draft-ietf-dnsop-edns-tcp-keepalive-04.txt   draft-ietf-dnsop-edns-tcp-keepalive-05.txt 
dnsop P. Wouters dnsop P. Wouters
Internet-Draft Red Hat Internet-Draft Red Hat
Intended status: Standards Track J. Abley Intended status: Standards Track J. Abley
Expires: April 22, 2016 Dyn, Inc. Expires: July 9, 2016 Dyn, Inc.
S. Dickinson S. Dickinson
Sinodun Sinodun
R. Bellis R. Bellis
ISC ISC
October 20, 2015 January 6, 2016
The edns-tcp-keepalive EDNS0 Option The edns-tcp-keepalive EDNS0 Option
draft-ietf-dnsop-edns-tcp-keepalive-04 draft-ietf-dnsop-edns-tcp-keepalive-05
Abstract Abstract
DNS messages between clients and servers may be received over either DNS messages between clients and servers may be received over either
UDP or TCP. UDP transport involves keeping less state on a busy UDP or TCP. UDP transport involves keeping less state on a busy
server, but can cause truncation and retries over TCP. Additionally, server, but can cause truncation and retries over TCP. Additionally,
UDP can be exploited for reflection attacks. Using TCP would reduce UDP can be exploited for reflection attacks. Using TCP would reduce
retransmits and amplification. However, clients commonly use TCP retransmits and amplification. However, clients commonly use TCP
only for fallback and servers typically use idle timeouts on the only for retries and servers typically use idle timeouts on the order
order of seconds. of seconds.
This document defines an EDNS0 option ("edns-tcp-keepalive") that This document defines an EDNS0 option ("edns-tcp-keepalive") that
allows DNS servers to signal a variable idle timeout. This allows DNS servers to signal a variable idle timeout. This
signalling facilitates a better balance of UDP and TCP transport signalling encourages the use of long-lived TCP connections by
between individual clients and servers, reducing the impact of allowing the state associated with TCP transport to be managed
problems associated with UDP transport and allowing the state effectively with minimal impact on the DNS transaction time.
associated with TCP transport to be managed effectively with minimal
impact on the DNS transaction time.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://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 April 22, 2016. This Internet-Draft will expire on July 9, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2016 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
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 4 2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 4
3. The edns-tcp-keepalive Option . . . . . . . . . . . . . . . . 5 3. The edns-tcp-keepalive Option . . . . . . . . . . . . . . . . 4
3.1. Option Format . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Option Format . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Use by DNS Clients . . . . . . . . . . . . . . . . . . . 6 3.2. Use by DNS Clients . . . . . . . . . . . . . . . . . . . 5
3.2.1. Sending Queries . . . . . . . . . . . . . . . . . . . 6 3.2.1. Sending Queries . . . . . . . . . . . . . . . . . . . 5
3.2.2. Receiving Responses . . . . . . . . . . . . . . . . . 6 3.2.2. Receiving Responses . . . . . . . . . . . . . . . . . 5
3.3. Use by DNS Servers . . . . . . . . . . . . . . . . . . . 6 3.3. Use by DNS Servers . . . . . . . . . . . . . . . . . . . 6
3.3.1. Receiving Queries . . . . . . . . . . . . . . . . . . 6 3.3.1. Receiving Queries . . . . . . . . . . . . . . . . . . 6
3.3.2. Sending Responses . . . . . . . . . . . . . . . . . . 7 3.3.2. Sending Responses . . . . . . . . . . . . . . . . . . 6
3.4. TCP Session Management . . . . . . . . . . . . . . . . . 7 3.4. TCP Session Management . . . . . . . . . . . . . . . . . 6
3.5. Non-Clean Paths . . . . . . . . . . . . . . . . . . . . . 8 3.5. Non-Clean Paths . . . . . . . . . . . . . . . . . . . . . 8
3.6. Anycast Considerations . . . . . . . . . . . . . . . . . 8 3.6. Anycast Considerations . . . . . . . . . . . . . . . . . 8
