Network Working Group J. Shih Internet Draft AT&T Corporation Intended status: Proposed Standard June 13, 2011 Expires: December 2011 IMAP4 Server-Initiated LOGOUT Command draft-shih-imap-server-logout-00.txt Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." 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Abstract Shih Expires December 13, 2011 [Page 1] Internet-Draft IMAP4 Server-Initiated LOGOUT June 2011 The Internet Message Access Protocol [RFC3501] requires a client to initiate a LOGOUT command to close the network connection. However, it's often desirable to have the server initiate the termination of the network connection. This allows the network to deactivate a service provided to a client. This document specifies the syntax of a server-initiated LOGOUT command, which will allow a server to tell the client that the connection needs to be closed. Table of Contents 1. Introduction ................................................. 2 2. Conventions used in this document ............................ 2 3. Specification ................................................ 3 4. Security Considerations ...................................... 3 5. IANA Considerations .......................................... 3 6. References ................................................... 3 7. Acknowledgments .............................................. 3 1. Introduction In some situations, the network may need to deactivate a service provided to a client. However, according to the current Internet Message Access Protocol, Version 4rev1 (IMAP4rev1) [RFC3501], only a client is allowed to originate the deactivation of an IMAP4rev1-based service by sending a LOGOUT command to the server. This document introduces a LOGOUT command sent out by a server. With this command, a server is able to initiate the closing of a network connection when necessary. This command informs the client of the server's intent to close the connection so that the client will not regard the disconnection as a malfunction when the server closes the connection. 2. Conventions used in this document In examples, "C:" and "S:" indicate lines sent by the client and server respectively. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [RFC2119]. In this document, these words will appear with that interpretation only when in ALL CAPS. Lower case uses of these words are not to be interpreted as carrying RFC-2119 significance. Shih Expires December 13, 2011 [Page 2] Internet-Draft IMAP4 Server-Initiated LOGOUT June 2011 3. Specification LOGOUT Command (initiated by the server) Arguments: none Responses: OPTIONAL untagged response: BYE Result: OK - logout completed BAD - command unknown or arguments invalid A server sends a LOGOUT command to a client to inform the client that the server needs to close the network connection. The client MAY send a BYE untagged response before the (tagged) OK response. In order to handle the case where a LOGOUT command can never trigger a final response, a timer is implemented in the server. When a LOGOUT command is sent to a client, the timer MUST be set for that particular client. The timer MUST have a timing interval longer than 32 seconds. The server SHALL close the connection when it receives the OK response from the client or the timer expires. Example: S: A001 LOGOUT C: * BYE IMAP4rev1 Client logging out C: A001 OK LOGOUT completed (Server and client then close the connection) 4. Security Considerations There are no known security issues with this extension. 5. IANA Considerations 6. References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3501] Crispin, M., "Internet Message Access Protocol - Version 4rev1", RFC 3501, March 2003. 7. Acknowledgments This document was prepared using 2-Word-v2.0.template.dot. Authors' Addresses Shih Expires December 13, 2011 [Page 3] Internet-Draft IMAP4 Server-Initiated LOGOUT June 2011 Jerry Shih AT&T Email: jerry.shih@ATT.COM Xin DING ZTE Corporation 68 Zijinghua Road, Nanjing, China 210012 Email: ding.xin@zte.com.cn Yan LU ZTE Corporation 68 Zijinghua Road, Nanjing, China 210012 Email: luyan@zte.com.cn Xiongwei Jia China Unicom Research Institute Email: jiaxw9@chinaunicom.cn Shih Expires December 13, 2011 [Page 4]