Problem and Applicability Statement for Better-Than-Nothing Security (BTNS)
RFC 5387
Network Working Group J. Touch
Request for Comments: 5387 USC/ISI
Category: Informational D. Black
EMC
Y. Wang
Microsoft
November 2008
Problem and Applicability Statement
for Better-Than-Nothing Security (BTNS)
Status of This Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
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Abstract
The Internet network security protocol suite, IPsec, requires
authentication, usually of network-layer entities, to enable access
control and provide security services. This authentication can be
based on mechanisms such as pre-shared symmetric keys, certificates
with associated asymmetric keys, or the use of Kerberos (via
Kerberized Internet Negotiation of Keys (KINK)). The need to deploy
authentication information and its associated identities can be a
significant obstacle to the use of IPsec.
This document explains the rationale for extending the Internet
network security protocol suite to enable use of IPsec security
services without authentication. These extensions are intended to
protect communication, providing "better-than-nothing security"
(BTNS). The extensions may be used on their own (this use is called
Stand-Alone BTNS, or SAB) or may be used to provide network-layer
security that can be authenticated by higher layers in the protocol
Touch, et al. Informational [Page 1]
RFC 5387 BTNS Problem and Applicability November 2008
stack (this use is called Channel-Bound BTNS, or CBB). The document
also explains situations for which use of SAB and/or CBB extensions
are applicable.
Table of Contents
1. Introduction ....................................................3
1.1. Authentication .............................................3
1.2. IPsec Channels and Channel Binding .........................4
1.3. BTNS Methods ...............................................6
1.4. BTNS Scope .................................................6
1.5. Structure of This Document .................................7
2. Problem Statement ...............................................7
2.1. Network Layer ..............................................8
2.1.1. Authentication Identities ...........................8
2.1.2. Authentication Methods ..............................8
2.1.3. Current IPsec Limits on Unauthenticated Peers .......9
2.2. Higher Layer Issues ........................................9
2.2.1. Transport Protection from Packet Spoofing ...........9
2.2.2. Authentication at Multiple Layers ..................10
3. BTNS Overview and Threat Models ................................12
3.1. BTNS Overview .............................................12
3.2. BTNS and IPsec Security Services ..........................13
3.3. BTNS and IPsec Modes ......................................14
4. Applicability Statement ........................................15
4.1. Benefits ..................................................16
4.2. Vulnerabilities ...........................................16
4.3. Stand-Alone BTNS (SAB) ....................................17
4.3.1. Symmetric SAB ......................................17
4.3.2. Asymmetric SAB .....................................18
4.4. Channel-Bound BTNS (CBB) ..................................18
4.5. Summary of Uses, Vulnerabilities, and Benefits ............19
5. Security Considerations ........................................20
5.1. Threat Models and Evaluation ..............................20
5.2. Interaction with Other Security Services ..................20
5.3. MITM and Masquerader Attacks ..............................21
5.4. Denial of Service (DoS) Attacks and Resource
Consumptions ..............................................22
5.5. Exposure to Anonymous Access ..............................22
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