Internet DRAFT - draft-housley-implementer-obligations
draft-housley-implementer-obligations
INTERNET-DRAFT R. Housley
Intended Status: Informational Vigil Security
Expires: 10 November 2014 10 May 2014
Expectations of Implementers of IETF Protocols
<draft-housley-implementer-obligations-02>
Abstract
By choosing to implement an IETF protocol, one is expected to follow
the specification, associated best current practices, and IANA
registry practices.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
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Copyright and License Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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publication of this document. Please review these documents
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to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
1. Introduction
This document provides advice to implementers of IETF protocols to
improve interoperability of their implementations.
IETF protocols foster interoperability. This interoperability brings
great benefits. IETF protocols are building blocks for many products
and services, and they enable innovation. Yet, IETF standards are
voluntary standards. No one is required to implement them.
Implementation is a choice. By making this choice, an implementor is
expected to:
(1) Follow the protocol specification;
(2) Follow associated Best Current Practices (BCPs); and
(3) Follow associated IANA registry practices.
When implementers meet these expectations, protocols interoperate as
intended by the IETF.
These expectations reflect the fundamental philosophy of the IETF.
That is, interoperability is achieved when people choose to
cooperate. By taking these actions one can expect to achieve greater
interoperability with others.
2. First Expectation: Follow the Protocol Specification
To repeat, IETF protocols foster interoperability, and this
interoperability brings great benefits. If one does not follow the
protocol specification, then interoperability is jeopardized.
Of course, one should follow Postel's Law while implementing the
specification:
In general, an implementation should be conservative in its
sending behavior, and liberal in its receiving behavior. [RFC760]
Following Postel's Law simply increases interoperability. One should
be careful to send well-formed protocol data units and carefully
follow elements of procedure; which avoids surprises for
communicating peers that use other implementations. On the other
hand, one should accept any protocol data unit that can be
interpreted, which heightens interoperability in the face of
technical errors by others.
Many protocol specifications are living documents; things that change
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over time. An implementer should plan to maintain their
implementation. It is not sufficient to do an initial implementation
of the protocol. One needs to apply changes as they come out. The
most obvious and urgent example involves specification revisions that
fix security issues that are found after the initial publication of a
protocol specification.
3. Second Expectation: Follow Associated Best Current Practices
Best Current Practices (BCPs) about IETF protocols (not the BCPs that
define IETF processes and procedures) are intended to standardize
practices.
The Internet is composed of networks operated by a great variety of
organizations, with diverse goals and rules. By following the BCPs,
implementers, operators, and administrators are able to provide a
common experience when using the protocol, regardless of their point
of attachment to the Internet.
Sometimes BCPs are referenced in the protocol specification. Often
the implementer needs to look through the BCP index to find related
BCPs.
4. Third Expectation: Follow Associated IANA Registry Practices
Many IETF protocols use identifiers consisting of constants and other
well-known values. Even after a protocol has been defined and
deployed, new values may be needed. To ensure that such quantities
have consistent values and interpretations across all
implementations, assignment is administered by a central authority,
the Internet Assigned Numbers Authority (IANA). In order to manage a
namespace (which might also be called an assigned number, an assigned
value, a code point, a a protocol constant, or a protocol parameter)
in support of a particular IETF protocol, IANA is given instructions
and conditions under which new values should be assigned or when
modifications to existing values can be made.
Implementers are expected to follow the IANA registry practices
associated with the protocol, especially in the assignment of new
values. By following these practices, other implementations will
learn about new values and make the appropriate updates to handle
them properly.
Note that IP addresses and the top levels of the DNS name hierarchy
are managed in IANA registries [RFC2860]. Please follow the IANA
registry practices for the assignment of special IP addresses and
top-level DNS names in the rare cases where such values are needed.
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5. Security Considerations
This document calls for implementers to follow the protocol
specification, follow associated best current practices, and follow
IANA registry practices. These actions improve interoperability, and
these actions may also reduce security incidents due to incomplete
protocol implementations.
It is not sufficient to do an initial implementation of the protocol.
Maintenance is needed to apply changes as they come out in the
future, especially to fix security issues that are found after the
initial publication of a protocol specification.
Security processing is an exception to Postel's Law. For example, a
password that is close, but not exactly right, is not sufficient to
gain access. Processing associated with integrity, authentication,
access control, and confidentiality mechanisms cannot be forgiving.
6. IANA Considerations
This document has no actions for IANA.
7. Acknowledgements
Thanks to the people that reviewed this document and suggested
important improvements, including Bernard Aboba, Richard Barnes,
Scott Brim, Randy Bush, John Curran, Lars Eggert, Adrian Farrel,
Stephen Farrell, and Joel Jaeggli.
8. Normative References
[RFC2860] Carpenter, B., Baker, F., and M. Roberts, "Memorandum of
Understanding Concerning the Technical Work of the
Internet Assigned Numbers Authority", RFC 2860, June 2000.
9. Informative References
[RFC760] Postel, J., "DoD standard Internet Protocol", RFC 760,
January 1980.
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Author's Address
Russ Housley
Vigil Security, LLC
918 Spring Knoll Drive
Herndon, VA 20170
USA
EMail: housley@vigilsec.com
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