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rfc:rfc4022

Network Working Group R. Raghunarayan, Ed. Request for Comments: 4022 Cisco Systems Obsoletes: 2452, 2012 March 2005 Category: Standards Track

                    Management Information Base
            for the Transmission Control Protocol (TCP)

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 (2005).

Abstract

 This memo defines a portion of the Management Information Base (MIB)
 for use with network management protocols in the Internet community.
 In particular, it describes managed objects used for implementations
 of the Transmission Control Protocol (TCP) in an IP version
 independent manner.  This memo obsoletes RFCs 2452 and 2012.

Table of Contents

 1.  The Internet-Standard Management Framework  . . . . . . . . .   2
 2.  Overview. . . . . . . . . . . . . . . . . . . . . . . . . . .   2
     2.1.  Relationship to Other MIBs. . . . . . . . . . . . . . .   2
 3.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   4
 4.  Acknowledgements. . . . . . . . . . . . . . . . . . . . . . .  20
 5.  References. . . . . . . . . . . . . . . . . . . . . . . . . .  20
     5.1.  Normative References. . . . . . . . . . . . . . . . . .  20
     5.2.  Informative References. . . . . . . . . . . . . . . . .  21
 6.  Security Considerations . . . . . . . . . . . . . . . . . . .  21
 7.  Contributors. . . . . . . . . . . . . . . . . . . . . . . . .  23
 Editor's Address. . . . . . . . . . . . . . . . . . . . . . . . .  23
 Full Copyright Statement. . . . . . . . . . . . . . . . . . . . .  24

Raghunarayan Standards Track [Page 1] RFC 4022 MIB for TCP March 2005

1. The Internet-Standard Management Framework

 For a detailed overview of the documents that describe the current
 Internet-Standard Management Framework, please refer to section 7 of
 RFC 3410 [RFC3410].
 Managed objects are accessed via a virtual information store, termed
 the Management Information Base or MIB.  MIB objects are generally
 accessed through the Simple Network Management Protocol (SNMP).
 Objects in the MIB are defined using the mechanisms defined in the
 Structure of Management Information (SMI).  This memo specifies a MIB
 module that is compliant to the SMIv2, which is described in STD 58,
 RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58, RFC 2580
 [RFC2580].

2. Overview

 The current TCP-MIB defined in this memo consists of two tables and a
 group of scalars:
  1. The tcp group of scalars includes two sets of objects:
       o  Parameters of a TCP protocol engine.  These include
          parameters such as the retransmission algorithm in use
          (e.g., vanj [VANJ]) and the retransmission timeout values.
       o  Statistics of a TCP protocol engine.  These include counters
          for the number of active/passive opens, input/output
          segments, and errors.  Discontinuities in the stats are
          identified identified via the sysUpTime object, defined in
          [RFC3418].
  1. The tcpConnectionTable provides access to status information

for all TCP connections handled by a TCP protocol engine. In

       addition, the table reports identification of the operating
       system level processes that handle the TCP connections.
  1. The tcpListenerTable provides access to information about all

TCP listening endpoints known by a TCP protocol engine. And as

       with the connection table, the tcpListenerTable also reports
       the identification of the operating system level processes that
       handle this listening TCP endpoint.

2.1. Relationship to Other MIBs

 This section discusses the relationship of this TCP-MIB module to
 other MIB modules.

Raghunarayan Standards Track [Page 2] RFC 4022 MIB for TCP March 2005

2.1.1. Relationship to RFC1213-MIB

 TCP related MIB objects were originally defined as part of the
 RFC1213-MIB defined in RFC 1213 [RFC1213].  The TCP related objects
 of the RFC1213-MIB were later copied into a separate MIB module and
 published in RFC 2012 [RFC2012] in SMIv2 format.
 The previous versions of the TCP-MIB both defined the tcpConnTable,
 which has been deprecated basically for two reasons:
 (1) The tcpConnTable only supports IPv4.
     The current approach in the IETF is to write IP version neutral
     MIBs, based on the InetAddressType and InetAddress constructs
     defined in [RFC4001], rather than to have different definitions
     for various version of IP.  This reduces the amount of overhead
     when new objects are introduced, as there is only one place to
     add them.  Hence, the approach taken in [RFC2452], of having
     separate tables, is not continued.
 (2) The tcpConnTable mixes listening endpoints with connections.
     It turns out that connections tend to have a different behaviour
     and management access pattern than listening endpoints.
     Therefore, splitting the original tcpConnTable into two tables
     allows for the addition of specific status and statistics objects
     for listening endpoints and connections.

