draft-ietf-dnssd-push-06.txt   draft-ietf-dnssd-push-07.txt 
Internet Engineering Task Force T. Pusateri Internet Engineering Task Force T. Pusateri
Internet-Draft Seeking affiliation Internet-Draft Seeking affiliation
Intended status: Standards Track S. Cheshire Intended status: Standards Track S. Cheshire
Expires: September 22, 2016 Apple Inc. Expires: October 6, 2016 Apple Inc.
March 21, 2016 April 4, 2016
DNS Push Notifications DNS Push Notifications
draft-ietf-dnssd-push-06 draft-ietf-dnssd-push-07
Abstract Abstract
The Domain Name System (DNS) was designed to return matching records The Domain Name System (DNS) was designed to return matching records
efficiently for queries for data that is relatively static. When efficiently for queries for data that is relatively static. When
those records change frequently, DNS is still efficient at returning those records change frequently, DNS is still efficient at returning
the updated results when polled. But there exists no mechanism for a the updated results when polled. But there exists no mechanism for a
client to be asynchronously notified when these changes occur. This client to be asynchronously notified when these changes occur. This
document defines a mechanism for a client to be notified of such document defines a mechanism for a client to be notified of such
changes to DNS records, called DNS Push Notifications. changes to DNS records, called DNS Push Notifications.
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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 September 22, 2016. This Internet-Draft will expire on October 6, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 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
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Transport . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. Transport . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Client-Initiated Termination . . . . . . . . . . . . . . 7 4.1. Client-Initiated Termination . . . . . . . . . . . . . . 7
4.2. Server-Initiated Termination . . . . . . . . . . . . . . 7 4.2. Server-Initiated Termination . . . . . . . . . . . . . . 9
5. State Considerations . . . . . . . . . . . . . . . . . . . . 9 5. State Considerations . . . . . . . . . . . . . . . . . . . . 11
6. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 10 6. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 12
6.1. Discovery . . . . . . . . . . . . . . . . . . . . . . . . 11 6.1. Discovery . . . . . . . . . . . . . . . . . . . . . . . . 13
6.2. DNS Push Notification SUBSCRIBE . . . . . . . . . . . . . 13 6.2. DNS Push Notification SUBSCRIBE . . . . . . . . . . . . . 15
6.3. DNS Push Notification UNSUBSCRIBE . . . . . . . . . . . . 18 6.3. DNS Push Notification UNSUBSCRIBE . . . . . . . . . . . . 20
6.4. DNS Push Notification Update Messages . . . . . . . . . . 19 6.4. DNS Push Notification Update Messages . . . . . . . . . . 21
6.5. DNS RECONFIRM . . . . . . . . . . . . . . . . . . . . . . 22 6.5. DNS RECONFIRM . . . . . . . . . . . . . . . . . . . . . . 24
6.6. DNS Push Notification Termination Message . . . . . . . . 24 6.6. DNS Push Notification Termination Message . . . . . . . . 25
7. Security Considerations . . . . . . . . . . . . . . . . . . . 26 7. Security Considerations . . . . . . . . . . . . . . . . . . . 28
7.1. Security Services . . . . . . . . . . . . . . . . . . . . 26 7.1. Security Services . . . . . . . . . . . . . . . . . . . . 28
7.2. TLS Name Authentication . . . . . . . . . . . . . . . . . 27 7.2. TLS Name Authentication . . . . . . . . . . . . . . . . . 28
7.3. TLS Compression . . . . . . . . . . . . . . . . . . . . . 27 7.3. TLS Compression . . . . . . . . . . . . . . . . . . . . . 29
7.4. TLS Session Resumption . . . . . . . . . . . . . . . . . 27 7.4. TLS Session Resumption . . . . . . . . . . . . . . . . . 29
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 28 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 29
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 28 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 30
10.1. Normative References . . . . . . . . . . . . . . . . . . 28 10.1. Normative References . . . . . . . . . . . . . . . . . . 30
10.2. Informative References . . . . . . . . . . . . . . . . . 30 10.2. Informative References . . . . . . . . . . . . . . . . . 31
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33
1. Introduction 1. Introduction
DNS records may be updated using DNS Update [RFC2136]. Other DNS records may be updated using DNS Update [RFC2136]. Other
mechanisms such as a Hybrid Proxy [I-D.ietf-dnssd-hybrid] can also mechanisms such as a Hybrid Proxy [I-D.ietf-dnssd-hybrid] can also
generate changes to a DNS zone. This document specifies a protocol generate changes to a DNS zone. This document specifies a protocol
for Unicast DNS clients to subscribe to receive asynchronous for Unicast DNS clients to subscribe to receive asynchronous
notifications of changes to RRSets of interest. It is immediately notifications of changes to RRSets of interest. It is immediately
relevant in the case of DNS Service Discovery [RFC6763] but is not relevant in the case of DNS Service Discovery [RFC6763] but is not
limited to that use case, and provides a general DNS mechanism for limited to that use case, and provides a general DNS mechanism for
DNS record change notifications. Familiarity with the DNS protocol DNS record change notifications. Familiarity with the DNS protocol
and DNS packet formats is assumed [RFC1034] [RFC1035] [RFC6195]. and DNS packet formats is assumed [RFC1034] [RFC1035] [RFC6895].
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
"Key words for use in RFCs to Indicate Requirement Levels" [RFC2119]. "Key words for use in RFCs to Indicate Requirement Levels" [RFC2119].
2. Motivation 2. Motivation
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them to press the "Print" button again when they wake their phone up. them to press the "Print" button again when they wake their phone up.
A DNS Push Notification client MUST NOT routinely keep a DNS Push A DNS Push Notification client MUST NOT routinely keep a DNS Push
Notification subscription active 24 hours a day 7 days a week just to Notification subscription active 24 hours a day 7 days a week just to
keep a list in memory up to date so that it will be really fast if keep a list in memory up to date so that it will be really fast if
the user does choose to bring up an on-screen display of that data. the user does choose to bring up an on-screen display of that data.
