idnits 2.17.1 draft-ietf-dnsop-edns-tcp-keepalive-05.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (January 6, 2016) is 3032 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 7320 (Obsoleted by RFC 8820) -- Obsolete informational reference (is this intentional?): RFC 6824 (Obsoleted by RFC 8684) Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 dnsop P. Wouters 3 Internet-Draft Red Hat 4 Intended status: Standards Track J. Abley 5 Expires: July 9, 2016 Dyn, Inc. 6 S. Dickinson 7 Sinodun 8 R. Bellis 9 ISC 10 January 6, 2016 12 The edns-tcp-keepalive EDNS0 Option 13 draft-ietf-dnsop-edns-tcp-keepalive-05 15 Abstract 17 DNS messages between clients and servers may be received over either 18 UDP or TCP. UDP transport involves keeping less state on a busy 19 server, but can cause truncation and retries over TCP. Additionally, 20 UDP can be exploited for reflection attacks. Using TCP would reduce 21 retransmits and amplification. However, clients commonly use TCP 22 only for retries and servers typically use idle timeouts on the order 23 of seconds. 25 This document defines an EDNS0 option ("edns-tcp-keepalive") that 26 allows DNS servers to signal a variable idle timeout. This 27 signalling encourages the use of long-lived TCP connections by 28 allowing the state associated with TCP transport to be managed 29 effectively with minimal impact on the DNS transaction time. 31 Status of This Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at http://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on July 9, 2016. 48 Copyright Notice 50 Copyright (c) 2016 IETF Trust and the persons identified as the 51 document authors. All rights reserved. 53 This document is subject to BCP 78 and the IETF Trust's Legal 54 Provisions Relating to IETF Documents 55 (http://trustee.ietf.org/license-info) in effect on the date of 56 publication of this document. Please review these documents 57 carefully, as they describe your rights and restrictions with respect 58 to this document. Code Components extracted from this document must 59 include Simplified BSD License text as described in Section 4.e of 60 the Trust Legal Provisions and are provided without warranty as 61 described in the Simplified BSD License. 63 Table of Contents 65 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 66 2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 4 67 3. The edns-tcp-keepalive Option . . . . . . . . . . . . . . . . 4 68 3.1. Option Format . . . . . . . . . . . . . . . . . . . . . . 5 69 3.2. Use by DNS Clients . . . . . . . . . . . . . . . . . . . 5 70 3.2.1. Sending Queries . . . . . . . . . . . . . . . . . . . 5 71 3.2.2. Receiving Responses . . . . . . . . . . . . . . . . . 5 72 3.3. Use by DNS Servers . . . . . . . . . . . . . . . . . . . 6 73 3.3.1. Receiving Queries . . . . . . . . . . . . . . . . . . 6 74 3.3.2. Sending Responses . . . . . . . . . . . . . . . . . . 6 75 3.4. TCP Session Management . . . . . . . . . . . . . . . . . 6 76 3.5. Non-Clean Paths . . . . . . . . . . . . . . . . . . . . . 8 77 3.6. Anycast Considerations . . . . . . . . . . . . . . . . . 8 78 4. Intermediary Considerations . . . . . . . . . . . . . . . . . 8 79 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 80 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 81 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 82 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 83 8.1. Normative References . . . . . . . . . . . . . . . . . . 9 84 8.2. Informative References . . . . . . . . . . . . . . . . . 10 85 Appendix A. Editors' Notes . . . . . . . . . . . . . . . . . . . 10 86 A.1. Abridged Change History . . . . . . . . . . . . . . . . . 10 87 A.1.1. draft-ietf-dnsop-edns-tcp-keepalive-05 . . . . . . . 10 88 A.1.2. draft-ietf-dnsop-edns-tcp-keepalive-04 . . . . . . . 11 89 A.1.3. draft-ietf-dnsop-edns-tcp-keepalive-03 . . . . . . . 11 90 A.1.4. draft-ietf-dnsop-edns-tcp-keepalive-02 . . . . . . . 12 91 A.1.5. draft-ietf-dnsop-edns-tcp-keepalive-01 . . . . . . . 12 92 A.1.6. draft-ietf-dnsop-edns-tcp-keepalive-00 . . . . . . . 12 93 A.1.7. draft-wouters-edns-tcp-keepalive-01 . . . . . . . . . 13 94 A.1.8. draft-wouters-edns-tcp-keepalive-00 . . . . . . . . . 