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diff --git a/contrib/bind9/doc/draft/draft-ietf-dnsext-dns-name-p-s-00.txt b/contrib/bind9/doc/draft/draft-ietf-dnsext-dns-name-p-s-00.txt deleted file mode 100644 index 438e8008a4c7..000000000000 --- a/contrib/bind9/doc/draft/draft-ietf-dnsext-dns-name-p-s-00.txt +++ /dev/null @@ -1,1397 +0,0 @@ -DNS Extensions Working Group G. Sisson -Internet-Draft B. Laurie -Expires: January 11, 2006 Nominet - July 10, 2005 - - - Derivation of DNS Name Predecessor and Successor - draft-ietf-dnsext-dns-name-p-s-00 - -Status of this Memo - - By submitting this Internet-Draft, each author represents that any - applicable patent or other IPR claims of which he or she is aware - have been or will be disclosed, and any of which he or she becomes - aware will be disclosed, in accordance with Section 6 of BCP 79. - - Internet-Drafts are working documents of the Internet Engineering - Task Force (IETF), its areas, and its working groups. Note that - other groups may also distribute working documents as Internet- - Drafts. - - Internet-Drafts are draft documents valid for a maximum of six months - and may be updated, replaced, or obsoleted by other documents at any - time. It is inappropriate to use Internet-Drafts as reference - material or to cite them other than as "work in progress." - - The list of current Internet-Drafts can be accessed at - http://www.ietf.org/ietf/1id-abstracts.txt. - - The list of Internet-Draft Shadow Directories can be accessed at - http://www.ietf.org/shadow.html. - - This Internet-Draft will expire on January 11, 2006. - -Copyright Notice - - Copyright (C) The Internet Society (2005). - -Abstract - - This document describes two methods for deriving the canonically- - ordered predecessor and successor of a DNS name. These methods may - be used for dynamic NSEC resource record synthesis, enabling - security-aware name servers to provide authenticated denial of - existence without disclosing other owner names in a DNSSEC-secured - zone. - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 1] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - -Table of Contents - - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3 - 3. Absolute Method . . . . . . . . . . . . . . . . . . . . . . . 4 - 3.1. Derivation of DNS Name Predecessor . . . . . . . . . . . . 4 - 3.2. Derivation of DNS Name Successor . . . . . . . . . . . . . 4 - 4. Modified Method . . . . . . . . . . . . . . . . . . . . . . . 5 - 4.1. Derivation of DNS Name Predecessor . . . . . . . . . . . . 6 - 4.2. Derivation of DNS Name Successor . . . . . . . . . . . . . 6 - 5. Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 - 5.1. Case Considerations . . . . . . . . . . . . . . . . . . . 7 - 5.2. Choice of Range . . . . . . . . . . . . . . . . . . . . . 7 - 5.3. Wild Card Considerations . . . . . . . . . . . . . . . . . 8 - 5.4. Possible Modifications . . . . . . . . . . . . . . . . . . 8 - 5.4.1. Restriction of Effective Maximum DNS Name Length . . . 8 - 5.4.2. Use of Modified Method With Zones Containing - SRV RRs . . . . . . . . . . . . . . . . . . . . . . . 9 - 6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 6.1. Examples of Immediate Predecessors Using Absolute - Method . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 6.2. Examples of Immediate Successors Using Absolute Method . . 13 - 6.3. Examples of Predecessors Using Modified Method . . . . . . 19 - 6.4. Examples of Successors Using Modified Method . . . . . . . 20 - 7. Security Considerations . . . . . . . . . . . . . . . . . . . 21 - 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 - 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22 - 10.1. Normative References . . . . . . . . . . . . . . . . . . . 22 - 10.2. Informative References . . . . . . . . . . . . . . . . . . 22 - 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 21 - Appendix A. Change History . . . . . . . . . . . . . . . . . . . 22 - A.1. Changes from sisson-02 to ietf-00 . . . . . . . . . . . . 22 - A.2. Changes from sisson-01 to sisson-02 . . . . . . . . . . . 23 - A.3. Changes from sisson-00 to sisson-01 . . . . . . . . . . . 23 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24 - Intellectual Property and Copyright Statements . . . . . . . . . . 