DNS Push Notifications are designed to be fast enough that there is DNS Push Notifications are designed to be fast enough that there is
no need to pre-load a "warm" list in memory just in case it might be no need to pre-load a "warm" list in memory just in case it might be
needed later. needed later.
Generally, a client SHOULD NOT keep a connection to a server open
indefinitely if it has no active subscriptions on that connection.
After 30 seconds with no active subscriptions the client SHOULD close
the idle connection, and, if needed in the future, open a new
connection.
3. Overview 3. Overview
The existing DNS Update protocol [RFC2136] provides a mechanism for The existing DNS Update protocol [RFC2136] provides a mechanism for
clients to add or delete individual resource records (RRs) or entire clients to add or delete individual resource records (RRs) or entire
resource record sets (RRSets) on the zone's server. resource record sets (RRSets) on the zone's server.
This specification adopts a simplified subset of these existing This specification adopts a simplified subset of these existing
syntax and semantics, and uses them for DNS Push Notification syntax and semantics, and uses them for DNS Push Notification
messages going in the opposite direction, from server to client, to messages going in the opposite direction, from server to client, to
communicate changes to a zone. The client subscribes for Push communicate changes to a zone. The client subscribes for Push
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class "IN", as it is today with existing DNS servers and clients. A class "IN", as it is today with existing DNS servers and clients. A
DNS Push Notification server MAY choose to implement only DNS class DNS Push Notification server MAY choose to implement only DNS class
"IN". "IN".
4. Transport 4. Transport
Implementations of DNS Update [RFC2136] MAY use either User Datagram Implementations of DNS Update [RFC2136] MAY use either User Datagram
Protocol (UDP) [RFC0768] or Transmission Control Protocol (TCP) Protocol (UDP) [RFC0768] or Transmission Control Protocol (TCP)
[RFC0793] as the transport protocol, in keeping with the historical [RFC0793] as the transport protocol, in keeping with the historical
precedent that DNS queries must first be sent over UDP [RFC1123]. precedent that DNS queries must first be sent over UDP [RFC1123].
This requirement to use UDP has subsequently been relaxed This requirement to use UDP has subsequently been relaxed [RFC7766].
[RFC5966][I-D.ietf-dnsop-5966bis].
In keeping with the more recent precedent, DNS Push Notification is In keeping with the more recent precedent, DNS Push Notification is
defined only for TCP. DNS Push Notification clients MUST use TLS defined only for TCP. DNS Push Notification clients MUST use TLS
over TCP. over TCP.
Connection setup over TCP ensures return reachability and alleviates Connection setup over TCP ensures return reachability and alleviates
concerns of state overload at the server through anonymous concerns of state overload at the server through anonymous
subscriptions. All subscribers are guaranteed to be reachable by the subscriptions. All subscribers are guaranteed to be reachable by the
server by virtue of the TCP three-way handshake. Because TCP SYN server by virtue of the TCP three-way handshake. Because TCP SYN
flooding attacks are possible with any protocol over TCP, flooding attacks are possible with any protocol over TCP,
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Section 7.2 for details. Section 7.2 for details.
A DNS Push Notification session begins with a client connecting to a A DNS Push Notification session begins with a client connecting to a
DNS Push Notification server. Over that connection the client then DNS Push Notification server. Over that connection the client then
issues DNS operation requests, such as SUBSCRIBE. issues DNS operation requests, such as SUBSCRIBE.
4.1. Client-Initiated Termination 4.1. Client-Initiated Termination
An individual subscription is terminated by sending an UNSUBSCRIBE An individual subscription is terminated by sending an UNSUBSCRIBE
message for that specific subscription, or all subscriptions can be message for that specific subscription, or all subscriptions can be
cancelled at once by the client closing the connection with a TCP cancelled at once by the client closing the connection. When a
RST. When a client terminates an individual subscription (via client terminates an individual subscription (via UNSUBSCRIBE) or all
UNSUBSCRIBE) or all subscriptions on that connection (by closing the subscriptions on that connection (by closing the connection) it is
connection) it is signalling to the server that it is longer signalling to the server that it is longer interested in receiving
interested in receiving those particular updates. It is informing those particular updates. It is informing the server that the server
the server that the server may release any state information it has may release any state information it has been keeping with regards to
been keeping with regards to these particular subscriptions. these particular subscriptions.
After terminating its last subscription on a connection via After terminating its last subscription on a connection via
UNSUBSCRIBE, a client MAY close the connection immediately with a TCP UNSUBSCRIBE, a client MAY close the connection immediately, or it may
FIN, or it may keep it open if it anticipates performing further keep it open if it anticipates performing further operations on that
operations on that connection in the future. If a client wishes to connection in the future. If a client wishes to keep an idle
keep an idle connection open, it MUST meet its keepalive obligations connection open, it MUST continue to meet its keepalive obligations
[I-D.ietf-dnsop-edns-tcp-keepalive] or the server is entitled to [I-D.ietf-dnsop-edns-tcp-keepalive] or the server is entitled to
close the connection (see below). close the connection (see below).
If a client plans to terminate one or more subscriptions on a If a client plans to terminate one or more subscriptions on a
connection and doesn't intend to keep that connection open, then as connection and doesn't intend to keep that connection open, then as
an efficiency optimization it MAY instead choose to simply close the an efficiency optimization it MAY instead choose to simply close the
connection with a TCP RST, which implicitly terminates all connection, which implicitly terminates all subscriptions on that
subscriptions on that connection. This may occur because the client connection. This may occur because the client computer is being shut
computer is being shut down, is going to sleep, the application down, is going to sleep, the application requiring the subscriptions
requiring the subscriptions has terminated, or simply because the has terminated, or simply because the last active subscription on
last active subscription on that connection has been cancelled. that connection has been cancelled.
When closing a connection, a client will generally do an abortive
disconnect, sending a TCP RST. This immediately discards all
remaining inbound and outbound data, which is appropriate if the
client no longer has any interest in this data. In the BSD sockets
API, sending a TCP RST is achieved by setting the SO_LINGER option
with a time of 0 seconds and then closing the socket.
