draft-ietf-hip-rfc4423-bis-05.txt   draft-ietf-hip-rfc4423-bis-06.txt 
Network Working Group R. Moskowitz Network Working Group R. Moskowitz, Ed.
Internet-Draft Verizon Internet-Draft Verizon
Obsoletes: 4423 (if approved) September 28, 2012 Obsoletes: 4423 (if approved) M. Komu
Intended status: Standards Track Intended status: Informational Aalto
Expires: April 1, 2013 Expires: May 11, 2014 November 7, 2013
Host Identity Protocol Architecture Host Identity Protocol Architecture
draft-ietf-hip-rfc4423-bis-05 draft-ietf-hip-rfc4423-bis-06
Abstract Abstract
This memo describes a new namespace, the Host Identity namespace, and This memo describes a new namespace, the Host Identity namespace, and
a new protocol layer, the Host Identity Protocol, between the a new protocol layer, the Host Identity Protocol, between the
internetworking and transport layers. Herein are presented the internetworking and transport layers. Herein are presented the
basics of the current namespaces, their strengths and weaknesses, and basics of the current namespaces, their strengths and weaknesses, and
how a new namespace will add completeness to them. The roles of this how a new namespace will add completeness to them. The roles of this
new namespace in the protocols are defined. new namespace in the protocols are defined.
This document obsoletes RFC 4423 and addresses the concerns raised by This document obsoletes RFC 4423 and addresses the concerns raised by
the IESG, particularly that of crypto agility. It incorporates the IESG, particularly that of crypto agility. It incorporates
lessons learned from the implementations of RFC 5201 and goes further 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 Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 1, 2013. This Internet-Draft will expire on May 11, 2014.
Copyright Notice 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. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
skipping to change at page 3, line 7 skipping to change at page 3, line 7
modifications of such material outside the IETF Standards Process. modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other it for publication as an RFC or to translate it into languages other
than English. than English.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Terms common to other documents . . . . . . . . . . . . . . 5 2.1. Terms common to other documents . . . . . . . . . . . . . 5
2.2. Terms specific to this and other HIP documents . . . . . . . 5 2.2. Terms specific to this and other HIP documents . . . . . 5
3. Background . . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Background . . . . . . . . . . . . . . . . . . . . . . . 7
3.1. A desire for a namespace for computing platforms . . . . . . 7 3.1. A desire for a namespace for computing platforms . . . . 7
4. Host Identity namespace . . . . . . . . . . . . . . . . . . 9 4. Host Identity namespace . . . . . . . . . . . . . . . . . 9
4.1. Host Identifiers . . . . . . . . . . . . . . . . . . . . . . 10 4.1. Host Identifiers . . . . . . . . . . . . . . . . . . . . 10
4.2. Host Identity Hash (HIH) . . . . . . . . . . . . . . . . . . 10 4.2. Host Identity Hash (HIH) . . . . . . . . . . . . . . . . 11
4.3. Host Identity Tag (HIT) . . . . . . . . . . . . . . . . . . 11 4.3. Host Identity Tag (HIT) . . . . . . . . . . . . . . . . . 11
4.4. Local Scope Identifier (LSI) . . . . . . . . . . . . . . . . 11 4.4. Local Scope Identifier (LSI) . . . . . . . . . . . . . . 11
4.5. Storing Host Identifiers in Directories . . . . . . . . . . 12 4.5. Storing Host Identifiers in directories . . . . . . . . . 12
5. New stack architecture . . . . . . . . . . . . . . . . . . . 12 5. New stack architecture . . . . . . . . . . . . . . . . . 13
5.1. Transport associations and end-points . . . . . . . . . . . 13 5.1. On the multiplicity of identities . . . . . . . . . . . . 14
6. End-host mobility and multi-homing . . . . . . . . . . . . . 13 6. Control plane . . . . . . . . . . . . . . . . . . . . . . 15
6.1. Rendezvous mechanism . . . . . . . . . . . . . . . . . . . . 14 6.1. Base exchange . . . . . . . . . . . . . . . . . . . . . . 15
6.2. Protection against flooding attacks . . . . . . . . . . . . 14 6.2. End-host mobility and multi-homing . . . . . . . . . . . 16
7. HIP and ESP . . . . . . . . . . . . . . . . . . . . . . . . 15 6.3. Rendezvous mechanism . . . . . . . . . . . . . . . . . . 16
8. HIP and MAC Security . . . . . . . . . . . . . . . . . . . . 16 6.4. Relay mechanism . . . . . . . . . . . . . . . . . . . . . 17
9. HIP and NATs . . . . . . . . . . . . . . . . . . . . . . . . 17 6.5. Termination of the control plane . . . . . . . . . . . . 17
9.1. HIP and Upper-layer checksums . . . . . . . . . . . . . . . 17 7. Data plane . . . . . . . . . . . . . . . . . . . . . . . 17
10. Multicast . . . . . . . . . . . . . . . . . . . . . . . . . 18 8. HIP and NATs . . . . . . . . . . . . . . . . . . . . . . 18
11. HIP policies . . . . . . . . . . . . . . . . . . . . . . . . 18 8.1. HIP and Upper-layer checksums . . . . . . . . . . . . . . 19
12. Benefits of HIP . . . . . . . . . . . . . . . . . . . . . . 18 9. Multicast . . . . . . . . . . . . . . . . . . . . . . . . 19
12.1. HIP's answers to NSRG questions . . . . . . . . . . . . . . 19 10. HIP policies . . . . . . . . . . . . . . . . . . . . . . 20
13. Changes from RFC 4423 . . . . . . . . . . . . . . . . . . . 21 11. Design considerations . . . . . . . . . . . . . . . . . . 20
14. Security considerations . . . . . . . . . . . . . . . . . . 21 11.1. Benefits of HIP . . . . . . . . . . . . . . . . . . . . . 20
14.1. HITs used in ACLs . . . . . . . . . . . . . . . . . . . . . 23 11.2. Drawbacks of HIP . . . . . . . . . . . . . . . . . . . . 23
14.2. Alternative HI considerations . . . . . . . . . . . . . . . 24 11.3. Deployment and adoption considerations . . . . . . . . . 24
15. IANA considerations . . . . . . . . . . . . . . . . . . . . 24 11.3.1. Deployment analysis . . . . . . . . . . . . . . . . . . . 25
16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 24 11.3.2. HIP in 802.15.4 networks . . . . . . . . . . . . . . . . 26
17. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 11.4. Answers to NSRG questions . . . . . . . . . . . . . . . . 26
17.1. Normative References . . . . . . . . . . . . . . . . . . . . 25 12. Security considerations . . . . . . . . . . . . . . . . . 28
17.2. Informative references . . . . . . . . . . . . . . . . . . . 26 12.1. MiTM Attacks . . . . . . . . . . . . . . . . . . . . . . 28
Author's Address . . . . . . . . . . . . . . . . . . . . . . 27 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 1. Introduction
The Internet has two important global namespaces: Internet Protocol The Internet has two important global namespaces: Internet Protocol
(IP) addresses and Domain Name Service (DNS) names. These two (IP) addresses and Domain Name Service (DNS) names. These two
namespaces have a set of features and abstractions that have powered namespaces have a set of features and abstractions that have powered
the Internet to what it is today. They also have a number of 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 weaknesses. Basically, since they are all we have, we try and do too
much with them. Semantic overloading and functionality extensions much with them. Semantic overloading and functionality extensions
have greatly complicated these namespaces. have greatly complicated these namespaces.
skipping to change at page 4, line 42 skipping to change at page 4, line 42
There is a subtle but important difference between Host Identities There is a subtle but important difference between Host Identities
and Host Identifiers. An Identity refers to the abstract entity that and Host Identifiers. An Identity refers to the abstract entity that
is identified. An Identifier, on the other hand, refers to the is identified. An Identifier, on the other hand, refers to the
concrete bit pattern that is used in the identification process. concrete bit pattern that is used in the identification process.
