GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc3887

Network Working Group T. Hansen Request for Comments: 3887 AT&T Laboratories Category: Standards Track September 2004

                  Message Tracking Query Protocol

Status of this Memo

 This document specifies an Internet standards track protocol for the
 Internet community, and requests discussion and suggestions for
 improvements.  Please refer to the current edition of the "Internet
 Official Protocol Standards" (STD 1) for the standardization state
 and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (2004).

Abstract

 Customers buying enterprise message systems often ask: Can I track
 the messages?  Message tracking is the ability to find out the path
 that a particular message has taken through a messaging system and
 the current routing status of that message.  This document describes
 the Message Tracking Query Protocol that is used in conjunction with
 extensions to the ESMTP protocol to provide a complete message
 tracking solution for the Internet.

1. Introduction

 The Message Tracking Models and Requirements document
 [RFC-MTRK-MODEL] discusses the models that message tracking solutions
 could follow, along with requirements for a message tracking solution
 that can be used with the Internet-wide message infrastructure.  This
 memo and its companions, [RFC-MTRK-ESMTP] and [RFC-MTRK-TSN],
 describe a complete message tracking solution that satisfies those
 requirements.  The memo [RFC-MTRK-ESMTP] defines an extension to the
 SMTP service that provides the information necessary to track
 messages.  This memo defines a protocol that can be used to query the
 status of messages that have been transmitted on the Internet via
 SMTP.  The memo [RFC-MTRK-TSN] describes the message/tracking-status
 [RFC-MIME] media type that is used to report tracking status
 information.  Using the model document's terminology, this solution
 uses active enabling and active requests with both request and
 chaining referrals.

Hansen Standards Track [Page 1] RFC 3887 Message Tracking Query Protocol September 2004

1.1. Terminology

 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 BCP 14, RFC 2119
 [RFC-KEYWORDS].
 All syntax descriptions use the ABNF specified by [RFC-ABNF].
 Terminal nodes not defined elsewhere in this document are defined in
 [RFC-ABNF], [RFC-URI], [RFC-MTRK-ESMTP], [RFC-SMTP], or
 [RFC-SMTPEXT].

2. Basic Operation

 The Message Tracking Query Protocol (MTQP) is similar to many other
 line-oriented Internet protocols, such as [POP3] and [NNTP].
 Initially, the server host starts the MTQP service by listening on
 TCP port 1038.
 When an MTQP client wishes to make use of the message tracking
 service, it establishes a TCP connection with the server host, as
 recorded from the initial message submission or as returned by a
 previous tracking request.  To find the server host, the MTQP client
 first does an SRV lookup for the server host using DNS SRV records,
 with a service name of "mtqp" and a protocol name of "tcp", as in
 _mtqp._tcp.smtp3.example.com.  (See the "Usage rules" section in
 [RFC-SRV] for details.)  If the SRV records do not exist, the MTQP
 client then does an address record lookup for the server host.  When
 the connection is established, the MTQP server sends a greeting.  The
 MTQP client and MTQP server then exchange commands and responses
 (respectively) until the connection is closed or aborted.

2.1. Tracking Service DNS Considerations

 Because of the ways server host lookups are performed, many different
 tracking server host configurations are supported.
 A mail system that uses a single mail server host and has the MTQP
 server host on the same server host will most likely have a single MX
 record pointing at the server host, and if not, will have an address
 record.  Both mail and MTQP clients will access that host directly.
 A mail system that uses a single mail server host, but wants tracking
 queries to be performed on a different machine, MUST have an SRV MTQP
 record pointing at that different machine.

Hansen Standards Track [Page 2] RFC 3887 Message Tracking Query Protocol September 2004

 A mail system that uses multihomed mail servers has two choices for
 providing tracking services: either all mail servers must be running
 tracking servers that are able to retrieve information on all
 messages, or the tracking service must be performed on one (or more)
 machine(s) that are able to retrieve information on all messages.  In
 the former case, no additional DNS records are needed beyond the MX
 records already in place for the mail system.  In the latter case,
 SRV MTQP records are needed that point at the machine(s) that are
 running the tracking service.  In both cases, note that the tracking
 service MUST be able to handle the queries for all messages accepted
 by that mail system.

2.2. Commands

 Commands in MTQP consist of a case-insensitive keyword, possibly
 followed by one or more parameters.  All commands are terminated by a
 CRLF pair.  Keywords and parameters consist of printable ASCII
 characters.  Keywords and parameters are separated by whitespace (one
 or more space or tab characters).  A command line is limited to 998
 characters before the CRLF.