If a client has performed operations on this connection that it would
not want lost (like DNS updates) then the client SHOULD do an orderly
disconnect, sending a TCP FIN. In the BSD sockets API, sending a TCP
FIN is achieved by calling "shutdown(s,SHUT_WR)" and keeping the
socket open until all remaining data has been read from it.
In the first SUBSCRIBE response on a connection, the server MUST
include an explicit EDNS(0) TCP Keepalive option. If the first
SUBSCRIBE response does not include an explicit EDNS(0) TCP Keepalive
option this is an error and the client MUST immediately close the TCP
connection and not attempt any further DNS Push Notification requests
to that server until one hour has passed. This situation may occur
if a client connects to a server that doesn't implement DNS Push
Notifications at all, and it is important not to burden such servers
with continuous retries.
Upon receiving an error response from the server, a client SHOULD NOT
close the connection. An error relating to one particular operation
on a connection does not necessarily imply that all other operations
on that connection have also failed, or that future operations will
fail. The client should assume that the server will make its own
decision about whether or not to close the connection, based on the
server's determination of whether the error condition pertains to
this particular operation, or would also apply to any subsequent
operations. If the server does not close the connection then the
client SHOULD continue to use that connection for subsequent
operations.
Upon receiving a Termination Message from the server (see below), a
client MUST immediately close the connection.
4.2. Server-Initiated Termination 4.2. Server-Initiated Termination
If a client makes a connection and then fails to send any DNS message If a client makes a connection and then fails to send any DNS message
that uses EDNS(0) TCP Keepalive [I-D.ietf-dnsop-edns-tcp-keepalive] that uses EDNS(0) TCP Keepalive [I-D.ietf-dnsop-edns-tcp-keepalive]
(either SUBSCRIBE, where Keepalive is implicit, or some other DNS (either SUBSCRIBE, where Keepalive is implicit, or some other DNS
message, with an explicit an EDNS(0) TCP Keepalive option) then after message, with an explicit an EDNS(0) TCP Keepalive option) then after
30 seconds of inactivity the server SHOULD close the connection. If 30 seconds of inactivity the server SHOULD close the connection. If
no data has been sent on the connection the server MAY abort the no data has been sent on the connection the server MAY abort the
connection with a TCP RST. If data has been sent on the connection connection with a TCP RST. If data has been sent on the connection
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so that the data is reliably delivered. so that the data is reliably delivered.
In the response to the first successful SUBSCRIBE, the included In the response to the first successful SUBSCRIBE, the included
EDNS(0) TCP Keepalive option specifies the idle timeout so that the EDNS(0) TCP Keepalive option specifies the idle timeout so that the
client knows the frequency of traffic it must generate to keep the client knows the frequency of traffic it must generate to keep the
connection alive. If the idle timeout for that connection changes, connection alive. If the idle timeout for that connection changes,
then the server communicates this by placing an updated EDNS(0) TCP then the server communicates this by placing an updated EDNS(0) TCP
Keepalive option in a subsequent message to the client. Keepalive option in a subsequent message to the client.
At both servers and clients, the generation or reception of any At both servers and clients, the generation or reception of any
request, response, update, or keepalive message resets the keepalive complete request, response, update, or keepalive message resets the
timer for that connection. keepalive timer for that connection.
In the absence of any requests, responses, or update messages on a In the absence of any requests, responses, or update messages on a
connection, a client MUST generate keepalive traffic before the idle connection, a client MUST generate keepalive traffic before the idle
timeout expires, or the server is entitled to close the connection. timeout expires, or the server is entitled to close the connection.
If a client disconnects from the network abruptly, without closing If a client disconnects from the network abruptly, without closing
its connection, the server learns of this after failing to receive its connection, the server learns of this after failing to receive
further traffic from that client. If no requests, responses, update further traffic from that client. If no requests, responses, update
messages or keepalive traffic occurs on a connection for 1.5 times messages or keepalive traffic occurs on a connection for 1.5 times
the idle timeout, then this indicates that the client is probably no the idle timeout, then this indicates that the client is probably no
longer on the network, and the server SHOULD abort the connection longer on the network, and the server SHOULD abort the connection
with a TCP RST. with a TCP RST. The time before the server closes the connection is
intentionally 50% longer than the time before the client is required
to generate keepalive traffic, to allow for differences in clock rate
and network propagation delays.
[We need to discuss the nature of "the required keepalives". Are [We need to discuss the nature of "the required keepalives". Are
they TCP-layer keepalives? DNS-layer keepalives? There is currently they TCP-layer keepalives? DNS-layer keepalives? There is currently
no DNS-layer keepalive or 'no-op' operation defined. What would that no DNS-layer keepalive or 'no-op' operation defined. What would that
operation be? A DNS QUERY containing zero questions? A DNS operation be? A DNS QUERY containing zero questions? A DNS
SUBSCRIBE containing zero questions? An "empty" DNS message over the SUBSCRIBE containing zero questions? An "empty" DNS message over the
TCP connection (just a pair of zero bytes, signifying a zero-length TCP connection (just a pair of zero bytes, signifying a zero-length
message)? One benefit of TCP-layer keepalives is that they transmit message)? One benefit of TCP-layer keepalives is that they transmit
fewer bytes, and involve less software overhead for processing those fewer bytes, and involve less software overhead for processing those
bytes. Another benefit is that it is more feasible to implement bytes. Another benefit is that it is more feasible to implement
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layer keepalives, and an API for a server to request the networking layer keepalives, and an API for a server to request the networking
stack to inform it when TCP-layer keepalives are not received by the stack to inform it when TCP-layer keepalives are not received by the
required deadline. TCP-layer keepalives also only verify liveness of required deadline. TCP-layer keepalives also only verify liveness of
the remote networking stack, whereas DNS-layer keepalives provide the remote networking stack, whereas DNS-layer keepalives provide
higher assurance of liveness of the remote server application higher assurance of liveness of the remote server application
software -- though this a limited benefit, since there is no reason software -- though this a limited benefit, since there is no reason
to expect that DNS Push Notification server software will routinely to expect that DNS Push Notification server software will routinely
become wedged and unresponsive.] become wedged and unresponsive.]