13 95 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 97 1. Introduction 99 DNS messages between clients and servers may be received over either 100 UDP or TCP [RFC1035]. Historically, DNS clients used API's that only 101 facilitated sending and receiving a single query over either UDP or 102 TCP. New APIs and deployment of DNSSEC validating resolvers on hosts 103 that in the past were using stub resolving only is increasing the DNS 104 client base that prefer using long lived TCP connections. Long-lived 105 TCP connections can result in lower request latency than the case 106 where UDP transport is used and truncated responses are received. 107 This is because clients that retry over TCP following a truncated UDP 108 response typically only use the TCP session for a single (request, 109 response) pair, continuing with UDP transport for subsequent queries. 111 UDP transport is stateless, and hence presents a much lower resource 112 burden on a busy DNS server than TCP. An exchange of DNS messages 113 over UDP can also be completed in a single round trip between 114 communicating hosts, resulting in optimally-short transaction times. 115 UDP transport is not without its risks, however. 117 A single-datagram exchange over UDP between two hosts can be 118 exploited to enable a reflection attack on a third party. Response 119 Rate Limiting [RRL] is designed to help mitigate such attacks against 120 authoritative-only servers. One feature of RRL is to let some amount 121 of responses "slip" through the rate limiter. These are returned 122 with the TC (truncation) bit set, which causes legitimate clients to 123 re-query using TCP transport. 125 [RFC1035] specified a maximum DNS message size over UDP transport of 126 512 bytes. Deployment of DNSSEC [RFC4033] and other protocols 127 subsequently increased the observed frequency at which responses 128 exceed this limit. EDNS0 [RFC6891] allows DNS messages larger than 129 512 bytes to be exchanged over UDP, with a corresponding increased 130 incidence of fragmentation. Fragmentation is known to be problematic 131 in general, and has also been implicated in increasing the risk of 132 cache poisoning attacks [fragmentation-considered-poisonous]. 134 TCP transport is less susceptible to the risks of fragmentation and 135 reflection attacks. However, TCP transport as currently deployed has 136 expensive setup overhead. 138 The overhead of the three-way TCP handshake for a single DNS 139 transaction is substantial, increasing the transaction time for a 140 single (request, response) pair of DNS messages from 1 x RTT to 2 x 141 RTT. There is no such overhead for a session that is already 142 established therefore the overhead of the initial TCP handshake is 143 minimised when the resulting session is used to exchange multiple DNS 144 message pairs over a single session. The extra RTT time for session 145 setup can be represented as the equation (1 + N)/N, where N 146 represents the number of DNS message pairs that utilize the session 147 and the result approaches unity as N increases. 149 With increased deployment of DNSSEC and new RRtypes containing 150 application specific cryptographic material, there is an increase in 151 the prevalence of truncated responses received over UDP with retries 152 over TCP. The overhead for a DNS transaction over UDP truncated due 153 to RRL is 3x RTT, higher than the overhead imposed on the same 154 transaction initiated over TCP. 156 The use of TCP transport requires state to be retained on DNS 157 servers. If a server is to perform adequately with a significant 158 query load received over TCP, it must manage its available resources 159 to ensure that all established TCP sessions are well-used, and idle 160 connections are closed after an appropriate amount of time. 162 This document proposes a signalling mechanism between DNS clients and 163 servers that encourages the use of long-lived TCP connections by 164 allowing the state associated with TCP transport to be managed 165 effectively with minimal impact on the DNS transaction time. 167 This mechanism will be of benefit both for stub-resolver and 168 resolver-authoritative TCP connections. In the latter case the 169 persistent nature of the TCP connection can provide improved defence 170 against attacks including DDoS. 172 The reduced overhead of this extension adds up significantly when 173 combined with other EDNS0 extensions, such as [CHAIN-QUERY] and 174 [DNS-over-TLS]. For example, the combination of these EDNS0 175 extensions make it possible for hosts on high-latency mobile networks 176 to natively and efficiently perform DNSSEC validation and encrypt 177 queries. 