' message. A HIP packet is - not used because it would either have to have unique content, and - thus difficult to generate, resulting in yet another DoS attack, or - just as spoofable as the ICMP message. Like in the previous case, - the defense against this attack is for the initiator to wait a - reasonable time period to get a valid HIP packet. If one does not - come, then the initiator has to assume that the ICMP message is - valid. Since this is the only point in the HIP base exchange where - this ICMP message is appropriate, it can be ignored at any other - point in the exchange. + Although the idea of informing about address changes by simply + sending packets with a new source address appears appealing, it is + not secure enough. That is, even if HIP does not rely on the source + address for anything (once the base exchange has been completed), it + appears to be necessary to check a mobile node's reachability at the + new address before actually sending any larger amounts of traffic to + the new address. -14.1. HITs used in ACLs + Blindly accepting new addresses would potentially lead to flooding + Denial-of-Service attacks against third parties [RFC4225]. In a + distributed flooding attack an attacker opens high volume HIP + connections with a large number of hosts (using unpublished HIs), and + then claims to all of these hosts that it has moved to a target + node's IP address. If the peer hosts were to simply accept the move, + the result would be a packet flood to the target node's address. To + prevent this type of attack, HIP mobility extensions include a return + routability check procedure where the reachability of a node is + separately checked at each address before using the address for + larger amounts of traffic. - It is expected that HITs will be used in ACLs. Future firewalls can - use HITs to control egress and ingress to networks, with an assurance - level difficult to achieve today. As discussed above in Section 7, - once a HIP session has been established, the SPI value in an ESP - packet may be used as an index, indicating the HITs. In practice, - firewalls can inspect HIP packets to learn of the bindings between - HITs, SPI values, and IP addresses. They can even explicitly control - ESP usage, dynamically opening ESP only for specific SPI values and - IP addresses. The signatures in HIP packets allow a capable firewall - to ensure that the HIP exchange is indeed happening between two known - hosts. This may increase firewall security. + A credit-based authorization approach Host Mobility with the Host + Identity Protocol [I-D.ietf-hip-rfc5206-bis] can be used between + hosts for sending data prior to completing the address tests. + Otherwise, if HIP is used between two hosts that fully trust each + other, the hosts may optionally decide to skip the address tests. + However, such performance optimization must be restricted to peers + that are known to be trustworthy and capable of protecting themselves + from malicious software. - A potential of HITs in ACLs is their 'flatness' means they cannot be - aggregated and this could result in large table searches +12.3. HITs used in ACLs + + At end-hosts, HITs can be used in IP-based access control lists at + the application and network layers". At middleboxes, HIP-aware + firewalls [lindqvist-enterprise] can use HITs or public keys to + control both ingress and egress access to networks or individual + hosts, even in the presence of mobile devices because the HITs and + public keys are topologically independent. As discussed earlier in + Section 7, once a HIP session has been established, the SPI value in + an ESP packet may be used as an index, indicating the HITs. In + practice, firewalls can inspect HIP packets to learn of the bindings + between HITs, SPI values, and IP addresses. They can even explicitly + control ESP usage, dynamically opening ESP only for specific SPI + values and IP addresses. The signatures in HIP packets allow a + capable firewall to ensure that the HIP exchange is indeed occurring + between two known hosts. This may increase firewall security. + + A potential drawback of HITs in ACLs is their 'flatness' means they + cannot be aggregated, and this could potentially result in larger + table searches in HIP-aware firewalls. A way to optimize this could + be to