2.3. Responses

 Responses in MTQP consist of a status indicator that indicates
 success or failure.  Successful commands may also be followed by
 additional lines of data.  All response lines are terminated by a
 CRLF pair and are limited to 998 characters before the CRLF.  There
 are several status indicators: "+OK" indicates success; "+OK+"
 indicates a success followed by additional lines of data, a multi-
 line success response; "-TEMP" indicates a temporary failure; "-ERR"
 indicates a permanent failure; and "-BAD" indicates a protocol error
 (such as for unrecognized commands).
 A status indicator MAY be followed by a series of machine-parsable,
 case-insensitive response information giving more data about the
 errors.  These are separated from the status indicator and each other
 by a single slash character ("/", decimal code 47).  Following that,
 there MAY be white space and a human-readable text message.  The
 human-readable text message is not intended to be presented to the
 end user, but should be appropriate for putting in a log for use in
 debugging problems.
 In a multi-line success response, each subsequent line is terminated
 by a CRLF pair and limited to 998 characters before the CRLF.  When
 all lines of the response have been sent, a final line is sent
 consisting of a single period (".", decimal code 046) and a CRLF
 pair.  If any line of the multi-line response begins with a period,
 the line is "dot-stuffed" by prepending the period with a second

Hansen Standards Track [Page 3] RFC 3887 Message Tracking Query Protocol September 2004

 period.  When examining a multi-line response, the client checks to
 see if the line begins with a period.  If so, and octets other than
 CRLF follow, the first octet of the line (the period) is stripped
 away.  If so, and if CRLF immediately follows the period, then the
 response from the MTQP server is ended and the line containing the
 ".CRLF" is not considered part of the multi-line response.
 An MTQP server MUST respond to an unrecognized, unimplemented, or
 syntactically invalid command by responding with a negative -BAD
 status indicator.  A server MUST respond to a command issued when the
 session is in an incorrect state by responding with a negative -ERR
 status indicator.

2.4. Firewall Considerations

 A firewall mail gateway has two choices when receiving a tracking
 query for a host within its domain: it may return a response to the
 query that says the message has been passed on, but no further
 information is available; or it may perform a chaining operation
 itself, gathering information on the message from the mail hosts
 behind the firewall, and returning to the MTQP client the information
 for each behind-the-firewall hop, or possibly just the final hop
 information, possibly also disguising the names of any hosts behind
 the firewall.  Which option is picked is an administrative decision
 and is not further mandated by this document.
 If a server chooses to perform a chaining operation itself, it MUST
 provide a response within 2 minutes, and SHOULD return a "no further
 information is available" response if it cannot provide an answer at
 the end of that time limit.

2.5. Optional Timers

 An MTQP server MAY have an inactivity autologout timer.  Such a timer
 MUST be of at least 10 minutes in duration.  The receipt of any
 command from the client during that interval should suffice to reset
 the autologout timer.  An MTQP server MAY limit the number of
 commands, unrecognized commands, or total connection time, or MAY use
 other criteria, to prevent denial of service attacks.
 An MTQP client MAY have an inactivity autologout timer while waiting
 for a response from the server.  Since an MTQP server may be a
 firewall, and may be chaining information from other servers, such a
 timer MUST be at least 2 minutes in duration.

Hansen Standards Track [Page 4] RFC 3887 Message Tracking Query Protocol September 2004

3. Initialization and Option Response

 Once the TCP connection has been opened by an MTQP client, the MTQP
 server issues an initial status response that indicates its
 readiness.  If the status response is positive (+OK or +OK+), the
 client may proceed with other commands.
 The initial status response MUST include the response information
 "/MTQP".  Negative responses MUST include a reason code as response
 information.  The following reason codes are defined here;
 unrecognized reason codes added in the future may be treated as
 equivalent to "unavailable".
    "/" "unavailable"
    "/" "admin"
 The reason code "/admin" SHOULD be used when the service is
 unavailable for administrative reasons.  The reason code
 "/unavailable" SHOULD be used when the service is unavailable for
 other reasons.
 If the server has any options enabled, they are listed as the multi-
 line response of the initial status response, one per line.  An
 option specification consists of an identifier, optionally followed
 by option-specific parameters.  An option specification may be
 continued onto additional lines by starting the continuation lines
 with white space.  The option identifier is case insensitive.  Option
 identifiers beginning with the characters "vnd." are reserved for
 vendor use.  (See below.)
 One option specification is defined here:
 STARTTLS [1*WSP "required"]
 This capability MUST be listed if the optional STARTTLS command is
 enabled on the MQTP server and one or more certificates have been
 properly installed.
 It has one optional parameter: the word "required" (The parameters
 for STARTTLS are case-insensitive).  If the server requires that TLS
 be used for some of the domains the server handles, the server MUST
 specify the "required" parameter.