4. Intermediary Considerations . . . . . . . . . . . . . . . . . 9 4. Intermediary Considerations . . . . . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . 9 8.1. Normative References . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . 10 8.2. Informative References . . . . . . . . . . . . . . . . . 10
Appendix A. Editors' Notes . . . . . . . . . . . . . . . . . . . 11 Appendix A. Editors' Notes . . . . . . . . . . . . . . . . . . . 10
A.1. Abridged Change History . . . . . . . . . . . . . . . . . 11 A.1. Abridged Change History . . . . . . . . . . . . . . . . . 10
A.1.1. draft-ietf-dnsop-edns-tcp-keepalive-04 . . . . . . . 11 A.1.1. draft-ietf-dnsop-edns-tcp-keepalive-05 . . . . . . . 10
A.1.2. draft-ietf-dnsop-edns-tcp-keepalive-03 . . . . . . . 11 A.1.2. draft-ietf-dnsop-edns-tcp-keepalive-04 . . . . . . . 11
A.1.3. draft-ietf-dnsop-edns-tcp-keepalive-02 . . . . . . . 12 A.1.3. draft-ietf-dnsop-edns-tcp-keepalive-03 . . . . . . . 11
A.1.4. draft-ietf-dnsop-edns-tcp-keepalive-01 . . . . . . . 12 A.1.4. draft-ietf-dnsop-edns-tcp-keepalive-02 . . . . . . . 12
A.1.5. draft-ietf-dnsop-edns-tcp-keepalive-00 . . . . . . . 12 A.1.5. draft-ietf-dnsop-edns-tcp-keepalive-01 . . . . . . . 12
A.1.6. draft-wouters-edns-tcp-keepalive-01 . . . . . . . . . 12 A.1.6. draft-ietf-dnsop-edns-tcp-keepalive-00 . . . . . . . 12
A.1.7. draft-wouters-edns-tcp-keepalive-00 . . . . . . . . . 13 A.1.7. draft-wouters-edns-tcp-keepalive-01 . . . . . . . . . 13
A.1.8. draft-wouters-edns-tcp-keepalive-00 . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction 1. Introduction
DNS messages between clients and servers may be received over either DNS messages between clients and servers may be received over either
UDP or TCP [RFC1035]. Historically, DNS clients used API's that only UDP or TCP [RFC1035]. Historically, DNS clients used API's that only
facilitated sending and receiving a single query over either UDP or facilitated sending and receiving a single query over either UDP or
TCP. New APIs and deployment of DNSSEC validating resolvers on hosts TCP. New APIs and deployment of DNSSEC validating resolvers on hosts
that in the past were using stub resolving only is increasing the DNS that in the past were using stub resolving only is increasing the DNS
client base that prefer using long lived TCP connections. Long-lived client base that prefer using long lived TCP connections. Long-lived
TCP connections can result in lower request latency than the case TCP connections can result in lower request latency than the case
where UDP transport is used and truncated responses are received, where UDP transport is used and truncated responses are received.
since clients that have fallen back to TCP transport in response to a This is because clients that retry over TCP following a truncated UDP
truncated response typically only uses the TCP session for a single response typically only use the TCP session for a single (request,
(request, response) pair, continuing with UDP transport for response) pair, continuing with UDP transport for subsequent queries.
subsequent queries. Clients wishing to use other stream-based
transport protocols for DNS would also benefit from the set-up
amortisation afforded by long lived connections.
UDP transport is stateless, and hence presents a much lower resource UDP transport is stateless, and hence presents a much lower resource
burden on a busy DNS server than TCP. An exchange of DNS messages burden on a busy DNS server than TCP. An exchange of DNS messages
over UDP can also be completed in a single round trip between over UDP can also be completed in a single round trip between
communicating hosts, resulting in optimally-short transaction times. communicating hosts, resulting in optimally-short transaction times.
UDP transport is not without its risks, however. UDP transport is not without its risks, however.
