draft-ietf-cbor-network-addresses-10.txt   draft-ietf-cbor-network-addresses-11.txt 
CBOR Working Group M. Richardson CBOR Working Group M. Richardson
Internet-Draft Sandelman Software Works Internet-Draft Sandelman Software Works
Intended status: Standards Track C. Bormann Intended status: Standards Track C. Bormann
Expires: 9 April 2022 Universität Bremen TZI Expires: 11 April 2022 Universität Bremen TZI
6 October 2021 8 October 2021
CBOR tags for IPv4 and IPv6 addresses and prefixes CBOR tags for IPv4 and IPv6 addresses and prefixes
draft-ietf-cbor-network-addresses-10 draft-ietf-cbor-network-addresses-11
Abstract Abstract
This specification defines two CBOR Tags for use with IPv6 and IPv4 This specification defines two CBOR Tags for use with IPv6 and IPv4
addresses and prefixes. addresses and prefixes.
// RFC-EDITOR-please-remove: This work is tracked at // RFC-EDITOR-please-remove: This work is tracked at
// https://github.com/cbor-wg/cbor-network-address // https://github.com/cbor-wg/cbor-network-address
Status of This Memo Status of This Memo
skipping to change at page 1, line 35 skipping to change at page 1, line 35
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 https://datatracker.ietf.org/drafts/current/. Drafts is at https://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 9 April 2022. This Internet-Draft will expire on 11 April 2022.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 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 (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
skipping to change at page 2, line 25 skipping to change at page 2, line 25
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Three Forms . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Three Forms . . . . . . . . . . . . . . . . . . . . . . . 3
3.1.1. Addresses . . . . . . . . . . . . . . . . . . . . . . 3 3.1.1. Addresses . . . . . . . . . . . . . . . . . . . . . . 3
3.1.2. Prefixes . . . . . . . . . . . . . . . . . . . . . . 3 3.1.2. Prefixes . . . . . . . . . . . . . . . . . . . . . . 3
3.1.3. Interface Definition . . . . . . . . . . . . . . . . 4 3.1.3. Interface Definition . . . . . . . . . . . . . . . . 4
3.2. IPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.2. IPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.3. IPv4 . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.3. IPv4 . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Encoder Considerations for Prefixes . . . . . . . . . . . . . 6 4. Tag validity . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Decoder Considerations for Prefixes . . . . . . . . . . . . . 6 4.1. Deterministic Encoding . . . . . . . . . . . . . . . . . 6
6. CDDL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4.2. Encoder Considerations for Prefixes . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 4.3. Decoder Considerations for Prefixes . . . . . . . . . . . 7
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 4.3.1. Example implementation . . . . . . . . . . . . . . . 7
8.1. Tag 54 - IPv6 . . . . . . . . . . . . . . . . . . . . . . 9 5. CDDL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.2. Tag 52 - IPv4 . . . . . . . . . . . . . . . . . . . . . . 9 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8.3. Tags 260 and 261 . . . . . . . . . . . . . . . . . . . . 9 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 7.1. Tag 54 - IPv6 . . . . . . . . . . . . . . . . . . . . . . 10
9.1. Normative References . . . . . . . . . . . . . . . . . . 9 7.2. Tag 52 - IPv4 . . . . . . . . . . . . . . . . . . . . . . 10
9.2. Informative References . . . . . . . . . . . . . . . . . 10 7.3. Tags 260 and 261 . . . . . . . . . . . . . . . . . . . . 10
Appendix A. Changelog . . . . . . . . . . . . . . . . . . . . . 10 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 10 8.1. Normative References . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 8.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. Changelog . . . . . . . . . . . . . . . . . . . . . 11
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction 1. Introduction
[RFC8949] defines a number of CBOR Tags for common items. Tags 260 [RFC8949] defines a number of CBOR Tags for common items. Tags 260
and 261 were later defined in drafts listed with IANA and 261 were later defined in drafts listed with IANA
[IANA.cbor-tags]. These tags were intended to cover addresses (260) [IANA.cbor-tags]. These tags were intended to cover addresses (260)
and prefixes (261). Tag 260 distinguishes between IPv6, IPv4, and and prefixes (261). Tag 260 distinguishes between IPv6, IPv4, and
MAC [RFC7042] addresses only through the length of the byte string MAC [RFC7042] addresses only through the length of the byte string
making it impossible, for example, to drop trailing zeros in the making it impossible, for example, to drop trailing zeros in the
encoding of IP addresses. Tag 261 was not documented well enough for encoding of IP addresses. Tag 261 was not documented well enough for
skipping to change at page 4, line 19 skipping to change at page 4, line 19
length of a prefix built out of the first length bits of the address, length of a prefix built out of the first length bits of the address,
they represent information that is commonly used to specify both the they represent information that is commonly used to specify both the
network prefix and the IP address of an interface. network prefix and the IP address of an interface.