25 - - - - - - - - - - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 2] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - -1. Introduction - - One of the proposals for avoiding the exposure of zone information - during the deployment DNSSEC is dynamic NSEC resource record (RR) - synthesis. This technique is described in [I-D.ietf-dnsext-dnssec- - trans] and [I-D.ietf-dnsext-dnssec-online-signing], and involves the - generation of NSEC RRs that just span the query name for non-existent - owner names. In order to do this, the DNS names which would occur - just prior to and just following a given query name must be - calculated in real time, as maintaining a list of all possible owner - names that might occur in a zone would be impracticable. - - Section 6.1 of [RFC4034] defines canonical DNS name order. This - document does not amend or modify this definition. However, the - derivation of immediate predecessor and successor, while trivial, is - non-obvious. Accordingly, several methods are described here as an - aid to implementors and a reference to other interested parties. - - This document describes two methods: - - 1. An ``absolute method'', which returns the immediate predecessor - or successor of a domain name such that no valid DNS name could - exist between that DNS name and the predecessor or successor. - - 2. A ``modified method'', which returns a predecessor and successor - which are more economical in size and computation. This method - is restricted to use with zones consisting only of single-label - owner names where a maximum-length owner name would not result in - a DNS name exceeding the maximum DNS name length. This is, - however, the type of zone for which the technique of online- - signing is most likely to be used. - - -2. Notational Conventions - - The following notational conventions are used in this document for - economy of expression: - - N: An unspecified DNS name. - - P(N): Immediate predecessor to N (absolute method). - - S(N): Immediate successor to N (absolute method). - - P'(N): Predecessor to N (modified method). - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 3] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - S'(N): Successor to N (modified method). - - -3. Absolute Method - - These derivations assume that all uppercase US-ASCII letters in N - have already been replaced by their corresponding lowercase - equivalents. Unless otherwise specified, processing stops after the - first step in which a condition is met. - -3.1. Derivation of DNS Name Predecessor - - To derive P(N): - - 1. If N is the same as the owner name of the zone apex, prepend N - repeatedly with labels of the maximum length possible consisting - of octets of the maximum sort value (e.g. 0xff) until N is the - maximum length possible; otherwise continue to the next step. - - 2. If the least significant (left-most) label of N consists of a - single octet of the minimum sort value (e.g. 0x00), remove that - label; otherwise continue to the next step. - - 3. If the least significant (right-most) octet in the least - significant (left-most) label of N is the minimum sort value, - remove the least significant octet and continue with step 5. - - 4. Decrement the value of the least significant (right-most) octet, - skipping any values that correspond to uppercase US-ASCII - letters, and then append the label with as many octets as - possible of the maximum sort value. Continue to the next step. - - 5. Prepend N repeatedly with labels of as long a length as possible - consisting of octets of the maximum sort value until N is the - maximum length possible. - -3.2. Derivation of DNS Name Successor - - To derive S(N): - - 1. If N is two or more octets shorter than the maximum DNS name - length, prepend N with a label containing a single octet of the - minimum sort value (e.g. 0x00); otherwise continue to the next - step. - - 2. If N is one or more octets shorter than the maximum DNS name - length and the least significant (left-most) label is one or more - octets shorter than the maximum label length, append an octet of - - - -Sisson & Laurie Expires January 11, 2006 [Page 4] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - the minimum sort value to the least significant label; otherwise - continue to the next step. - - 3. Increment the value of the least significant (right-most) octet - in the least significant (left-most) label that is less than the - maximum sort value (e.g. 0xff), skipping any values that - correspond to uppercase US-ASCII letters, and then remove any - octets to the right of that one. If all octets in the label are - the maximum sort value, then continue to the next step. - - 4. Remove the least significant (left-most) label. If N is now the - same as the owner name of the zone apex, do nothing. (This