Although the Host Identifiers could be used in many authentication Although the Host Identifiers could be used in many authentication
systems, such as IKEv2 [RFC4306], the presented architecture systems, such as IKEv2 [RFC4306], the presented architecture
introduces a new protocol, called the Host Identity Protocol (HIP), introduces a new protocol, called the Host Identity Protocol (HIP),
and a cryptographic exchange, called the HIP base exchange; see also and a cryptographic exchange, called the HIP base exchange; see also
Section 7. The HIP protocols provide for limited forms of trust Section 7. HIP provides for limited forms of trust between systems,
between systems, enhance mobility, multi-homing and dynamic IP enhance mobility, multi-homing and dynamic IP renumbering, aid in
renumbering, aid in protocol translation / transition, and reduce protocol translation / transition, and reduce certain types of
certain types of denial-of-service (DoS) attacks. denial-of-service (DoS) attacks.
When HIP is used, the actual payload traffic between two HIP hosts is When HIP is used, the actual payload traffic between two HIP hosts is
typically, but not necessarily, protected with ESP. The Host typically, but not necessarily, protected with ESP. The Host
Identities are used to create the needed ESP Security Associations Identities are used to create the needed ESP Security Associations
(SAs) and to authenticate the hosts. When ESP is used, the actual (SAs) and to authenticate the hosts. When ESP is used, the actual
payload IP packets do not differ in any way from standard ESP payload IP packets do not differ in any way from standard ESP
protected IP packets. protected IP packets.
Much has been learned about HIP since [RFC4423] was published. This Much has been learned about HIP [RFC6538] since [RFC4423] was
document expands Host Identities beyond use to enable IP connectivity published. This document expands Host Identities beyond use to
and security to general interhost secure signalling at any protocol enable IP connectivity and security to general interhost secure
layer. The signal may establish a security association between the signalling at any protocol layer. The signal may establish a
hosts, or simply pass information within the channel. security association between the hosts, or simply pass information
within the channel.
2. Terminology 2. Terminology
2.1. Terms common to other documents 2.1. Terms common to other documents
+---------------+---------------------------------------------------+ +---------------+---------------------------------------------------+
| Term | Explanation | | Term | Explanation |
+---------------+---------------------------------------------------+ +---------------+---------------------------------------------------+
| Public key | The public key of an asymmetric cryptographic key | | Public key | The public key of an asymmetric cryptographic key |
| | pair. Used as a publicly known identifier for | | | pair. Used as a publicly known identifier for |
| | cryptographic identity authentication. Public is | | | cryptographic identity authentication. Public is |
| | a relative term here, ranging from known to peers | | | a relative term here, ranging from known to peers |
| | only to known to the World. | | | only to known to the World. |
| | | | | |
| Private key | The private or secret key of an asymmetric | | Private key | The private or secret key of an asymmetric |
| | cryptographic key pair. Assumed to be known only | | | cryptographic key pair. Assumed to be known only |
| | to the party identified by the corresponding | | | to the party identified by the corresponding |
| | public key. Used by the identified party to | | | public key. Used by the identified party to |
| | authenticate its identity to other parties. | | | authenticate its identity to other parties. |
| | | | | |
| Public key | An asymmetric cryptographic key pair consisting | | Public key | An asymmetric cryptographic key pair consisting |
| pair | of public and private keys. For example, | | pair | of public and private keys. For example, |
| | Rivest-Shamir-Adelman (RSA) and Digital Signature | | | Rivest-Shamir-Adelman (RSA), Digital Signature |
| | Algorithm (DSA) key pairs are such key pairs. | | | Algorithm (DSA) and Elliptic Curve DSA (ECDSA) |
| | key pairs are such key pairs. |
| | | | | |
| End-point | A communicating entity. For historical reasons, | | End-point | A communicating entity. For historical reasons, |
| | the term 'computing platform' is used in this | | | the term 'computing platform' is used in this |
| | document as a (rough) synonym for end-point. | | | document as a (rough) synonym for end-point. |
+---------------+---------------------------------------------------+ +---------------+---------------------------------------------------+
2.2. Terms specific to this and other HIP documents 2.2. Terms specific to this and other HIP documents
It should be noted that many of the terms defined herein are It should be noted that many of the terms defined herein are
tautologous, self-referential or defined through circular reference tautologous, self-referential or defined through circular reference
to other terms. This is due to the succinct nature of the to other terms. This is due to the succinct nature of the
definitions. See the text elsewhere in this document and in RFC 5201 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 | | Term | Explanation |
+---------------+---------------------------------------------------+ +---------------+---------------------------------------------------+
| Computing | An entity capable of communicating and computing, | | Computing | An entity capable of communicating and computing, |
| platform | for example, a computer. See the definition of | | platform | for example, a computer. See the definition of |
| | 'End-point', above. | | | 'End-point', above. |
| | | | | |
| HIP base | A cryptographic protocol; see also Section 7. | | HIP base | A cryptographic protocol; see also Section 7. |
| exchange | | | exchange | |
| | | | | |
| HIP packet | An IP packet that carries a 'Host Identity | | HIP packet | An IP packet that carries a 'Host Identity |
| | Protocol' message. | | | Protocol' message. |
| | | | | |
| Host Identity | An abstract concept assigned to a 'computing | | Host Identity | An abstract concept assigned to a 'computing |
| | platform'. See 'Host Identifier', below. | | | platform'. See 'Host Identifier', below. |
| | | | | |
| Host Identity | A name space formed by all possible Host | | Host Identity | A name space formed by all possible Host |
| namespace | Identifiers. | | namespace | Identifiers. |
| | | | | |
| Host Identity | A protocol used to carry and authenticate Host | | Host Identity | A protocol used to carry and authenticate Host |
| Protocol | Identifiers and other information. | | 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. | | Hash | Identity Tag from the Host Identity. |
| | | | | |
| Host Identity | A 128-bit datum created by taking a cryptographic | | Host Identity | A 128-bit datum created by taking a cryptographic |
| Tag | hash over a Host Identifier plus bits to identify | | Tag | hash over a Host Identifier plus bits to identify |
| | which hash used. | | | which hash used. |
| | | | | |
| Host | A public key used as a name for a Host Identity. | | Host | A public key used as a name for a Host Identity. |
| Identifier | | | Identifier | |
| | | | | |
| Local Scope | A 32-bit datum denoting a Host Identity. | | Local Scope | A 32-bit datum denoting a Host Identity. |
| Identifier | | | Identifier | |
| | | | | |
| Public Host | A published or publicly known Host Identfier used | | Public Host | A published or publicly known Host Identifier |
| Identifier | as a public name for a Host Identity, and the | | Identifier | used as a public name for a Host Identity, and |
| and Identity | corresponding Identity. | | and Identity | the corresponding Identity. |
| | | | | |
| Unpublished | A Host Identifier that is not placed in any | | Unpublished | A Host Identifier that is not placed in any |
| Host | public directory, and the corresponding Host | | Host | public directory, and the corresponding Host |
| Identifier | Identity. Unpublished Host Identities are | | Identifier | Identity. Unpublished Host Identities are |
| and Identity | typically short lived in nature, being often | | and Identity | typically short lived in nature, being often |
| | replaced and possibly used just once. | | | replaced and possibly used just once. |
| | | | | |
| Rendezvous | A mechanism used to locate mobile hosts based on | | Rendezvous | A mechanism used to locate mobile hosts based on |
| Mechanism | their HIT. | | Mechanism | their HIT. |
+---------------+---------------------------------------------------+ +---------------+---------------------------------------------------+
3. Background 3. Background
The Internet is built from three principal components: computing The Internet is built from three principal components: computing
platforms (end-points), packet transport (i.e., internetworking) platforms (end-points), packet transport (i.e., internetworking)
infrastructure, and services (applications). The Internet exists to infrastructure, and services (applications). The Internet exists to
service two principal components: people and robotic services 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 named in order to interact in a scalable manner. Here we concentrate
on naming computing platforms and packet transport elements. on naming computing platforms and packet transport elements.
There are two principal namespaces in use in the Internet for these There are two principal namespaces in use in the Internet for these
components: IP addresses, and Domain Names. Domain Names provide components: IP addresses, and Domain Names. Domain Names provide
hierarchically assigned names for some computing platforms and some hierarchically assigned names for some computing platforms and some
services. Each hierarchy is delegated from the level above; there is services. Each hierarchy is delegated from the level above; there is
no anonymity in Domain Names. Email, HTTP, and SIP addresses all no anonymity in Domain Names. Email, HTTP, and SIP addresses all
reference Domain Names. reference Domain Names.