2.1.2. Relationship to IPV6-TCP-MIB

 The IPV6-TCP-MIB defined in RFC 2452 has been moved to Historic
 status because the approach of having separate IP version specific
 tables is not followed anymore.  Implementation of RFC 2452 is no
 longer suggested.

2.1.3. Relationship to HOST-RESOURCES-MIB and SYSAPPL-MIB

 The tcpConnectionTable and the tcpListenerTable report the
 identification of the operating system level process that handles a
 connection or a listening endpoint.  The value is reported as an
 Unsigned32, which is expected to be the same as the hrSWRunIndex of
 the HOST-RESOURCES-MIB [RFC2790] (if the value is smaller than
 2147483647) or the sysApplElmtRunIndex of the SYSAPPL-MIB [RFC2287].
 This allows management applications to identify the TCP connections
 that belong to an operating system level process, which has proven to
 be valuable in operational environments.

Raghunarayan Standards Track [Page 3] RFC 4022 MIB for TCP March 2005

3. Definitions

TCP-MIB DEFINITIONS ::= BEGIN

IMPORTS

  MODULE-IDENTITY, OBJECT-TYPE, Integer32, Unsigned32,
  Gauge32, Counter32, Counter64, IpAddress, mib-2
                                     FROM SNMPv2-SMI
  MODULE-COMPLIANCE, OBJECT-GROUP    FROM SNMPv2-CONF
  InetAddress, InetAddressType,
  InetPortNumber                     FROM INET-ADDRESS-MIB;

tcpMIB MODULE-IDENTITY

  LAST-UPDATED "200502180000Z"  -- 18 February 2005
  ORGANIZATION
         "IETF IPv6 MIB Revision Team
          http://www.ietf.org/html.charters/ipv6-charter.html"
  CONTACT-INFO
         "Rajiv Raghunarayan (editor)
          Cisco Systems Inc.
          170 West Tasman Drive
          San Jose, CA 95134
          Phone: +1 408 853 9612
          Email: <raraghun@cisco.com>
          Send comments to <ipv6@ietf.org>"
  DESCRIPTION
         "The MIB module for managing TCP implementations.
          Copyright (C) The Internet Society (2005). This version
          of this MIB module is a part of RFC 4022; see the RFC
          itself for full legal notices."
  REVISION      "200502180000Z"  -- 18 February 2005
  DESCRIPTION
         "IP version neutral revision, published as RFC 4022."
  REVISION      "9411010000Z"
  DESCRIPTION
         "Initial SMIv2 version, published as RFC 2012."
  REVISION      "9103310000Z"
  DESCRIPTION
         "The initial revision of this MIB module was part of
          MIB-II."
  ::= { mib-2 49 }

– the TCP base variables group

Raghunarayan Standards Track [Page 4] RFC 4022 MIB for TCP March 2005

tcp OBJECT IDENTIFIER ::= { mib-2 6 }

– Scalars

tcpRtoAlgorithm OBJECT-TYPE

  SYNTAX      INTEGER {
                  other(1),    -- none of the following
                  constant(2), -- a constant rto
                  rsre(3),     -- MIL-STD-1778, Appendix B
                  vanj(4),     -- Van Jacobson's algorithm
                  rfc2988(5)   -- RFC 2988
              }
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The algorithm used to determine the timeout value used for
          retransmitting unacknowledged octets."
  ::= { tcp 1 }