will - occur only if N is the maximum possible name in canonical DNS - name order, and thus has wrapped to the owner name of zone apex.) - Otherwise repeat starting at step 2. - - -4. Modified Method - - This method is for use with zones consisting only of single-label - owner names where an owner name consisting of label of maximum length - would not result in a DNS name which exceeded the maximum DNS name - length. This method is computationally simpler and returns values - which are more economical in size than the absolute method. It - differs from the absolute method detailed above in the following - ways: - - 1. Step 1 of the derivation P(N) has been omitted as the existence - of the owner name of the zone apex never requires denial. - - 2. A new step 1 has been introduced which removes unnecessary - labels. - - 3. Step 4 of the derivation P(N) has been omitted as it is only - necessary for zones containing owner names consisting of more - than one label. This omission generally results in a significant - reduction of the length of derived predecessors. - - 4. Step 1 of the derivation S(N) had been omitted as it is only - necessary for zones containing owner names consisting of more - than one label. This omission results in a tiny reduction of the - length of derived successors, and maintains consistency with the - modification of step 4 of the derivation P(N) described above. - - 5. Steps 2 and 4 of the derivation S(N) have been modified to - eliminate checks for maximum DNS name length, as it is an - assumption of this method that no DNS name in the zone can exceed - the maximum DNS name length. - - - -Sisson & Laurie Expires January 11, 2006 [Page 5] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - These derivations assume that all uppercase US-ASCII letters in N - have already been replaced by their corresponding lowercase - equivalents. Unless otherwise specified, processing stops after the - first step in which a condition is met. - -4.1. Derivation of DNS Name Predecessor - - To derive P'(N): - - 1. If N has more labels than the number of labels in the owner name - of the apex + 1, repeatedly remove the least significant (left- - most) label until N has no more labels than the number of labels - in the owner name of the apex + 1; otherwise continue to next - step. - - 2. If the least significant (left-most) label of N consists of a - single octet of the minimum sort value (e.g. 0x00), remove that - label; otherwise continue to the next step. - - 3. If the least significant (right-most) octet in the least - significant (left-most) label of N is the minimum sort value, - remove the least significant octet. - - 4. Decrement the value of the least significant (right-most) octet, - skipping any values which correspond to uppercase US-ASCII - letters, and then append the label with as many octets as - possible of the maximum sort value. - -4.2. Derivation of DNS Name Successor - - To derive S'(N): - - 1. If N has more labels than the number of labels in the owner name - of the apex + 1, repeatedly remove the least significant (left- - most) label until N has no more labels than the number of labels - in the owner name of the apex + 1. Continue to next step. - - 2. If the least significant (left-most) label of N is one or more - octets shorter than the maximum label length, append an octet of - the minimum sort value to the least significant label; otherwise - continue to the next step. - - 3. Increment the value of the least significant (right-most) octet - in the least significant (left-most) label that is less than the - maximum sort value (e.g. 0xff), skipping any values which - correspond to uppercase US-ASCII letters, and then remove any - octets to the right of that one. If all octets in the label are - the maximum sort value, then continue to the next step. - - - -Sisson & Laurie Expires January 11, 2006 [Page 6] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - 4. Remove the least significant (left-most) label. (This will occur - only if the least significant label is the maximum label length - and consists entirely of octets of the maximum sort value, and - thus has wrapped to the owner name of the zone apex.) - - -5. Notes - -5.1. Case Considerations - - Section 3.5 of [RFC1034] specifies that "while upper and lower case - letters are allowed in [DNS] names, no significance is attached to - the case". Additionally, Section 6.1 of [RFC4034] states that when - determining canonical DNS name order, "uppercase US-ASCII letters are - treated as if