The length of the byte string is always 16 bytes (for IPv6) and 4 The length of the byte string is always 16 bytes (for IPv6) and 4
bytes (for IPv4). bytes (for IPv4).
This form is called the Interface Format. This form is called the Interface Format.
Interface Format definitions support an optional third element to the Interface Format definitions support an optional third element to the
array, which is to be used as the IPv6 Link-Local interface array, which is to be used as the IPv6 Link-Local zone identifier
identifier Section 4 of [RFC3542]. This may be an integer, in which from Section 4 of [RFC3542] and Section 6 of [RFC4007]; for symmetry
case it is to be interpreted as the interface index. This may be a this is also provided for IPv4 as in [RFC4001] and [RFC6991]. The
string, in which case it is to be interpreted as an interface name. zone identifier may be an integer, in which case it is to be
interpreted as the interface index. It may be a text string, in
which case it is to be interpreted as an interface name.
As explained in [RFC4007] the zone identifiers are strictly local to
the node. They are useful for communications within a node about
connected addresses (for instance, where a link-local peer is
discovered by one daemon, and another daemon needs to be informed).
They may also have utility in some management protocols.
In the cases where the Interface Format is being used to represent In the cases where the Interface Format is being used to represent
only an address with an interface identifier, and no interface prefix only an address with a zone identifier, and no interface prefix
information, then the prefix length may be replaced with the CBOR information, then the prefix length may be replaced with the CBOR
"false" (0xF4). "null" (0xF6).
3.2. IPv6 3.2. IPv6
IANA has allocated tag 54 for IPv6 uses. (This is the ASCII code for IANA has allocated tag 54 for IPv6 uses. (This is the ASCII code for
'6'.) '6'.)
An IPv6 address is to be encoded as a sixteen-byte byte string An IPv6 address is to be encoded as a sixteen-byte byte string
(Section 3.1 of [RFC8949], major type 2), enclosed in Tag number 54. (Section 3.1 of [RFC8949], major type 2), enclosed in Tag number 54.
For example: For example:
54(h'20010db81234deedbeefcafefacefeed') 54(h'20010db81234deedbeefcafefacefeed')
An IPv6 prefix, such as 2001:db8:1234::/48 is to be encoded as a two 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. Trailing zero element array, with the length of the prefix first. See Section 4
bytes MUST be omitted. for the detailed construction of the second element.
For example: For example:
54([48, h'20010db81234']) 54([48, h'20010db81234'])
An IPv6 address combined with a prefix length, such as being used for An IPv6 address combined with a prefix length, such as being used for
configuring an interface, is to be encoded as a two element array, configuring an interface, is to be encoded as a two element array,
with the (full-length) IPv6 address first and the length of the with the (full-length) IPv6 address first and the length of the
associated network the prefix next. associated network the prefix next; a third element can be added for
the zone identifier.
For example: For example:
54([h'20010db81234deedbeefcafefacefeed', 56]) 54([h'20010db81234deedbeefcafefacefeed', 56])
The address-with-prefix form can be reliably distinguished from the The address-with-prefix form can be reliably distinguished from the
prefix form only in the sequence of the array elements. prefix form only in the sequence of the array elements.