Hansen Standards Track [Page 5] RFC 3887 Message Tracking Query Protocol September 2004

3.1. Examples

 Example #1 (no options):
 S: +OK/MTQP MTQP server ready
 Example #2 (service temporarily unavailable):
 S: -TEMP/MTQP/admin Service down for admin, call back later
 Example #3 (service permanently unavailable):
 S: -ERR/MTQP/unavailable Service down
 Example #4 (alternative for no options):
 S: +OK+/MTQP MTQP server ready
 S: .
 Example #5 (options available):
 S: +OK+/MTQP MTQP server ready
 S: starttls
 S: vnd.com.example.option2 with parameters private to example.com
 S: vnd.com.example.option3 with a very long
 S:  list of parameters
 S: .

4. TRACK Command

 Syntax:
 track-command = "TRACK" 1*WSP unique-envid 1*WSP mtrk-secret CRLF
   mtrk-secret = base64
 Unique-envid is defined in [RFC-MTRK-ESMTP].  Mtrk-secret is the
 secret A described in [RFC-MTRK-ESMTP], encoded using base64.
 When the client issues the TRACK command, and the user is validated,
 the MTQP server retrieves tracking information about an email
 message.  To validate the user, the value of mtrk-secret is hashed
 using SHA1, as described in [RFC-SHA1].  The hash value is then
 compared with the value passed with the message when it was
 originally sent.  If the hash values match, the user is validated.
 A successful response MUST be multi-line, consisting of a [RFC-MIME]
 body part.  The MIME body part MUST be of type multipart/related,
 with subparts of message/tracking-status, as defined in
 [RFC-MTRK-TSN].  The response contains the tracking information about
 the email message that used the given tracking-id.  A negative
 response to the TRACK command may include these reason codes:

Hansen Standards Track [Page 6] RFC 3887 Message Tracking Query Protocol September 2004

    "/" "tls-required"
    "/" "admin"
    "/" "unavailable"
    "/" "noinfo"
    "/" "insecure"
 The reason code "/tls-required" SHOULD be used when the server has
 decided to require TLS.  The reason code "/admin" SHOULD be used when
 the server has become unavailable, due to administrative reasons,
 since the connection was initialized.  The reason code "/unavailable"
 SHOULD be used when the server has become unavailable, for other
 reasons, since the connection was initialized.  The reason code
 "/insecure" is described later.
 If a message has not been seen by the MTQP server, the server MUST
 choose between two choices: it MAY return a positive response with an
 action field of "opaque" in the tracking information, or it MAY
 return a negative response with a reason code of "noinfo".

4.1. Examples

 In each of the examples below, the unique-envid is
 "<12345-20010101@example.com>", the secret A is "abcdefgh", and the
 SHA1 hash B is (in hex) "734ba8b31975d0dbae4d6e249f4e8da270796c94".
 The message came from example.com and the MTQP server is
 example2.com.

Example #6 Message Delivered: C: TRACK 12345-20010101@example.com YWJjZGVmZ2gK S: +OK+ Tracking information follows S: Content-Type: multipart/related; boundary=; type=tracking-status S: S: – S: Content-Type: message/tracking-status S: S: Original-Envelope-Id: 12345-20010101@example.com S: Reporting-MTA: dns; example2.com S: Arrival-Date: Mon, 1 Jan 2001 15:15:15 -0500 S: S: Original-Recipient: rfc822; user1@example1.com S: Final-Recipient: rfc822; user1@example1.com S: Action: delivered S: Status: 2.5.0 S: S: –– S: .

Hansen Standards Track [Page 7] RFC 3887 Message Tracking Query Protocol September 2004

Example #7 Message Transferred: C: TRACK 12345-20010101@example.com YWJjZGVmZ2gK S: +OK+ Tracking information follows S: Content-Type: multipart/related; boundary=; type=tracking-status S: S: – S: Content-Type: message/tracking-status S: S: Original-Envelope-Id: 12345-20010101@example.com S: Reporting-MTA: dns; example2.com S: Arrival-Date: Mon, 1 Jan 2001 15:15:15 -0500 S: S: Original-Recipient: rfc822; user1@example1.com S: Final-Recipient: rfc822; user1@example1.com S: Action: transferred S: Remote-MTA: dns; example3.com S: Last-Attempt-Date: Mon, 1 Jan 2001 19:15:03 -0500 S: Status:2.4.0 S: S: –– S: .

