Commit d8b60149 authored by Andreas Gustafsson's avatar Andreas Gustafsson
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updated drafts

parent ac9003d5
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DNSEXT Working Group Olafur Gudmundsson (NAI Labs)
INTERNET-DRAFT June 2000
INTERNET-DRAFT October 2000
<draft-ietf-dnsext-message-size-00.txt>
<draft-ietf-dnsext-message-size-01.txt>
Updates: RFC 2535
Updates: RFC 2535, RFC 2874
......@@ -40,7 +40,7 @@ Status of this Memo
Comments should be sent to the authors or the DNSEXT WG mailing list
namedroppers@ops.ietf.org
This draft expires on December 29, 2000.
This draft expires on March 29, 2001.
Copyright Notice
......@@ -55,9 +55,9 @@ Status of this Memo
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INTERNET-DRAFT DNSSEC and IPng message size requirement June 2000
INTERNET-DRAFT DNSSEC and IPng message size requirement October 2000
Abstract
......@@ -65,7 +65,7 @@ Abstract
This document mandates support for EDNS0 in DNS entities claiming to
support DNS Security Extensions and A6 records. This requirement is
necessary because these new features increase the size of DNS
messages. If EDNS0 is not supported fallback to TCP will happen,
messages. If EDNS0 is not supported fall back to TCP will happen,
having a detrimental impact on query latency and DNS server load.
......@@ -73,8 +73,8 @@ Abstract
1 - Introduction
Familiarity with the DNS [RFC1034, RFC1035], DNS Security Extensions
[RFC2535], EDNS0[RFC2671] and A6 [RFCA6] is helpful.
Familiarity with the DNS[RFC1034, RFC1035], DNS Security
Extensions[RFC2535], EDNS0[RFC2671] and A6[RFC2874] is helpful.
RFC 1035[RFC1035] Section 2.3.4 requires that DNS messages over UDP
have a data payload of 512 octets or less. Most DNS software today
......@@ -88,13 +88,16 @@ Abstract
Compared to UDP, TCP is an expensive protocol to use for a simple
transaction like DNS: a TCP connection requires 5 packets for setup
and teardown, excluding data packets, thus requiring at least 3
and tear down, excluding data packets, thus requiring at least 3
round trips on top of the one for the original UDP query. The DNS
server also needs to keep a state of the connection during this
transaction. As many DNS servers answer thousands of queries per
second, requiring them to use TCP will cause significant overhead and
delays.
1.1 - DNSSEC motivations
DNSSEC[RFC2535] secures DNS by adding a Public Key signature on each
RR set. These signatures range in size from about 80 octets to 800
octets most are going to be in the range of 80..200 octets. The
......@@ -102,30 +105,40 @@ Abstract
will significantly increase the size of DNS answers from secure
zones.
It is important that security aware servers and resolvers get all the
data in Answer and Authority section in one query without truncation.
In some cases it is important that some Additional Data be sent
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along, mainly in delegation cases.
TSIG[RFC2845] allows for the light weight authentication of DNS
messages, but increases the size of the messages by at least 70
octets. DNSSEC allows for computationally expensive message
authentication with a standard public key signature. As only one TSIG
or SIG(0) can be attached to each DNS answer the size increase of
message authentication is not significant, but may still lead to a
truncation.
1.2 - IPv6 Motivations
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message authentication is not significant.
IPv6 addresses[A6] are 128 bits and are represented in the DNS by
multiple A6 records, each consisting of a domain name and a bit
IPv6 addresses[RFC2874] are 128 bits and are represented in the DNS
by multiple A6 records, each consisting of a domain name and a bit
field. The domain name refers to an address prefix that may require
additional A6 RRs to be included in the answer. Answers where
queried name has multiple A6 addresses may overflow a 512-octet UDP
packet size.
1.3 Root server and TLD server motivations
The current number of root servers is limited to 13 as that is the
maximum number of name servers and their address records that fit in
one 512-octet DNS message. If root servers start advertising A6 or
......@@ -133,17 +146,50 @@ INTERNET-DRAFT DNSSEC and IPng message size requirement June 2000
an single 512-octet DNS message. Resulting in a large number of TCP
connections to the root servers.
It is important that a high level domains have a high number of
domain name servers for redundancy, latency and load balancing
reasons.
1.4 UDP vs TCP for DNS messages
Given all these factors, it is essential that any implementations
that supports DNSSEC and or A6 be able to use larger DNS messages
than 512 octets.