A single-datagram exchange over UDP between two hosts can be A single-datagram exchange over UDP between two hosts can be
exploited to enable a reflection attack on a third party. Response exploited to enable a reflection attack on a third party. Response
Rate Limiting [RRL] is designed to help mitigate such attacks against Rate Limiting [RRL] is designed to help mitigate such attacks against
skipping to change at page 3, line 47 skipping to change at page 3, line 44
512 bytes. Deployment of DNSSEC [RFC4033] and other protocols 512 bytes. Deployment of DNSSEC [RFC4033] and other protocols
subsequently increased the observed frequency at which responses subsequently increased the observed frequency at which responses
exceed this limit. EDNS0 [RFC6891] allows DNS messages larger than exceed this limit. EDNS0 [RFC6891] allows DNS messages larger than
512 bytes to be exchanged over UDP, with a corresponding increased 512 bytes to be exchanged over UDP, with a corresponding increased
incidence of fragmentation. Fragmentation is known to be problematic incidence of fragmentation. Fragmentation is known to be problematic
in general, and has also been implicated in increasing the risk of in general, and has also been implicated in increasing the risk of
cache poisoning attacks [fragmentation-considered-poisonous]. cache poisoning attacks [fragmentation-considered-poisonous].
TCP transport is less susceptible to the risks of fragmentation and TCP transport is less susceptible to the risks of fragmentation and
reflection attacks. However, TCP transport as currently deployed has reflection attacks. However, TCP transport as currently deployed has
expensive overhead. expensive setup overhead.
The overhead of the three-way TCP handshake for a single DNS The overhead of the three-way TCP handshake for a single DNS
transaction is substantial, increasing the transaction time for a transaction is substantial, increasing the transaction time for a
single (request, response) pair of DNS messages from 1 x RTT to 2 x single (request, response) pair of DNS messages from 1 x RTT to 2 x
RTT. There is no such overhead for a session that is already RTT. There is no such overhead for a session that is already
established, however, and the overall impact of the TCP setup established therefore the overhead of the initial TCP handshake is
handshake when the resulting session is used to exchange N DNS minimised when the resulting session is used to exchange multiple DNS
message pairs over a single session, (1 + N)/N, approaches unity as N message pairs over a single session. The extra RTT time for session
increases. setup can be represented as the equation (1 + N)/N, where N
represents the number of DNS message pairs that utilize the session
and the result approaches unity as N increases.
With increased deployment of DNSSEC and new RRtypes containing With increased deployment of DNSSEC and new RRtypes containing
application specific cryptographic material, there is an increase in application specific cryptographic material, there is an increase in
the prevalence of truncated responses received over UDP with fallback the prevalence of truncated responses received over UDP with retries
to TCP. over TCP. The overhead for a DNS transaction over UDP truncated due
to RRL is 3x RTT, higher than the overhead imposed on the same
(It should perhaps be noted that the overhead for a DNS transaction transaction initiated over TCP.
over UDP truncated due to RRL is 3x RTT, higher than the overhead
imposed on the same transaction initiated over TCP.)
The use of TCP transport requires state to be retained on DNS The use of TCP transport requires state to be retained on DNS
servers. If a server is to perform adequately with a significant servers. If a server is to perform adequately with a significant
query load received over TCP, it must manage its available resources query load received over TCP, it must manage its available resources
to ensure that all established TCP sessions are well-used, and idle to ensure that all established TCP sessions are well-used, and idle
connections are closed after an appropriate amount of time. connections are closed after an appropriate amount of time.
This document proposes a signalling mechanism between DNS clients and This document proposes a signalling mechanism between DNS clients and
servers that provides a means to better balance the use of UDP and servers that encourages the use of long-lived TCP connections by
TCP transport (thereby helping to manage the impact of problems allowing the state associated with TCP transport to be managed
associated with UDP), whilst constraining the impact of TCP on effectively with minimal impact on the DNS transaction time.
response times and server resources to a manageable level.
This mechanism will be of benefit both for stub-resolver and This mechanism will be of benefit both for stub-resolver and
resolver-authoritative TCP connections. In the latter case the resolver-authoritative TCP connections. In the latter case the
persistent nature of the TCP connection can provide improved defence persistent nature of the TCP connection can provide improved defence
against attacks including DDoS. against attacks including DDoS.