179 2. Requirements Notation 181 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 182 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 183 document are to be interpreted as described in [RFC2119]. 185 3. The edns-tcp-keepalive Option 187 This document specifies a new EDNS0 [RFC6891] option, edns-tcp- 188 keepalive, which can be used by DNS clients and servers to signal a 189 willingness to keep an idle TCP session open to conduct future DNS 190 transactions, with the idle timeout being specified by the server. 191 This specification does not distinguish between different types of 192 DNS client and server in the use of this option. 194 3.1. Option Format 196 The edns-tcp-keepalive option is encoded as follows: 198 1 2 3 199 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 1 200 +-------------------------------+-------------------------------+ 201 ! OPTION-CODE ! OPTION-LENGTH ! 202 +-------------------------------+-------------------------------+ 203 | TIMEOUT ! 204 +-------------------------------+ 206 where: 208 OPTION-CODE: the EDNS0 option code assigned to edns-tcp-keepalive, 209 TBD1 211 OPTION-LENGTH: the value 0 if the TIMEOUT is omitted, the value 2 212 if it is present; 214 TIMEOUT: an idle timeout value for the TCP connection, specified in 215 units of 100 milliseconds, encoded in network byte order. 217 3.2. Use by DNS Clients 219 3.2.1. Sending Queries 221 DNS clients MUST NOT include the edns-tcp-keepalive option in queries 222 sent using UDP transport. 224 DNS clients MAY include the edns-tcp-keepalive option in the first 225 query sent to a server using TCP transport to signal their desire to 226 keep the connection open when idle. 228 DNS clients MAY include the edns-tcp-keepalive option in subsequent 229 queries sent to a server using TCP transport to signal their 230 continued desire to keep the connection open when idle. 232 Clients MUST specify an OPTION-LENGTH of 0 and omit the TIMEOUT 233 value. 235 3.2.2. Receiving Responses 237 A DNS client that receives a response using UDP transport that 238 includes the edns-tcp-keepalive option MUST ignore the option. 240 A DNS client that receives a response using TCP transport that 241 includes the edns-tcp-keepalive option MAY keep the existing TCP 242 session open when it is idle. It SHOULD honour the timeout received 243 in that response (overriding any previous timeout) and initiate close 244 of the connection before the timeout expires. 246 A DNS client that receives a response that includes the edns-tcp- 247 keepalive option with a TIMEOUT value of 0 SHOULD send no more 248 queries on that connection and initiate closing the connection as 249 soon as it has received all outstanding responses. 251 A DNS client that sent a query containing the edns-keepalive-option 252 but receives a response that does not contain the edns-keepalive- 253 option SHOULD assume the server does not support keepalive and behave 254 following the guidance in [DRAFT-5966bis]. This holds true even if a 255 previous edns-keepalive-option exchange occurred on the existing TCP 256 connection. 258 3.3. Use by DNS Servers 260 3.3.1. Receiving Queries 262 A DNS server that receives a query using UDP transport that includes 263 the edns-tcp-keepalive option MUST ignore the option. 265 A DNS server that receives a query using TCP transport that includes 266 the edns-tcp-keepalive option MAY modify the local idle timeout 267 associated with that TCP session if resources permit. 269 3.3.2. Sending Responses 271 A DNS server that receives a query sent using TCP transport that 272 includes an OPT RR MAY include the edns-tcp-keepalive option in the 273 response to signal the expected idle timeout on a connection. 