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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (January 27, 2011) is 4131 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) == Unused Reference: 'RFC0793' is defined on line 191, but no explicit reference was found in the text ** Downref: Normative reference to an Unknown state RFC: RFC 1016 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Transport Area Working Group F. Gont 3 (tsvwg) UTN/FRH 4 Internet-Draft January 27, 2011 5 Updates: 792, 1122, 1812 6 (if approved) 7 Intended status: Standards Track 8 Expires: July 31, 2011 10 Deprecation of ICMP Source Quench messages 11 draft-ietf-tsvwg-source-quench-00.txt 13 Abstract 15 This document formally deprecates the use of ICMP Source Quench 16 messages by transport protocols, formally updating RFC 792, RFC 1122, 17 and RFC 1812. Additionally, it requests that the status of RFC 1016 18 be changed to "Historic". 20 Status of this Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on July 31, 2011. 37 Copyright Notice 39 Copyright (c) 2011 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 55 2. ICMP Source Quench messages . . . . . . . . . . . . . . . . . . 3 56 3. Updating RFC 1122 . . . . . . . . . . . . . . . . . . . . . . . 4 57 4. Updating RFC 1812 . . . . . . . . . . . . . . . . . . . . . . . 4 58 5. General Advice to Transport Protocols . . . . . . . . . . . . . 4 59 6. Changing the status of RFC 1016 Historic . . . . . . . . . . . 4 60 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 61 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 62 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 63 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 64 10.1. Normative References . . . . . . . . . . . . . . . . . . . 5 65 10.2. Informative References . . . . . . . . . . . . . . . . . . 6 66 Appendix A. Survey of support of ICMP Source Quench in some 67 popular TCP/IP implementations . . . . . . . . . . . . 6 68 Appendix B. Changes from previous versions of the draft (to 69 be removed by the RFC Editor before publishing 70 this document as an RFC) . . . . . . . . . . . . . . . 6 71 B.1. Changes from draft-gont-tsvwg-source-quench-01 . . . . . . 7 72 B.2. Changes from draft-gont-tsvwg-source-quench-00 . . . . . . 7 73 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7 75 1. Introduction 77 The ICMP specification [RFC0792] defined the ICMPv4 Source Quench 78 message (type 4, code 0), which was meant as a mechanism for 79 congestion control. ICMP Source Quench has been known to be an 80 ineffective (and unfair) antidote for congestion, and generation of 81 ICMP Source Quench messages by routers has been formally deprecated 82 by [RFC1812] since 1995. However, reaction to ICMP Source Quench 83 messages in transport protocols has never been formally deprecated. 85 This document formally deprecates reaction to ICMP Source Quench 86 messages by transport protocols such as TCP, formally updating 87 [RFC0792], [RFC1122], and [RFC1812]. Additionally, it requests that 88 the status of [RFC1016] be changed to "Historic". 90 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 91 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 92 document are to be interpreted as described in RFC 2119 [RFC2119]. 94 2. ICMP Source Quench messages 96 The ICMP specification [RFC0792] defined the ICMP Source Quench 97 message (type 4, code 0), which was meant to provide a mechanism for 98 congestion control. The Host Requirements RFC [RFC1122] stated in 99 Section 4.2.3.9 that hosts MUST react to ICMP Source Quench messages 100 by slowing transmission on the connection, and further added that the 101 RECOMMENDED procedure was to put the corresponding connection in the 102 slow-start phase of TCP's congestion control algorithm [RFC5681]. 104 [RFC1812] noted that research suggested that ICMP Source Quench was 105 an ineffective (and unfair) antidote for congestion, and formally 106 deprecated the generation of ICMP Source Quench messages by routers, 107 stating that routers SHOULD NOT send ICMP Source Quench messages in 108 response to congestion. 110 [RFC5927] discussed the use of ICMP Source Quench messages for 111 performing "blind throughput-reduction" attacks, and noted that most 112 TCP implementations silently ignore ICMP Source Quench messages. 114 We note that TCP implements its own congestion control mechanisms 115 [RFC5681] [RFC3168], that do not depend on ICMP Source Quench 116 messages. 118 It is interesting to note that ICMPv6 [RFC4443] does not specify a 119 "Source Quench" message. 121 3. Updating RFC 1122 123 This document hereby updates Section 3.2.2.3 of [RFC1122] as follows: 125 A host SHOULD NOT send ICMP Source Quench messages. 127 If a Source Quench message is received, the IP layer MAY silently 128 discard it. 130 Section 4.2.3.9 of [RFC1122] is updated as follows: 132 TCP SHOULD silently discard any received ICMP Source Quench 133 messages. 