utilize bloom filters for grouping of HITs [sarela-bloom]. + However, it should be noted that it is also easier to exclude + individual, misbehaving hosts out when the firewall rules concern + individual HITs rather than groups. There has been considerable bad experience with distributed ACLs that contain public key related material, for example, with SSH. If the owner of a key needs to revoke it for any reason, the task of finding all locations where the key is held in an ACL may be impossible. If the reason for the revocation is due to private key theft, this could be a serious issue. A host can keep track of all of its partners that might use its HIT in an ACL by logging all remote HITs. It should only be necessary to log responder hosts. With this information, the host can notify the - various hosts about the change to the HIT. There has been no attempt - to develop a secure method to issue the HIT revocation notice. + various hosts about the change to the HIT. There has been attempts + to develop a secure method to issue the HIT revocation notice + [zhang-revocation]. - HIP-aware NATs, however, are transparent to the HIP aware systems by - design. Thus, the host may find it difficult to notify any NAT that - is using a HIT in an ACL. Since most systems will know of the NATs - for their network, there should be a process by which they can notify - these NATs of the change of the HIT. This is mandatory for systems - that function as responders behind a NAT. In a similar vein, if a - host is notified of a change in a HIT of an initiator, it should - notify its NAT of the change. In this manner, NATs will get updated - with the HIT change. + Some of the HIP-aware middleboxes, such as firewalls + [lindqvist-enterprise] or NATs [ylitalo-spinat], may observe the on- + path traffic passively. Such middleboxes are transparent by their + nature and may not get a notification when a host moves to a + different network. Thus, such middleboxes should maintain soft state + and timeout when the control and data plane between two HIP end-hosts + has been idle too long. Correspondingly, the two end-hosts may send + periodically keepalives, such as UPDATE packets or ICMP messages + inside the ESP tunnel, to sustain state at the on-path middleboxes. -14.2. Alternative HI considerations + Another aspect related to HIP-aware middleboxes is that the + association between the control and data plane, in the case of ESP, + is weak and can be exploited under certain assumptions as described + by Heer et al[heer-end-host]. In the scenario, the attacker has + already gained access to the target network protected by a HIP-aware + firewall, but wants to circumvent the HIP-based firewall. To achieve + this, the attacker passively observes a base exchange between two HIP + hosts and later replays it. This way, the attacker manages to + penetrate the firewall and can use a fake ESP tunnel to transport its + own data. This is possible because the firewall cannot distinguish + when the ESP tunnel is valid. As a solution, HIP-aware middleboxes + may participate to the control plane interaction by adding random + nonce parameters to the control traffic, which the the end-hosts have + to sign to guarantee the freshness of the control traffic + [heer-midauth]. As an alternative, extensions for transporting data + plane directly over the control plane can be used [RFC6078]. + +12.4. Alternative HI considerations The definition of the Host Identifier states that the HI need not be a public key. It implies that the HI could be any value; for example a FQDN. This document does not describe how to support such a non- - cryptographic HI. A non-cryptographic HI would still offer the - services of the HIT or LSI for NAT traversal. It would be possible - to carry HITs in HIP packets that had neither privacy nor - authentication. Since such a mode would offer so little additional - functionality for so much addition to the IP kernel, it has not been - defined. Given how little public key cryptography HIP requires, HIP - should only be implemented using public key Host Identities. + cryptographic HI, but examples of such protocol variants do exist + ([urien-rfid], [urien-rfid-draft]). A non-cryptographic HI would + still offer the services of the HIT or LSI for NAT traversal. It + would be possible