they were lowercase US-ASCII letters". Consequently, - values corresponding to US-ASCII uppercase letters must be skipped - when decrementing and incrementing octets in the derivations - described in Section 3.1 and Section 3.2. - - The following pseudo-code is illustrative: - - Decrement the value of an octet: - - if (octet == '[') // '[' is just after uppercase 'Z' - octet = '@'; // '@' is just prior to uppercase 'A' - else - octet--; - - Increment the value of an octet: - - if (octet == '@') // '@' is just prior to uppercase 'A' - octet = '['; // '[' is just after uppercase 'Z' - else - octet++; - -5.2. Choice of Range - - [RFC2181] makes the clarification that "any binary string whatever - can be used as the label of any resource record". Consequently the - minimum sort value may be set as 0x00 and the maximum sort value as - 0xff, and the range of possible values will be any DNS name which - contains octets of any value other than those corresponding to - uppercase US-ASCII letters. - - However, if all owner names in a zone are in the letter-digit-hyphen, - or LDH, format specified in [RFC1034], it may be desirable to - restrict the range of possible values to DNS names containing only - LDH values. This has the effect of: - - - -Sisson & Laurie Expires January 11, 2006 [Page 7] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - 1. making the output of tools such as `dig' and `nslookup' less - subject to confusion; - - 2. minimising the impact that NSEC RRs containing DNS names with - non-LDH values (or non-printable values) might have on faulty DNS - resolver implementations; and - - 3. preventing the possibility of results which are wildcard DNS - names (see Section 5.3). - - This may be accomplished by using a minimum sort value of 0x1f (US- - ASCII character `-') and a maximum sort value of 0x7a (US-ASCII - character lowercase `z'), and then skipping non-LDH, non-lowercase - values when incrementing or decrementing octets. - -5.3. Wild Card Considerations - - Neither derivation avoids the possibility that the result may be a - DNS name containing a wildcard label, i.e. a label containing a - single octet with the value 0x2a (US-ASCII character `*'). With - additional tests, wildcard DNS names may be explicitly avoided; - alternatively, if the range of octet values can be restricted to - those corresponding to letter-digit-hyphen, or LDH, characters (see - Section 5.2), such DNS names will not occur. - - Note that it is improbable that a result which is a wildcard DNS name - will occur unintentionally; even if one does occur either as the - owner name of, or in the RDATA of an NSEC RR, it is treated as a - literal DNS name with no special meaning. - -5.4. Possible Modifications - -5.4.1. Restriction of Effective Maximum DNS Name Length - - [RFC1034] specifies that "the total number of octets that represent a - [DNS] name (i.e., the sum of all label octets and label lengths) is - limited to 255", including the null (zero-length) label which - represents the root. For the purpose of deriving predecessors and - successors during NSEC RR synthesis, the maximum DNS name length may - be effectively restricted to the length of the longest DNS name in - the zone. This will minimise the size of responses containing - synthesised NSEC RRs but, especially in the case of the modified - method, may result in some additional computational complexity. - - Note that this modification will have the effect of revealing - information about the longest name in the zone. Moreover, when the - contents of the zone changes, e.g. during dynamic updates and zone - transfers, care must be taken to ensure that the effective maximum - - - -Sisson & Laurie Expires January 11, 2006 [Page 8] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - DNS name length agrees with the new contents. - -5.4.2. Use of Modified Method With Zones Containing SRV RRs - - Normally the modified method cannot be used in zones that contain - SRV RRs [RFC2782], as SRV RRs have owner names which contain multiple - labels. However the use of SRV RRs can be accommodated by various - techniques. There are at least four possible ways to do this: - - 1. Use conventional NSEC RRs for the region of the zone that - contains first-level labels beginning with the underscore (`_') - character. For the purposes of generating these NSEC RRs, the - existence of (possibly fictional) ownernames `9{63}' and `a' - could be assumed, providing a lower and upper bound for this - region. Then all queries where the QNAME doesn't exist but - contains a first-level label beginning with an underscore could - be handled using the normal DNSSEC protocol. - - This approach would make it possible to enumerate all DNS names - in the zone containing a first-level label beginning with - underscore, including all SRV RRs, but this may be of less a - concern to the zone administrator than incurring the overhead of - the absolute method or of the following variants of the modified - method. - - 2. The absolute method could be used for synthesising NSEC RRs for - all queries where the QNAME contains a leading underscore. - However this re-introduces the susceptibility of the absolute - method to denial of service activity, as an attacker could send - queries for an effectively inexhaustible supply of domain names - beginning with a leading underscore. - - 3. A variant of the modified method could be used for synthesising - NSEC RRs for all queries where the QNAME contains a leading - underscore. This variant would assume that all predecessors and - successors to queries where the QNAME contains a leading - underscore may consist of two lablels rather than only one. This - introduces a little additional complexity without incurring the - full increase in response size and computational complexity as - the absolute method. - - 4. Finally, a variant the modified method which assumes that all - owner names in the zone consist of one or two labels could be - used. However this negates much of the reduction in response - size of the modified method and may be nearly as computationally - complex as the absolute method. - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 9] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - -6. Examples - - In the following examples: - - the owner name of the zone apex is "example.com."; - - the range of octet values is 0x00 - 0xff excluding values - corresponding to uppercase US-ASCII letters; and - - non-printable octet values are expressed as three-digit decimal - numbers preceded by a backslash (as specified in Section 5.1 of - [RFC1035]). - -6.1. Examples of Immediate Predecessors Using Absolute Method - - Example of typical case: - - P(foo.example.com.) = - - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255.\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255.\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255.fon\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255.example.com. - - or, in alternate notation: - - \255{49}.\255{63}.\255{63}.fon\255{60}.example.com. - - where {n} represents the number of repetitions of an octet. - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 10] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - Example where least significant (left-most) label of DNS name - consists of a single octet of the minimum sort value: - - P(\000.foo.example.com.) = foo.example.com. - - Example where least significant (right-most) octet of least - significant (left-most) label has the minimum sort value: - - P(foo\000.example.com.) = - - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255.\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255.\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255.\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255.foo.example.com. - - or, in alternate notation: - - \255{45}.\255{63}.\255{63}.\255{63}.foo.example.com. - - - - - - - - - - - - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 11] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - Example where DNS name contains an octet which must be decremented by - skipping values corresponding to US-ASCII uppercase letters: - - P(fo\[.example.com.) = - - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255.\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255.\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255.fo\@\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255.example.com. - - or, in alternate notation: - - \255{49}.\255{63}.\255{63}.fo\@\255{60}.example.com. - - where {n} represents the number of repetitions of an octet. - - - - - - - - - - - - - - - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 12] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - Example where DNS name is the owner name of the zone apex, and - consequently wraps to the DNS name with the maximum possible sort - order in the zone: - - P(example.com.) = - - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255.\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255.\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255.