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That is, every time an interface is connected to the network, it is That is, every time an interface is connected to the network, it is
assigned an IP address. assigned an IP address.
In the current Internet, the transport layers are coupled to the IP In the current Internet, the transport layers are coupled to the IP
addresses. Neither can evolve separately from the other. IPng addresses. Neither can evolve separately from the other. IPng
deliberations were strongly shaped by the decision that a deliberations were strongly shaped by the decision that a
corresponding TCPng would not be created. corresponding TCPng would not be created.
There are three critical deficiencies with the current namespaces. There are three critical deficiencies with the current namespaces.
Firstly, dynamic readdressing cannot be directly managed. Secondly, 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. Finally, authentication for systems and datagrams is not provided.
All of these deficiencies arise because computing platforms are not All of these deficiencies arise because computing platforms are not
well named with the current namespaces. well named with the current namespaces.
3.1. A desire for a namespace for computing platforms 3.1. A desire for a namespace for computing platforms
An independent namespace for computing platforms could be used in An independent namespace for computing platforms could be used in
end-to-end operations independent of the evolution of the end-to-end operations independent of the evolution of the
internetworking layer and across the many internetworking layers. internetworking layer and across the many internetworking layers.
This could support rapid readdressing of the internetworking layer This could support rapid readdressing of the internetworking layer
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Such a namespace (for computing platforms) and the names in it should Such a namespace (for computing platforms) and the names in it should
have the following characteristics: have the following characteristics:
o The namespace should be applied to the IP 'kernel' or stack. The o The namespace should be applied to the IP 'kernel' or stack. The
IP stack is the 'component' between applications and the packet IP stack is the 'component' between applications and the packet
transport infrastructure. transport infrastructure.
o The namespace should fully decouple the internetworking layer from o The namespace should fully decouple the internetworking layer from
the higher layers. The names should replace all occurrences of IP the higher layers. The names should replace all occurrences of IP
addresses within applications (like in the Transport Control addresses within applications (like in the Transport Control
Block, TCB). This may require changes to the current APIs. In Block, TCB). This replacement can be handled transparently for
the long run, it is probable that some new APIs are needed. 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 o The introduction of the namespace should not mandate any
administrative infrastructure. Deployment must come from the administrative infrastructure. Deployment must come from the
bottom up, in a pairwise deployment. bottom up, in a pairwise deployment.
o The names should have a fixed length representation, for easy o The names should have a fixed length representation, for easy
inclusion in datagram headers and existing programming interfaces inclusion in datagram headers and existing programming interfaces
(e.g the TCB). (e.g the TCB).
o Using the namespace should be affordable when used in protocols. o Using the namespace should be affordable when used in protocols.
skipping to change at page 9, line 9 skipping to change at page 9, line 12
expect a collision until approximately 2**50 (1 quadrillion) expect a collision until approximately 2**50 (1 quadrillion)
hashes were generated. hashes were generated.
o The names should have a localized abstraction so that it can be o The names should have a localized abstraction so that it can be
used in existing protocols and APIs. used in existing protocols and APIs.
o It must be possible to create names locally. When such names are o It must be possible to create names locally. When such names are
not published, this can provide anonymity at the cost of making not published, this can provide anonymity at the cost of making
resolvability very difficult. 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 namespace should provide authentication services.
o The names should be long lived, but replaceable at any time. This o The names should be long lived, but replaceable at any time. This
impacts access control lists; short lifetimes will tend to result impacts access control lists; short lifetimes will tend to result
in tedious list maintenance or require a namespace infrastructure in tedious list maintenance or require a namespace infrastructure
for central control of access lists. for central control of access lists.
In this document, a new namespace approaching these ideas is called In this document, a new namespace approaching these ideas is called
the Host Identity namespace. Using Host Identities requires its own the Host Identity namespace. Using Host Identities requires its own
protocol layer, the Host Identity Protocol, between the protocol layer, the Host Identity Protocol, between the
skipping to change at page 9, line 40 skipping to change at page 9, line 40
with an IP stack. This identity is normally associated with, but not with an IP stack. This identity is normally associated with, but not
limited to, an IP stack. A system can have multiple identities, some limited to, an IP stack. A system can have multiple identities, some
'well known', some unpublished or 'anonymous'. A system may self- 'well known', some unpublished or 'anonymous'. A system may self-
assert its own identity, or may use a third-party authenticator like assert its own identity, or may use a third-party authenticator like
DNSSEC [RFC2535], PGP, or X.509 to 'notarize' the identity assertion DNSSEC [RFC2535], PGP, or X.509 to 'notarize' the identity assertion
to another namespace. It is expected that the Host Identifiers will to another namespace. It is expected that the Host Identifiers will
initially be authenticated with DNSSEC and that all implementations initially be authenticated with DNSSEC and that all implementations
will support DNSSEC as a minimal baseline. will support DNSSEC as a minimal baseline.
In theory, any name that can claim to be 'statistically globally In theory, any name that can claim to be 'statistically globally
unique' may serve as a Host Identifier. However, in the authors' unique' may serve as a Host Identifier. In the HIP architecture, the
opinion, a public key of a 'public key pair' makes the best Host public key of a private-public key pair has been chosen as the Host
Identifier. As specified in the Host Identity Protocol [RFC5201-bis] Identifier because it can be self managed and it is computationally
specification, a public-key-based HI can authenticate the HIP packets difficult to forge. As specified in the Host Identity Protocol
and protect them for man-in-the-middle attacks. Since authenticated [I-D.ietf-hip-rfc5201-bis] specification, a public-key-based HI can
datagrams are mandatory to provide much of HIP's denial-of-service authenticate the HIP packets and protect them for man-in-the-middle
protection, the Diffie-Hellman exchange in HIP BEX has to be attacks. Since authenticated datagrams are mandatory to provide much
authenticated. Thus, only public-key HI and authenticated HIP of HIP's denial-of-service protection, the Diffie-Hellman exchange in
messages are supported in practice. 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 In this document, the non-cryptographic forms of HI and HIP are
presented to complete the theory of HI, but they should not be presented to complete the theory of HI, but they should not be
implemented as they could produce worse denial-of-service attacks implemented as they could produce worse denial-of-service attacks
than the Internet has without Host Identity. There is on-going than the Internet has without Host Identity. There has been past
research in challenge puzzles to use non-cryptographic HI, like research in challenge puzzles to use non-cryptographic HI, for Radio
RFIDs, in an HIP exchange tailored to the workings of such Frequency IDentification (RFID), in an HIP exchange tailored to the
challenges. workings of such challenges (as described further in [urien-rfid] and
[urien-rfid-draft]).
4.1. Host Identifiers 4.1. Host Identifiers
Host Identity adds two main features to Internet protocols. The Host Identity adds two main features to Internet protocols. The
first is a decoupling of the internetworking and transport layers; first is a decoupling of the internetworking and transport layers;
see Section 5. This decoupling will allow for independent evolution see Section 5. This decoupling will allow for independent evolution
of the two layers. Additionally, it can provide end-to-end services of the two layers. Additionally, it can provide end-to-end services
over multiple internetworking realms. The second feature is host over multiple internetworking realms. The second feature is host
authentication. Because the Host Identifier is a public key, this authentication. Because the Host Identifier is a public key, this
key can be used for authentication in security protocols like ESP. key can be used for authentication in security protocols like ESP.
skipping to change at page 10, line 38 skipping to change at page 10, line 40
Architecturally, any other Internet naming convention might form a Architecturally, any other Internet naming convention might form a
usable base for Host Identifiers. However, non-cryptographic names usable base for Host Identifiers. However, non-cryptographic names
should only be used in situations of high trust - low risk. That is 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 any place where host authentication is not needed (no risk of host
spoofing) and no use of ESP. However, at least for interconnected spoofing) and no use of ESP. However, at least for interconnected
networks spanning several operational domains, the set of networks spanning several operational domains, the set of
environments where the risk of host spoofing allowed by non- environments where the risk of host spoofing allowed by non-
cryptographic Host Identifiers is acceptable is the null set. Hence, cryptographic Host Identifiers is acceptable is the null set. Hence,
the current HIP documents do not specify how to use any other types 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 The actual Host Identifiers are never directly used at the transport
protocols. The corresponding Host Identifiers (public keys) may be or network layers. The corresponding Host Identifiers (public keys)
stored in various DNS or LDAP directories as identified elsewhere in may be stored in various DNS or other directories as identified
this document, and they are passed in the HIP base exchange. A Host elsewhere in this document, and they are passed in the HIP base
Identity Tag (HIT) is used in other protocols to represent the Host exchange. A Host Identity Tag (HIT) is used in other protocols to
Identity. Another representation of the Host Identities, the Local represent the Host Identity. Another representation of the Host
Scope Identifier (LSI), can also be used in protocols and APIs. Identities, the Local Scope Identifier (LSI), can also be used in
protocols and APIs.