Example #8 Message Delayed and a Dot-Stuffed Header: C: TRACK 12345-20010101@example.com YWJjZGVmZ2gK S: +OK+ Tracking information follows S: Content-Type: multipart/related; boundary=; type=tracking-status S: ..Dot-Stuffed-Header: as an example S: S: – S: Content-Type: message/tracking-status S: S: Original-Envelope-Id: 12345-20010101@example.com S: Reporting-MTA: dns; example2.com S: Arrival-Date: Mon, 1 Jan 2001 15:15:15 -0500 S: S: Original-Recipient: rfc822; user1@example1.com S: Final-Recipient: rfc822; user1@example1.com S: Action: delayed S: Status: 4.4.1 (No answer from host) S: Remote-MTA: dns; example3.com S: Last-Attempt-Date: Mon, 1 Jan 2001 19:15:03 -0500 S: Will-Retry-Until: Thu, 4 Jan 2001 15:15:15 -0500 S: S: –– S: .

Hansen Standards Track [Page 8] RFC 3887 Message Tracking Query Protocol September 2004

Example #9 Two Users, One Relayed, One Failed: C: TRACK 12345-20010101@example.com YWJjZGVmZ2gK S: +OK+ Tracking information follows S: Content-Type: multipart/related; boundary=; type=tracking-status S: S: – S: Content-Type: message/tracking-status S: S: Original-Envelope-Id: 12345-20010101@example.com S: Reporting-MTA: dns; example2.com S: Arrival-Date: Mon, 1 Jan 2001 15:15:15 -0500 S: S: Original-Recipient: rfc822; user1@example1.com S: Final-Recipient: rfc822; user1@example1.com S: Action: relayed S: Status: 2.1.9 S: Remote-MTA: dns; example3.com S: Last-Attempt-Date: Mon, 1 Jan 2001 19:15:03 -0500 S: S: Original-Recipient: rfc822; user2@example1.com S: Final-Recipient: rfc822; user2@example1.com S: Action: failed S: Status 5.2.2 (Mailbox full) S: Remote-MTA: dns; example3.com S: Last-Attempt-Date: Mon, 1 Jan 2001 19:15:03 -0500 S: S: –– S: .

Example #10 Firewall: C: TRACK 12345-20010101@example.com YWJjZGVmZ2gK S: +OK+ Tracking information follows S: Content-Type: multipart/related; boundary=; type=tracking-status S: S: – S: Content-Type: message/tracking-status S: S: Original-Envelope-Id: 12345-20010101@example.com S: Reporting-MTA: dns; example2.com S: Arrival-Date: Mon, 1 Jan 2001 15:15:15 -0500 S: S: Original-Recipient: rfc822; user1@example1.com S: Final-Recipient: rfc822; user1@example1.com S: Action: relayed S: Status: 2.1.9 S: Remote-MTA: dns; smtp.example3.com S: Last-Attempt-Date: Mon, 1 Jan 2001 19:15:03 -0500 S:

Hansen Standards Track [Page 9] RFC 3887 Message Tracking Query Protocol September 2004

S: – S: Content-Type: message/tracking-status S: S: Original-Envelope-Id: 12345-20010101@example.com S: Reporting-MTA: dns; smtp.example3.com S: Arrival-Date: Mon, 1 Jan 2001 15:15:15 -0500 S: S: Original-Recipient: rfc822; user2@example1.com S: Final-Recipient: rfc822; user4@example3.com S: Action: delivered S: Status: 2.5.0 S: S: –– S: .

Example #11 Firewall, Combining Per-Recipient Blocks: C: TRACK 12345-20010101@example.com YWJjZGVmZ2gK S: +OK+ Tracking information follows S: Content-Type: multipart/related; boundary=; type=tracking-status S: S: – S: Content-Type: message/tracking-status S: S: Original-Envelope-Id: 12345-20010101@example.com S: Reporting-MTA: dns; example2.com S: Arrival-Date: Mon, 1 Jan 2001 15:15:15 -0500 S: S: Original-Recipient: rfc822; user1@example1.com S: Final-Recipient: rfc822; user1@example1.com S: Action: relayed S: Status: 2.1.9 S: Remote-MTA: dns; smtp.example3.com S: Last-Attempt-Date: Mon, 1 Jan 2001 19:15:03 -0500 S: S: Original-Recipient: rfc822; user2@example1.com S: Final-Recipient: rfc822; user4@example3.com S: Action: delivered S: Status:2.5.0 S: S: –– S: .