274 Servers MUST specify the TIMEOUT value that is currently associated 275 with the TCP session. It is reasonable for this value to change 276 according to local resource constraints or in consideration of 277 intermediary behaviour (for example TCP middleboxes or NATs). The 278 DNS server SHOULD send a edns-tcp-keepalive option with a timeout of 279 0 if it deems its local resources are too low to service more TCP 280 keepalive sessions, or if it wants clients to close currently open 281 connections. 283 3.4. TCP Session Management 285 Both DNS clients and servers are subject to resource constraints 286 which will limit the extent to which TCP sessions can persist. 287 Effective limits for the number of active sessions that can be 288 maintained on individual clients and servers should be established, 289 either as configuration options or by interrogation of process limits 290 imposed by the operating system. Servers that implement edns-tcp- 291 keepalive should also engage in TCP connection management by 292 recycling existing connections when appropriate, closing connections 293 gracefully and managing request queues to enable fair use. 295 In the event that there is greater demand for TCP sessions than can 296 be accommodated, servers may reduce the TIMEOUT value signalled in 297 successive DNS messages to minimise idle time on existing sessions. 298 This also allows, for example, clients with other candidate servers 299 to query to establish new TCP sessions with different servers in 300 expectation that an existing session is likely to be closed, or to 301 fall back to UDP. 303 Based on TCP session resources servers may signal a TIMEOUT value of 304 0 to request clients to close connections as soon as possible. This 305 is useful when server resources become very low or a denial-of- 306 service attack is detected and further maximises the shifting of 307 TIME_WAIT state to well-behaved clients. 309 However it should be noted that RCF6891 states: 311 Lack of presence of an OPT record in a request MUST be taken as an 312 indication that the requestor does not implement any part of this 313 specification and that the responder MUST NOT include an OPT 314 record in its response. 316 Since servers must be faithful to this specification even on a 317 persistent TCP connection it means that (following the initial 318 exchange of timeouts) a server may not be presented with the 319 opportunity to signal a change in the idle timeout associated with a 320 connection if the client does not send any further requests 321 containing EDNS0 OPT RRs. This limitation makes persistent 322 connection handling via an initial idle timeout signal more 323 attractive than a mechanism that establishes default persistence and 324 then uses a connection close signal (in a similar manner to HTTP 1.1 325 [RFC7320]). 327 If a client includes the edns-tcp-keepalive option in the first 328 query, it SHOULD include an EDNS0 OPT RR periodically in any further 329 messages it sends during the TCP session. This will increase the 330 chance of the client being notified should the server modify the 331 timeout associated with a session. The algorithm for choosing when 332 to do this is out of scope of this document and is left up to the 333 implementor and/or operator. 335 DNS clients and servers MAY close a TCP session at any time in order 336 to manage local resource constraints. The algorithm by which clients 337 and servers rank active TCP sessions in order to determine which to 338 close is not specified in this document. 340 3.5. Non-Clean Paths 342 Many paths between DNS clients and servers suffer from poor hygiene, 343 limiting the free flow of DNS messages that include particular EDNS0 344 options, or messages that exceed a particular size. A fallback 345 strategy similar to that described in [RFC6891] section 6.2.2 SHOULD 346 be employed to avoid persistent interference due to non-clean paths. 348 3.6. Anycast Considerations 350 DNS servers of various types are commonly deployed using anycast 351 [RFC4786]. 