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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 (August 21, 2009) is 5361 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: February 22, 2010 M. Williams 6 August 21, 2009 8 Transport Layer Security and Datagram Transport Layer Security Heartbeat 9 Extension 10 draft-seggelmann-tls-dtls-heartbeat-01.txt 12 Status of this Memo 14 This Internet-Draft is submitted to IETF in full conformance with the 15 provisions of BCP 78 and BCP 79. 17 Internet-Drafts are working documents of the Internet Engineering 18 Task Force (IETF), its areas, and its working groups. Note that 19 other groups may also distribute working documents as Internet- 20 Drafts. 22 Internet-Drafts are draft documents valid for a maximum of six months 23 and may be updated, replaced, or obsoleted by other documents at any 24 time. It is inappropriate to use Internet-Drafts as reference 25 material or to cite them other than as "work in progress." 27 The list of current Internet-Drafts can be accessed at 28 http://www.ietf.org/ietf/1id-abstracts.txt. 30 The list of Internet-Draft Shadow Directories can be accessed at 31 http://www.ietf.org/shadow.html. 33 This Internet-Draft will expire on February 22, 2010. 35 Copyright Notice 37 Copyright (c) 2009 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents in effect on the date of 42 publication of this document (http://trustee.ietf.org/license-info). 43 Please review these documents carefully, as they describe your rights 44 and restrictions with respect to this document. 46 Abstract 48 This document describes the Heartbeat Extension for the Transport 49 Layer Security (TLS) and Datagram Transport Layer Security (DTLS) 50 protocol. 52 The Heartbeat Extension provides a new protocol for TLS/DTLS allowing 53 the usage of keep-alive functionality without performing a 54 renegotiation and a basis for PMTU discovery for DTLS. 56 Table of Contents 58 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 2. Heartbeat Hello Extension . . . . . . . . . . . . . . . . . . . 3 60 3. Heartbeat Protocol . . . . . . . . . . . . . . . . . . . . . . 4 61 4. Heartbeat Request and Response Messages . . . . . . . . . . . . 5 62 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 63 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 64 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5 65 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 66 8.1. Normative References . . . . . . . . . . . . . . . . . . . 5 67 8.2. Informative References . . . . . . . . . . . . . . . . . . 6 68 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 70 1. Introduction 72 1.1. Overview 74 This document describes the Heartbeat Extension for the Transport 75 Layer Security (TLS) and Datagram Transport Layer Security (DTLS) 76 protocols, as defined in [RFC5246] and [RFC4347]. 78 DTLS is designed to secure traffic running on top of unreliable 79 transport protocols. Such protocols have usually no session 80 management. The only mechanism available at the DTLS layer to figure 81 out if a peer is still alive is performing a costly renegotiation. 82 If the application uses unidirectional traffic there is no other way. 83 Furthermore, DTLS needs to perform PMTU discovery but has no specific 84 message type to realize it without affecting user message transfer. 86 TLS is based on reliable protocols but there is not necessarily a 87 feature available to keep the connection alive without continuous 88 data transfer. 90 The Heartbeat Extension as described in this document overcomes these 91 limitations. The user can use the new HeartbeatRequest message which 92 has to be answered by the peer with a HeartbeartResponse immediately. 93 To perform PMTU discovery HeartbeatRequest messages containing 94 padding can be used as described in [RFC4821] for SCTP using the PAD- 95 chunk defined in [RFC4820]. 97 1.2. Conventions 99 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 100 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 101 document are to be interpreted as described in [RFC2119]. 