to carry HITs in HIP packets that had neither + privacy nor authentication. Such schemes may be employed for + resource constrained devices, such as small sensors operating on + battery power, but are not further analyzed here. If it is desirable to use HIP in a low security situation where public key computations are considered expensive, HIP can be used with very short Diffie-Hellman and Host Identity keys. Such use makes the participating hosts vulnerable to MitM and connection hijacking attacks. However, it does not cause flooding dangers, since the address check mechanism relies on the routing system and not on cryptographic strength. -15. IANA considerations +13. IANA considerations This document has no actions for IANA. -16. Acknowledgments +14. Acknowledgments For the people historically involved in the early stages of HIP, see - the Acknowledgements section in the Host Identity Protocol + the Acknowledgments section in the Host Identity Protocol specification. During the later stages of this document, when the editing baton was - transfered to Pekka Nikander, the comments from the early - implementors and others, including Jari Arkko, Tom Henderson, Petri + transferred to Pekka Nikander, the comments from the early + implementers and others, including Jari Arkko, Tom Henderson, Petri Jokela, Miika Komu, Mika Kousa, Andrew McGregor, Jan Melen, Tim - Shepard, Jukka Ylitalo, and Jorma Wall, were invaluable. Finally, - Lars Eggert, Spencer Dawkins and Dave Crocker provided valuable input - during the final stages of publication, most of which was - incorporated but some of which the authors decided to ignore in order - to get this document published in the first place. + Shepard, Jukka Ylitalo, Sasu Tarkoma, and Jorma Wall, were + invaluable. Also, the comments from Lars Eggert, Spencer Dawkins and + Dave Crocker were also useful. The authors want to express their special thanks to Tom Henderson, who took the burden of editing the document in response to IESG comments at the time when both of the authors were busy doing other things. Without his perseverance original document might have never made it as RFC4423. - This latest effort to update and move HIP forward within the IETF - process owes its impetuous to the three HIP development teams: - Boeing, HIIT (Helsinki Institute for Information Technology), and - NomadicLab of Ericsson. Without their collective efforts HIP would - have withered as on the IETF vine as a nice concept. + This main effort to update and move HIP forward within the IETF + process owes its impetuous to a number of HIP development teams. The + authors are grateful for Boeing, Helsinki Institute for Information + Technology (HIIT), NomadicLab of Ericsson, and the three + universities: RWTH Aachen, Aalto and University of Helsinki, for + their efforts. Without their collective efforts HIP would have + withered as on the IETF vine as a nice concept. -17. References + Thanks also for Suvi Koskinen for her help with proofreading and with + the reference jungle. -17.1. Normative References +15. Changes from RFC 4423 - [RFC5201-bis] + In a nutshell, the changes from RFC 4424 [RFC4423] are mostly + editorial, including clarifications on topics described in a + difficult way and omitting some of the non-architectural + (implementation) details that are already described in other + documents. A number of missing references to the literature were + also added. New topics include the drawbacks of HIP, discussion on + 802.15.4 and MAC security, deployment considerations and description + of the base exchange. + +16. References + +16.1. Normative References + + [I-D.ietf-hip-multihoming] + Henderson, T., Vogt, C., and J. Arkko, "Host Multihoming + with the Host Identity Protocol", + draft-ietf-hip-multihoming-03 (work in progress), + July 2013. + + [I-D.ietf-hip-native-nat-traversal] + Keranen, A. and J. Melen, "Native NAT Traversal Mode for + the Host Identity Protocol", + draft-ietf-hip-native-nat-traversal-05 (work in progress), + June 2013. + + [I-D.ietf-hip-rfc5201-bis] Moskowitz, R., Heer, T., Jokela, P., and T. Henderson, "Host Identity Protocol Version 2 (HIPv2)", - draft-ietf-hip-rfc5201-bis-09 (work in progress), - July 2012. + draft-ietf-hip-rfc5201-bis-14 (work in progress), + October 2013. [I-D.ietf-hip-rfc5202-bis] Jokela, P., Moskowitz, R., and