353 Changes in network topology between clients and anycast servers may 354 cause disruption to TCP sessions making use of edns-tcp-keepalive 355 more often than with TCP sessions that omit it, since the TCP 356 sessions are expected to be longer-lived. It might be possible for 357 anycast servers to avoid disruption due to topology changes by making 358 use of TCP multipath [RFC6824] to anchor the server side of the TCP 359 connection to an unambiguously-unicast address. 361 4. Intermediary Considerations 363 It is RECOMMENDED that DNS intermediaries which terminate TCP 364 connections implement edns-tcp-keepalive. An intermediary that does 365 not implement edns-tcp-keepalive but sits between a client and server 366 that both support edns-tcp-keepalive might close idle connections 367 unnecessarily. 369 5. Security Considerations 371 The edns-tcp-keepalive option can potentially be abused to request 372 large numbers of long-lived sessions in a quick burst. When a DNS 373 Server detects abusive behaviour, it SHOULD immediately close the TCP 374 connection and free the resources used. 376 Servers could choose to monitor client behaviour with respect to the 377 edns-tcp-keepalive option to build up profiles of clients that do not 378 honour the specified timeout. 380 Readers are advised to familiarise themselves with the security 381 considerations outlined in [DRAFT-5966bis] 383 6. IANA Considerations 385 The IANA is directed to assign an EDNS0 option code for the edns-tcp- 386 keepalive option from the DNS EDNS0 Option Codes (OPT) registry as 387 follows: 389 +-------+--------------------+----------+-----------------+ 390 | Value | Name | Status | Reference | 391 +-------+--------------------+----------+-----------------+ 392 | TBD1 | edns-tcp-keepalive | Standard | [This document] | 393 +-------+--------------------+----------+-----------------+ 395 7. Acknowledgements 397 The authors acknowledge the contributions of Jinmei TATUYA and Mark 398 Andrews. Thanks to Duane Wessels for detailed review and the many 399 others who contributed to the mailing list discussion. 401 8. References 403 8.1. Normative References 405 [DRAFT-5966bis] 406 Dickinson, J., Dickinson, S., Bellis, R., Mankin, A., and 407 D. Wessels, "DNS Transport over TCP - Implementation 408 Requirements", draft-ietf-dnsop-5966bis (work in 409 progress), December 2015. 411 [RFC1035] Mockapetris, P., "Domain names - implementation and 412 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 413 November 1987, . 415 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 416 Requirement Levels", BCP 14, RFC 2119, 417 DOI 10.17487/RFC2119, March 1997, 418 . 420 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 421 Rose, "DNS Security Introduction and Requirements", 422 RFC 4033, DOI 10.17487/RFC4033, March 2005, 423 . 425 [RFC4786] Abley, J. and K. Lindqvist, "Operation of Anycast 426 Services", BCP 126, RFC 4786, DOI 10.17487/RFC4786, 427 December 2006, . 429 [RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms 430 for DNS (EDNS(0))", STD 75, RFC 6891, 431 DOI 10.17487/RFC6891, April 2013, 432 . 434 [RFC7320] Nottingham, M., "URI Design and Ownership", BCP 190, 435 RFC 7320, DOI 10.17487/RFC7320, July 2014, 436 . 438 8.2. Informative References 440 [CHAIN-QUERY] 441 Wouters, P., "Chain Query requests in DNS", draft-ietf- 442 dnsop-edns-chain-query (work in progress), November 2015. 444 [DNS-over-TLS] 445 Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D., 446 and P. Hoffman, "TLS for DNS: Initiation and Performance 447 Considerations", draft-ietf-dprive-dns-over-tls (work in 448 progress), December 2015. 450 [fragmentation-considered-poisonous] 451 Herzberg, A. and H. Shulman, "Fragmentation Considered 452 Poisonous", arXiv 1205.4011, May 2012, 453 . 455 [RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure, 456 "TCP Extensions for Multipath Operation with Multiple 457 Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013, 458 . 460 [RRL] Vixie, P. and V. Schryver, "DNS Response Rate Limiting 461 (DNS RRL)", ISC-TN 2012-1-Draft1, April 2012, 462 . 464 Appendix A. Editors' Notes 466 A.1. Abridged Change History 468 [Note to RFC Editor: please remove this section prior to 469 publication.] 