Some example of a link-local IPv6 address with a 64-bit prefix: Some example of a link-local IPv6 address with a 64-bit prefix:
54([h'fe8000000000020202fffffffe030303', 64, 'eth0']) 54([h'fe8000000000020202fffffffe030303', 64, 'eth0'])
with a numeric interface identifier: with a numeric zone identifier:
54([h'fe8000000000020202fffffffe030303', 64, 42]) 54([h'fe8000000000020202fffffffe030303', 64, 42])
An IPv6 link-local address without a prefix length: An IPv6 link-local address without a prefix length:
54([h'fe8000000000020202fffffffe030303', false, 42]) 54([h'fe8000000000020202fffffffe030303', null, 42])
Interface identifiers may be used with any kind of IPv6 address, not Zone identifiers may be used with any kind of IP address, not just
just Link-Local addresses. In particular, they are valid for Link-Local addresses. In particular, they are valid for multicast
multicast addresses, and there may still be some significance for addresses, and there may still be some significance for Globally
Globally Unique Addresses (GUA). Unique Addresses (GUA).
3.3. IPv4 3.3. IPv4
IANA has allocated tag 52 for IPv4 uses. (This is the ASCII code for IANA has allocated tag 52 for IPv4 uses. (This is the ASCII code for
'4'.) '4'.)
An IPv4 address is to be encoded as a four-byte byte string An IPv4 address is to be encoded as a four-byte byte string
(Section 3.1 of [RFC8949], major type 2), enclosed in Tag number 52. (Section 3.1 of [RFC8949], major type 2), enclosed in Tag number 52.
For example: For example:
skipping to change at page 5, line 40 skipping to change at page 6, line 4
IANA has allocated tag 52 for IPv4 uses. (This is the ASCII code for IANA has allocated tag 52 for IPv4 uses. (This is the ASCII code for
'4'.) '4'.)
An IPv4 address is to be encoded as a four-byte byte string An IPv4 address is to be encoded as a four-byte byte string
(Section 3.1 of [RFC8949], major type 2), enclosed in Tag number 52. (Section 3.1 of [RFC8949], major type 2), enclosed in Tag number 52.
For example: For example:
52(h'c0000201') 52(h'c0000201')
An IPv4 prefix, such as 192.0.2.0/24 is to be encoded as a two An IPv4 prefix, such as 192.0.2.0/24 is to be encoded as a two
element array, with the length of the prefix first. Trailing zero element array, with the length of the prefix first. See Section 4
bytes MUST be omitted. for the detailed construction of the second element.
For example: For example:
52([24, h'c00002']) 52([24, h'c00002'])
An IPv4 address combined with a prefix length, such as being used for An IPv4 address combined with a prefix length, such as being used for
configuring an interface, is to be encoded as a two element array, configuring an interface, is to be encoded as a two element array,
with the (full-length) IPv4 address first and the length of the with the (full-length) IPv4 address first and the length of the
associated network the prefix next. associated network the prefix next; a third element can be added for
the zone identifier.
For example, 192.0.2.1/24 is to be encoded as a two element array, For example, 192.0.2.1/24 is to be encoded as a two element array,
with the length of the prefix (implied 192.0.2.0/24) last. with the length of the prefix (implied 192.0.2.0/24) last.
52([h'c0000201', 24]) 52([h'c0000201', 24])
The address-with-prefix form can be reliably distinguished from the The address-with-prefix form can be reliably distinguished from the
prefix form only in the sequence of the array elements. prefix form only in the sequence of the array elements.
4. Encoder Considerations for Prefixes 4. Tag validity
For the byte strings used in representing prefixes, an encoder MUST This section discusses when a tag 54 or tag 52 is valid
omit any right-aligned (trailing) sequence of bytes that are all (Section 5.3.2 of [RFC8949]). As with all CBOR tags, validity
zero. checking can be handled in a generic CBOR library or in the
application. A generic CBOR library needs to document whether and
how it handles validity checking.
There is no relationship between the number of bytes omitted and the The rule ip-address-or-prefix in Figure 1 shows how to check the
prefix length. For instance, the prefix 2001:db8::/64 is encoded as: overall structure of these tags and their content, the ranges of
integer values, and the lengths of byte strings. An instance of tag
52 or 54 is valid if it matches that rule and, for ipv6-prefix and
ipv4-prefix, the considerations of Sections 4.2 and 4.3.