Hansen Standards Track [Page 10] RFC 3887 Message Tracking Query Protocol September 2004

Example #12 Firewall, Hiding System Names Behind the Firewall: C: TRACK 12345-20010101@example.com YWJjZGVmZ2gK S: +OK+ Tracking information follows S: Content-Type: multipart/related; boundary=; type=tracking-status S: S: – S: Content-Type: message/tracking-status S: S: Original-Envelope-Id: 12345-20010101@example.com S: Reporting-MTA: dns; example2.com S: Arrival-Date: Mon, 1 Jan 2001 15:15:15 -0500 S: S: Original-Recipient: rfc822; user1@example1.com S: Final-Recipient: rfc822; user1@example1.com S: Action: relayed S: Status: 2.1.9 S: Remote-MTA: dns; example2.com S: Last-Attempt-Date: Mon, 1 Jan 2001 19:15:03 -0500 S: S: – S: Content-Type: message/tracking-status S: S: Original-Envelope-Id: 12345-20010101@example.com S: Reporting-MTA: dns; example2.com S: Arrival-Date: Mon, 1 Jan 2001 15:15:15 -0500 S: S: Original-Recipient: rfc822; user2@example1.com S: Final-Recipient: rfc822; user4@example1.com S: Action: delivered S: Status: 2.5.0 S: S: –– S: .

5. COMMENT Command

 Syntax:
   comment-command =  "COMMENT" opt-text CRLF
          opt-text = [WSP *(VCHAR / WSP)]
 When the client issues the COMMENT command, the MTQP server MUST
 respond with a successful response (+OK or +OK+).  All optional text
 provided with the COMMENT command are ignored.

Hansen Standards Track [Page 11] RFC 3887 Message Tracking Query Protocol September 2004

6. STARTTLS Command

 Syntax:
   starttls-command = "STARTTLS" 1*WSP domain *WSP CRLF
             domain = (sub-domain 1*("." sub-domain))
 TLS [TLS] is a popular mechanism for enhancing TCP communications
 with confidentiality and authentication.  All MTQP servers MUST
 implement TLS.  However, TLS MAY be disabled by a server
 administrator, either explicitly or by failing to install any
 certificates for TLS to use.  If an MTQP server supports TLS and has
 one or more certificates available it MUST include "STARTTLS" in the
 option specifications list on protocol startup.
    Note: TLS SHOULD be enabled on MQTP servers whenever possible.
 The parameter MUST be a fully qualified domain name (FQDN).  A client
 MUST specify the hostname it believes it is speaking with so that the
 server may respond with the proper TLS certificate.  This is useful
 for virtual servers that provide message tracking for multiple
 domains (i.e., virtual hosting).
 If the server returns a negative response, it MAY use one of the
 following response codes:
    "/" "unsupported"
    "/" "unavailable"
    "/" "tls-in-progress"
    "/" "bad-fqdn"
 If TLS is not supported, then a response code of "/unsupported"
 SHOULD be used.  If TLS is not available for some other reason, then
 a response code of "/unavailable" SHOULD be used.  If a TLS session
 is already in progress, then it is a protocol error and "-BAD" MUST
 be returned with a response code of "/tls-in-progress".  If there is
 a mismatch between the supplied FQDN and the FQDN found in the
 dNSName field of the subjectAltName extension of the server's
 certificate [RFC-X509], then it is a protocol error and "-BAD" MUST
 be returned with a response code of "/bad-fqdn".
 After receiving a positive response to a STARTTLS command, the client
 MUST start the TLS negotiation before giving any other MTQP commands.
 If the MTQP client is using pipelining (see below), the STARTTLS
 command must be the last command in a group.