J. Melen, "Using the Encapsulating Security Payload (ESP) Transport Format with the Host Identity Protocol (HIP)", - draft-ietf-hip-rfc5202-bis-01 (work in progress), - September 2012. + draft-ietf-hip-rfc5202-bis-04 (work in progress), + September 2013. + + [I-D.ietf-hip-rfc5203-bis] + Laganier, J. and L. Eggert, "Host Identity Protocol (HIP) + Registration Extension", draft-ietf-hip-rfc5203-bis-02 + (work in progress), September 2012. [I-D.ietf-hip-rfc5204-bis] Laganier, J. and L. Eggert, "Host Identity Protocol (HIP) Rendezvous Extension", draft-ietf-hip-rfc5204-bis-02 (work in progress), September 2012. [I-D.ietf-hip-rfc5205-bis] Laganier, J., "Host Identity Protocol (HIP) Domain Name System (DNS) Extension", draft-ietf-hip-rfc5205-bis-02 (work in progress), September 2012. [I-D.ietf-hip-rfc5206-bis] Henderson, T., Vogt, C., and J. Arkko, "Host Mobility with - the Host Identity Protocol", draft-ietf-hip-rfc5206-bis-04 - (work in progress), July 2012. + the Host Identity Protocol", draft-ietf-hip-rfc5206-bis-06 + (work in progress), July 2013. -17.2. Informative references + [I-D.ietf-hip-rfc6253-bis] + Heer, T. and S. Varjonen, "Host Identity Protocol + Certificates", draft-ietf-hip-rfc6253-bis-01 (work in + progress), October 2013. + + [RFC5482] Eggert, L. and F. Gont, "TCP User Timeout Option", + RFC 5482, March 2009. + +16.2. Informative references + + [IEEE.802-15-4.2011] + "Information technology - Telecommunications and + information exchange between systems - Local and + metropolitan area networks - Specific requirements - Part + 15.4: Wireless Medium Access Control (MAC) and Physical + Layer (PHY) Specifications for Low-Rate Wireless Personal + Area Networks (WPANs)", IEEE Standard 802.15.4, + September 2011, . + + [Nik2001] Nikander, P., "Denial-of-Service, Address Ownership, and + Early Authentication in the IPv6 World", in Proceesings + of Security Protocols, 9th International Workshop, + Cambridge, UK, April 25-27 2001, LNCS 2467, pp. 12-26, + Springer, 2002. [RFC2136] Vixie, P., Thomson, S., Rekhter, Y., and J. Bound, "Dynamic Updates in the Domain Name System (DNS UPDATE)", RFC 2136, April 1997. [RFC2535] Eastlake, D., "Domain Name System Security Extensions", RFC 2535, March 1999. [RFC2766] Tsirtsis, G. and P. Srisuresh, "Network Address Translation - Protocol Translation (NAT-PT)", RFC 2766, @@ -1154,69 +1593,266 @@ Address Translator (Traditional NAT)", RFC 3022, January 2001. [RFC3102] Borella, M., Lo, J., Grabelsky, D., and G. Montenegro, "Realm Specific IP: Framework", RFC 3102, October 2001. [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. Levkowetz, "Extensible Authentication Protocol (EAP)", RFC 3748, June 2004. - [RFC4025] Richardson, M., "A Method for Storing IPsec Keying - Material in DNS", RFC 4025, March 2005. - [RFC4225] Nikander, P., Arkko, J., Aura, T., Montenegro, G., and E. Nordmark, "Mobile IP Version 6 Route Optimization Security Design Background", RFC 4225, December 2005. [RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", RFC 4306, December 2005. [RFC4423] Moskowitz, R. and P. Nikander, "Host Identity Protocol (HIP) Architecture", RFC 4423, May 2006. - [RFC5770] Komu, M., Henderson, T., Tschofenig, H., Melen, J., and A. + [RFC5218] Thaler, D. and B. Aboba, "What Makes For a Successful + Protocol?", RFC 5218, July 2008. - Keranen, "Basic Host Identity Protocol (HIP) Extensions - for Traversal of Network Address Translators", RFC 5770, - April 2010. + [RFC5338] Henderson, T., Nikander, P., and M. Komu, "Using the Host + Identity Protocol with Legacy Applications", RFC 5338, + September 2008. - [nsrg-report] - Lear, E. and R. Droms, "What's In A Name:Thoughts from the - NSRG", draft-irtf-nsrg-report-10 (work in progress), - September 2003. + [RFC5887] Carpenter, B., Atkinson, R., and H. Flinck, "Renumbering + Still Needs Work", RFC 5887, May 2010. - [IEEE.802-15-4.2011] - "Information technology - Telecommunications and - information exchange between systems - Local and - metropolitan area networks - Specific requirements - Part - 15.4: Wireless Medium Access Control (MAC) and Physical - Layer (PHY) Specifications for Low-Rate Wireless Personal - Area Networks (WPANs)", IEEE Standard 802.15.4, - September 2011, . + [RFC6078] Camarillo, G. and J. Melen, "Host Identity Protocol (HIP) + Immediate