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Versions: 00                                                            
Internet Draft          Web Based Management             June 13, 1996


                 Web Based System and Network Management

                    <draft-mellquist-web-sys-00.txt>

                          Brian Harrison
                     Hewlett-Packard Company
                     harrison@ppg01.sc.hp.com

                        Peter E. Mellquist
                     Hewlett-Packard Company
                    mellqust@hprnd.rose.hp.com

                          Adrian Pell
                     Hewlett-Packard Company
                       arp@hplb.hpl.hp.com


                          June, 13 1996


                        Status of this Memo


  This document is an Internet-Draft.  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.''

  To learn the current status of any Internet-Draft, please check
  the ``1id-abstracts.txt'' listing contained in the Internet-
  Drafts Shadow Directories on ftp.is.co.za (Africa),
  nic.nordu.net (Europe), munnari.oz.au (Pacific Rim),
  ds.internic.net (US East Coast), or ftp.isi.edu (US West Coast).

1. Abstract

  This document describes the application of the Hyper Text
  Transfer Protocol (HTTP) for system and network management.
  Presented are mechanisms which facilitate system and network
  management including the discovery of HTTP management entities,
  how management content may be accessed, and lastly, the role of
  a Simple Network Management Protocol (SNMP) agent providing
  SNMP information through the use of HTTP.

  Management and HTTP may be categorized into two groups, the
  management of HTTP[3] and management using HTTP. The focus of
  this document is on the latter, "web based management".

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2.  Overview

  Web based management is the application of World Wide Web (WWW)
  tools for the management of systems and networks. This includes
  using HTTP servers and browsers for providing static, dynamic and
  interactive content of management information. An HTTP server
  acting in a management role can provide information in a variety
  of forms including Hyper Text Markup Language (HTML), graphics,
  executable code and binary encoded information. Together, this
  capability allows HTTP to function as a powerful protocol for
  the management of systems and networks. For HTTP servers acting
  in a management role, the HTTP server may also be providing non-
  management content. It is therefore necessary to provide a mechanism
  for a WWW browser or network management application to have direct
  access to the management information.

  As presented in this document, HTTP is not meant to replace SNMP.
  HTTP working together with SNMP can provide many benefits including
  ease-of-use, zero client-side installation, and security. SNMP
  is required for the instrumentation of systems and networks.


3. HTTP Management Transport Control Protocol (TCP) Port Definition

  The standardized TCP port for HTTP is port 80 [1]. A HTTP server
  listening on this port may provide content spanning a wide
  information base including non-management related content.
  For management usage, this requires that the management content
  be inter-mixed with non-management content. A WWW browser or
  network management application must therefore have knowledge or
  the ability to determine where the management content resides on
  a HTTP server. A well known HTTP management TCP port solves this
  problem by allowing only management content through the HTTP
  management interface. This allows a browser or network management
  application to easily use or discover a HTTP server acting in a
  management role. The proposed HTTP management TCP port is
  port 280 (The actual port number is pending IANA[4] approval). The
  recommended port for management is therefore port 280. In cases
  where this port is not available, port 80 may be used. An
  alternative to a standardized HTTP management port, a standardized
  Universal Request Indicator (URI), was considered. Although this
  mechanism could work, it was decided that the problems of
  attempting to standardize on a character sequence would prove to
  be too difficult.

  A HTTP server operating in a management mode on port 280 may
  also be using port 80 for non-management content. This allows
  for the clean separation of management and non-management
  content. A TCP port 280 interface should only supply management
  content. A HTTP server which does not utilize TCP port 280 for
  management content may inter-mix management and non-management
  content on port 80. In this case, a browser or network management
  application must determine the HTTP management capability through
  other means, see HTTP Manageable MIB.



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4. HTTP Manageable MIB

  A SNMP agent in operation together with an HTTP server allows
  management information to be accessed using either the SNMP
  protocol or using HTTP. In order to determine if an SNMP agent
  also supports HTTP, a SNMP Management Information Base (MIB) is
  utilized. The "HTTP Manageable MIB" provides SNMP objects which
  advertise an agent's HTTP capabilities. This allows a network
  management application using SNMP to query the "HTTP Manageable
  MIB" to determine its HTTP management capabilities and interface.
  The presence of this MIB in an agent implies that a HTTP server is
  operational in a management context. In order to determine the
  exact interface for HTTP access, the "HTTP Manageable MIB" provides
  a MIB object, "httpMgDefaultURL". This object represents the
  complete Universal Request Locator (URL) for management access to
  the agent via HTTP. The value of this URL will reflect port 280
  usage when applicable.

  A second MIB object defines an agent's capability to perform SNMP
  over HTTP. The "httpMgSNMPEnabled" object represents a truth
  value indicating if the HTTP server can perform SNMP over HTTP.
  If set true, the HTTP server supports the SNMP over HTTP tunneling
  protocol as described in the subsequent section.