4.2. Host Identity Hash (HIH) 4.2. Host Identity Hash (HIH)
The Host Identity Hash is the cryptographic hash used in producing The Host Identity Hash is the cryptographic hash algorithm used in
the HIT from the HI. It is also the hash used through out the HIP producing the HIT from the HI. It is also the hash used through out
protocol for consistancy and simplicity. It is possible to for the the HIP protocol for consistency and simplicity. It is possible to
two hosts in the HIP exchange to use different hashes. 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 Multiple HIHs within HIP are needed to address the moving target of
creation and eventual compromise of cryptographic hashes. This creation and eventual compromise of cryptographic hashes. This
significantly complicates HIP and offers an attacker an additional 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) 4.3. Host Identity Tag (HIT)
A Host Identity Tag is a 128-bit representation for a Host Identity. 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 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 and a hash identifier. There are two advantages of using the HIT
over using the Host Identifier in protocols. Firstly, its fixed over using the Host Identifier in protocols. Firstly, its fixed
length makes for easier protocol coding and also better manages the length makes for easier protocol coding and also better manages the
packet size cost of this technology. Secondly, it presents the packet size cost of this technology. Secondly, it presents the
identity in a consistent format to the protocol independent of the identity in a consistent format to the protocol independent of the
cryptographic algorithms used. cryptographic algorithms used.
There can be multiple HITs per Host Identifier when multiple hashes In essence, the HIT is a hash over the public key. As such, two
are supported. An Initator may have to initially guess which HIT to algorithms affect the generation of a HIT: the public-key algorithm
use for the Responder, typically based on what it prefers, until it of the HI and the used HIH. The two algorithms are encoded in the
learns the appropriate HIT through the HIP exchange. 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 In the HIP packets, the HITs identify the sender and recipient of a
packet. Consequently, a HIT should be unique in the whole IP 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 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 a single HIT mapping to more than one Host Identity, the Host
Identifiers (public keys) will make the final difference. If there 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 is more than one public key for a given node, the HIT acts as a hint
for the correct public key to use. for the correct public key to use.
4.4. Local Scope Identifier (LSI) 4.4. Local Scope Identifier (LSI)
An LSI is a 32-bit localized representation for a Host Identity. The 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 purpose of an LSI is to facilitate using Host Identities in existing
protocols and APIs. LSI's advantage over HIT is its size; its APIs for IPv4-based applications. Besides facilitating HIP-based
disadvantage is its local scope. 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 In the first scenario, two IPv4-only applications are residing on two
command and as the address in a socket call. Thus, LSIs act as a separate hosts connected by IPv6-only network. With HIP-based
bridge for Host Identities into IPv4-based protocols and APIs. LSIs connectivity, the two applications are able to communicate despite of
also make it possible for some IPv4 applications to run over an IPv6 the mismatch in the protocol families of the applications and the
network. 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 The public Host Identifiers should be stored in DNS; the unpublished
Host Identifiers should not be stored anywhere (besides the Host Identifiers should not be stored anywhere (besides the
communicating hosts themselves). The (public) HI along with the communicating hosts themselves). The (public) HI along with the
supported HIHs are stored in a new RR type. This RR type is defined supported HIHs are stored in a new RR type. This RR type is defined
in HIP DNS Extension [I-D.ietf-hip-rfc5205-bis]. in HIP DNS Extension [I-D.ietf-hip-rfc5205-bis].
Alternatively, or in addition to storing Host Identifiers in the DNS, Alternatively, or in addition to storing Host Identifiers in the DNS,
they may be stored in various other directories (e.g. LDAP, DHT) or they may be stored in various other directories. For instance,
in a Public Key Infrastructure (PKI). Such a practice may allow them Light-weight Directory Access Protocol (LDAP) or in a Public Key
to be used for purposes other than pure host identification. 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 5. New stack architecture
One way to characterize Host Identity is to compare the proposed new One way to characterize Host Identity is to compare the proposed new
architecture with the current one. As discussed above, the IP architecture with the current one. As discussed above, the IP
addresses can be seen to be a confounding of routing direction addresses can be seen to be a confounding of routing direction
vectors and interface names. Using the terminology from the IRTF vectors and interface names. Using the terminology from the IRTF
Name Space Research Group Report [nsrg-report] and, e.g., the Name Space Research Group Report [nsrg-report] and, e.g., the
unpublished Internet-Draft Endpoints and Endpoint Names unpublished Internet-Draft Endpoints and Endpoint Names
[chiappa-endpoints], the IP addresses currently embody the dual role [chiappa-endpoints], the IP addresses currently embody the dual role
skipping to change at page 12, line 41 skipping to change at page 13, line 47
point-of-attachment, thereby acting as a end-point name. point-of-attachment, thereby acting as a end-point name.
In the HIP architecture, the end-point names and locators are In the HIP architecture, the end-point names and locators are
separated from each other. IP addresses continue to act as locators. separated from each other. IP addresses continue to act as locators.
The Host Identifiers take the role of end-point identifiers. It is The Host Identifiers take the role of end-point identifiers. It is
important to understand that the end-point names based on Host important to understand that the end-point names based on Host
Identities are slightly different from interface names; a Host Identities are slightly different from interface names; a Host
Identity can be simultaneously reachable through several interfaces. Identity can be simultaneously reachable through several interfaces.
The difference between the bindings of the logical entities are 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 Transport ---- Socket Transport ------ Socket
association | association | association | association |
| | | |
| | | |
| | | |
End-point | End-point --- Host Identity End-point | End-point --- Host Identity
\ | | \ | |
\ | | \ | |
\ | | \ | |
\ | | \ | |
Location --- IP address Location --- IP address Location --- IP address Location --- IP address
Figure 1 Figure 1
5.1. Transport associations and end-points
Architecturally, HIP provides for a different binding of transport- Architecturally, HIP provides for a different binding of transport-
layer protocols. That is, the transport-layer associations, i.e., layer protocols. That is, the transport-layer associations, i.e.,
TCP connections and UDP associations, are no longer bound to IP 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 5.1. On the multiplicity of identities
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.
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 HIP decouples the transport from the internetworking layer, and binds
the transport associations to the Host Identities (through actually the transport associations to the Host Identities (through actually
either the HIT or LSI). Consequently, HIP can provide for a degree either the HIT or LSI). After the initial key exchange, the HIP
of internetworking mobility and multi-homing at a low infrastructure layer maintains transport-layer connectivity and data flows using its
cost. HIP mobility includes IP address changes (via any method) to mobility [I-D.ietf-hip-rfc5206-bis] and multihoming
either party. Thus, a system is considered mobile if its IP address [I-D.ietf-hip-multihoming] extensions. Consequently, HIP can provide
can change dynamically for any reason like PPP, DHCP, IPv6 prefix for a degree of internetworking mobility and multi-homing at a low
reassignments, or a NAT device remapping its translation. Likewise, infrastructure cost. HIP mobility includes IP address changes (via
a system is considered multi-homed if it has more than one globally any method) to either party. Thus, a system is considered mobile if
routable IP address at the same time. HIP links IP addresses its IP address can change dynamically for any reason like PPP, DHCP,
together, when multiple IP addresses correspond to the same Host IPv6 prefix reassignments, or a NAT device remapping its translation.