54([64, h'20010db8']) 4.1. Deterministic Encoding
An encoder MUST take care to set all trailing bits in the final byte The tag validity rules, combined with the rules in Section 4.2.1 of
to zero, if any. While decoders are expected to ignore them, such [RFC8949], lead to deterministic encoding for tags 54 and 52 and
garbage entities could be used as a covert channel, or may reveal the require no further Additional Deterministic Encoding Considerations
state of what would otherwise be private memory contents. So for as per Section 4.2.2 of [RFC8949].
example, 2001:db8:1230::/44 MUST be encoded as:
52([44, h'20010db81230']) 4.2. Encoder Considerations for Prefixes
For the byte strings used as the second element in the array
representing a prefix:
(1) An encoder MUST set any unused bytes, and any unused bits in the
final byte, if any, to zero. Unused bytes/bits are bytes/bits that
are not covered by the prefix length given. So for example,
2001:db8:1230::/44 MUST be encoded as:
54([44, h'20010db81230'])
even though variations like: even though variations like:
54([44, h'20010db81233']) 54([44, h'20010db81233'])
54([45, h'20010db8123f']) 54([44, h'20010db8123f'])
54([44, h'20010db8123012'])
would be parsed in the exact same way; they MUST be considered start with the same 44 bits, but are not valid.
invalid.
The same considerations apply to IPv4 prefixes. (Analogous examples can be constructed for IPv4 prefixes.)
5. Decoder Considerations for Prefixes (2) An encoder MUST then omit any right-aligned (trailing) sequence
of bytes that are all zero.
A decoder MUST consider all bits to the right of the prefix length to There is no relationship between the number of bytes omitted and the
be zero. prefix length. For instance, the prefix 2001:db8::/64 is encoded as:
A decoder MUST handle the case where a prefix length specifies that 54([64, h'20010db8'])
4.3. Decoder Considerations for Prefixes
A decoder MUST check that all unused bits encoded in the byte string
ipv6-prefix-bytes/ipv4-prefix-bytes, i.e., the bits to the right of
the prefix length, are zero.
A decoder MUST also check that the byte string does not end in a zero
byte.
Since encoders are required to remove zero-valued trailing bytes, a
decoder MUST handle the case where a prefix length specifies that
more bits are relevant than are actually present in the byte-string. more bits are relevant than are actually present in the byte-string.
As a pathological case, ::/128 can be encoded as
As an example, ::/128 is encoded as
54([128, h'']) 54([128, h''])
A recommendation for implementations is to first create an array of
16 (or 4) zero bytes. 4.3.1. Example implementation
A recommendation for prefix decoder implementations is to first
create an array of 16 (or 4) zero bytes.
Then taking whichever is smaller between (a) the length of the Then taking whichever is smaller between (a) the length of the
included byte-string, and (b) the number of bytes covered by the included byte-string, and (b) the number of bytes covered by the
prefix-length rounded up to the next multiple of 8: fail if that prefix-length rounded up to the next multiple of 8: fail if that
number is greater than 16 (or 4), and then copy that many bytes from number is greater than 16 (or 4), and then copy that many bytes from
the byte-string into the array. the byte-string into the byte array.
Finally, looking at the last three bits of the prefix-length in bits
(that is, the prefix-length modulo 8), use a static array of 8 values
to force the lower, non-relevant bits to zero, or simply:
unused_bits = (8 - (prefix_length_in_bits & 7)) % 8;
if (length_in_bytes > 0)
address_bytes[length_in_bytes - 1] &= (0xFF << unused_bits);
A particularly paranoid decoder could examine the lower non-relevant Finally, looking at the number of unused bits in the last byte (if
bits to determine if they are non-zero, and reject the prefix. This any) of the range covered by the prefix length, check that any unused
would detect non-compliant encoders, or a possible covert channel. bits in the byte string are zero:
unused_bits = (8 - (prefix_length_in_bits % 8)) % 8;