After sending an error response to a client, the server MAY close the After sending an error response to a client, the server MAY close the
connection with a TCP FIN. connection with a TCP FIN, or may allow the connection to remain
open. For error conditions that only affect the single operation in
question, the server SHOULD return an error response to the client
and leave the connection open for further operations. For error
conditions that are likely to make all operations unsuccessful in the
immediate future, the server SHOULD return an error response to the
client and then close the connection with a TCP FIN.
If the server is overloaded and needs to shed load, it MAY send a If the server is overloaded and needs to shed load, it SHOULD send a
Termination Message to the client and close the connection with a TCP Termination Message to the client and close the connection with a TCP
FIN. FIN.
Apart from the cases described above, a server MUST NOT close a Apart from the cases described above, a server MUST NOT close a
connection with a DNS Push Notification client, except in connection with a DNS Push Notification client, except in
extraordinary error conditions. Closing the connection is the extraordinary error conditions. Closing the connection is the
client's responsibility, to be done at the client's discretion, when client's responsibility, to be done at the client's discretion, when
it so chooses. A DNS Push Notification server only closes a DNS Push it so chooses. A DNS Push Notification server only closes a DNS Push
Notification connection under exceptional circumstances, such as when Notification connection under exceptional circumstances, such as when
the server application software or underlying operating system is the server application software or underlying operating system is
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However, server implementers and operators should be aware that this However, server implementers and operators should be aware that this
connection sharing may not be possible in all cases. A single client connection sharing may not be possible in all cases. A single client
device may be home to multiple independent client software instances device may be home to multiple independent client software instances
that don't know about each other, so a DNS Push Notification server that don't know about each other, so a DNS Push Notification server
MUST be prepared to accept multiple connections from the same client MUST be prepared to accept multiple connections from the same client
IP address. This is undesirable from an efficiency standpoint, but IP address. This is undesirable from an efficiency standpoint, but
may be unavoidable in some situations, so a DNS Push Notification may be unavoidable in some situations, so a DNS Push Notification
server MUST be prepared to accept multiple connections from the same server MUST be prepared to accept multiple connections from the same
client IP address. client IP address.
Clients SHOULD silently ignore unrecognized messages (both requests
and responses) over the TLS/TCP connection. For example, UNSUBSCRIBE
and RECONFIRM currently generate no response, but if future versions
of this specification change that, existing clients SHOULD silently
ignore these unexpected responses. This allows for backwards
compatibility with future enhancements.
6.1. Discovery 6.1. Discovery
The first step in DNS Push Notification subscription is to discover The first step in DNS Push Notification subscription is to discover
an appropriate DNS server that supports DNS Push Notifications for an appropriate DNS server that supports DNS Push Notifications for
the desired zone. The client MUST also determine which TCP port on the desired zone. The client MUST also determine which TCP port on
the server is listening for connections, which need not be (and often the server is listening for connections, which need not be (and often
is not) the typical TCP port 53 used for conventional DNS. is not) the typical TCP port 53 used for conventional DNS, or TCP
port 853 used for DNS over TLS [I-D.ietf-dprive-dns-over-tls].
1. The client begins the discovery by sending a DNS query to the 1. The client begins the discovery by sending a DNS query to the
local resolver with record type SOA [RFC1035] for the name of the local resolver with record type SOA [RFC1035] for the name of the
record it wishes to subscribe. record it wishes to subscribe.
2. If the SOA record exists, it MUST be returned in the Answer 2. If the SOA record exists, it MUST be returned in the Answer
Section of the reply. If not, the local resolver SHOULD include Section of the response. If not, the local resolver SHOULD
the SOA record for the zone of the requested name in the include the SOA record for the zone of the requested name in the
Authority Section. Authority Section.
3. If no SOA record is returned, the client then strips off the 3. If no SOA record is returned, the client then strips off the
leading label from the requested name. If the resulting name has leading label from the requested name. If the resulting name has
at least one label in it, the client sends a new SOA query and at least one label in it, the client sends a new SOA query and
processing continues at step 2 above. If the resulting name is processing continues at step 2 above. If the resulting name is
empty (the root label) then this is a network configuration error empty (the root label) then this is a network configuration error
and the client gives up. The client MAY retry the operation at a and the client gives up. The client MAY retry the operation at a
later time. later time.
4. Once the SOA is known, the client sends a DNS query with type SRV 4. Once the SOA is known (either by virtue of being seen in the
[RFC2782] for the record name "_dns-push-tls._tcp.<zone>", where Answer Section, or in the Authority Section), the client sends a
<zone> is the owner name of the discovered SOA record. DNS query with type SRV [RFC2782] for the record name
"_dns-push-tls._tcp.<zone>", where <zone> is the owner name of
the discovered SOA record.
5. If the zone in question does not offer DNS Push Notifications 5. If the zone in question does not offer DNS Push Notifications
then SRV record MUST NOT exist and the SRV query will return a then SRV record MUST NOT exist and the SRV query will return a
negative answer. negative answer.
6. If the zone in question is set up to offer DNS Push Notifications 6. If the zone in question is set up to offer DNS Push Notifications
then this SRV record MUST exist. The SRV "target" contains the then this SRV record MUST exist. The SRV "target" contains the
name of the server providing DNS Push Notifications for the zone. name of the server providing DNS Push Notifications for the zone.