Identity, and if one address becomes unusable, or a more preferred Likewise, a system is considered multi-homed if it has more than one
address becomes available, existing transport associations can easily globally routable IP address at the same time. HIP links IP
be moved to another address. 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 When a node moves while communication is already on-going, address
changes are rather straightforward. The peer of the mobile node can changes are rather straightforward. The peer of the mobile node can
just accept a HIP or an integrity protected ESP packet from any just accept a HIP or an integrity protected ESP packet from any
address and ignore the source address. However, as discussed in 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 inform the peer of the new address(es), and the peer must verify that
the mobile node is reachable through these addresses. This is the mobile node is reachable through these addresses. This is
especially helpful for those situations where the peer node is especially helpful for those situations where the peer node is
sending data periodically to the mobile node (that is re-starting a sending data periodically to the mobile node (that is re-starting a
connection after the initial connection). 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 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 order to start the HIP exchange, the initiator node has to know how
to reach the mobile node. Although infrequently moving HIP nodes to reach the mobile node. Although infrequently moving HIP nodes
could use Dynamic DNS [RFC2136] to update their reachability could use Dynamic DNS [RFC2136] to update their reachability
information in the DNS, an alternative to using DNS in this fashion information in the DNS, an alternative to using DNS in this fashion
is to use a piece of new static infrastructure to facilitate is to use a piece of new static infrastructure to facilitate
rendezvous between HIP nodes. rendezvous between HIP nodes.
The mobile node keeps the rendezvous infrastructure continuously The mobile node keeps the rendezvous infrastructure continuously
skipping to change at page 14, line 41 skipping to change at page 17, line 19
address mappings. address mappings.
The rendezvous mechanism is also needed if both of the nodes happen The rendezvous mechanism is also needed if both of the nodes happen
to change their address at the same time, either because they are 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 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 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 case, the HIP UPDATE packets will cross each other in the network and
never reach the peer node. never reach the peer node.
The HIP rendezvous mechanism is defined in HIP Rendezvous The HIP rendezvous mechanism is defined in HIP Rendezvous
[I-D.ietf-hip-rfc5204-bis]. specifications [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.
A credit-based authorization approach Host Mobility with the Host 6.4. Relay mechanism
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.
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 6.5. Termination of the control plane
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.
In practice, the HIP base exchange uses the cryptographic Host The control plane between two hosts can be terminated using a secure
Identifiers to set up a pair of ESP Security Associations (SAs) to two message procotol as specified in (XX FIXME). The related state
enable ESP in an end-to-end manner. This is implemented in a way (i.e. host associations) should be removed upon successful
that can span addressing realms. termination.
While it would be possible, at least in theory, to use some existing 7. Data plane
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.
Second, from a conceptual point of view, the IPsec Security Parameter The control and data plane are decoupled in the HIP architecture.
Index (SPI) in ESP provides a simple compression of the HITs. This This means that the encapsulation format for data plane used for
does require per-HIT-pair SAs (and SPIs), and a decrease of policy carrying the application-layer traffic is changeable and can is
granularity over other Key Management Protocols, such as IKE and dynamically negotiated during the key exchange. For instance,
IKEv2. In other words, from an architectural point of view, HIP only HICCUPS extensions [RFC6078] define a way to transport application-
supports host-to-host (or endpoint-to-endpoint) Security layer datagrams directly over the HIP control plane, protected by
Associations. 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 The ESP SAs are established and terminated between the initiator and
called Bump-in-the-Wire (BITW) implementations, only ESP transport the responder hosts. Usually, the hosts create at least two SAs, one
mode is supported. An ESP SA pair is indexed by the SPIs and the two in each direction (initiator-to-responder SA and responder-to-
HITs (both HITs since a system can have more than one HIT). The SAs initiator SA). If the IP addresses of either host are changed, the
need not to be bound to IP addresses; all internal control of the SA HIP mobility extensions can be used to re-negotiate the corresponding
is by the HITs. Thus, a host can easily change its address using SAs.
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].
It should be noted that there are already BITW implementations of HIP On the wire, the difference in the use of identifiers between the HIP
providing virtual private network (VPN) services. This is still control and data plane is that the HITs are included in all control
consistent to the SA bindings above. 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 Since HIP does not negotiate any SA lifetimes, all lifetimes are
local policy. The only lifetimes a HIP implementation must support local policy. The only lifetimes a HIP implementation must support
are sequence number rollover (for replay protection), and SA timeout. are sequence number rollover (for replay protection), and SA timeout.
An SA times out if no packets are received using that SA. An SA times out if no packets are received using that SA.
Implementations may support lifetimes for the various ESP transforms. Implementations may support lifetimes for the various ESP transforms
and other data-plane protocols.
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.
9. HIP and NATs 8. HIP and NATs
Passing packets between different IP addressing realms requires 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 example, when a packet is passed between the public Internet and a
private address space, or between IPv4 and IPv6 networks. The private address space, or between IPv4 and IPv6 networks. The
address translation is usually implemented as Network Address address translation is usually implemented as Network Address
Translation (NAT) [RFC3022] or NAT Protocol translation (NAT-PT) Translation (NAT) [RFC3022] or NAT Protocol translation (NAT-PT)
[RFC2766]. [RFC2766].
In a network environment where identification is based on the IP In a network environment where identification is based on the IP
addresses, identifying the communicating nodes is difficult when NAT addresses, identifying the communicating nodes is difficult when NATs
is used. With HIP, the transport-layer end-points are bound to the are employed because the private address spaces introduced by NATs
Host Identities. Thus, a connection between two hosts can traverse are overlapping. In other words, two hosts cannot distinguished from
many addressing realm boundaries. The IP addresses are used only for each other solely based on their IP address. With HIP, the
routing purposes; they may be changed freely during packet traversal. transport-layer end-points (i.e. applications) are bound to unique
Host Identities rather than overlapping private addresses. This
For a HIP-based flow, a HIP-aware NAT or NAT-PT system tracks the makes it possible for two end-points to distinguish one other even
mapping of HITs, and the corresponding ESP SPIs, to an IP address. when they are located in private address realms. Thus, the IP
The NAT system has to learn mappings both from HITs and from SPIs to addresses used only for routing purposes; they may be changed freely
IP addresses. Many HITs (and SPIs) can map to a single IP address on during when a packet between two hosts traverses possibly multiple
a NAT, simplifying connections on address poor NAT interfaces. The addressing realm boundaries.
NAT can gain much of its knowledge from the HIP packets themselves;
however, some NAT configuration may be necessary.
NAT systems cannot touch the datagrams within the ESP envelope, thus NAT traversal extensions for HIP [I-D.ietf-hip-native-nat-traversal]
application-specific address translation must be done in the end can be used to realize the actual end-to-end connectivity through NAT
systems. HIP provides for 'Distributed NAT', and uses the HIT or the devices. To support basic backward compatibility with legacy NATs,
LSI as a placeholder for embedded IP addresses. 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 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 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 is, it is not feasible to calculate the TCP checksum using the actual
IP addresses in the pseudo header; the addresses received in the IP addresses in the pseudo header; the addresses received in the
incoming packet are not necessarily the same as they were on the incoming packet are not necessarily the same as they were on the
sending host. Furthermore, it is not possible to recompute the sending host. Furthermore, it is not possible to recompute the
upper-layer checksums in the NAT/NAT-PT system, since the traffic is upper-layer checksums in the NAT/NAT-PT system, since the traffic is
ESP protected. Consequently, the TCP and UDP checksums are ESP protected. Consequently, the TCP and UDP checksums are
calculated using the HITs in the place of the IP addresses in the calculated using the HITs in the place of the IP addresses in the
pseudo header. Furthermore, only the IPv6 pseudo header format is pseudo header. Furthermore, only the IPv6 pseudo header format is
used. This provides for IPv4 / IPv6 protocol translation. used. This provides for IPv4 / IPv6 protocol translation.
10. Multicast 9. Multicast
Since its inception, a few studies have looked at how HIP might A number of studies have intestigating HIP-based multicast have been
affect IP-layer or application-layer multicast. 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 There are a number of variables that will influence the HIP exchanges
that each host must support. All HIP implementations should support that each host must support. All HIP implementations should support
at least 2 HIs, one to publish in DNS or similar directory service at least 2 HIs, one to publish in DNS or similar directory service
and an unpublished one for anonymous usage. Although unpublished HIs and an unpublished one for anonymous usage. Although unpublished HIs
will be rarely used as responder HIs, they are likely be common for will be rarely used as responder HIs, they are likely be common for
initiators. Support for multiple HIs is recommended. This provides initiators. Support for multiple HIs is recommended. This provides
new challenges for systems or users to decide which type of HI to new challenges for systems or users to decide which type of HI to
expose when they start a new session. expose when they start a new session.