The original 512 restriction was put in place to avoid fragmentation
of DNS responses. A fragmented UDP message that suffers a loss off
one of the fragments renders the answer useless and DNS must
retransmit the query. TCP connection requires number of round trips
for establishment, data transfer and tear down, but only the lost
data segments are retransmitted.
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In the early days number of IP implementations did not handle
fragmentation well, but all modern operating systems have overcome
that issue thus sending fragmented messages is fine from that
standpoint. The open issue is the effect of losses on fragmented
messages. If connection has high loss ratio only TCP will allow
reliable transfer of DNS data, most links have low loss ratios thus
sending fragmented UDP packet in one round trip is better than
establishing a TCP connection to transfer few thousand octets.
1.5 EDNS0 and large UDP messages
EDNS0[RFC2671] allows clients to declare the maximum size of UDP
message they are willing to handle. Thus, if the expected answer is
between 512 octets and the maximum size that the client can accept,
the additional overhead of a TCP connection can be avoided.
1.2 - Requirements
1.7 - Requirements
The key words "MUST", "REQUIRED", "SHOULD", "RECOMMENDED", and "MAY"
in this document are to be interpreted as described in RFC 2119.
......@@ -151,14 +197,24 @@ INTERNET-DRAFT DNSSEC and IPng message size requirement June 2000
2 - Protocol changes:
This document updates [RFC2535] and [A6].
This document updates [RFC2535] and [RFC2874], by adding new
requirements.
All RFC2535-compliant servers and resolvers MUST support EDNS0 and
advertise message size of at least 1280 octets.
advertise message size of at least 1220 octets, but SHOULD advertise
message size of 4000. This value might be too low to get full
answers for high level servers and successor of this document may
require a larger value.
All RFC2874-compliant servers and resolver MUST support EDNS0 and
advertise message size of at least 1024 octets, but SHOULD advertise
message size of 2048.
All [A6] compliant servers and resolver MUST support EDNS0 and
advertise message size of at least 1280 octets.
All RFC2535 and RFC2874 compliant entities MUST be able to handle
fragmented IP and IPv6 UDP packets.
All hosts supporting both RFC2535 and RFC2874 MUST use the larger
required value in EDNS0 advertisements.
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3 Acknowledgments
Harald Alvestrand, Rob Austein, Randy Bush, David Conrad, Andreas
Gustafsson, Bob Halley and Edward Lewis where instrumental in
motivating and shaping this document.
Gustafsson, Bob Halley, Edward Lewis and Kazu Yamamoto where
instrumental in motivating and shaping this document.
4 - Security Considerations:
......@@ -188,10 +244,12 @@ INTERNET-DRAFT DNSSEC and IPng message size requirement June 2000
None
References:
[RFC1034] P. Mockapetris, ``Domain Names - Concepts and Facilities''
STD 13, RFC 1034, November 1987.
[RFC1035] P. Mockapetris, ``Domain Names - Implementation and
Specification'', STD 13, RFC 1035, November 1987.
......@@ -209,8 +267,8 @@ References:
2845, May 2000.
[A6] M. Crawford, C. Huitema, S. Thompson, ``DNS Extensions to
Support IPv6 Address Aggregation and Renumbering'', RFCxxx,
[RFC2874] M. Crawford, C. Huitema, S. Thompson, ``DNS Extensions to
Support IPv6 Address Aggregation and Renumbering'', RFC2874,
Sometime 2000.
......@@ -221,11 +279,9 @@ References:
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Author Address
......@@ -279,4 +335,4 @@ Full Copyright Statement
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DNSEXT Working Group Brian Wellington (Nominum)
INTERNET-DRAFT October 2000
DNSIND Working Group Brian Wellington (Nominum)
INTERNET-DRAFT May 2000
<draft-ietf-dnsext-signing-auth-01.txt>
<draft-ietf-dnsext-signing-auth-02.txt>
Updates: RFC 2535
......@@ -32,10 +31,10 @@ Status of this Memo
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
Comments should be sent to the authors or the DNSIND WG mailing list
namedroppers@internic.net.
Comments should be sent to the authors or the DNSEXT WG mailing list
namedroppers@ops.ietf.org.
This draft expires on November 12, 2000.
This draft expires on April 2, 2000.
Copyright Notice
......@@ -50,14 +49,18 @@ Abstract
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secure resolution process. Specifically, this affects the
authorization of keys to sign sets of records.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
1 - Introduction
......@@ -91,7 +94,7 @@ necessary.