135 4. Updating RFC 1812 137 This document hereby updates Section 4.3.3.3 of [RFC1812] as follows: 139 A router SHOULD ignore any ICMP Source Quench messages it 140 receives. 142 5. General Advice to Transport Protocols 144 If a Source Quench message is received by a transport-protocol 145 instance (e.g., a TCP connection), it SHOULD be silently ignored. 147 6. Changing the status of RFC 1016 Historic 149 This document requests the RFC Editor to change the status of 150 [RFC1016] to "Historic". 152 7. Security Considerations 154 ICMP Source Quench messages could be leveraged for performing blind 155 throughput-reduction attacks against TCP and similar protocols. This 156 attack vector, along with possible countermeasures, have been 157 discussed in great detail in [RFC5927] and [CPNI-TCP]. However, as 158 noted in [RFC5927] and [CPNI-TCP], virtually all current versions of 159 popular TCP implementations already silently ignore ICMP Source 160 Quench messages. 162 Silently ignoring ICMP Source Quench messages, as specified in this 163 document, eliminates the aforementioned attack vector. 165 If deemed necessary, ICMP Source Quench messages could be filtered at 166 firewalls. 168 8. IANA Considerations 170 This document has no actions for IANA. The RFC-Editor can remove 171 this section before publication of this document as an RFC. 173 9. Acknowledgements 175 The author of this document would like to thank (in alphabetical 176 order) Fred Baker, David Black, Scott Bradner, James Carlson, Antonio 177 De Simone, Gorry Fairhurst, Alfred Hoenes, Mahesh Jethanandani, Dan 178 Wing, and Andrew Yourtchenko, for providing valuable feedback on 179 earlier versions of this document. 181 This document has benefited from discussions within the TCPM Working 182 Group while working on [RFC5927]. 184 10. References 186 10.1. Normative References 188 [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, 189 RFC 792, September 1981. 191 [RFC0793] Postel, J., "Transmission Control Protocol", STD 7, 192 RFC 793, September 1981. 194 [RFC1016] Prue, W. and J. Postel, "Something a host could do with 195 source quench: The Source Quench Introduced Delay 196 (SQuID)", RFC 1016, July 1987. 198 [RFC1122] Braden, R., "Requirements for Internet Hosts - 199 Communication Layers", STD 3, RFC 1122, October 1989. 201 [RFC1812] Baker, F., "Requirements for IP Version 4 Routers", 202 RFC 1812, June 1995. 204 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 205 Requirement Levels", BCP 14, RFC 2119, March 1997. 207 [RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition 208 of Explicit Congestion Notification (ECN) to IP", 209 RFC 3168, September 2001. 211 [RFC5681] Allman, M., Paxson, V., and E. Blanton, "TCP Congestion 212 Control", RFC 5681, September 2009. 214 10.2. Informative References 216 [CPNI-TCP] 217 CPNI, "Security Assessment of the Transmission Control 218 Protocol (TCP)", 2009, . 221 [FreeBSD] The FreeBSD Project, "http://www.freebsd.org". 223 [Linux] The Linux Project, "http://www.kernel.org". 225 [NetBSD] The NetBSD Project, "http://www.netbsd.org". 227 [OpenBSD] The OpenBSD Project, "http://www.openbsd.org". 229 [OpenSolaris] 230 OpenSolaris, "http://www.opensolaris.org". 232 [RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control 233 Message Protocol (ICMPv6) for the Internet Protocol 234 Version 6 (IPv6) Specification", RFC 4443, March 2006. 236 [RFC5927] Gont, F., "ICMP Attacks against TCP", RFC 5927, July 2010. 238 Appendix A. Survey of support of ICMP Source Quench in some popular 239 TCP/IP implementations 241 A large number of implementations completely ignore ICMP Source 242 Quench messages meant for TCP connections. This behavior has been 243 implemented in, at least, Linux [Linux] since 2004, and in FreeBSD 244 [FreeBSD], NetBSD [NetBSD], OpenBSD [OpenBSD], and Solaris 10 since 245 2005. Additionally, OpenSolaris [OpenSolaris] has always shipped 246 with support for ICMP Source Quench messages disabled. 248 Appendix B. Changes from previous versions of the draft (to be removed 249 by the RFC Editor before publishing this document as an 250 RFC) 252 B.1. Changes from draft-gont-tsvwg-source-quench-01 254 o Addresses nits and editorial chagnes suggested by Gorry Fairhurst. 256 o Added the status of Solaris and OpenSolaris to Appendix A. 258 o Document resubmitted as draft-ietf. 260 B.2. Changes from draft-gont-tsvwg-source-quench-00 262 o This revision reflects the recent discussion about ICMP Source 263 Quench messages on the tsvwg mailing-list. A detailed list of the 264 changes is available at: 265 http://www.ietf.org/mail-archive/web/tsvwg/current/msg10407.html 267 Author's Address 269 Fernando Gont 270 Universidad Tecnologica Nacional / Facultad Regional Haedo 271 Evaristo Carriego 2644 272 Haedo, Provincia de Buenos Aires 1706 273 Argentina 275 Phone: +54 11 4650 8472 276 Email: fernando@gont.com.ar 277 URI: http://www.gont.com.ar