Carriage and Conveyance of Upper-Layer Protocol + Signaling (HICCUPS)", RFC 6078, January 2011. + + [RFC6250] Thaler, D., "Evolution of the IP Model", RFC 6250, + May 2011. + + [RFC6281] Cheshire, S., Zhu, Z., Wakikawa, R., and L. Zhang, + "Understanding Apple's Back to My Mac (BTMM) Service", + RFC 6281, June 2011. + + [RFC6317] Komu, M. and T. Henderson, "Basic Socket Interface + Extensions for the Host Identity Protocol (HIP)", + RFC 6317, July 2011. + + [RFC6537] Ahrenholz, J., "Host Identity Protocol Distributed Hash + Table Interface", RFC 6537, February 2012. + + [RFC6538] Henderson, T. and A. Gurtov, "The Host Identity Protocol + (HIP) Experiment Report", RFC 6538, March 2012. + + [amir-hip] + Amir, K., Forsgren, H., Grahn, K., Karvi, T., and G. + Pulkkis, "Security and Trust of Public Key Cryptography + for HIP and HIP Multicast", International Journal of + Dependable and Trustworthy Information Systems (IJDTIS), + 2(3), 17-35, DOI: 10.4018/jdtis.2011070102, 2013. + + [aura-dos] + Aura, T., Nikander, P., and J. Leiwo, "DOS-resistant + Authentication with Client Puzzles", 8th International + Workshop on Security Protocols, pages 170-177. Springer, , + April 2001. + + [beal-dos] + Beal, J. and T. Shephard, "Deamplification of DoS Attacks + via Puzzles", , October 2004. [chiappa-endpoints] Chiappa, J., "Endpoints and Endpoint Names: A Proposed Enhancement to the Internet Architecture", URL http://www.chiappa.net/~jnc/tech/endpoints.txt, 1999. - [Nik2001] Nikander, P., "Denial-of-Service, Address Ownership, and - Early Authentication in the IPv6 World", in Proceesings - of Security Protocols, 9th International Workshop, - Cambridge, UK, April 25-27 2001, LNCS 2467, pp. 12-26, - Springer, 2002. + [heer-end-host] + Heer, T., Hummen, R., Komu, M., Goetz, S., and K. Wehre, + "End-host Authentication and Authorization for Middleboxes + based on a Cryptographic Namespace", ICC2009 Communication + and Information Systems Security Symposium, , 2009. - [Bel1998] Bellovin, S., "EIDs, IPsec, and HostNAT", in Proceedings - of 41th IETF, Los Angeles, CA, - URL http://www1.cs.columbia.edu/~smb/talks/hostnat.pdf, - March 1998. + [heer-midauth] + Heer, T. and M. Komu, "End-Host Authentication for HIP + Middleboxes", Working draft draft-heer-hip-middle-auth-02, + September 2009. -Author's Address + [henderson-vpls] + Henderson, T. and D. Mattes, "", Working + draft draft-henderson-hip-vpls-06, June 2013. - Robert Moskowitz + [hip-srtp] + Tschofenig, H., Muenz, F., and M. Shanmugam, "Using SRTP + transport format with HIP", Working + draft draft-tschofenig-hiprg-hip-srtp-01, October 2005. + + [karvonen-usable] + Karvonen, K., Komu, M., and A. Gurtov, "Usable Security + Management with Host Identity Protocol", 7th ACS/IEEE + International Conference on Computer Systems and + Applications, (AICCSA-2009), 2009. + + [komu-cloud] + Komu, M., Sethi, M., Mallavarapu, R., Oirola, H., Khan, + R., and S. Tarkoma, "Secure Networking for Virtual + Machines in the Cloud", International Workshop on Power + and QoS Aware Computing (PQoSCom2012), IEEE, ISBN: 978-1- + 4244-8567-3, September 2012. + + [komu-diss] + Komu, M., "A Consolidated Namespace for Network + Applications, Developers, Administrators and Users", + Dissertation, Aalto University, Espoo, Finland ISBN: 978- + 952-60-4904-5 (printed), ISBN: 978-952-60-4905-2 + (electronic). , December 2012. + + [komu-leap] + Komu, M. and J. Lindqvist, "Leap-of-Faith Security is + Enough for IP Mobility", 6th Annual IEEE Consumer + Communications and Networking Conference IEEE CCNC 2009, + Las Vegas, Nevada, , January 2009. + + [komu-mitigation] + Komu, M., Tarkoma, S., and A. Lukyanenko, "Mitigation of + Unsolicited Traffic Across Domains with Host Identities + and Puzzles", 15th Nordic Conference on Secure IT Systems + (NordSec 2010), Springer Lecture Notes in Computer + Science, Volume 7127, pp. 33-48, ISBN: 978-3-642-27936-2, + October 2010. + + [kovacshazi-host] + Kovacshazi, Z. and R. Vida, "Host Identity Specific + Multicast", International conference on Networking and + Services (ICNS'06), IEEE Computer Society, Los Alamitos, + CA, USA, http://doi.ieeecomputersociety.org/10.1109/ + ICNS.2007.66, 2007. + + [leva-barriers] + Levae, A., Komu, M., and S. Luukkainen, "Adoption Barriers + of Network-layer Protocols: the Case of