The port number on which to contact the server is in the SRV The port number on which to contact the server is in the SRV
record "port" field. The address(es) of the target host MAY be record "port" field. The address(es) of the target host MAY be
skipping to change at page 13, line 17 skipping to change at page 15, line 17
A DNS Push Notification client indicates its desire to receive DNS A DNS Push Notification client indicates its desire to receive DNS
Push Notifications for a given domain name by sending a SUBSCRIBE Push Notifications for a given domain name by sending a SUBSCRIBE
request over the established TCP connection to the server. A request over the established TCP connection to the server. A
SUBSCRIBE request is formatted identically to a conventional DNS SUBSCRIBE request is formatted identically to a conventional DNS
QUERY request [RFC1035], except that the opcode is SUBSCRIBE (6) QUERY request [RFC1035], except that the opcode is SUBSCRIBE (6)
instead of QUERY (0). If neither QTYPE nor QCLASS are ANY (255) then instead of QUERY (0). If neither QTYPE nor QCLASS are ANY (255) then
this is a specific subscription to changes for the given name, type this is a specific subscription to changes for the given name, type
and class. If one or both of QTYPE or QCLASS are ANY (255) then this and class. If one or both of QTYPE or QCLASS are ANY (255) then this
subscription matches any type and/or any class, as appropriate. subscription matches any type and/or any class, as appropriate.
NOTE: A little-known quirk of DNS is that in DNS QUERY requests,
QTYPE and QCLASS 255 mean "ANY" not "ALL". They indicate that the
server should respond with ANY matching records of its choosing, not
necessarily ALL matching records. This can lead to some surprising
and unexpected results, were a query returns some valid answers but
not all of them, and makes QTYPE=ANY queries less useful than people
sometimes imagine.
When used in conjunction with DNS SUBSCRIBE, QTYPE and QCLASS 255
should be interpreted to mean "ALL", not "ANY". After accepting a
subscription where one or both of QTYPE or QCLASS are 255, the server
MUST send Push Notification Updates for ALL record changes that match
the subscription, not just some of them.
In a SUBSCRIBE request the DNS Header QR bit MUST be zero. In a SUBSCRIBE request the DNS Header QR bit MUST be zero.
If the QR bit is not zero the message is not a SUBSCRIBE request. If the QR bit is not zero the message is not a SUBSCRIBE request.
The AA, TC, RD, RA, Z, AD, and CD bits, the ID field, and the RCODE The AA, TC, RD, RA, Z, AD, and CD bits, and the RCODE field, MUST be
field, MUST be zero on transmission, and MUST be silently ignored on zero on transmission, and MUST be silently ignored on reception.
reception.
The ID field may be set to any value of the client's choosing, and
the server MUST echo this value back in the response message. The
client is not required to select unique ID values; it is permissible
to use the same value (e.g., zero) for all operations. Since the
name, qtype, and qclass are sufficient to uniquely identify a
SUBSCRIBE operation on a connection, the name, qtype, and qclass in a
SUBSCRIBE response are sufficient to correlate a response with its
corresponding request. However, for convenience, the client may put
any value it chooses in the ID field of the SUBSCRIBE request, and
the server MUST echo that value back unchanged in the SUBSCRIBE
response. Note that the ID field of Push Notification Update
Messages is always zero, since a Push Notification Update Message
could potentially match more than one subscription, or could relate
to a subscription that the client has just cancelled with an
UNSUBSCRIBE message.
Like a DNS QUERY request, a SUBSCRIBE request MUST contain exactly Like a DNS QUERY request, a SUBSCRIBE request MUST contain exactly
one question. Since SUBSCRIBE requests are sent over TCP, multiple one question. Since SUBSCRIBE requests are sent over TCP, multiple
SUBSCRIBE requests can be concatenated in a single TCP stream and SUBSCRIBE requests can be concatenated in a single TCP stream and
packed efficiently into TCP segments, so the ability to pack multiple packed efficiently into TCP segments, so the ability to pack multiple
SUBSCRIBE operations into a single DNS message within that TCP stream SUBSCRIBE operations into a single DNS message within that TCP stream
would add extra complexity for little benefit. would add extra complexity for little benefit.
ANCOUNT MUST be zero, and the Answer Section MUST be empty. ANCOUNT MUST be zero, and the Answer Section MUST be empty.
Any records in the Answer Section MUST be silently ignored. Any records in the Answer Section MUST be silently ignored.
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Since all SUBSCRIBE operations are implicitly long-lived operations, Since all SUBSCRIBE operations are implicitly long-lived operations,
the server MUST interpret a SUBSCRIBE request as if it contained an the server MUST interpret a SUBSCRIBE request as if it contained an
EDNS(0) TCP Keepalive option [I-D.ietf-dnsop-edns-tcp-keepalive]. A EDNS(0) TCP Keepalive option [I-D.ietf-dnsop-edns-tcp-keepalive]. A
client MUST NOT include an actual EDNS(0) TCP Keepalive option in the client MUST NOT include an actual EDNS(0) TCP Keepalive option in the
request, since it is automatic, and implied by the semantics of request, since it is automatic, and implied by the semantics of
SUBSCRIBE. If a server receives a SUBSCRIBE request that does SUBSCRIBE. If a server receives a SUBSCRIBE request that does
contain an actual EDNS(0) TCP Keepalive option this is an error and contain an actual EDNS(0) TCP Keepalive option this is an error and
the server MUST immediately close the TCP connection. the server MUST immediately close the TCP connection.
A SUBSCRIBE operation MAY include an explicit EDNS(0) [RFC6891] OPT A SUBSCRIBE operation MAY include an explicit EDNS(0) [RFC6891] OPT
record where necessary to carry additional information. record where necessary to carry additional EDNS(0) information other
than a TCP Keepalive option.
The presence of a SUBSCRIBE operation on a connection indicates to The presence of a SUBSCRIBE operation on a connection indicates to
the server that the client fully implements EDNS(0) [RFC6891], and the server that the client fully implements EDNS(0) [RFC6891], and
can correctly understand any response that conforms to that can correctly understand any response that conforms to that
specification. After receiving a SUBSCRIBE request, the server MAY specification. After receiving a SUBSCRIBE request, the server MAY
include OPT record in any of its responses, as needed. include OPT record in any of its responses, as needed.
Each SUBSCRIBE request generates exactly one SUBSCRIBE response from Each SUBSCRIBE request generates exactly one SUBSCRIBE response from
the server. the server.
In a SUBSCRIBE response the DNS Header QR bit MUST be one. In a SUBSCRIBE response the DNS Header QR bit MUST be one.