The reduced overhead of this extension adds up significantly when The reduced overhead of this extension adds up significantly when
combined with other EDNS0 extensions, such as [CHAIN-QUERY] and combined with other EDNS0 extensions, such as [CHAIN-QUERY] and
[DNS-over-TLS]. For example, the combination of these EDNS0 [DNS-over-TLS]. For example, the combination of these EDNS0
extensions make it possible for hosts on high-latency mobile networks extensions make it possible for hosts on high-latency mobile networks
skipping to change at page 5, line 9 skipping to change at page 4, line 48
2. Requirements Notation 2. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. The edns-tcp-keepalive Option 3. The edns-tcp-keepalive Option
This document specifies a new EDNS0 [RFC6891] option, edns-tcp- This document specifies a new EDNS0 [RFC6891] option, edns-tcp-
keepalive, which can be used by DNS clients and servers to signal a keepalive, which can be used by DNS clients and servers to signal a
willingness to keep an idle TCP session open for a certain amount of willingness to keep an idle TCP session open to conduct future DNS
time to conduct future DNS transactions. This specification does not transactions, with the idle timeout being specified by the server.
distinguish between different types of DNS client and server in the This specification does not distinguish between different types of
use of this option. DNS client and server in the use of this option.
3.1. Option Format 3.1. Option Format
The edns-tcp-keepalive option is encoded as follows: The edns-tcp-keepalive option is encoded as follows:
1 2 3 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+ +-------------------------------+-------------------------------+
! OPTION-CODE ! OPTION-LENGTH ! ! OPTION-CODE ! OPTION-LENGTH !
+-------------------------------+-------------------------------+ +-------------------------------+-------------------------------+
skipping to change at page 6, line 30 skipping to change at page 6, line 4
Clients MUST specify an OPTION-LENGTH of 0 and omit the TIMEOUT Clients MUST specify an OPTION-LENGTH of 0 and omit the TIMEOUT
value. value.
3.2.2. Receiving Responses 3.2.2. Receiving Responses
A DNS client that receives a response using UDP transport that A DNS client that receives a response using UDP transport that
includes the edns-tcp-keepalive option MUST ignore the option. includes the edns-tcp-keepalive option MUST ignore the option.
A DNS client that receives a response using TCP transport that A DNS client that receives a response using TCP transport that
includes the edns-tcp-keepalive option MAY keep the existing TCP includes the edns-tcp-keepalive option MAY keep the existing TCP
session open when it is idle. It SHOULD honour the timeout and session open when it is idle. It SHOULD honour the timeout received
initiate close of the connection before the timeout expires. in that response (overriding any previous timeout) and initiate close
of the connection before the timeout expires.
A DNS client that receives a response that includes the edns-tcp- A DNS client that receives a response that includes the edns-tcp-
keepalive option with a TIMEOUT value of 0 SHOULD send no more keepalive option with a TIMEOUT value of 0 SHOULD send no more
queries on that connection and initiate closing the connection as queries on that connection and initiate closing the connection as
soon as it has received all outstanding responses. soon as it has received all outstanding responses.
A DNS client that sent a query containing the edns-keepalive-option A DNS client that sent a query containing the edns-keepalive-option
but receives a response that does not contain the edns-keepalive- but receives a response that does not contain the edns-keepalive-
option should assume the server does not support keepalive and behave option SHOULD assume the server does not support keepalive and behave
following the guidance in [DRAFT-5966bis]. This holds true even if a following the guidance in [DRAFT-5966bis]. This holds true even if a
previous edns-keepalive-option exchange occurred on the existing TCP previous edns-keepalive-option exchange occurred on the existing TCP
connection. connection.
3.3. Use by DNS Servers 3.3. Use by DNS Servers
3.3.1. Receiving Queries 3.3.1. Receiving Queries
A DNS server that receives a query using UDP transport that includes A DNS server that receives a query using UDP transport that includes
the edns-tcp-keepalive option MUST ignore the option. the edns-tcp-keepalive option MUST ignore the option.
skipping to change at page 8, line 47 skipping to change at page 8, line 23
be employed to avoid persistent interference due to non-clean paths. be employed to avoid persistent interference due to non-clean paths.