  Below is the MIB definition for the "HTTP Manageable MIB". Note, the
  MIB is currently designed to reside under the Hewlett-Packard MIB
  branch. The long term intent will be to move this MIB under a
  standard branch (The actual MIB branch is pending IANA[4] approval).


  HP-httpManageable-MIB DEFINITIONS ::= BEGIN

  IMPORTS
     OBJECT-TYPE, MODULE-IDENTITY, NOTIFICATION-TYPE
       FROM SNMPv2-SMI
     DisplayString, TruthValue
       FROM SNMPv2-TC
     OBJECT-GROUP, MODULE-COMPLIANCE
       FROM SNMPv2-CONF;

  hp        OBJECT IDENTIFIER ::= { enterprises 11 }
  nm        OBJECT IDENTIFIER ::= { hp 2 }
  hpWebMgmt OBJECT IDENTIFIER ::= { nm 36 }

  httpMgMod MODULE-IDENTITY
    LAST-UPDATED "9606120000Z"
    ORGANIZATION "Hewlett-Packard Web-based Management Working Group"
    CONTACT-INFO
    "WG E-mail: webmgmt@sysman.hpl.hp.com
         Chair: Brian Harrison
        Postal: Hewlett-Packard
                5301 Stevens Creek Blvd
                Santa Clara  CA 95052  USA
           Tel: +1-408-553-3786
           Fax: +1-408-553-2909
        E-mail: harrison@ppg01.sc.hp.com"

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    DESCRIPTION
      "Management information for HTTP manageable devices.
       This MIB gives SNMP systems information on how to
       manage a device using HTTP."
    REVISION     "9606120000Z"
    DESCRIPTION  "Initial Version"

              ::= { hpWebMgmt 1 }

    httpMgTraps         OBJECT IDENTIFIER ::= { httpMgMod 0 } -- future
    httpMgObjects       OBJECT IDENTIFIER ::= { httpMgMod 1 }
    httpMgGroups        OBJECT IDENTIFIER ::= { httpMgMod 2 }
    httpMgCompliances   OBJECT IDENTIFIER ::= { httpMgMod 3 }

    -- MIB Objects
    -- Default attributes for managing via HTTP
    httpMgDefaults      OBJECT IDENTIFIER ::= { httpMgObjects 1 }

    httpMgDefaultURL    OBJECT-TYPE
        SYNTAX      DisplayString
        MAX-ACCESS  read-write
        STATUS      current
        DESCRIPTION
            "A Uniform Resource Locator (URL), as defined in RFC1738,
             for the default management information for this device.
             This URL is typically used by a HTTP browser to display
             management information for this device.  This default
             page should contain links to any other management
             pages for this device."
        ::= { httpMgDefaults 1}

    httpMgSNMPEnabled OBJECT-TYPE
        SYNTAX       TruthValue
        MAX-ACCESS   read-write
        STATUS       current
        DESCRIPTION
              "Indicates whether a HTTP server supports SNMP
              over HTTP where SNMP requests may be contained
              in the Entity-Body of a HTTP POST operation"
        ::= { httpMgDefaults 2 }

    -- Compliance statements

    httpMgMinCompliance MODULE-COMPLIANCE
        STATUS  current
        DESCRIPTION
            "The compliance statement for SNMP entities which
             are http manageable."

        MODULE  -- this module
        MANDATORY-GROUPS { httpMgDefaultGroup }

        ::= { httpMgCompliances 1 }




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    httpMgDefaultGroup OBJECT-GROUP
        OBJECTS { httpMgDefaultURL, httpMgSNMPEnabled }
        STATUS current
        DESCRIPTION
            "The objects providing information applicable to all
             http manageable systems"
              ::= { httpMgGroups 1 }

  END

5. SNMP over HTTP

  A HTTP server acting in a management role may provide a variety of
  content including HTML, graphics, executable code and binary data.
  SNMP Protocol Data Units (PDUs) may be transmitted over HTTP in the
  following manner as "application/octet-stream" Content-Type data.

  As described in the "HTTP Manageable MIB", the "httpMgSNMPEnabled"
  MIB object determines if a SNMP / HTTP agent can support SNMP over
  HTTP. If this object is set true, SNMP / HTTP tunneling is
  supported. The URL used for this capability is the one defined
  in the "httpMgDefaultURL" MIB object. This URL will include port
  280 reference when appropriate.

  Once a HTTP server has been determined to support SNMP over HTTP,
  SNMP requests may be made by encapsulating the encoded PDU in a
  HTTP request entity body [1].