SIGs may also be used for transaction security. In this case, a SIG
record with a type covered field of 0 is attached to a message, and is
used to protect message integrity. This is referred to as a SIG(0)
[RFC2535].
[RFC2535, RFC2931].
The following sections define requirements for all of the fields of a
SIG record. These requirements MUST be met in order for a DNSSEC
......@@ -102,13 +105,9 @@ SIG, there are requirements that it MUST meet.
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2.1 - Type Covered
......@@ -153,18 +152,23 @@ that future algorithms will impose contraints.
The signer's name field of a data SIG MUST contain the name of the zone
to which the data and signature belong. The combination of signer's
name, key tag, and algorithm MUST identify a zone key if the SIG is to
be considered material. This document defines a standard policy for
DNSSEC validation; local policy may override the standard policy.
be considered material. The only exception that the signer's name field
in a SIG KEY at a zone apex SHOULD contain the parent zone's name,
unless the KEY set is self-signed. This document defines a standard
policy for DNSSEC validation; local policy may override the standard
policy.
There are no restrictions on the signer field of a SIG(0) record. The
combination of signer's name, key tag, and algorithm MUST identify a key
if this SIG(0) is to be processed.
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There are no restrictions on the signer field of a SIG(0) record. The
combination of signer's name, key tag, and algorithm MUST identify a key
if this SIG(0) is to be processed.
2.8 - Signature
......@@ -210,20 +214,20 @@ otherwise.
The primary reason that RFC 2535 allows host and user keys to generate
material DNSSEC signatures is to allow dynamic update without online
zone keys; that is, avoid storing private keys in an online server. The
desire to avoid online signing keys cannot be achieved, though, because
they are necessary to sign NXT and SOA sets [SSU]. These online zone
keys can sign any incoming data. Removing the goal of having no online
keys removes the reason to allow host and user keys to generate material
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signatures. in the DNS.
zone keys; that is, avoid storing private keys in an online server. The
desire to avoid online signing keys cannot be achieved, though, because
they are necessary to sign NXT and SOA sets [SSU]. These online zone
keys can sign any incoming data. Removing the goal of having no online
keys removes the reason to allow host and user keys to generate material
signatures.
Limiting material signatures to zone keys simplifies the validation
process. The length of the verification chain is bounded by the name's
......@@ -266,19 +270,20 @@ The signing KEY record MUST have a protocol value of 3 (DNSSEC) or 255
MUST NOT trust any signature that it generates.
3.5 - Algorithm Number
The algorithm field MUST be identical to that of the generated SIG
record, and MUST meet all requirements for an algorithm value in a SIG
record.
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3.5 - Algorithm Number
The algorithm field MUST be identical to that of the generated SIG
record, and MUST meet all requirements for an algorithm value in a SIG
record.
4 - Security considerations
This document defines a standard baseline for a DNSSEC capable resolver.
......@@ -308,33 +313,31 @@ informative comments (in alphabetical order):
[RFC1035] P. Mockapetris, ``Domain Names - Implementation and
Specification,'' RFC 1035, ISI, November 1987.
[RFC2119] S. Bradner, ``Key words for use in RFCs to Indicate
Requirement Levels,'' BCP 14, RFC 2119, Harvard, March 1997.
[RFC2136] P. Vixie (Ed.), S. Thomson, Y. Rekhter, J. Bound ``Dynamic
Updates in the Domain Name System,'' RFC 2136, ISC & Bellcore
& Cisco & DEC, April 1997.
[RFC2535] D. Eastlake, ``Domain Name System Security Extensions,'' RFC
2065, IBM, March 1999.
[SSU] B. Wellington, ``Simple Secure Domain Name System (DNS)
Dynamic Update,'' draft-ietf-dnsext-simple-secure-
update-01.txt, Nominum, May 2000.
2535, IBM, March 1999.
[RFC2931] D. Eastlake, ``DNS Request and Transaction Signatures (
SIG(0)s ),'' RFC 2931, Motorola, September 2000.
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[SSU] B. Wellington, ``Simple Secure Domain Name System (DNS)
Dynamic Update,'' draft-ietf-dnsext-simple-secure-
update-02.txt, Nominum, October 2000.
7 - Author's Address
......@@ -382,9 +385,5 @@ FITNESS FOR A PARTICULAR PURPOSE."