3.6. Anycast Considerations 3.6. Anycast Considerations
DNS servers of various types are commonly deployed using anycast DNS servers of various types are commonly deployed using anycast
[RFC4786]. [RFC4786].
Changes in network topology between clients and anycast servers may Changes in network topology between clients and anycast servers may
cause disruption to TCP sessions making use of edns-tcp-keepalive cause disruption to TCP sessions making use of edns-tcp-keepalive
more often than with TCP sessions that omit it, since the TCP more often than with TCP sessions that omit it, since the TCP
sessions are expected to be longer-lived. Anycast servers MAY make sessions are expected to be longer-lived. It might be possible for
anycast servers to avoid disruption due to topology changes by making
use of TCP multipath [RFC6824] to anchor the server side of the TCP use of TCP multipath [RFC6824] to anchor the server side of the TCP
connection to an unambiguously-unicast address in order to avoid connection to an unambiguously-unicast address.
disruption due to topology changes.
4. Intermediary Considerations 4. Intermediary Considerations
It is RECOMMENDED that DNS intermediaries which terminate TCP It is RECOMMENDED that DNS intermediaries which terminate TCP
connections implement edns-tcp-keepalive. An intermediary that does connections implement edns-tcp-keepalive. An intermediary that does
not implement edns-tcp-keepalive but sits between a client and server not implement edns-tcp-keepalive but sits between a client and server
that both support edns-tcp-keepalive might close idle connections that both support edns-tcp-keepalive might close idle connections
unnecessarily. unnecessarily.
5. Security Considerations 5. Security Considerations
The edns-tcp-keepalive option can potentially be abused to request The edns-tcp-keepalive option can potentially be abused to request
large numbers of sessions in a quick burst. When a DNS Server large numbers of long-lived sessions in a quick burst. When a DNS
detects abusive behaviour, it SHOULD immediately close the TCP Server detects abusive behaviour, it SHOULD immediately close the TCP
connection and free the resources used. connection and free the resources used.
Servers could choose to monitor client behaviour with respect to the Servers could choose to monitor client behaviour with respect to the
edns-tcp-keepalive option to build up profiles of clients that do not edns-tcp-keepalive option to build up profiles of clients that do not
honour the specified timeout. honour the specified timeout.
Readers are advised to familiarise themselves with the security Readers are advised to familiarise themselves with the security
considerations outlined in [DRAFT-5966bis] considerations outlined in [DRAFT-5966bis]
6. IANA Considerations 6. IANA Considerations
The IANA is directed to assign an EDNS0 option code for the edns-tcp- The IANA is directed to assign an EDNS0 option code for the edns-tcp-
keepalive option from the DNS EDNS0 Option Codes (OPT) registry as keepalive option from the DNS EDNS0 Option Codes (OPT) registry as
follows: follows:
+-------+--------------------+----------+-----------------+ +-------+--------------------+----------+-----------------+
| Value | Name | Status | Reference | | Value | Name | Status | Reference |
+-------+--------------------+----------+-----------------+ +-------+--------------------+----------+-----------------+
| TBD1 | edns-tcp-keepalive | Optional | [This document] | | TBD1 | edns-tcp-keepalive | Standard | [This document] |
+-------+--------------------+----------+-----------------+ +-------+--------------------+----------+-----------------+
7. Acknowledgements 7. Acknowledgements
The authors acknowledge the contributions of Jinmei TATUYA and Mark The authors acknowledge the contributions of Jinmei TATUYA and Mark
Andrews. Thanks to Duane Wessels for detailed review and the many Andrews. Thanks to Duane Wessels for detailed review and the many
others who contributed to the mailing list discussion. others who contributed to the mailing list discussion.
8. References 8. References
8.1. Normative References 8.1. Normative References
[DRAFT-5966bis]
Dickinson, J., Dickinson, S., Bellis, R., Mankin, A., and
D. Wessels, "DNS Transport over TCP - Implementation
Requirements", draft-ietf-dnsop-5966bis (work in
progress), December 2015.
[RFC1035] Mockapetris, P., "Domain names - implementation and [RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <http://www.rfc-editor.org/info/rfc1035>. November 1987, <http://www.rfc-editor.org/info/rfc1035>.