if (length_in_bytes > 0 && if (length_in_bytes > 0 &&
(address_bytes[length_in_bytes - 1] & ~(0xFF << unused_bits)) (address_bytes[length_in_bytes - 1] & ~(0xFF << unused_bits))
!= 0) != 0)
fail(); fail();
6. CDDL 5. CDDL
For use with CDDL [RFC8610], the typenames defined in Figure 1 are For use with CDDL [RFC8610], the typenames defined in Figure 1 are
recommended: recommended:
ip-address-or-prefix = ipv6-address-or-prefix / ip-address-or-prefix = ipv6-address-or-prefix /
ipv4-address-or-prefix ipv4-address-or-prefix
ipv6-address-or-prefix = #6.54(ipv6-address / ipv6-address-or-prefix = #6.54(ipv6-address /
ipv6-address-with-prefix / ipv6-address-with-prefix /
ipv6-prefix) ipv6-prefix)
ipv4-address-or-prefix = #6.52(ipv4-address / ipv4-address-or-prefix = #6.52(ipv4-address /
ipv4-address-with-prefix / ipv4-address-with-prefix /
ipv4-prefix) ipv4-prefix)
ipv6-address = bytes .size 16 ipv6-address = bytes .size 16
ipv4-address = bytes .size 4 ipv4-address = bytes .size 4
ipv6-address-with-prefix = [ipv6-address, ipv6-prefix-value, ipv6-address-with-prefix = [ipv6-address,
?ipv6-interface-identifier] ipv6-prefix-length / null,
ipv4-address-with-prefix = [ipv4-address, ipv4-prefix-length] ?ip-zone-identifier]
ipv4-address-with-prefix = [ipv4-address,
ipv4-prefix-length / null,
?ip-zone-identifier]
ipv6-prefix-value = ipv6-prefix-length
/ false
ipv6-prefix-length = 0..128 ipv6-prefix-length = 0..128
ipv4-prefix-length = 0..32 ipv4-prefix-length = 0..32
ipv6-prefix = [ipv6-prefix-length, ipv6-prefix-bytes] ipv6-prefix = [ipv6-prefix-length, ipv6-prefix-bytes]
ipv4-prefix = [ipv4-prefix-length, ipv4-prefix-bytes] ipv4-prefix = [ipv4-prefix-length, ipv4-prefix-bytes]
ipv6-prefix-bytes = bytes .size (uint .le 16) ipv6-prefix-bytes = bytes .size (uint .le 16)
ipv4-prefix-bytes = bytes .size (uint .le 4) ipv4-prefix-bytes = bytes .size (uint .le 4)
ipv6-interface-identifier = uint / tstr ip-zone-identifier = uint / text
Figure 1 Figure 1: CDDL types for tags 54 and 52
7. Security Considerations 6. Security Considerations
This document provides an CBOR encoding for IPv4 and IPv6 address This document provides an CBOR encoding for IPv4 and IPv6 address
information. Any applications using these encodings will need to information. Any applications using these encodings will need to
consider the security implications of this data in their specific consider the security implications of these data in their specific
context. For example, identifying which byte sequences in a protocol context. For example, identifying which byte sequences in a protocol
are addresses may allow an attacker or eavesdropper to better are addresses may allow an attacker or eavesdropper to better
understand what parts of a packet to attack. understand what parts of a packet to attack.
The right-hand bits of the prefix, after the prefix-length, are Applications need to check the validity (Section 4) of a tag before
ignored by this protocol. A malicious party could use them to acting on any of its contents. If the validity checking is not done
transmit covert data in a way that would not affect the primary use in the generic CBOR decoder, it needs to be done in the application;
of this encoding. Such abuse would be detected by examination of the in any case it needs to be done before the tag is transformed into a
raw protocol bytes. Users of this encoding should be aware of this platform-specific representation that could conceal validity errors.
possibility.
There are many ways in which the encodings may be invalid: wrong byte The right-hand bits of the prefix, after the prefix-length, are set
lengths (too long, too short), or invalid prefix lengths (greater to zero by this protocol. (Otherwise, a malicious party could use
than 32 for IPv4, greater than 128 for IPv6, negative values, etc.) them to transmit covert data in a way that would not affect the
These are all invalid and this error needs to be signaled to the primary use of this encoding. Such abuse is detected by tag validity
application, and the entire content thrown away. checking, and can also be detected by examination of the raw protocol
bytes.)