Opportunistic mode (where the initator starts a HIP exchange without Opportunistic mode (where the initiator starts a HIP exchange without
prior knowledge of the responder's HI) presents a policy tradeoff. prior knowledge of the responder's HI) presents a security tradeoff.
It provides some security benefits but may be subject to MITM. 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 Many initiators would want to use a different HI for different
responders. The implementations should provide for a policy of responders. The implementations should provide for a policy of
initiator HIT to responder HIT. This policy should also include initiator HIT to responder HIT. This policy should also include
preferred transforms and local lifetimes. preferred transforms and local lifetimes.
Responders would need a similar policy, describing the hosts allowed Responders would need a similar policy, describing the hosts allowed
to participate in HIP exchanges, and the preferred transforms and to participate in HIP exchanges, and the preferred transforms and
local lifetimes. 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 In the beginning, the network layer protocol (i.e., IP) had the
following four "classic" invariants: 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". "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. source and destination addresses.
o Omniscient: Each host knows what address a partner host can use to 4. Omniscient: Each host knows what address a partner host can use
send packets to it. to send packets to it.
Actually, the fourth can be inferred from 1 and 3, but it is worth 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. mentioning for reasons that will be obvious soon if not already.
In the current "post-classic" world, we are intentionally trying to In the current "post-classic" world, we are intentionally trying to
get rid of the second invariant (both for mobility and for multi- 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. 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 Realm Specific IP [RFC3102] is an attempt to reinstate the fourth
invariant without the first invariant. IPv6 is an attempt to invariant without the first invariant. IPv6 is an attempt to
reinstate the first invariant. reinstate the first invariant.
Few systems on the Internet have DNS names that are meaningful. That Few client-side systems on the Internet have DNS names that are
is, if they have a Fully Qualified Domain Name (FQDN), that name meaningful. That is, if they have a Fully Qualified Domain Name
typically belongs to a NAT device or a dial-up server, and does not (FQDN), that name typically belongs to a NAT device or a dial-up
really identify the system itself but its current connectivity. server, and does not really identify the system itself but its
FQDNs (and their extensions as email names) are application-layer current connectivity. FQDNs (and their extensions as email names)
names; more frequently naming services than a particular system. are application-layer names; more frequently naming services than a
This is why many systems on the Internet are not registered in the particular system. This is why many systems on the Internet are not
DNS; they do not have services of interest to other Internet hosts. 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 DNS names are references to IP addresses. This only demonstrates the
interrelationship of the networking and application layers. DNS, as interrelationship of the networking and application layers. DNS, as
the Internet's only deployed, distributed database is also the the Internet's only deployed, distributed database is also the
repository of other namespaces, due in part to DNSSEC and application repository of other namespaces, due in part to DNSSEC and application
specific key records. Although each namespace can be stretched (IP specific key records. Although each namespace can be stretched (IP
with v6, DNS with KEY records), neither can adequately provide for with v6, DNS with KEY records), neither can adequately provide for
host authentication or act as a separation between internetworking host authentication or act as a separation between internetworking
and transport layers. and transport layers.
The Host Identity (HI) namespace fills an important gap between the The Host Identity (HI) namespace fills an important gap between the
IP and DNS namespaces. An interesting thing about the HI is that it 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 actually allows one to give up all but the 3rd network-layer
invariant. That is to say, as long as the source and destination invariant. That is to say, as long as the source and destination
addresses in the network-layer protocol are reversible, then things addresses in the network-layer protocol are reversible, then things
work ok because HIP takes care of host identification, and work ok because HIP takes care of host identification, and
reversibility allows one to get a packet back to one's partner host. reversibility allows one to receive a packet back to one's partner
You do not care if the network-layer address changes in transit host. You do not care if the network-layer address changes in
(mutable) and you don't care what network-layer address the partner transit (mutable) and you don't care what network-layer address the
is using (non-omniscient). 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 The IRTF Name Space Research Group has posed a number of evaluating
questions in their report [nsrg-report]. In this section, we provide questions in their report [nsrg-report]. In this section, we provide
answers to these questions. answers to these questions.
1. How would a stack name improve the overall functionality of the 1. How would a stack name improve the overall functionality of the
Internet? Internet?
HIP decouples the internetworking layer from the transport HIP decouples the internetworking layer from the transport
layer, allowing each to evolve separately. The decoupling layer, allowing each to evolve separately. The decoupling
skipping to change at page 21, line 31 skipping to change at page 28, line 17
of a resolution mechanisms would be required? of a resolution mechanisms would be required?
For most purposes, an approach where DNS names are resolved For most purposes, an approach where DNS names are resolved
simultaneously to HIs and IP addresses is sufficient. simultaneously to HIs and IP addresses is sufficient.
However, if it becomes necessary to resolve HIs into IP However, if it becomes necessary to resolve HIs into IP
addresses or back to DNS names, a flat resolution addresses or back to DNS names, a flat resolution
infrastructure is needed. Such an infrastructure could be infrastructure is needed. Such an infrastructure could be
based on the ideas of Distributed Hash Tables, but would based on the ideas of Distributed Hash Tables, but would
require significant new development and deployment. 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 HIP takes advantage of the new Host Identity paradigm to provide
secure authentication of hosts and to provide a fast key exchange for 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 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 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 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 potentially could be more damaging to a host's ability to conduct
business as usual. business as usual.
Resource exhausting denial-of-service attacks take advantage of the Resource exhausting denial-of-service attacks take advantage of the
cost of setting up a state for a protocol on the responder compared cost of setting up a state for a protocol on the responder compared
to the 'cheapness' on the initiator. HIP allows a responder to 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 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 effort to reduce the cost to the responder. This is done by having
the responder start the authenticated Diffie-Hellman exchange instead the responder start the authenticated Diffie-Hellman exchange instead
of the initiator, making the HIP base exchange 4 packets long. There of the initiator, making the HIP base exchange 4 packets long. The
are more details on this process in the Host Identity Protocol. 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 Man-in-the-middle (MitM) attacks are difficult to defend against,
host receives a start of transport without a HIP negotiation, it can without third-party authentication. A skillful MitM could easily
attempt to force a HIP exchange before accepting the connection. handle all parts of the HIP base exchange, but HIP indirectly
This has the potential for DoS attacks against both hosts. If the provides the following protection from a MitM attack. If the
method to force the start of HIP is expensive on either host, the responder's HI is retrieved from a signed DNS zone or securely
attacker need only spoof a TCP SYN. This would put both systems into obtained by some other means, the initiator can use this to
the expensive operations. HIP avoids this attack by having the authenticate the signed HIP packets. Likewise, if the initiator's HI
responder send a simple HIP packet that it can pre-build. Since this is in a secure DNS zone, the responder can retrieve it and validate
packet is fixed and easily replayed, the initiator only reacts to it the signed HIP packets. However, since an initiator may choose to
if it has just started a connection to the responder. 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 Other types of MitM attacks against HIP can be mounted using ICMP
third-party authentication. A skillful MitM could easily handle all messages that can be used to signal about problems. As a overall
parts of the HIP base exchange, but HIP indirectly provides the guideline, the ICMP messages should be considered as unreliable
following protection from a MitM attack. If the responder's HI is "hints" and should be acted upon only after timeouts. The exact
retrieved from a signed DNS zone or secured by some other means, the attack scenarios and countermeasures are described in full detail the
initiator can use this to authenticate the signed HIP packets. base exchange specification [I-D.ietf-hip-rfc5201-bis].
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.