[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,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
skipping to change at page 10, line 32 skipping to change at page 10, line 18
<http://www.rfc-editor.org/info/rfc6891>. <http://www.rfc-editor.org/info/rfc6891>.
[RFC7320] Nottingham, M., "URI Design and Ownership", BCP 190, [RFC7320] Nottingham, M., "URI Design and Ownership", BCP 190,
RFC 7320, DOI 10.17487/RFC7320, July 2014, RFC 7320, DOI 10.17487/RFC7320, July 2014,
<http://www.rfc-editor.org/info/rfc7320>. <http://www.rfc-editor.org/info/rfc7320>.
8.2. Informative References 8.2. Informative References
[CHAIN-QUERY] [CHAIN-QUERY]
Wouters, P., "Chain Query requests in DNS", draft-ietf- Wouters, P., "Chain Query requests in DNS", draft-ietf-
dnsop-edns-chain-query (work in progress), October 2015. dnsop-edns-chain-query (work in progress), November 2015.
[DNS-over-TLS] [DNS-over-TLS]
Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D., Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
and P. Hoffman, "TLS for DNS: Initiation and Performance and P. Hoffman, "TLS for DNS: Initiation and Performance
Considerations", draft-ietf-dprive-dns-over-tls-01 (work Considerations", draft-ietf-dprive-dns-over-tls (work in
in progress), October 2015. progress), December 2015.
[DRAFT-5966bis]
Dickinson, J., Dickinson, S., Bellis, R., Mankin, A., and
D. Wessels, "DNS Transport over TCP - Implementation
Requirements", draft-ietf-dnsop-5966bis-03 (work in
progress), September 2015.
[fragmentation-considered-poisonous] [fragmentation-considered-poisonous]
Herzberg, A. and H. Shulman, "Fragmentation Considered Herzberg, A. and H. Shulman, "Fragmentation Considered
Poisonous", arXiv 1205.4011, May 2012. Poisonous", arXiv 1205.4011, May 2012,
<http://arxiv.org/abs/1205.4011>.
[RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure, [RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,
"TCP Extensions for Multipath Operation with Multiple "TCP Extensions for Multipath Operation with Multiple
Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013, Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013,
<http://www.rfc-editor.org/info/rfc6824>. <http://www.rfc-editor.org/info/rfc6824>.
[RRL] Vixie, P. and V. Schryver, "DNS Response Rate Limiting [RRL] Vixie, P. and V. Schryver, "DNS Response Rate Limiting
(DNS RRL)", ISC-TN 2012-1-Draft1, April 2012. (DNS RRL)", ISC-TN 2012-1-Draft1, April 2012,
<http://ss.vix.su/~vixie/isc-tn-2012-1.txt>.
Appendix A. Editors' Notes Appendix A. Editors' Notes
A.1. Abridged Change History A.1. Abridged Change History
[Note to RFC Editor: please remove this section prior to [Note to RFC Editor: please remove this section prior to
publication.] publication.]
A.1.1. draft-ietf-dnsop-edns-tcp-keepalive-04 A.1.1. draft-ietf-dnsop-edns-tcp-keepalive-05
Reword Abstract and paragraph 9 in Introduction to remove discussion
on balancing UDP/TCP and talk about encouraging use of long-lived TCP
sessions.
Section 3.2.2: should -> SHOULD
Changed draft-ietf-dnsop-5966bis to be a normative reference,
therefore adding a dependancy on publication of that as RFC.
Reword sentence referring to RFC6824 since it is informational.
Update IANA option to Standard.
Remove last sentence from 1st paragraph of introduction.
Reword paragraph 6 in Introduction, merge paragraph 7 and 8.
Reword Section 3, first sentence to clarify the timeout is specified
by the server.
Correct missing URIs in 2 references.
Clarify statement in Section 3.2.2 as how clients should handle
updating the timeout when receiving a response.
Reworded first paragraph of Introduction discussing TCP vs (UDP +
retry over TCP). Changed 'fallback' to 'retry' in 2 places.