Hansen Standards Track [Page 12] RFC 3887 Message Tracking Query Protocol September 2004

6.1. Processing After the STARTTLS Command

 If the TLS handshake fails, the server SHOULD abort the connection.
 After the TLS handshake has been completed, both parties MUST
 immediately decide whether or not to continue based on the
 authentication and confidentiality achieved.  The MTQP client and
 server may decide to move ahead even if the TLS negotiation ended
 with no authentication and/or no confidentiality because most MTQP
 services are performed with no authentication and no confidentiality,
 but some MTQP clients or servers may want to continue only if a
 particular level of authentication and/or confidentiality was
 achieved.
 If the MTQP client decides that the level of authentication or
 confidentiality is not high enough for it to continue, it SHOULD
 issue an MTQP QUIT command immediately after the TLS negotiation is
 complete.
 If the MTQP server decides that the level of authentication or
 confidentiality is not high enough for it to continue, it MAY abort
 the connection.  If it decides that the level of authentication or
 confidentiality is not high enough for it to continue, and it does
 not abort the connection, it SHOULD reply to every MTQP command from
 the client (other than a QUIT command) with a negative "-ERR"
 response and a response code of "/insecure".

6.2. Result of the STARTTLS Command

 Upon completion of the TLS handshake, the MTQP protocol is reset to
 the initial state (the state in MTQP after a server starts up).  The
 server MUST discard any knowledge obtained from the client prior to
 the TLS negotiation itself.  The client MUST discard any knowledge
 obtained from the server, such as the list of MTQP options, which was
 not obtained from the TLS negotiation itself.
 At the end of the TLS handshake, the server acts as if the connection
 had been initiated and responds with an initial status response and,
 optionally, a list of server options.  The list of MTQP server
 options received after the TLS handshake MUST be different than the
 list returned before the TLS handshake.  In particular, a server MUST
 NOT return the STARTTLS option in the list of server options after a
 TLS handshake has been completed.
 Both the client and the server MUST know if there is a TLS session
 active.  A client MUST NOT attempt to start a TLS session if a TLS
 session is already active.

Hansen Standards Track [Page 13] RFC 3887 Message Tracking Query Protocol September 2004

7. QUIT Command

    Syntax:
      quit-command = "QUIT" CRLF
 When the client issues the QUIT command, the MTQP session terminates.
 The QUIT command has no parameters.  The server MUST respond with a
 successful response.  The client MAY close the session from its end
 immediately after issuing this command (if the client is on an
 operating system where this does not cause problems).

8. Pipelining

 The MTQP client may elect to transmit groups of MTQP commands in
 batches without waiting for a response to each individual command.
 The MTQP server MUST process the commands in the order received.
 Specific commands may place further constraints on pipelining.  For
 example, STARTTLS must be the last command in a batch of MTQP
 commands.

8.1. Examples

 The following two examples are identical:
 Example #13 :
 C: TRACK <tracking-id> YWJjZGVmZ2gK
 S: +OK+ Tracking information follows
 S:
 S: ... tracking details #1      go here ...
 S: .
 C: TRACK <tracking-id-2> QUJDREVGR0gK
 S: +OK+ Tracking information follows
 S:
 S: ... tracking details #2      go here ...
 S: .

Hansen Standards Track [Page 14] RFC 3887 Message Tracking Query Protocol September 2004

 Example #14 :
 C: TRACK <tracking-id> YWJjZGVmZ2gK
 C: TRACK <tracking-id-2> QUJDREVGR0gK
 S: +OK+ Tracking information follows
 S:
 S: ... tracking details #1      go here ...
 S: .
 S: +OK+ Tracking information follows
 S:
 S: ... tracking details #2      go here ...
 S: .

9. The MTQP URI Scheme

9.1. Intended usage

 The MTQP URI scheme is used to designate MTQP servers on Internet
 hosts accessible using the MTQP protocol.  It performs an MTQP query
 and returns tracking status information.

9.2. URI Scheme Name

 The name of the URI scheme is "mtqp".

9.3. URI Scheme Syntax

 An MTQP URI takes one of the following forms:
    mtqp://<mserver>/track/<unique-envid>/<mtrk-secret>
    mtqp://<mserver>:<port>/track/<unique-envid>/<mtrk-secret>
 The first form is used to refer to an MTQP server on the standard
 port, while the second form specifies a non-standard port.  Both of
 these forms specify that the TRACK command is to be issued using the
 given tracking id (unique-envid) and authorization secret (mtrk-
 secret).  The path element "/track/" MUST BE treated case
 insensitively, but the unique-envid and mtrk-secret MUST NOT be.

9.3.1. Formal Syntax

 This is an ABNF description of the MTQP URI.
 mtqp-uri = "mtqp://" authority "/track/" unique-envid "/" mtrk-secret

Hansen Standards Track [Page 15] RFC 3887 Message Tracking Query Protocol September 2004

9.4. Encoding Rules

 The encoding of unique-envid is discussed in [RFC-MTRK-ESMTP].
 Mtrk-secret is required to be base64 encoded.  If the "/", "?" and
 "%" octets appear in unique-envid or mtrk-secret, they are further
 required to be represented by a "%" followed by two hexadecimal
 characters.  (The two characters give the hexadecimal representation
 of that octet).