The need to support multiple hashes for generating the HIT from the The need to support multiple hashes for generating the HIT from the
HI affords the MitM a potentially powerful downgrade attack due to HI affords the MitM to mount a potentially powerful downgrade attack
the a-priori need of the HIT in the HIP base exchange. The base due to the a-priori need of the HIT in the HIP base exchange. The
exchange has been augmented to deal with such an attack by restarting base exchange has been augmented to deal with such an attack by
on detecting the attack. At worst this would only lead to a restarting on detecting the attack. At worst this would only lead to
situation in which the base exchange would never finish (or would be a situation in which the base exchange would never finish (or would
aborted after some retries). As a drawback, this leads to an 6-way be aborted after some retries). As a drawback, this leads to an
base exchange which may seem bad at first. However, since this only 6-way base exchange which may seem bad at first. However, since this
happens in an attack scenario and since the attack can be handled (so only occurs in an attack scenario and since the attack can be handled
it is not interesting to mount anymore), we assume the additional (so it is not interesting to mount anymore), we assume the subsequent
messages are not a problem at all. Since the MitM cannot be messages do not represent a security threat. Since the MitM cannot
successful with a downgrade attack, these sorts of attacks will only be successful with a downgrade attack, these sorts of attacks will
occur as 'nuisance' attacks. So, the base exchange would still be only occur as 'nuisance' attacks. So, the base exchange would still
usually just four packets even though implementations must be be usually just four packets even though implementations must be
prepared to protect themselves against the downgrade attack. prepared to protect themselves against the downgrade attack.
In HIP, the Security Association for ESP is indexed by the SPI; the In HIP, the Security Association for ESP is indexed by the SPI; the
source address is always ignored, and the destination address may be source address is always ignored, and the destination address may be
ignored as well. Therefore, HIP-enabled Encapsulated Security ignored as well. Therefore, HIP-enabled Encapsulated Security
Payload (ESP) is IP address independent. This might seem to make it Payload (ESP) is IP address independent. This might seem to make
easier for an attacker, but ESP with replay protection is already as attacking easier, but ESP with replay protection is already as well
well protected as possible, and the removal of the IP address as a protected as possible, and the removal of the IP address as a check
check should not increase the exposure of ESP to DoS attacks. should not increase the exposure of ESP to DoS attacks.
Since not all hosts will ever support HIP, ICMPv4 'Destination 12.2. Protection against flooding attacks
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.
Another MitM attack is simulating a responder's administrative Although the idea of informing about address changes by simply
rejection of a HIP initiation. This is a simple ICMP 'Destination sending packets with a new source address appears appealing, it is
Unreachable, Administratively Prohibited' message. A HIP packet is not secure enough. That is, even if HIP does not rely on the source
not used because it would either have to have unique content, and address for anything (once the base exchange has been completed), it
thus difficult to generate, resulting in yet another DoS attack, or appears to be necessary to check a mobile node's reachability at the
just as spoofable as the ICMP message. Like in the previous case, new address before actually sending any larger amounts of traffic to
the defense against this attack is for the initiator to wait a the new address.
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.
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 A credit-based authorization approach Host Mobility with the Host
use HITs to control egress and ingress to networks, with an assurance Identity Protocol [I-D.ietf-hip-rfc5206-bis] can be used between
level difficult to achieve today. As discussed above in Section 7, hosts for sending data prior to completing the address tests.
once a HIP session has been established, the SPI value in an ESP Otherwise, if HIP is used between two hosts that fully trust each
packet may be used as an index, indicating the HITs. In practice, other, the hosts may optionally decide to skip the address tests.
firewalls can inspect HIP packets to learn of the bindings between However, such performance optimization must be restricted to peers
HITs, SPI values, and IP addresses. They can even explicitly control that are known to be trustworthy and capable of protecting themselves
ESP usage, dynamically opening ESP only for specific SPI values and from malicious software.
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 potential of HITs in ACLs is their 'flatness' means they cannot be 12.3. HITs used in ACLs
aggregated and this could result in large table searches
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 There has been considerable bad experience with distributed ACLs that
contain public key related material, for example, with SSH. If the 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 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 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 the reason for the revocation is due to private key theft, this could
be a serious issue. be a serious issue.
A host can keep track of all of its partners that might use its HIT 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 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 log responder hosts. With this information, the host can notify the
various hosts about the change to the HIT. There has been no attempt various hosts about the change to the HIT. There has been attempts
to develop a secure method to issue the HIT revocation notice. 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 Some of the HIP-aware middleboxes, such as firewalls
design. Thus, the host may find it difficult to notify any NAT that [lindqvist-enterprise] or NATs [ylitalo-spinat], may observe the on-
is using a HIT in an ACL. Since most systems will know of the NATs path traffic passively. Such middleboxes are transparent by their
for their network, there should be a process by which they can notify nature and may not get a notification when a host moves to a
these NATs of the change of the HIT. This is mandatory for systems different network. Thus, such middleboxes should maintain soft state
that function as responders behind a NAT. In a similar vein, if a and timeout when the control and data plane between two HIP end-hosts
host is notified of a change in a HIT of an initiator, it should has been idle too long. Correspondingly, the two end-hosts may send
notify its NAT of the change. In this manner, NATs will get updated periodically keepalives, such as UPDATE packets or ICMP messages
with the HIT change. 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 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 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- a FQDN. This document does not describe how to support such a non-
cryptographic HI. A non-cryptographic HI would still offer the cryptographic HI, but examples of such protocol variants do exist
services of the HIT or LSI for NAT traversal. It would be possible ([urien-rfid], [urien-rfid-draft]). A non-cryptographic HI would
to carry HITs in HIP packets that had neither privacy nor still offer the services of the HIT or LSI for NAT traversal. It
authentication. Since such a mode would offer so little additional would be possible to carry HITs in HIP packets that had neither
functionality for so much addition to the IP kernel, it has not been privacy nor authentication. Such schemes may be employed for
defined. Given how little public key cryptography HIP requires, HIP resource constrained devices, such as small sensors operating on
should only be implemented using public key Host Identities. battery power, but are not further analyzed here.
If it is desirable to use HIP in a low security situation where If it is desirable to use HIP in a low security situation where
public key computations are considered expensive, HIP can be used public key computations are considered expensive, HIP can be used
with very short Diffie-Hellman and Host Identity keys. Such use with very short Diffie-Hellman and Host Identity keys. Such use
makes the participating hosts vulnerable to MitM and connection makes the participating hosts vulnerable to MitM and connection
hijacking attacks. However, it does not cause flooding dangers, hijacking attacks. However, it does not cause flooding dangers,
since the address check mechanism relies on the routing system and since the address check mechanism relies on the routing system and
not on cryptographic strength. not on cryptographic strength.
15. IANA considerations 13. IANA considerations
This document has no actions for IANA. This document has no actions for IANA.
16. Acknowledgments 14. Acknowledgments
For the people historically involved in the early stages of HIP, see 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. specification.
During the later stages of this document, when the editing baton was During the later stages of this document, when the editing baton was
transfered to Pekka Nikander, the comments from the early transferred to Pekka Nikander, the comments from the early
implementors and others, including Jari Arkko, Tom Henderson, Petri implementers and others, including Jari Arkko, Tom Henderson, Petri
Jokela, Miika Komu, Mika Kousa, Andrew McGregor, Jan Melen, Tim Jokela, Miika Komu, Mika Kousa, Andrew McGregor, Jan Melen, Tim
Shepard, Jukka Ylitalo, and Jorma Wall, were invaluable. Finally, Shepard, Jukka Ylitalo, Sasu Tarkoma, and Jorma Wall, were
Lars Eggert, Spencer Dawkins and Dave Crocker provided valuable input invaluable. Also, the comments from Lars Eggert, Spencer Dawkins and
during the final stages of publication, most of which was Dave Crocker were also useful.
incorporated but some of which the authors decided to ignore in order
to get this document published in the first place.
The authors want to express their special thanks to Tom Henderson, The authors want to express their special thanks to Tom Henderson,
who took the burden of editing the document in response to IESG 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 comments at the time when both of the authors were busy doing other
things. Without his perseverance original document might have never things. Without his perseverance original document might have never
made it as RFC4423. made it as RFC4423.
This latest effort to update and move HIP forward within the IETF This main effort to update and move HIP forward within the IETF
process owes its impetuous to the three HIP development teams: process owes its impetuous to a number of HIP development teams. The
Boeing, HIIT (Helsinki Institute for Information Technology), and authors are grateful for Boeing, Helsinki Institute for Information
NomadicLab of Ericsson. Without their collective efforts HIP would Technology (HIIT), NomadicLab of Ericsson, and the three
have withered as on the IETF vine as a nice concept. 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, Moskowitz, R., Heer, T., Jokela, P., and T. Henderson,
"Host Identity Protocol Version 2 (HIPv2)", "Host Identity Protocol Version 2 (HIPv2)",
draft-ietf-hip-rfc5201-bis-09 (work in progress), draft-ietf-hip-rfc5201-bis-14 (work in progress),
July 2012. October 2013.