103 2. Heartbeat Hello Extension 105 The support of Heartbeats is indicated with Hello Extensions. A peer 106 can not only indicate that its implementation supports Heartbeats, it 107 can also choose whether it is willed to receive and respond or only 108 to send them. This decision can be changed with every renegotiation. 109 HeartbeatRequests MUST NOT be sent to a peer denying acceptance. 111 enum { 112 peer_allowed_to_send(1), 113 peer_not_allowed_to_send(2), 114 (255) 115 } HeartbeatMode; 117 struct { 118 HeartbeatMode mode; 119 } HeartbeatExtension; 121 3. Heartbeat Protocol 123 The Heartbeat protocol is a new protocol on top of the Record Layer. 124 The protocol itself consists of two message types, HeartbeatRequest 125 and HeartbeatResponse. 127 enum { 128 heartbeat_request(1), 129 heartbeat_response(2), 130 (255) 131 } HeartbeatMessageType; 133 Like the ChangeCipherSpec, a HeartbeatRequest can arrive at any time 134 during the lifetime of a connection. Whenever a HeartbeatRequest is 135 received, it has to be answered with a corresponding 136 HeartbeatResponse message immediately. 138 However, a HeartbeatRequest message SHOULD NOT be sent during 139 handshakes and there MUST NOT be more than one HeartbeatRequest 140 message in flight at a time. 142 When using DTLS, HeartbeatRequest messages MUST be retransmitted 143 using the simple timeout and retransmission scheme DTLS uses for 144 flights. In particular, after a number of retransmissions without 145 receiving a corresponding HeartbeatResponse message having the 146 expected payload the DTLS connection SHOULD be terminated. The 147 threshold used for this SHOULD be the same as for DTLS handshake 148 messages. 150 When using TLS, HeartbeatRequest messages only need to be sent once. 151 The transport layer will handle retransmissions. If no corresponding 152 HeartbeatResponse message has been received after a user configured 153 amount of time, the TLS connection SHOULD be terminated. 155 4. Heartbeat Request and Response Messages 157 The Heartbeat protocol messages consist of their type and an 158 arbitrary payload and padding. 160 struct { 161 HeartbeatMessageType type; 162 opaque payload<0..2^14-5>; 163 opaque padding<0..2^14-5>; 164 } HeartbeatMessage; 166 The length of payload and padding in total MUST NOT exceed 2^14-5 167 bytes. 169 When a HeartbeatRequest message is received, a corresponding 170 HeartbeatResponse message MUST be sent carrying an exact copy of the 171 payload of the HeartbeatRequest. The padding MUST NOT be included in 172 the HeartbeatResponse message, i.e. the padding field has a length of 173 zero. 175 If a received HeartbeatResponse message does not contain the expected 176 payload the message MUST be discarded silently. If it does contain 177 the expected payload the retransmission timer MUST be stopped. 179 5. IANA Considerations 181 The extension, content and message types have to be assigned by IANA. 183 6. Security Considerations 185 This document does not add any additional security considerations in 186 addition to the ones given in [RFC4347] and [RFC5246]. 188 7. Acknowledgments 190 The authors wish to thank Eric Rescorla, and Pasi Eronen for their 191 invaluable comments. 193 8. References 195 8.1. Normative References 197 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 198 Requirement Levels", BCP 14, RFC 2119, March 1997. 200 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 201 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 203 [RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer 204 Security", RFC 4347, April 2006. 206 8.2. Informative References 208 [RFC4820] Tuexen, M., Stewart, R., and P. Lei, "Padding Chunk and 209 Parameter for the Stream Control Transmission Protocol 210 (SCTP)", RFC 4820, March 2007. 212 [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU 213 Discovery", RFC 4821, March 2007. 215 Authors' Addresses 217 Robin Seggelmann 218 Muenster Univ. of Applied Sciences 219 Stegerwaldstr. 39 220 48565 Steinfurt 221 Germany 223 Email: seggelmann@fh-muenster.de 225 Michael Tuexen 226 Muenster Univ. of Applied Sciences 227 Stegerwaldstr. 39 228 48565 Steinfurt 229 Germany 231 Email: tuexen@fh-muenster.de 233 Michael Williams 235 Email: michael.glenn.williams@gmail.com