\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255.example.com. - - or, in alternate notation: - - \255{49}.\255{63}.\255{63}.\255{63}.example.com. - -6.2. Examples of Immediate Successors Using Absolute Method - - Example of typical case: - - S(foo.example.com.) = \000.foo.example.com. - - - - - - - - - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 13] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - Example where DNS name is one octet short of the maximum DNS name - length: - - N = fooooooooooooooooooooooooooooooooooooooooooooooo - .ooooooooooooooooooooooooooooooooooooooooooooooo - oooooooooooooooo.ooooooooooooooooooooooooooooooo - oooooooooooooooooooooooooooooooo.ooooooooooooooo - oooooooooooooooooooooooooooooooooooooooooooooooo.example.com. - - or, in alternate notation: - - fo{47}.o{63}.o{63}.o{63}.example.com. - - S(N) = - - fooooooooooooooooooooooooooooooooooooooooooooooo - \000.ooooooooooooooooooooooooooooooooooooooooooo - oooooooooooooooooooo.ooooooooooooooooooooooooooo - oooooooooooooooooooooooooooooooooooo.ooooooooooo - oooooooooooooooooooooooooooooooooooooooooooooooo - oooo.example.com. - - or, in alternate notation: - - fo{47}\000.o{63}.o{63}.o{63}.example.com. - - - - - - - - - - - - - - - - - - - - - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 14] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - Example where DNS name is the maximum DNS name length: - - N = fooooooooooooooooooooooooooooooooooooooooooooooo - o.oooooooooooooooooooooooooooooooooooooooooooooo - ooooooooooooooooo.oooooooooooooooooooooooooooooo - ooooooooooooooooooooooooooooooooo.oooooooooooooo - oooooooooooooooooooooooooooooooooooooooooooooooo - o.example.com. - - or, in alternate notation: - - fo{48}.o{63}.o{63}.o{63}.example.com. - - S(N) = - - fooooooooooooooooooooooooooooooooooooooooooooooo - p.oooooooooooooooooooooooooooooooooooooooooooooo - ooooooooooooooooo.oooooooooooooooooooooooooooooo - ooooooooooooooooooooooooooooooooo.oooooooooooooo - oooooooooooooooooooooooooooooooooooooooooooooooo - o.example.com. - - or, in alternate notation: - - fo{47}p.o{63}.o{63}.o{63}.example.com. - - - - - - - - - - - - - - - - - - - - - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 15] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - Example where DNS name is the maximum DNS name length and the least - significant (left-most) label has the maximum sort value: - - N = \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255.ooooooooooooooooooooooooooooooooooooooooooo - oooooooooooooooooooo.ooooooooooooooooooooooooooo - oooooooooooooooooooooooooooooooooooo.ooooooooooo - oooooooooooooooooooooooooooooooooooooooooooooooo - oooo.example.com. - - or, in alternate notation: - - \255{49}.o{63}.o{63}.o{63}.example.com. - - S(N) = - - oooooooooooooooooooooooooooooooooooooooooooooooo - oooooooooooooop.oooooooooooooooooooooooooooooooo - ooooooooooooooooooooooooooooooo.oooooooooooooooo - ooooooooooooooooooooooooooooooooooooooooooooooo. - example.com. - - or, in alternate notation: - - o{62}p.o{63}.o{63}.example.com. - - - - - - - - - - - - - - - - - - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 16] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - Example where DNS name is the maximum DNS name length and the eight - least significant (right-most) octets of the least significant (left- - most) label have the maximum sort value: - - N = foooooooooooooooooooooooooooooooooooooooo\255 - \255\255\255\255\255\255\255.ooooooooooooooooooo - oooooooooooooooooooooooooooooooooooooooooooo.ooo - oooooooooooooooooooooooooooooooooooooooooooooooo - oooooooooooo.ooooooooooooooooooooooooooooooooooo - oooooooooooooooooooooooooooo.example.com. - - or, in alternate notation: - - fo{40}\255{8}.o{63}.o{63}.o{63}.example.com. - - S(N) = - - fooooooooooooooooooooooooooooooooooooooop.oooooo - oooooooooooooooooooooooooooooooooooooooooooooooo - ooooooooo.oooooooooooooooooooooooooooooooooooooo - ooooooooooooooooooooooooo.oooooooooooooooooooooo - ooooooooooooooooooooooooooooooooooooooooo.example.com. - - or, in alternate notation: - - fo{39}p.o{63}.o{63}.o{63}.example.com. - - - - - - - - - - - - - - - - - - - - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 17] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - Example where DNS name is the maximum DNS name length and contains an - octet which must be incremented by skipping values corresponding to - US-ASCII uppercase letters: - - N = fooooooooooooooooooooooooooooooooooooooooooooooo - \@.ooooooooooooooooooooooooooooooooooooooooooooo - oooooooooooooooooo.ooooooooooooooooooooooooooooo - oooooooooooooooooooooooooooooooooo.ooooooooooooo - oooooooooooooooooooooooooooooooooooooooooooooooo - oo.example.com. - - or, in alternate notation: - - fo{47}\@.o{63}.o{63}.o{63}.example.com. - - S(N) = - - fooooooooooooooooooooooooooooooooooooooooooooooo - \[.ooooooooooooooooooooooooooooooooooooooooooooo - oooooooooooooooooo.ooooooooooooooooooooooooooooo - oooooooooooooooooooooooooooooooooo.ooooooooooooo - oooooooooooooooooooooooooooooooooooooooooooooooo - oo.example.com. - - or, in alternate notation: - - fo{47}\[.o{63}.o{63}.o{63}.example.com. - - - - - - - - - - - - - - - - - - - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 18] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - Example where DNS name has the maximum possible sort order in the - zone, and consequently wraps to the owner name of the zone apex: - - N = \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255.\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255.\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255.\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255.example.com. - - or, in alternate notation: - - \255{49}.\255{63}.\255{63}.\255{63}.example.com. - - S(N) = example.com. - -6.3. Examples of Predecessors Using Modified Method - - Example of typical case: - - P'(foo.example.com.) = - - fon\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255.example.com. - - or, in alternate notation: - - fon\255{60}.example.com. - - - - -Sisson & Laurie Expires January 11, 2006 [Page 19] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - Example where DNS name contains more labels than DNS names in the - zone: - - P'(bar.foo.example.com.) = foo.example.com. - - Example where least significant (right-most) octet of least - significant (left-most) label has the minimum sort value: - - P'(foo\000.example.com.) = foo.example.com. - - Example where least significant (left-most) label has the minimum - sort value: - - P'(\000.example.com.) = example.com. - - Example where DNS name is the owner name of the zone apex, and - consequently wraps to the DNS name with the maximum possible sort - order in the zone: - - P'(example.com.) = - - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255.example.com. - - or, in alternate notation: - - \255{63}.example.com. - -6.4. Examples of Successors Using Modified Method - - Example of typical case: - - S'(foo.example.com.) = foo\000.example.com. - - Example where DNS name contains more labels than DNS names in the - zone: - - S'(bar.foo.example.com.) = foo\000.example.com. - - - - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 20] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - - Example where least significant (left-most) label has the maximum - sort value, and consequently wraps to the owner name of the zone - apex: - - N = \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255\255\255\255\255\255\255\255\255\255 - \255\255\255.example.com. - - or, in alternate notation: - - \255{63}.example.com. - - S'(N) = example.com. - - -7. Security Considerations - - The derivation of some predecessors/successors requires the testing - of more conditions than others. Consequently the effectiveness of a - denial-of-service attack may be enhanced by sending queries that - require more conditions to be tested. The modified method involves - the testing of fewer conditions than the absolute method and - consequently is somewhat less susceptible to this exposure. - - -8. IANA Considerations - - This document has no IANA actions. - - Note to RFC Editor: This section is included to make it clear during - pre-publication review that this document has no IANA actions. It - may therefore be removed should it be published as an RFC. - - -9. Acknowledgments - - The authors would like to thank Olaf Kolkman, Olafur Gudmundsson and - Niall O'Reilly for their review and input. - - -10. References - - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 21] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - -10.1 Normative References - - [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", - STD 13, RFC 1034, November 1987. - - [RFC1035] Mockapetris, P., "Domain names - implementation and - specification", STD 13, RFC 1035, November 1987. - - [RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS - Specification", RFC 2181, July 1997. - - [RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for - specifying the location of services (DNS SRV)", RFC 2782, - February 2000. - - [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. - Rose, "Resource