[I-D.ietf-hip-rfc5202-bis] [I-D.ietf-hip-rfc5202-bis]
Jokela, P., Moskowitz, R., and J. Melen, "Using the Jokela, P., Moskowitz, R., and J. Melen, "Using the
Encapsulating Security Payload (ESP) Transport Format with Encapsulating Security Payload (ESP) Transport Format with
the Host Identity Protocol (HIP)", the Host Identity Protocol (HIP)",
draft-ietf-hip-rfc5202-bis-01 (work in progress), draft-ietf-hip-rfc5202-bis-04 (work in progress),
September 2012. 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] [I-D.ietf-hip-rfc5204-bis]
Laganier, J. and L. Eggert, "Host Identity Protocol (HIP) Laganier, J. and L. Eggert, "Host Identity Protocol (HIP)
Rendezvous Extension", draft-ietf-hip-rfc5204-bis-02 (work Rendezvous Extension", draft-ietf-hip-rfc5204-bis-02 (work
in progress), September 2012. in progress), September 2012.
[I-D.ietf-hip-rfc5205-bis] [I-D.ietf-hip-rfc5205-bis]
Laganier, J., "Host Identity Protocol (HIP) Domain Name Laganier, J., "Host Identity Protocol (HIP) Domain Name
System (DNS) Extension", draft-ietf-hip-rfc5205-bis-02 System (DNS) Extension", draft-ietf-hip-rfc5205-bis-02
(work in progress), September 2012. (work in progress), September 2012.
[I-D.ietf-hip-rfc5206-bis] [I-D.ietf-hip-rfc5206-bis]
Henderson, T., Vogt, C., and J. Arkko, "Host Mobility with Henderson, T., Vogt, C., and J. Arkko, "Host Mobility with
the Host Identity Protocol", draft-ietf-hip-rfc5206-bis-04 the Host Identity Protocol", draft-ietf-hip-rfc5206-bis-06
(work in progress), July 2012. (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, <http://standards.ieee.org/getieee802/
download/802.15.4-2011.pdf>.
[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, [RFC2136] Vixie, P., Thomson, S., Rekhter, Y., and J. Bound,
"Dynamic Updates in the Domain Name System (DNS UPDATE)", "Dynamic Updates in the Domain Name System (DNS UPDATE)",
RFC 2136, April 1997. RFC 2136, April 1997.
[RFC2535] Eastlake, D., "Domain Name System Security Extensions", [RFC2535] Eastlake, D., "Domain Name System Security Extensions",
RFC 2535, March 1999. RFC 2535, March 1999.
[RFC2766] Tsirtsis, G. and P. Srisuresh, "Network Address [RFC2766] Tsirtsis, G. and P. Srisuresh, "Network Address
Translation - Protocol Translation (NAT-PT)", RFC 2766, Translation - Protocol Translation (NAT-PT)", RFC 2766,
skipping to change at page 26, line 39 skipping to change at page 35, line 17
Address Translator (Traditional NAT)", RFC 3022, Address Translator (Traditional NAT)", RFC 3022,
January 2001. January 2001.
[RFC3102] Borella, M., Lo, J., Grabelsky, D., and G. Montenegro, [RFC3102] Borella, M., Lo, J., Grabelsky, D., and G. Montenegro,
"Realm Specific IP: Framework", RFC 3102, October 2001. "Realm Specific IP: Framework", RFC 3102, October 2001.
[RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
Levkowetz, "Extensible Authentication Protocol (EAP)", Levkowetz, "Extensible Authentication Protocol (EAP)",
RFC 3748, June 2004. 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. [RFC4225] Nikander, P., Arkko, J., Aura, T., Montenegro, G., and E.
Nordmark, "Mobile IP Version 6 Route Optimization Security Nordmark, "Mobile IP Version 6 Route Optimization Security
Design Background", RFC 4225, December 2005. Design Background", RFC 4225, December 2005.
[RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", [RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol",
RFC 4306, December 2005. RFC 4306, December 2005.
[RFC4423] Moskowitz, R. and P. Nikander, "Host Identity Protocol [RFC4423] Moskowitz, R. and P. Nikander, "Host Identity Protocol
(HIP) Architecture", RFC 4423, May 2006. (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 [RFC5338] Henderson, T., Nikander, P., and M. Komu, "Using the Host
for Traversal of Network Address Translators", RFC 5770, Identity Protocol with Legacy Applications", RFC 5338,
April 2010. September 2008.
[nsrg-report] [RFC5887] Carpenter, B., Atkinson, R., and H. Flinck, "Renumbering
Lear, E. and R. Droms, "What's In A Name:Thoughts from the Still Needs Work", RFC 5887, May 2010.
NSRG", draft-irtf-nsrg-report-10 (work in progress),
September 2003.
[IEEE.802-15-4.2011] [RFC6078] Camarillo, G. and J. Melen, "Host Identity Protocol (HIP)
"Information technology - Telecommunications and Immediate Carriage and Conveyance of Upper-Layer Protocol
information exchange between systems - Local and Signaling (HICCUPS)", RFC 6078, January 2011.
metropolitan area networks - Specific requirements - Part
15.4: Wireless Medium Access Control (MAC) and Physical [RFC6250] Thaler, D., "Evolution of the IP Model", RFC 6250,
Layer (PHY) Specifications for Low-Rate Wireless Personal May 2011.
Area Networks (WPANs)", IEEE Standard 802.15.4,
September 2011, <http://standards.ieee.org/getieee802/ [RFC6281] Cheshire, S., Zhu, Z., Wakikawa, R., and L. Zhang,
download/802.15.4-2011.pdf>. "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-endpoints]
Chiappa, J., "Endpoints and Endpoint Names: A Proposed Chiappa, J., "Endpoints and Endpoint Names: A Proposed
Enhancement to the Internet Architecture", Enhancement to the Internet Architecture",
URL http://www.chiappa.net/~jnc/tech/endpoints.txt, 1999. URL http://www.chiappa.net/~jnc/tech/endpoints.txt, 1999.
[Nik2001] Nikander, P., "Denial-of-Service, Address Ownership, and [heer-end-host]
Early Authentication in the IPv6 World", in Proceesings Heer, T., Hummen, R., Komu, M., Goetz, S., and K. Wehre,
of Security Protocols, 9th International Workshop, "End-host Authentication and Authorization for Middleboxes
Cambridge, UK, April 25-27 2001, LNCS 2467, pp. 12-26, based on a Cryptographic Namespace", ICC2009 Communication
Springer, 2002. and Information Systems Security Symposium, , 2009.
[Bel1998] Bellovin, S., "EIDs, IPsec, and HostNAT", in Proceedings [heer-midauth]
of 41th IETF, Los Angeles, CA, Heer, T. and M. Komu, "End-Host Authentication for HIP
URL http://www1.cs.columbia.edu/~smb/talks/hostnat.pdf, Middleboxes", Working draft draft-heer-hip-middle-auth-02,
March 1998. 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
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[lindqvist-enterprise]
Lindqvist, J., Vehmersalo, E., Manner, J., and M. Komu,
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[nsrg-report]
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[paine-hip]
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[sarela-bloom]
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[scultz-intermittent]
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[shields-hip]
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[tritilanunt-dos]
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[urien-rfid]
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[varjonen-split]
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[xin-hip-lib]
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[xueyong-hip]
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[xueyong-secure]
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[ylitalo-diss]
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Authors' Addresses
Robert Moskowitz (editor)
Verizon Verizon
1000 Bent Creek Blvd, Suite 200 1000 Bent Creek Blvd, Suite 200
Mechanicsburg, PA Mechanicsburg, PA
USA USA
Email: robert.moskowitz@verizon.com Email: robert.moskowitz@verizon.com
Miika Komu
Aalto University
Konemiehentie 2
Espoo
Finland
Email: miika.komu@aalto.fi
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