8. IANA Considerations 7. IANA Considerations
IANA has allocated two tags from the Specification Required area of IANA has allocated two tags from the Specification Required area of
the Concise Binary Object Representation (CBOR) Tags the Concise Binary Object Representation (CBOR) Tags
[IANA.cbor-tags]: [IANA.cbor-tags]:
8.1. Tag 54 - IPv6 7.1. Tag 54 - IPv6
Data Item: byte string or array Data Item: byte string or array
Semantics: IPv6, [prefixlen,IPv6], [IPv6,prefixpart] Semantics: IPv6, [prefixlen,IPv6], [IPv6,prefixpart]
8.2. Tag 52 - IPv4 7.2. Tag 52 - IPv4
Data Item: byte string or array Data Item: byte string or array
Semantics: IPv4, [prefixlen,IPv4], [IPv4,prefixpart] Semantics: IPv4, [prefixlen,IPv4], [IPv4,prefixpart]
8.3. Tags 260 and 261 7.3. Tags 260 and 261
IANA is requested to add the note "DEPRECATED in favor of 52 and 54 IANA is requested to add the note "DEPRECATED in favor of 52 and 54
for IP addresses" to registrations 260 and 261 for IP addresses" to registrations 260 and 261
9. References 8. References
9.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
skipping to change at page 10, line 10 skipping to change at page 11, line 10
Definition Language (CDDL): A Notational Convention to Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610, JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/info/rfc8610>. June 2019, <https://www.rfc-editor.org/info/rfc8610>.
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object [RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949, Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020, DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/info/rfc8949>. <https://www.rfc-editor.org/info/rfc8949>.
9.2. Informative References 8.2. Informative References
[IANA.cbor-tags] [IANA.cbor-tags]
IANA, "Concise Binary Object Representation (CBOR) Tags", IANA, "Concise Binary Object Representation (CBOR) Tags",
<http://www.iana.org/assignments/cbor-tags>. <http://www.iana.org/assignments/cbor-tags>.
[RFC3542] Stevens, W., Thomas, M., Nordmark, E., and T. Jinmei, [RFC3542] Stevens, W., Thomas, M., Nordmark, E., and T. Jinmei,
"Advanced Sockets Application Program Interface (API) for "Advanced Sockets Application Program Interface (API) for
IPv6", RFC 3542, DOI 10.17487/RFC3542, May 2003, IPv6", RFC 3542, DOI 10.17487/RFC3542, May 2003,
<https://www.rfc-editor.org/info/rfc3542>. <https://www.rfc-editor.org/info/rfc3542>.
[RFC4001] Daniele, M., Haberman, B., Routhier, S., and J.
Schoenwaelder, "Textual Conventions for Internet Network
Addresses", RFC 4001, DOI 10.17487/RFC4001, February 2005,
<https://www.rfc-editor.org/info/rfc4001>.
[RFC4007] Deering, S., Haberman, B., Jinmei, T., Nordmark, E., and
B. Zill, "IPv6 Scoped Address Architecture", RFC 4007,
DOI 10.17487/RFC4007, March 2005,
<https://www.rfc-editor.org/info/rfc4007>.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/info/rfc6991>.
[RFC7042] Eastlake 3rd, D. and J. Abley, "IANA Considerations and [RFC7042] Eastlake 3rd, D. and J. Abley, "IANA Considerations and
IETF Protocol and Documentation Usage for IEEE 802 IETF Protocol and Documentation Usage for IEEE 802
Parameters", BCP 141, RFC 7042, DOI 10.17487/RFC7042, Parameters", BCP 141, RFC 7042, DOI 10.17487/RFC7042,
October 2013, <https://www.rfc-editor.org/info/rfc7042>. October 2013, <https://www.rfc-editor.org/info/rfc7042>.
Appendix A. Changelog Appendix A. Changelog
This section is to be removed before publishing as an RFC. This section is to be removed before publishing as an RFC.
* 03 * 03
* 02 * 02
* 01 added security considerations about covert channel * 01 added security considerations about covert channel
Acknowledgements Acknowledgements
Roman Danyliw, Donald Eastlake, Ben Kaduk, Barry Leiba, and Eric Roman Danyliw, Donald Eastlake, Ben Kaduk, Barry Leiba, and Éric
Vyncke reviewed the document and provided suggested text. Vyncke reviewed the document and provided suggested text. Jürgen
Schönwälder helped finding the history of IPv4 zone identifiers.
Authors' Addresses Authors' Addresses
Michael Richardson Michael Richardson
Sandelman Software Works Sandelman Software Works
Email: mcr+ietf@sandelman.ca Email: mcr+ietf@sandelman.ca
Carsten Bormann Carsten Bormann
Universität Bremen TZI Universität Bremen TZI
 End of changes. 51 change blocks. 
104 lines changed or deleted 156 lines changed or added

This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/