CBOR tags for IPv4 and IPv6 addresses and prefixes
draft-ietf-cbor-network-addresses-00

CBOR Working Group                                         M. Richardson
Internet-Draft                                  Sandelman Software Works
Intended status: Standards Track                            6 March 2021
Expires: 7 September 2021

           CBOR tags for IPv4 and IPv6 addresses and prefixes
                  draft-ietf-cbor-network-addresses-00

Abstract

   This document describes two CBOR Tags to be used with IPv4 and IPv6
   addresses and prefixes.

   RFC-EDITOR-please remove: This work is tracked at
   https://github.com/mcr/cbor-network-address.git

Status of This Memo

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   This Internet-Draft will expire on 7 September 2021.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Protocol  . . . . . . . . . . . . . . . . . . . . . . . . . .   2
     2.1.  IPv6  . . . . . . . . . . . . . . . . . . . . . . . . . .   2
     2.2.  IPv4  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  TBD1 - IPv6 . . . . . . . . . . . . . . . . . . . . . . .   3
     4.2.  TBD2 - IPv4 . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   3
   6.  Changelog . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   3
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   [RFC8949] defines a number of CBOR Tags for common items.

   Not included are ones to indicate if the item is an IPv4 or IPv6
   address, or if it is an address plus prefix length.  This document
   defines them.

2.  Protocol

   These tags can applied to byte strings to represent a single address.

   When applied to an array, the represent a CIDR-style prefix.  When a
   byte string (without prefix) appears in a context where a prefix is
   expected, then it is to be assumed that all bits are relevant.  That
   is, for IPv4, a /32 is implied, and for IPv6, a /128 is implied.

2.1.  IPv6

   IANA has allocated tag TBD1 for IPv6 uses.

   An IPv6 address is to be encoded as up to sixteen-byte bytestring
   ([RFC8949] section, 3.1, major type 2), prefixed with tag TBD1.
   Trailing zero octets may be omitted.

   An IPv6 prefix, such as 2001:db8:1234::/48 is to be encoded as a two
   element array, with the length of the prefix first:

       TBD1([ 48, h'20010db81234'])

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2.2.  IPv4

   IANA has allocated tag TBD2 for IPv4 uses.

   An IPv4 address is to be encoded as a four-byte bytestring ([RFC8949]
   section, 3.1, major type 2), prefixed with tag TBD2.  Trailing zero
   octets may be omitted.

   An IPv4 prefix, such as 192.0.2.1/24 is to be encoded as a two
   element array, with the length of the prefix first:

       TBD2([ 24, h'C0000201'])

3.  Security Considerations

   Identifying which byte sequences in a protocol are addresses may
   allow an attacker or eavesdropper to better understand what parts of
   a packet to attack.

   Reading the relevant RFC may provide more information, so it would
   seem that any additional security that was provided by not being able
   to identify what are IP addresses falls into the security by
   obscurity category.

4.  IANA Considerations

   IANA is asked to allocate two tags from the Specification Required
   area of the Concise Binary Object Representation (CBOR) Tags, in the
   ("1+1") area.

4.1.  TBD1 - IPv6

   Data Item: byte-string and array
   Semantics: IPv6 or [IPv6,prefixlen]

4.2.  TBD2 - IPv4

   Data Item: byte-string and array
   Semantics: IPv4 or [IPv4,prefixlen]

5.  Acknowledgements

   none yet

6.  Changelog

7.  Normative References

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   [BCP14]    Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8949]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", STD 94, RFC 8949,
              DOI 10.17487/RFC8949, December 2020,
              <https://www.rfc-editor.org/info/rfc8949>.

Author's Address

   Michael Richardson
   Sandelman Software Works

   Email: mcr+ietf@sandelman.ca

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