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DNSIND Working Group Brian Wellington (NAILabs)
INTERNET-DRAFT May 2000
DNSEXT Working Group Brian Wellington (Nominum)
INTERNET-DRAFT October 2000
<draft-ietf-dnsext-simple-secure-update-01.txt>
<draft-ietf-dnsext-simple-secure-update-02.txt>
Updates: RFC 2535, RFC 2136,
Replaces: RFC 2137, [update2]
Updates: RFC 2535, RFC 2136
Replaces: RFC 2137
......@@ -32,10 +32,10 @@ Status of this Memo
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
Comments should be sent to the authors or the DNSIND WG mailing list
namedroppers@internic.net.
Comments should be sent to the authors or the DNSEXT WG mailing list
namedroppers@ops.ietf.org.
This draft expires on November 12, 2000.
This draft expires on April 2, 2000.
Copyright Notice
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to be flexible and useful while requiring as few changes to the
......@@ -60,6 +60,10 @@ INTERNET-DRAFT Secure Dynamic Update May 2000
communication based on authenticated requests and transactions is
used to provide authorization.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
1 - Introduction
......@@ -71,12 +75,12 @@ the basis for this work.
Familiarity with the DNS system [RFC1034, RFC1035] and dynamic update
[RFC2136] is helpful and is assumed by this document. In addition,
knowledge of DNS security extensions [RFC2535], SIG(0) transaction
security [RFC2535], and TSIG transaction security [TSIG] is recommended.
This document updates portions of RFC 2535, in particular section 3.1.2.
This document obsoletes RFC 2137, an alternate proposal for secure
dynamic update, due to implementation experience.
security [RFC2535, RFC2931], and TSIG transaction security [RFC2845] is
recommended.
This document updates portions of RFC 2535, in particular section 3.1.2,
and RFC 2136. This document obsoletes RFC 2137, an alternate proposal
for secure dynamic update, due to implementation experience.
1.1 - Overview of DNS Dynamic Update
......@@ -89,27 +93,27 @@ for the zone. The primary server for a dynamic zone must increment the
zone SOA serial number when an update occurs or before the next
retrieval of the SOA.
1.2 - Overview of DNS Transaction Security
Exchanges of DNS messages which include TSIG [TSIG] or SIG(0) [RFC2535]
records allow two DNS entities to authenticate DNS requests and
responses sent between them. A TSIG MAC (message authentication code)
is derived from a shared secret, and a SIG(0) is generated from a
private key whose public counterpart is stored in DNS. In both cases, a
record containing the message signature/MAC is included as the final
resource record in a DNS message. Keyed hashes, used in TSIG, are
inexpensive to calculate and verify. Public key encryption, as used in
SIG(0), is more scalable as the public keys are stored in DNS.
Exchanges of DNS messages which include TSIG [RFC2845] or SIG(0)
[RFC2535, RFC2931] records allow two DNS entities to authenticate DNS
requests and responses sent between them. A TSIG MAC (message
authentication code) is derived from a shared secret, and a SIG(0) is
generated from a private key whose public counterpart is stored in DNS.
In both cases, a record containing the message signature/MAC is included
as the final resource record in a DNS message. Keyed hashes, used in
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TSIG, are inexpensive to calculate and verify. Public key encryption,
as used in SIG(0), is more scalable as the public keys are stored in
DNS.
1.3 - Comparison of data authentication and message authentication
Message based authentication, using TSIG or SIG(0), provides protection
......@@ -139,7 +143,6 @@ RRset is straightforward, and this signature could be permanently used
to protect the data, as specified in [RFC2535]. However, if an RRset is
deleted, there is no data for a SIG to cover.
1.4 - Data and message signatures
As specified in [signing-auth], the DNSSEC validation process performed
......@@ -152,19 +155,19 @@ authentication of the data itself.
The primary usefulness of host and user keys, with respect to DNSSEC, is
to authenticate messages, including dynamic updates. Thus, host and
user keys MAY be used to generate SIG(0) records to authenticate updates
and MAY be used in the TKEY [TKEY] process to generate TSIG shared
and MAY be used in the TKEY [RFC2930] process to generate TSIG shared
secrets. In both cases, no SIG records generated by non-zone keys will
be used in a DNSSEC validation process unless local policy dictates.
Authentication of data, once it is present in DNS, only involves DNSSEC
zone keys and signatures generated by them.
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Authentication of data, once it is present in DNS, only involves DNSSEC
zone keys and signatures generated by them.
1.5 - Signatory strength
......@@ -199,6 +202,26 @@ server MUST indicate failure by returning a message with RCODE REFUSED.
Other TSIG, SIG(0), or dynamic update errors are returned as specified
in the appropriate protocol description.
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