471 A.1.1. draft-ietf-dnsop-edns-tcp-keepalive-05 473 Reword Abstract and paragraph 9 in Introduction to remove discussion 474 on balancing UDP/TCP and talk about encouraging use of long-lived TCP 475 sessions. 477 Section 3.2.2: should -> SHOULD 479 Changed draft-ietf-dnsop-5966bis to be a normative reference, 480 therefore adding a dependancy on publication of that as RFC. 482 Reword sentence referring to RFC6824 since it is informational. 484 Update IANA option to Standard. 486 Remove last sentence from 1st paragraph of introduction. 488 Reword paragraph 6 in Introduction, merge paragraph 7 and 8. 490 Reword Section 3, first sentence to clarify the timeout is specified 491 by the server. 493 Correct missing URIs in 2 references. 495 Clarify statement in Section 3.2.2 as how clients should handle 496 updating the timeout when receiving a response. 498 Reworded first paragraph of Introduction discussing TCP vs (UDP + 499 retry over TCP). Changed 'fallback' to 'retry' in 2 places. 501 A.1.2. draft-ietf-dnsop-edns-tcp-keepalive-04 503 Adding wording to sections 3.2.1 and 3.4 to clarify client behaviour 504 on subsequent queries on a TCP connection. 506 Changed the should to a SHOULD in section 3.2.2 508 Changed Nameserver to DNS server in section 5. 510 Updated references. 512 Changed reference to RFC6824 to be informative. 514 Corrected reference to requested EDNS0 option code to be 'TBD1'. 516 A.1.3. draft-ietf-dnsop-edns-tcp-keepalive-03 518 Clarified that a response to a query with any OPT RR may contain the 519 ends-tcp-keepalive option. 521 Corrected TIMEOUT length from 4 to 2 in the diagram. 523 Updated references, including name change of STARTTLS -> DNS-over-TLS 524 and adding reference for cache poisoning. 526 Updated wording in section on Intermediary Considerations. 528 Updated wording describing RRL. 530 Added paragraph to security section describing client behaviour 531 profiles. 533 Added wording to introduction on use case for stub/resolver/ 534 authoritative. 536 A.1.4. draft-ietf-dnsop-edns-tcp-keepalive-02 538 Changed timeout value to idle timeout and re-phrased document around 539 this. 541 Changed units of timeout to 100ms to allow values less than 1 second. 543 Change specification to remove use of the option over UDP. This is 544 potentially confusing, could cause issues with ALG's and adds only 545 limited value. 547 Changed semantics so the client no longer sends a timeout. The 548 client timeout is of limited value as servers should be managing 549 connections based on their view of their resources, not on client 550 requests as this is open to abuse. Additionally this identifies 551 cases were the option is simply being reflected back. 553 Changed semantics for the meaning of a server sending a timeout of 0. 554 The maximum timeout value of 6553.5s (~1.8h) is already large and a 555 distinct 'connection close'-like signal is potentially more useful. 557 Added more detail on server side requirements when supporting 558 keepalive in terms of resource and connection management. 560 Added discussion of EDNS0 per-message limitation and implications of 561 this. 563 Added reference to STARTTLS draft and RFC7320. 565 A.1.5. draft-ietf-dnsop-edns-tcp-keepalive-01 567 Version bump with no changes 569 A.1.6. draft-ietf-dnsop-edns-tcp-keepalive-00 571 Clarifications, working group adoption. 573 A.1.7. draft-wouters-edns-tcp-keepalive-01 575 Also allow clients to specify KEEPALIVE timeout values, clarify 576 motivation of document. 578 A.1.8. draft-wouters-edns-tcp-keepalive-00 580 Initial draft. 582 Authors' Addresses 584 Paul Wouters 585 Red Hat 587 Email: pwouters@redhat.com 589 Joe Abley 590 Dyn, Inc. 591 470 Moore Street 592 London, ON N6C 2C2 593 Canada 595 Phone: +1 519 670 9327 596 Email: jabley@dyn.com 598 Sara Dickinson 599 Sinodun Internet Technologies 600 Magdalen Centre 601 Oxford Science Park 602 Oxford OX4 4GA 603 UK 605 Email: sara@sinodun.com 606 URI: http://sinodun.com 608 Ray Bellis 609 Internet Systems Consortium, Inc 610 950 Charter Street 611 Redwood City CA 94063 612 USA 614 Phone: +1 650 423 1200 615 Email: ray@isc.org 616 URI: http://www.isc.org