Host Identity + Protocol", The International Journal of Computer and + Telecommunications Networking, ISSN: 1389-1286, + March 2013. + + [lindqvist-enterprise] + Lindqvist, J., Vehmersalo, E., Manner, J., and M. Komu, + "Enterprise Network Packet Filtering for Mobile + Cryptographic Identities", International Journal of + Handheld Computing Research, 1 (1), 79-94, , January- + March 2010. + + [nsrg-report] + Lear, E. and R. Droms, "What's In A Name:Thoughts from the + NSRG", draft-irtf-nsrg-report-10 (work in progress), + September 2003. + + [paine-hip] + Paine, R., "Beyond HIP: The End to Hacking As We Know It", + BookSurge Publishing, ISBN: 1439256047, 9781439256046, + 2009. + + [pham-leap] + Pham, V. and T. Aura, "Security Analysis of Leap-of-Faith + Protocols", Seventh ICST International Conference on + Security and Privacy for Communication Networks, , + September 2011. + + [sarela-bloom] + Saerelae, M., Esteve Rothenberg, C., Zahemszky, A., + Nikander, P., and J. Ott, "BloomCasting: Security in Bloom + filter based multicast", , Lecture Notes in Computer + Science 2012, , pages 1-16, Springer Berlin Heidelberg, + 2012. + + [scultz-intermittent] + Schuetz, S., Eggert, L., Schmid, S., and M. Brunner, + "Protocol enhancements for intermittently connected + hosts", SIGCOMM Comput. Commun. Rev., 35(3):5-18, , + July 2005. + + [shields-hip] + Shields, C. and J. Garcia-Luna-Aceves, "The HIP protocol + for hierarchical multicast routing", Proceedings of the + seventeenth annual ACM symposium on Principles of + distributed computing, pages 257-266. ACM, New York, NY, + USA, ISBN: 0-89791-977-7, DOI: 10.1145/277697.277744, + 1998. + + [tritilanunt-dos] + Tritilanunt, S., Boyd, C., Foo, E., and J. Nieto, + "Examining the DoS Resistance of HIP", OTM Workshops (1), + volume 4277 of Lecture Notes in Computer Science, pages + 616-625,Springer , 2006. + + [urien-rfid] + Urien, P., Chabanne, H., Bouet, M., de Cunha, D., Guyot, + V., Pujolle, G., Paradinas, P., Gressier, E., and J. + Susini, "HIP-based RFID Networking Architecture", IFIP + International Conference on Wireless and Optical + Communications Networks, DOI: 10.1109/WOCN.2007.4284140, + July 2007. + + [urien-rfid-draft] + Urien, P., Lee, G., and G. Pujolle, "HIP support for + RFIDs", IRTF Working draft draft-irtf-hiprg-rfid-07, + April 2013. + + [varjonen-split] + Varjonen, S., Komu, M., and A. Gurtov, "Secure and + Efficient IPv4/IPv6 Handovers Using Host-Based Identifier- + Location Split", Journal of Communications Software and + Systems, 6(1), 2010, ISSN: 18456421, 2010. + + [xin-hip-lib] + Xin, G., "Host Identity Protocol Version 2.5", Master's + Thesis, Aalto University, Espoo, Finland, , June 2012. + + [xueyong-hip] + Xueyong, Z., Zhiguo, D., and W. Xinling, "A Multicast + Routing Algorithm Applied to HIP-Multicast Model", + Proceedings of the 2011 International Conference on + Network Computing and Information Security - Volume 01 + (NCIS '11), Vol. 1. IEEE Computer Society, Washington, DC, + USA, pages 169-174, DOI: 10.1109/NCIS.2011.42, 2011. + + [xueyong-secure] + Xueyong, Z. and J. Atwood, "A Secure Multicast Model for + Peer-to-Peer and Access Networks Using the Host Identity + Protocol", Consumer Communications and Networking + Conference. CCNC 2007. 4th IEEE, pages 1098,1102, DOI: + 10.1109/CCNC.2007.221, January 2007. + + [ylitalo-diss] + Ylitalo, J., "Secure Mobility at Multiple Granularity + Levels over Heterogeneous Datacom Networks", Dissertation, + Helsinki University of Technology, Espoo, Finland ISBN + 978-951-22-9531-9, 2008. + + [ylitalo-spinat] + Ylitalo, J., Salmela, P., and H. Tschofenig, "SPINAT: + + Integrating IPsec into overlay routing", Proceedings of + the First International Conference on Security and Privacy + for Emerging Areas in Communication Networks (SecureComm + 2005). Athens, Greece. IEEE Computer Society, pages 315- + 326, ISBN: 0-7695-2369-2, September 2005. + + [zhang-revocation] + Zhang, D., Kuptsov, D., and S. Shen, "Host Identifier + Revocation in HIP", IRTF Working + draft draft-irtf-hiprg-revocation-05, Mar 2012. + +Authors' Addresses + + Robert Moskowitz (editor) Verizon 1000 Bent Creek Blvd, Suite 200 Mechanicsburg, PA USA Email: robert.moskowitz@verizon.com + + Miika Komu + Aalto University + Konemiehentie 2 + Espoo + Finland + + Email: miika.komu@aalto.fi