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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 (February 21, 2010) is 5140 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 5246 (Obsoleted by RFC 8446) ** Obsolete normative reference: RFC 4347 (Obsoleted by RFC 6347) Summary: 3 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group R. Seggelmann 3 Internet-Draft M. Tuexen 4 Intended status: Standards Track Muenster Univ. of Applied Sciences 5 Expires: August 25, 2010 M. Williams 6 February 21, 2010 8 Transport Layer Security and Datagram Transport Layer Security Heartbeat 9 Extension 10 draft-seggelmann-tls-dtls-heartbeat-02.txt 12 Abstract 14 This document describes the Heartbeat Extension for the Transport 15 Layer Security (TLS) and Datagram Transport Layer Security (DTLS) 16 protocol. 18 The Heartbeat Extension provides a new protocol for TLS/DTLS allowing 19 the usage of keep-alive functionality without performing a 20 renegotiation and a basis for PMTU discovery for DTLS. 22 Status of this Memo 24 This Internet-Draft is submitted to IETF in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF), its areas, and its working groups. Note that 29 other groups may also distribute working documents as Internet- 30 Drafts. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 The list of current Internet-Drafts can be accessed at 38 http://www.ietf.org/ietf/1id-abstracts.txt. 40 The list of Internet-Draft Shadow Directories can be accessed at 41 http://www.ietf.org/shadow.html. 43 This Internet-Draft will expire on August 25, 2010. 45 Copyright Notice 47 Copyright (c) 2010 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (http://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 63 2. Heartbeat Hello Extension . . . . . . . . . . . . . . . . . . . 3 64 3. Heartbeat Protocol . . . . . . . . . . . . . . . . . . . . . . 4 65 4. Heartbeat Request and Response Messages . . . . . . . . . . . . 5 66 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 67 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 68 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5 69 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 70 8.1. Normative References . . . . . . . . . . . . . . . . . . . 6 71 8.2. Informative References . . . . . . . . . . . . . . . . . . 6 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 74 1. Introduction 76 1.1. Overview 78 This document describes the Heartbeat Extension for the Transport 79 Layer Security (TLS) and Datagram Transport Layer Security (DTLS) 80 protocols, as defined in [RFC5246] and [RFC4347]. 82 DTLS is designed to secure traffic running on top of unreliable 83 transport protocols. Such protocols have usually no session 84 management. The only mechanism available at the DTLS layer to figure 85 out if a peer is still alive is performing a costly renegotiation. 86 If the application uses unidirectional traffic there is no other way. 87 Furthermore, DTLS needs to perform PMTU discovery but has no specific 88 message type to realize it without affecting user message transfer. 90 TLS is based on reliable protocols but there is not necessarily a 91 feature available to keep the connection alive without continuous 92 data transfer. 94 The Heartbeat Extension as described in this document overcomes these 95 limitations. The user can use the new HeartbeatRequest message which 96 has to be answered by the peer with a HeartbeartResponse immediately. 97 To perform PMTU discovery HeartbeatRequest messages containing 98 padding can be used as described in [RFC4821] for SCTP using the PAD- 99 chunk defined in [RFC4820]. 101 1.2. Conventions 103 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 104 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 105 document are to be interpreted as described in [RFC2119]. 107 2. Heartbeat Hello Extension 109 The support of Heartbeats is indicated with Hello Extensions. A peer 110 can not only indicate that its implementation supports Heartbeats, it 111 can also choose whether it is willed to receive and respond or only 112 to send them. This decision can be changed with every renegotiation. 113 HeartbeatRequests MUST NOT be sent to a peer denying acceptance. 115 enum { 116 peer_allowed_to_send(1), 117 peer_not_allowed_to_send(2), 118 (255) 119 } HeartbeatMode; 121 struct { 122 HeartbeatMode mode; 123 } HeartbeatExtension; 125 3. Heartbeat Protocol 127 The Heartbeat protocol is a new protocol on top of the Record Layer. 128 The protocol itself consists of two message types, HeartbeatRequest 129 and HeartbeatResponse. 131 enum { 132 heartbeat_request(1), 133 heartbeat_response(2), 134 (255) 135 } HeartbeatMessageType; 137 Like the ChangeCipherSpec, a HeartbeatRequest can arrive at any time 138 during the lifetime of a connection. Whenever a HeartbeatRequest is 139 received, it has to be answered with a corresponding 140 HeartbeatResponse message immediately. 142 However, a HeartbeatRequest message SHOULD NOT be sent during 143 handshakes and there MUST NOT be more than one HeartbeatRequest 144 message in flight at a time. 146 When using DTLS, HeartbeatRequest messages MUST be retransmitted 147 using the simple timeout and retransmission scheme DTLS uses for 148 flights. In particular, after a number of retransmissions without 149 receiving a corresponding HeartbeatResponse message having the 150 expected payload the DTLS connection SHOULD be terminated. The 151 threshold used for this SHOULD be the same as for DTLS handshake 152 messages. 154 When using TLS, HeartbeatRequest messages only need to be sent once. 155 The transport layer will handle retransmissions. If no corresponding 156 HeartbeatResponse message has been received after a user configured 157 amount of time, the TLS connection SHOULD be terminated. 159 4. Heartbeat Request and Response Messages 161 The Heartbeat protocol messages consist of their type and an 162 arbitrary payload and padding. 164 struct { 165 HeartbeatMessageType type; 166 opaque payload<0..2^14-5>; 167 opaque padding<0..2^14-5>; 168 } HeartbeatMessage; 170 The length of payload and padding in total MUST NOT exceed 2^14-5 171 bytes. 173 When a HeartbeatRequest message is received, a corresponding 174 HeartbeatResponse message MUST be sent carrying an exact copy of the 175 payload of the HeartbeatRequest. The padding of the received 176 HeartbeatRequest message MUST be ignored. It MUST NOT be included in 177 the HeartbeatResponse message, i.e. the padding field of the 178 HeartbeatResponse message MUST have a length of zero. 180 If a received HeartbeatResponse message does not contain the expected 181 payload the message MUST be discarded silently. If it does contain 182 the expected payload the retransmission timer MUST be stopped. 184 5. IANA Considerations 186 The extension, content and message types have to be assigned by IANA. 188 6. Security Considerations 190 This document does not add any additional security considerations in 191 addition to the ones given in [RFC4347] and [RFC5246]. 193 7. Acknowledgments 195 The authors wish to thank Eric Rescorla, and Pasi Eronen for their 196 invaluable comments. 198 8. References 199 8.1. Normative References 201 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 202 Requirement Levels", BCP 14, RFC 2119, March 1997. 204 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 205 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 207 [RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer 208 Security", RFC 4347, April 2006. 210 8.2. Informative References 212 [RFC4820] Tuexen, M., Stewart, R., and P. Lei, "Padding Chunk and 213 Parameter for the Stream Control Transmission Protocol 214 (SCTP)", RFC 4820, March 2007. 216 [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU 217 Discovery", RFC 4821, March 2007. 219 Authors' Addresses 221 Robin Seggelmann 222 Muenster Univ. of Applied Sciences 223 Stegerwaldstr. 39 224 48565 Steinfurt 225 Germany 227 Email: seggelmann@fh-muenster.de 229 Michael Tuexen 230 Muenster Univ. of Applied Sciences 231 Stegerwaldstr. 39 232 48565 Steinfurt 233 Germany 235 Email: tuexen@fh-muenster.de 237 Michael Williams 239 Email: michael.glenn.williams@gmail.com