If the QR bit is not one the message is not a SUBSCRIBE response. If the QR bit is not one the message is not a SUBSCRIBE response.
The AA, TC, RD, RA, Z, AD, and CD bits, and the ID field, MUST be The AA, TC, RD, RA, Z, AD, and CD bits, MUST be zero on transmission,
zero on transmission, and MUST be silently ignored on reception. and MUST be silently ignored on reception.
The ID field MUST echo the value given in the ID field of the
SUBSCRIBE request.
The Question Section MUST echo back the values provided by the client The Question Section MUST echo back the values provided by the client
in the SUBSCRIBE request that generated this SUBSCRIBE response. in the SUBSCRIBE request that generated this SUBSCRIBE response.
ANCOUNT MUST be zero, and the Answer Section MUST be empty. ANCOUNT MUST be zero, and the Answer Section MUST be empty.
Any records in the Answer Section MUST be silently ignored. Any records in the Answer Section MUST be silently ignored.
If the subscription was accepted and there are positive answers for If the subscription was accepted and there are positive answers for
the requested name, type and class, then these positive answers MUST the requested name, type and class, then these positive answers MUST
be communicated to the client in an immediately following Push be communicated to the client in an immediately following Push
Notification Update, not in the Answer Section of the SUBSCRIBE Notification Update, not in the Answer Section of the SUBSCRIBE
skipping to change at page 17, line 7 skipping to change at page 19, line 7
with continuous retries. with continuous retries.
The server MAY include EDNS(0) TCP Keepalive options in subsequent The server MAY include EDNS(0) TCP Keepalive options in subsequent
messages, if the idle timeout changes. If the client receives messages, if the idle timeout changes. If the client receives
subsequent messages that do not contain an explicit EDNS(0) TCP subsequent messages that do not contain an explicit EDNS(0) TCP
Keepalive option then the idle timeout for that connection remains Keepalive option then the idle timeout for that connection remains
unchanged at that time. unchanged at that time.
In an error response, with nonzero RCODE, the server MUST contain an In an error response, with nonzero RCODE, the server MUST contain an
EDNS(0) TCP Keepalive option specifying the delay before the client EDNS(0) TCP Keepalive option specifying the delay before the client
tries again: submits further requests to this server:
For RCODE = 1 (FORMERR) the delay may be any value selected by the For RCODE = 1 (FORMERR) the delay may be any value selected by the
implementer. A value of one minute is RECOMMENDED, to avoid high implementer. A value of one minute is RECOMMENDED, to avoid high
load from defective clients. load from defective clients.
For RCODE = 2 (SERVFAIL), which occurs due to resource exhaustion, For RCODE = 2 (SERVFAIL), which occurs due to resource exhaustion,
the delay should be chosen according to the level of server the delay should be chosen according to the level of server
overload and the anticipated duration of that overload. By overload and the anticipated duration of that overload. By
default, a value of one minute is RECOMMENDED. default, a value of one minute is RECOMMENDED.
skipping to change at page 18, line 9 skipping to change at page 20, line 9
"_dns-push-tls._tcp.<zone>" SRV record, but the server itself is "_dns-push-tls._tcp.<zone>" SRV record, but the server itself is
not currently configured to support DNS Push Notifications for not currently configured to support DNS Push Notifications for
that zone. Since it is possible that the misconfiguration may be that zone. Since it is possible that the misconfiguration may be
repaired at any time, the retry delay should not be set too high. repaired at any time, the retry delay should not be set too high.
By default, a value of 5 minutes is RECOMMENDED. By default, a value of 5 minutes is RECOMMENDED.
For other RCODE values, the retry delay should be set by the For other RCODE values, the retry delay should be set by the
server as appropriate for that error condition. By default, a server as appropriate for that error condition. By default, a
value of 5 minutes is RECOMMENDED. value of 5 minutes is RECOMMENDED.
For RCODE = 9 (NOTAUTH), the time delay applies to requests for other
names falling within the same zone. Requests for names falling
within other zones are not subject to the delay. For all other
RCODEs the time delay applies to all subsequent requests to this
server.
After sending an error response the server MAY close the TCP After sending an error response the server MAY close the TCP
connection with a FIN, or MAY allow it to remain open. Clients MUST connection with a FIN, or MAY allow it to remain open, depending on
correctly handle both cases. the nature of the error. Clients MUST correctly handle both cases.
6.3. DNS Push Notification UNSUBSCRIBE 6.3. DNS Push Notification UNSUBSCRIBE
To cancel an individual subscription without closing the entire To cancel an individual subscription without closing the entire
connection, the client sends an UNSUBSCRIBE message over the connection, the client sends an UNSUBSCRIBE message over the
established TCP connection to the server. The UNSUBSCRIBE message is established TCP connection to the server. The UNSUBSCRIBE message is
formatted identically to the SUBSCRIBE message which created the formatted identically to the SUBSCRIBE message which created the
subscription, with the exact same name, type and class, except that subscription, with the exact same name, type and class, except that
the opcode is UNSUBSCRIBE (7) instead of SUBSCRIBE (6). the opcode is UNSUBSCRIBE (7) instead of SUBSCRIBE (6).
skipping to change at page 24, line 14 skipping to change at page 25, line 24
6.6. DNS Push Notification Termination Message 6.6. DNS Push Notification Termination Message
If a server is low on resources it MAY simply terminate a client If a server is low on resources it MAY simply terminate a client
connection with a TCP RST. However, the likely behaviour of the connection with a TCP RST. However, the likely behaviour of the
client may be simply to reconnect immediately, putting more burden on client may be simply to reconnect immediately, putting more burden on
the server. Therefore, a server SHOULD instead choose to shed client the server. Therefore, a server SHOULD instead choose to shed client
load by (a) sending a DNS Push Notification Termination Message and load by (a) sending a DNS Push Notification Termination Message and
then (b) immediately closing the client connection with a TCP FIN then (b) immediately closing the client connection with a TCP FIN
instead of RST, thereby facilitating reliable delivery of the instead of RST, thereby facilitating reliable delivery of the
Termination Message. Termination Message. Upon successful reception of the Termination
Message the client is expected to close the connection. The server
SHOULD set a timer and, if the client has not closed the connection
within a reasonable time, the server SHOULD then terminate the TCP
connection with a TCP RST. The RECOMMENDED time the server should
wait before terminating the TCP connection with a TCP RST is ten
seconds.