10. IANA Considerations

 System port number 1038 has been assigned to the Message Tracking
 Query Protocol by the Internet Assigned Numbers Authority (IANA).
 The service name "MTQP" has been registered with the IANA.
 The IANA has also registered the URI registration template found in
 Appendix A in accordance with [BCP35].
 This document requests that IANA maintain one new registry: MTQP
 options.  The registry's purpose is to register options to this
 protocol.  Options whose names do not begin with "vnd." MUST be
 defined in a standards track or IESG approved experimental RFC.  New
 MTQP options MUST include the following information as part of their
 definition:
    option identifier
    option parameters
    added commands
    standard commands affected
    specification reference
    discussion
 One MTQP option is defined in this document, with the following
 registration definition:
    option identifier: STARTTLS
    option parameters: none
    added commands: STARTTLS
    standard commands affected: none
    specification reference: RFC 3887
    discussion: see RFC 3887
 Additional vendor-specific options for this protocol have names that
 begin with "vnd.".  After the "vnd." would appear the reversed domain
 name of the vendor, another dot ".", and a name for the option
 itself.  For example, "vnd.com.example.extinfo" might represent a

Hansen Standards Track [Page 16] RFC 3887 Message Tracking Query Protocol September 2004

 vendor-specific extension providing extended information by the owner
 of the "example.com" domain.  These names MAY be registered with
 IANA.

11. Security Considerations

 If the originator of a message were to delegate his or her tracking
 request to a third party, this would be vulnerable to snooping over
 unencrypted sessions.  The user can decide on a message-by-message
 basis if this risk is acceptable.
 The security of tracking information is dependent on the randomness
 of the secret chosen for each message and the level of exposure of
 that secret.  If different secrets are used for each message, then
 the maximum exposure from tracking any message will be that single
 message for the time that the tracking information is kept on any
 MTQP server.  If this level of exposure is too much, TLS may be used
 to reduce the exposure further.
 It should be noted that message tracking is not an end-to-end
 mechanism.  Thus, if an MTQP client/server pair decide to use TLS
 confidentiality, they are not securing tracking queries with any
 prior or successive MTQP servers.
 Both the MTQP client and server must check the result of the TLS
 negotiation to see whether acceptable authentication or
 confidentiality was achieved.  Ignoring this step completely
 invalidates using TLS for security.  The decision about whether
 acceptable authentication or confidentiality was achieved is made
 locally, is implementation-dependent, and is beyond the scope of this
 document.
 The MTQP client and server should note carefully the result of the
 TLS negotiation.  If the negotiation results in no confidentiality,
 or if it results in confidentiality using algorithms or key lengths
 that are deemed not strong enough, or if the authentication is not
 good enough for either party, the client may choose to end the MTQP
 session with an immediate QUIT command, or the server may choose to
 not accept any more MTQP commands.
 A man-in-the-middle attack can be launched by deleting the "STARTTLS"
 option response from the server.  This would cause the client not to
 try to start a TLS session.  An MTQP client can protect against this
 attack by recording the fact that a particular MTQP server offers TLS
 during one session and generating an alarm if it does not appear in
 an option response for a later session.

Hansen Standards Track [Page 17] RFC 3887 Message Tracking Query Protocol September 2004

 Similarly, the identity of the server as expressed in the server's
 certificate should be cached, and an alarm generated if they do not
 match in a later session.
 If TLS is not used, a tracking request is vulnerable to replay
 attacks, such that a snoop can later replay the same handshake again
 to potentially gain more information about a message's status.
 Before the TLS handshake has begun, any protocol interactions are
 performed in the clear and may be modified by an active attacker.
 For this reason, clients and servers MUST discard any knowledge
 obtained prior to the start of the TLS handshake upon completion of
 the TLS handshake.
 If a client/server pair successfully performs a TLS handshake and the
 server does chaining referrals, then the server SHOULD attempt to
 negotiate TLS at the same (or better) security level at the next hop.
 In a hop-by-hop scenario, STARTTLS is a request for "best effort"
 security and should be treated as such.
 SASL is not used because authentication is per message rather than
 per user.