A.1.2. draft-ietf-dnsop-edns-tcp-keepalive-04
Adding wording to sections 3.2.1 and 3.4 to clarify client behaviour Adding wording to sections 3.2.1 and 3.4 to clarify client behaviour
on subsequent queries on a TCP connection. on subsequent queries on a TCP connection.
Changed the should to a SHOULD in section 3.2.2 Changed the should to a SHOULD in section 3.2.2
Changed Nameserver to DNS server in section 5. Changed Nameserver to DNS server in section 5.
Updated references. Updated references.
Changed reference to RFC6824 to be informative. Changed reference to RFC6824 to be informative.
Corrected reference to requested EDNS0 option code to be 'TBD1'. Corrected reference to requested EDNS0 option code to be 'TBD1'.
A.1.2. draft-ietf-dnsop-edns-tcp-keepalive-03 A.1.3. draft-ietf-dnsop-edns-tcp-keepalive-03
Clarified that a response to a query with any OPT RR may contain the Clarified that a response to a query with any OPT RR may contain the
ends-tcp-keepalive option. ends-tcp-keepalive option.
Corrected TIMEOUT length from 4 to 2 in the diagram. Corrected TIMEOUT length from 4 to 2 in the diagram.
Updated references, including name change of STARTTLS -> DNS-over-TLS Updated references, including name change of STARTTLS -> DNS-over-TLS
and adding reference for cache poisoning. and adding reference for cache poisoning.
Updated wording in section on Intermediary Considerations. Updated wording in section on Intermediary Considerations.
Updated wording describing RRL. Updated wording describing RRL.
Added paragraph to security section describing client behaviour Added paragraph to security section describing client behaviour
profiles. profiles.
Added wording to introduction on use case for stub/resolver/ Added wording to introduction on use case for stub/resolver/
authoritative. authoritative.
A.1.3. draft-ietf-dnsop-edns-tcp-keepalive-02 A.1.4. draft-ietf-dnsop-edns-tcp-keepalive-02
Changed timeout value to idle timeout and re-phrased document around Changed timeout value to idle timeout and re-phrased document around
this. this.
Changed units of timeout to 100ms to allow values less than 1 second. Changed units of timeout to 100ms to allow values less than 1 second.
Change specification to remove use of the option over UDP. This is Change specification to remove use of the option over UDP. This is
potentially confusing, could cause issues with ALG's and adds only potentially confusing, could cause issues with ALG's and adds only
limited value. limited value.
skipping to change at page 12, line 37 skipping to change at page 12, line 44
distinct 'connection close'-like signal is potentially more useful. distinct 'connection close'-like signal is potentially more useful.
Added more detail on server side requirements when supporting Added more detail on server side requirements when supporting
keepalive in terms of resource and connection management. keepalive in terms of resource and connection management.
Added discussion of EDNS0 per-message limitation and implications of Added discussion of EDNS0 per-message limitation and implications of
this. this.
Added reference to STARTTLS draft and RFC7320. Added reference to STARTTLS draft and RFC7320.
A.1.4. draft-ietf-dnsop-edns-tcp-keepalive-01 A.1.5. draft-ietf-dnsop-edns-tcp-keepalive-01
Version bump with no changes Version bump with no changes
A.1.5. draft-ietf-dnsop-edns-tcp-keepalive-00 A.1.6. draft-ietf-dnsop-edns-tcp-keepalive-00
Clarifications, working group adoption. Clarifications, working group adoption.
A.1.6. draft-wouters-edns-tcp-keepalive-01 A.1.7. draft-wouters-edns-tcp-keepalive-01
Also allow clients to specify KEEPALIVE timeout values, clarify Also allow clients to specify KEEPALIVE timeout values, clarify
motivation of document. motivation of document.
A.1.7. draft-wouters-edns-tcp-keepalive-00 A.1.8. draft-wouters-edns-tcp-keepalive-00
Initial draft. Initial draft.
Authors' Addresses Authors' Addresses
Paul Wouters Paul Wouters
Red Hat Red Hat
Email: pwouters@redhat.com Email: pwouters@redhat.com
 End of changes. 36 change blocks. 
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