The format of a Termination Message is similar to a Push Notification The format of a Termination Message is similar to a Push Notification
Update. Update.
The following figure shows the existing DNS Update header format: The following figure shows the existing DNS Update header format:
1 1 1 1 1 1 1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| ID | | ID |
skipping to change at page 26, line 8 skipping to change at page 27, line 48
the EDNS(0) TCP Keepalive option's idle timeout MAY be zero, the EDNS(0) TCP Keepalive option's idle timeout MAY be zero,
indicating that the client SHOULD attempt to re-establish its indicating that the client SHOULD attempt to re-establish its
subscriptions immediately. subscriptions immediately.
In the case where a server is terminating a large number of In the case where a server is terminating a large number of
connections at once (e.g., if the system is restarting) and the connections at once (e.g., if the system is restarting) and the
server doesn't want to be inundated with a flood of simultaneous server doesn't want to be inundated with a flood of simultaneous
retries, it SHOULD send different EDNS(0) TCP Keepalive values to retries, it SHOULD send different EDNS(0) TCP Keepalive values to
each client. These adjustments MAY be selected randomly, each client. These adjustments MAY be selected randomly,
pseudorandomly, or deterministically (e.g., incrementing the time pseudorandomly, or deterministically (e.g., incrementing the time
value by one for each successive client, yielding a post-restart value by one tenth of a second for each successive client, yielding a
reconnection rate of ten clients per second). post-restart reconnection rate of ten clients per second).
7. Security Considerations 7. Security Considerations
TLS support is REQUIRED in DNS Push Notifications. There is no TLS support is REQUIRED in DNS Push Notifications. There is no
provision for opportunistic encryption using a mechanism like provision for opportunistic encryption using a mechanism like
"STARTTLS". "STARTTLS".
DNSSEC is RECOMMENDED for DNS Push Notifications. TLS alone does not DNSSEC is RECOMMENDED for DNS Push Notifications. TLS alone does not
provide complete security. TLS certificate verification can provide provide complete security. TLS certificate verification can provide
reasonable assurance that the client is really talking to the server reasonable assurance that the client is really talking to the server
skipping to change at page 28, line 11 skipping to change at page 29, line 45
This document defines three DNS OpCodes: SUBSCRIBE with (tentative) This document defines three DNS OpCodes: SUBSCRIBE with (tentative)
value 6, UNSUBSCRIBE with (tentative) value 7, and RECONFIRM with value 6, UNSUBSCRIBE with (tentative) value 7, and RECONFIRM with
(tentative) value 8. (tentative) value 8.
9. Acknowledgements 9. Acknowledgements
The authors would like to thank Kiren Sekar and Marc Krochmal for The authors would like to thank Kiren Sekar and Marc Krochmal for
previous work completed in this field. previous work completed in this field.
This draft has been improved due to comments from Ran Atkinson, Tim This draft has been improved due to comments from Ran Atkinson, Tim
Chown, Mark Delany, Ralph Droms, Bernie Holz, Jan Komissar, Manju Chown, Mark Delany, Ralph Droms, Bernie Volz, Jan Komissar, Manju
Shankar Rao, Markus Stenberg, and Dave Thaler. Shankar Rao, Markus Stenberg, Dave Thaler, and Soraia Zlatkovic.
10. References 10. References
10.1. Normative References 10.1. Normative References
[I-D.ietf-dnsop-5966bis]
Dickinson, J., Dickinson, S., Bellis, R., Mankin, A., and
D. Wessels, "DNS Transport over TCP - Implementation
Requirements", draft-ietf-dnsop-5966bis-06 (work in
progress), January 2016.
[I-D.ietf-dnsop-edns-tcp-keepalive] [I-D.ietf-dnsop-edns-tcp-keepalive]
Wouters, P., Abley, J., Dickinson, S., and R. Bellis, "The Wouters, P., Abley, J., Dickinson, S., and R. Bellis, "The
edns-tcp-keepalive EDNS0 Option", draft-ietf-dnsop-edns- edns-tcp-keepalive EDNS0 Option", draft-ietf-dnsop-edns-
tcp-keepalive-06 (work in progress), February 2016. tcp-keepalive-06 (work in progress), February 2016.
[I-D.ietf-tls-tls13] [I-D.ietf-tls-tls13]
Rescorla, E., "The Transport Layer Security (TLS) Protocol Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", draft-ietf-tls-tls13-11 (work in progress), Version 1.3", draft-ietf-tls-tls13-12 (work in progress),
December 2015. March 2016.
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, DOI [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, DOI
10.17487/RFC0768, August 1980, 10.17487/RFC0768, August 1980,
<http://www.rfc-editor.org/info/rfc768>. <http://www.rfc-editor.org/info/rfc768>.
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC [RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC
793, DOI 10.17487/RFC0793, September 1981, 793, DOI 10.17487/RFC0793, September 1981,
<http://www.rfc-editor.org/info/rfc793>. <http://www.rfc-editor.org/info/rfc793>.
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
skipping to change at page 29, line 25 skipping to change at page 31, line 10
[RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, [RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound,
"Dynamic Updates in the Domain Name System (DNS UPDATE)", "Dynamic Updates in the Domain Name System (DNS UPDATE)",
RFC 2136, DOI 10.17487/RFC2136, April 1997, RFC 2136, DOI 10.17487/RFC2136, April 1997,
<http://www.rfc-editor.org/info/rfc2136>. <http://www.rfc-editor.org/info/rfc2136>.
[RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for [RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
specifying the location of services (DNS SRV)", RFC 2782, specifying the location of services (DNS SRV)", RFC 2782,
DOI 10.17487/RFC2782, February 2000, DOI 10.17487/RFC2782, February 2000,
<http://www.rfc-editor.org/info/rfc2782>. <http://www.rfc-editor.org/info/rfc2782>.
[RFC4953] Touch, J., "Defending TCP Against Spoofing Attacks", RFC
4953, DOI 10.17487/RFC4953, July 2007,
<http://www.rfc-editor.org/info/rfc4953>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/ (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/
RFC5246, August 2008, RFC5246, August 2008,
<http://www.rfc-editor.org/info/rfc5246>. <http://www.rfc-editor.org/info/rfc5246>.
[RFC5966] Bellis, R., "DNS Transport over TCP - Implementation
Requirements", RFC 5966, DOI 10.17487/RFC5966, August
2010, <http://www.rfc-editor.org/info/rfc5966>.
[RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS) [RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS)
Extensions: Extension Definitions", RFC 6066, DOI Extensions: Extension Definitions", RFC 6066, DOI
10.17487/RFC6066, January 2011, 10.17487/RFC6066, January 2011,
<http://www.rfc-editor.org/info/rfc6066>. <http://www.rfc-editor.org/info/rfc6066>.
[RFC6195] Eastlake 3rd, D., "Domain Name System (DNS) IANA
Considerations", RFC 6195, DOI 10.17487/RFC6195, March
2011, <http://www.rfc-editor.org/info/rfc6195>.
[RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms [RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms
for DNS (EDNS(0))", STD 75, RFC 6891, DOI 10.17487/ for DNS (EDNS(0))", STD 75, RFC 6891, DOI 10.17487/
RFC6891, April 2013, RFC6891, April 2013,
<http://www.rfc-editor.org/info/rfc6891>. <http://www.rfc-editor.org/info/rfc6891>.
[RFC6895] Eastlake 3rd, D., "Domain Name System (DNS) IANA
Considerations", BCP 42, RFC 6895, DOI 10.17487/RFC6895,
April 2013, <http://www.rfc-editor.org/info/rfc6895>.
[RFC7673] Finch, T., Miller, M., and P. Saint-Andre, "Using DNS- [RFC7673] Finch, T., Miller, M., and P. Saint-Andre, "Using DNS-
Based Authentication of Named Entities (DANE) TLSA Records Based Authentication of Named Entities (DANE) TLSA Records
with SRV Records", RFC 7673, DOI 10.17487/RFC7673, October with SRV Records", RFC 7673, DOI 10.17487/RFC7673, October
2015, <http://www.rfc-editor.org/info/rfc7673>. 2015, <http://www.rfc-editor.org/info/rfc7673>.
[RFC7766] Dickinson, J., Dickinson, S., Bellis, R., Mankin, A., and
D. Wessels, "DNS Transport over TCP - Implementation
Requirements", RFC 7766, DOI 10.17487/RFC7766, March 2016,
<http://www.rfc-editor.org/info/rfc7766>.
10.2. Informative References 10.2. Informative References
[I-D.ietf-dnssd-hybrid] [I-D.ietf-dnssd-hybrid]
Cheshire, S., "Hybrid Unicast/Multicast DNS-Based Service Cheshire, S., "Hybrid Unicast/Multicast DNS-Based Service
Discovery", draft-ietf-dnssd-hybrid-03 (work in progress), Discovery", draft-ietf-dnssd-hybrid-03 (work in progress),
November 2015. November 2015.
[I-D.ietf-dprive-dns-over-tls]
Zi, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
and P. Hoffman, "Specification for DNS over TLS", draft-
ietf-dprive-dns-over-tls-09 (work in progress), March
2016.
[I-D.sekar-dns-llq] [I-D.sekar-dns-llq]
Sekar, K., "DNS Long-Lived Queries", draft-sekar-dns- Sekar, K., "DNS Long-Lived Queries", draft-sekar-dns-
llq-01 (work in progress), August 2006. llq-01 (work in progress), August 2006.
[IPJ.9-4-TCPSYN] [IPJ.9-4-TCPSYN]
Eddy, W., "Defenses Against TCP SYN Flooding Attacks", The Eddy, W., "Defenses Against TCP SYN Flooding Attacks", The
Internet Protocol Journal, Cisco Systems, Volume 9, Number Internet Protocol Journal, Cisco Systems, Volume 9, Number
4, December 2006. 4, December 2006.
[RFC1996] Vixie, P., "A Mechanism for Prompt Notification of Zone [RFC1996] Vixie, P., "A Mechanism for Prompt Notification of Zone
Changes (DNS NOTIFY)", RFC 1996, DOI 10.17487/RFC1996, Changes (DNS NOTIFY)", RFC 1996, DOI 10.17487/RFC1996,
August 1996, <http://www.rfc-editor.org/info/rfc1996>. August 1996, <http://www.rfc-editor.org/info/rfc1996>.
[RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom [RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom
Syndication Format", RFC 4287, DOI 10.17487/RFC4287, Syndication Format", RFC 4287, DOI 10.17487/RFC4287,
December 2005, <http://www.rfc-editor.org/info/rfc4287>. December 2005, <http://www.rfc-editor.org/info/rfc4287>.
[RFC4953] Touch, J., "Defending TCP Against Spoofing Attacks", RFC
4953, DOI 10.17487/RFC4953, July 2007,
<http://www.rfc-editor.org/info/rfc4953>.
[RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig, [RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig,
"Transport Layer Security (TLS) Session Resumption without "Transport Layer Security (TLS) Session Resumption without
Server-Side State", RFC 5077, DOI 10.17487/RFC5077, Server-Side State", RFC 5077, DOI 10.17487/RFC5077,
January 2008, <http://www.rfc-editor.org/info/rfc5077>. January 2008, <http://www.rfc-editor.org/info/rfc5077>.
[RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762, [RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
DOI 10.17487/RFC6762, February 2013, DOI 10.17487/RFC6762, February 2013,
<http://www.rfc-editor.org/info/rfc6762>. <http://www.rfc-editor.org/info/rfc6762>.
[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service [RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
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