12. Protocol Syntax

 This is a collected ABNF description of the MTQP protocol.

mtqp-uri = "mtqp:" authority "/track/" unique-envid "/" mtrk-secret conversation = command-response *(client-command command-response) ; client side client-command = track-command / starttls-command / quit-command /comment-command track-command = "TRACK" 1*WSP unique-envid 1*WSP mtrk-secret CRLF mtrk-secret = base64 starttls-command = "STARTTLS" 1*WSP domain *WSP CRLF domain = (sub-domain 1*("." sub-domain)) quit-command = "QUIT" CRLF comment-command = "COMMENT" opt-text CRLF Hansen Standards Track [Page 18] RFC 3887 Message Tracking Query Protocol September 2004 ; server side command-response = success-response / temp-response / error-response / bad-response temp-response = "-TEMP" response-info opt-text CRLF opt-text = [WSP *(VCHAR / WSP)] error-response = "-ERR" response-info opt-text CRLF bad-response = "-BAD" response-info opt-text CRLF success-response = single-line-success / multi-line-success single-line-success = "+OK" response-info opt-text CRLF multi-line-success = "+OK+" response-info opt-text CRLF *dataline dotcrlf dataline = *998OCTET CRLF dotcrlf = "." CRLF NAMECHAR = ALPHA / DIGIT / "-" / "_" response-info = *( "/" ( "admin" / "unavailable" / "unsupported" / "tls-in-progress" / "insecure" / "tls-required" / 1*NAMECHAR ) ) 13. Acknowledgements The description of STARTTLS is based on [RFC-SMTP-TLS]. Hansen Standards Track [Page 19] RFC 3887 Message Tracking Query Protocol September 2004 14. References 14.1. Normative References [RFC-MIME] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996. [RFC-ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. [RFC-SRV] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for specifying the location of services (DNS SRV)", RFC 2782, February 2000. [RFC-SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821, April 2001. [RFC-SMTPEXT] Myers, J., "SMTP Service Extension for Authentication", RFC 2554, March 1999. [RFC-MTRK-ESMTP] Allman, E. and T. Hansen, "SMTP Service Extension for Message Tracking", RFC 3885, September 2004. [RFC-MTRK-MODEL] Hansen, T., "Message Tracking Models and Requirements", RFC 3885, September 2004. [RFC-MTRK-TSN] Allman, E., "The Message/Tracking-Status MIME Extension", RFC 3886, September 2004. [RFC-URI] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998. [TLS] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC 2246, January 1999. Hansen Standards Track [Page 20] RFC 3887 Message Tracking Query Protocol September 2004 14.2. Informational References [BCP35] Petke, R. and I. King, "Registration Procedures for URL Scheme Names", BCP 35, RFC 2717, November 1999. [RFC-SHA1] Eastlake, D. and P. Jones, "US Secure Hash Algorithm 1 (SHA1)", RFC 3174, September 2001. [RFC-KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC-SMTP-TLS] Hoffman, P., "SMTP Service Extension for Secure SMTP over Transport Layer Security", RFC 3207, February 2002. [RFC-X509] Housley, R., Polk, W., Ford, W. and D. Solo, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 3280, April 2002. [POP3] Myers, J. and M. Rose, "Post Office Protocol - Version 3", STD 53, RFC 1939, May 1996. [NNTP] Kantor, B. and P. Lapsley, "Network News Transfer Protocol", RFC 977, February 1986. Hansen Standards Track [Page 21] RFC 3887 Message Tracking Query Protocol September 2004 Appendix A. MTQP URI Registration Template Scheme name: mtqp Scheme syntax: see section 9.1 Character encoding considerations: see section 9.4 Intended usage: see section 9.3 Applications and/or protocols which use this scheme: MTQP Interoperability considerations: as specified for MTQP Security considerations: see section 11.0 Relevant publications: [RFC-MTRK-ESMTP], [RFC-MTRK-MODEL], [RFC-MTRK-TSN] Contact: MSGTRK Working Group Author/Change Controller: IESG Author's Address Tony Hansen AT&T Laboratories Middletown, NJ 07748 USA Phone: +1.732.420.8934 EMail: tony+msgtrk@maillennium.att.com Hansen Standards Track [Page 22] RFC 3887 Message Tracking Query Protocol September 2004 Full Copyright Statement Copyright (C) The Internet Society (2004). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/S HE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the IETF's procedures with respect to rights in IETF Documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf- ipr@ietf.org. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Hansen Standards Track [Page 23]

/data/webs/external/dokuwiki/data/pages/rfc/rfc3887.txt · Last modified: 2004/09/27 19:16 (external edit)