                  Web Based Managed Entity
        ------------------------------------------
       |   -----------                ----------  |
       |  |   SNMP    |     SNMP     |  HTTP    | |
       |  |   Agent   |<============>|  Server  | |
       |  |           |              |          | |
       |  |           |              |          | |
       |   --|-----|---               --|----|--  |
        -----|-----|--------------------|----|----
    Port 161 |     |                    |    |  Port 80
    --<--->--      |                    |     -<----->-- SNMP/HTTP
    Port 162       |                    |       Port 280
    ------>--------                      ------<----->-- SNMP/HTTP

  The Backus Naur Form (BNF) for a HTTP 1.0 compliant request is as
  follows. Please refer to the HTTP 1.0 specification for more
  details on HTTP [1].

  Full-Request   = Request-Line
                 *( General-Header
                  | Request-Header
                  | Entity-Header )  CRLF
                 [ Entity-Body ]

  Entity-Header fields define optional metainformation about the
  Entity-Body or, if no body is present, about the resource
  identified by the request. For SNMP / HTTP tunneling, the Entity-
  Header and Entity-Body fields are utilized.

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  Entity-Header  = Allow
                 | Content-Encoding
                 | Content-Length
                 | Content-Type
                 | Expires
                 | Last-Modified
                 | extension-header

  For the transfer of a SNMP encoded PDU, the "Content-Type" and
  "Content-Length" specifiers are required. HTTP uses Internet
  Media Types for the Content-Type found in the Entity-Header
  field [4].The Content-Type Entity-Header field indicates the
  media type of the Entity-Body. The PDU is treated as
  media-type "application/octet-stream". The "Content-Length"
  value is the length, in octets, of the encoded PDU.

  SNMP over HTTP is defined for SNMP get, set, get-next, get-bulk
  and inform operations. When making making SNMP requests over
  HTTP, the PDU type is encoded within the request PDU. The HTTP
  POST operation is utilized for all SNMP operations. The POST
  operation allows sending the enclosed Entity-Body to the
  specified URL. Applications such as WWW browsers do not cache
  HTTP POST requests. This allows all transactions to go on the
  wire.

  To differentiate a SNMP / HTTP management request from other
  HTTP management requests, a standard URI, "snmp-request" is
  utilized. This URI is used for all SNMP get, set, next, bulk
  and inform PDUs since the PDU type is encoded within the PDU.

  Example of SNMP get over HTTP. Assume we have an encoded SNMP get
  PDU of 275 bytes in length.

    POST /snmp-request HTTP/1.0
    Content-Type: application/octet-stream
    Content-Length: 275
    [ 275 bytes of PDU ]

  Returned will be the HTTP response with the PDU response found in
  the Entity-Body.

    HTTP/1.0 20 OK
    Content-Type: application/octet-stream
    Content-Length: 275
    [ 275 bytes of PDU]

  SNMP get-next, set, get-bulk and inform SNMP operations work in a
  similar manner.

  It should be mentioned that SNMP over HTTP is accomplished without
  the introduction of yet-another-management protocol. Instead, HTTP
  can be used to transfer information between a managed entity and WWW
  browser or network management application. In doing so, HTTP has the
  potential of offering many benefits including secure transfer of
  information.


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6. Conclusion

  The utilization of web based system and network management offers
  much potential. Without proper standardization, this new form of
  management will not provide an open systems solution for the
  management of heterogenous multi-vendor environments. In intent
  of this Internet Draft is to offer areas of standardization for
  web based management and in doing so seek a single unified
  approach.

7. References:

  [1] T. Berners-Lee, R. Fielding,H. Frystyk, "Hypertext Transfer Protocol
      HTTP/1.0" RFC 1945, MIT/LCS,  UC Irvine, May 1996.

  [2] McCloghrie, K., and M. Rose, Editors, "Management Information
      Base for Network Management of TCP/IP-based internets: MIB-
      II", STD 17, RFC 1213, Hughes LAN Systems, Performance
      Systems International, March 1991.

  [3] Hazewinkel, H., E. van Hengstum, A. Pras, "Definitions of Managed
      Objects for HTTP", draft-hazewinkel-httpmib-00.txt, University of
      Twente, April 1996

  [4] J. Postel. "Assigned Numbers", STD 2, RFC 1700, USC/ISI,
      October 1994.


8. Acknowledgments

  This document was produced as a result of the Hewlett-Packard
  Web-based Management Working Group and the effort of its
  participants.

  The authors gratefully acknowledges the work and comments of
  the following individuals:


     Steve Gase,GASE_STEVE/HP-Boise_unixgw1@hpflash
         Hewlett-Packard Company

     Jean-Jacques Moreau, jjm@hplb.hpl.hp.com
         Hewlett-Packard Company

     Jeff Morgan, morgan@hpl.hp.com
         Hewlett-Packard Company

     Brian O'Keefe, bok@nsmdserv.cnd.hp.com
         Hewlett-Packard Company

     Jitendra Singh,SINGH_JITENDRA/hp-santaclara_om3@hpflash
         Hewlett-Packard Company





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