Records for the DNS Security Extensions", - RFC 4034, March 2005. - -10.2 Informative References - - [I-D.ietf-dnsext-dnssec-online-signing] - Ihren, J. and S. Weiler, "Minimally Covering NSEC Records - and DNSSEC On-line Signing", - draft-ietf-dnsext-dnssec-online-signing-00 (work in - progress), May 2005. - - [I-D.ietf-dnsext-dnssec-trans] - Arends, R., Koch, P., and J. Schlyter, "Evaluating DNSSEC - Transition Mechanisms", - draft-ietf-dnsext-dnssec-trans-02 (work in progress), - February 2005. - - -Appendix A. Change History - -A.1. Changes from sisson-02 to ietf-00 - - o Added notes on use of SRV RRs with modified method. - - o Changed reference from weiler-dnssec-online-signing to ietf- - dnsext-dnssec-online-signing. - - o Changed reference from ietf-dnsext-dnssec-records to RFC 4034. - - o Miscellaneous minor changes to text. - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 22] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - -A.2. Changes from sisson-01 to sisson-02 - - o Added modified version of derivation (with supporting examples). - - o Introduced notational conventions N, P(N), S(N), P'(N) and S'(N). - - o Added clarification to derivations about when processing stops. - - o Miscellaneous minor changes to text. - -A.3. Changes from sisson-00 to sisson-01 - - o Split step 3 of derivation of DNS name predecessor into two - distinct steps for clarity. - - o Added clarifying text and examples related to the requirement to - avoid uppercase characters when decrementing or incrementing - octets. - - o Added optimisation using restriction of effective maximum DNS name - length. - - o Changed examples to use decimal rather than octal notation as per - [RFC1035]. - - o Corrected DNS name length of some examples. - - o Added reference to weiler-dnssec-online-signing. - - o Miscellaneous minor changes to text. - - - - - - - - - - - - - - - - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 23] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - -Authors' Addresses - - Geoffrey Sisson - Nominet - Sandford Gate - Sandy Lane West - Oxford - OX4 6LB - GB - - Phone: +44 1865 332339 - Email: geoff@nominet.org.uk - - - Ben Laurie - Nominet - 17 Perryn Road - London - W3 7LR - GB - - Phone: +44 20 8735 0686 - Email: ben@algroup.co.uk - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Sisson & Laurie Expires January 11, 2006 [Page 24] - -Internet-Draft DNS Name Predecessor and Successor July 2005 - - -Intellectual Property Statement - - The IETF takes no position regarding the validity or scope of any - Intellectual Property Rights or other rights that might be claimed to - pertain to the implementation or use of the technology described in - this document or the extent to which any license under such rights - might or might not be available; nor does it represent that it has - made any independent effort to identify any such rights. Information - on the procedures with respect to rights in RFC documents can be - found in BCP 78 and BCP 79. - - Copies of IPR disclosures made to the IETF Secretariat and any - assurances of licenses to be made available, or the result of an - attempt made to obtain a general license or permission for the use of - such proprietary rights by implementers or users of this - specification can be obtained from the IETF on-line IPR repository at - http://www.ietf.org/ipr. - - The IETF invites any interested party to bring to its attention any - copyrights, patents or patent applications, or other proprietary - rights that may cover technology that may be required to implement - this standard. Please address the information to the IETF at - ietf-ipr@ietf.org. - - -Disclaimer of Validity - - This document and the information contained herein are provided on an - "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS - OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET - ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, - INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE - INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED - WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. - - -Copyright Statement - - Copyright (C) The Internet Society (2005). This document is subject - to the rights, licenses and restrictions contained in BCP 78, and - except as set forth therein, the authors retain all their rights. - - -Acknowledgment - - Funding for the RFC Editor function is currently provided by the - Internet Society. - - - - -Sisson & Laurie Expires January 11, 2006 [Page 25] - |