tcpRtoMin OBJECT-TYPE

  SYNTAX     Integer32 (0..2147483647)
  UNITS      "milliseconds"
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The minimum value permitted by a TCP implementation for
          the retransmission timeout, measured in milliseconds.
          More refined semantics for objects of this type depend
          on the algorithm used to determine the retransmission
          timeout; in particular, the IETF standard algorithm
          rfc2988(5) provides a minimum value."
  ::= { tcp 2 }

tcpRtoMax OBJECT-TYPE

  SYNTAX     Integer32 (0..2147483647)
  UNITS      "milliseconds"
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The maximum value permitted by a TCP implementation for
          the retransmission timeout, measured in milliseconds.
          More refined semantics for objects of this type depend
          on the algorithm used to determine the retransmission
          timeout; in particular, the IETF standard algorithm
          rfc2988(5) provides an upper bound (as part of an
          adaptive backoff algorithm)."
  ::= { tcp 3 }

Raghunarayan Standards Track [Page 5] RFC 4022 MIB for TCP March 2005

tcpMaxConn OBJECT-TYPE

  SYNTAX     Integer32 (-1 | 0..2147483647)
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The limit on the total number of TCP connections the entity
          can support.  In entities where the maximum number of
          connections is dynamic, this object should contain the
          value -1."
  ::= { tcp 4 }

tcpActiveOpens OBJECT-TYPE

  SYNTAX     Counter32
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The number of times that TCP connections have made a direct
          transition to the SYN-SENT state from the CLOSED state.
          Discontinuities in the value of this counter are
          indicated via discontinuities in the value of sysUpTime."
  ::= { tcp 5 }

tcpPassiveOpens OBJECT-TYPE

  SYNTAX     Counter32
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The number of times TCP connections have made a direct
          transition to the SYN-RCVD state from the LISTEN state.
          Discontinuities in the value of this counter are
          indicated via discontinuities in the value of sysUpTime."
  ::= { tcp 6 }

tcpAttemptFails OBJECT-TYPE

  SYNTAX     Counter32
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The number of times that TCP connections have made a direct
          transition to the CLOSED state from either the SYN-SENT
          state or the SYN-RCVD state, plus the number of times that
          TCP connections have made a direct transition to the
          LISTEN state from the SYN-RCVD state.
          Discontinuities in the value of this counter are
          indicated via discontinuities in the value of sysUpTime."

Raghunarayan Standards Track [Page 6] RFC 4022 MIB for TCP March 2005

  ::= { tcp 7 }

tcpEstabResets OBJECT-TYPE

  SYNTAX     Counter32
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The number of times that TCP connections have made a direct
          transition to the CLOSED state from either the ESTABLISHED
          state or the CLOSE-WAIT state.
          Discontinuities in the value of this counter are
          indicated via discontinuities in the value of sysUpTime."
  ::= { tcp 8 }

tcpCurrEstab OBJECT-TYPE

  SYNTAX     Gauge32
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The number of TCP connections for which the current state
          is either ESTABLISHED or CLOSE-WAIT."
  ::= { tcp 9 }

tcpInSegs OBJECT-TYPE

  SYNTAX     Counter32
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The total number of segments received, including those
          received in error.  This count includes segments received
          on currently established connections.
          Discontinuities in the value of this counter are
          indicated via discontinuities in the value of sysUpTime."
  ::= { tcp 10 }

tcpOutSegs OBJECT-TYPE

  SYNTAX     Counter32
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The total number of segments sent, including those on
          current connections but excluding those containing only
          retransmitted octets.
          Discontinuities in the value of this counter are
          indicated via discontinuities in the value of sysUpTime."

Raghunarayan Standards Track [Page 7] RFC 4022 MIB for TCP March 2005

  ::= { tcp 11 }

tcpRetransSegs OBJECT-TYPE

  SYNTAX     Counter32
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The total number of segments retransmitted; that is, the
          number of TCP segments transmitted containing one or more
          previously transmitted octets.
          Discontinuities in the value of this counter are
          indicated via discontinuities in the value of sysUpTime."
  ::= { tcp 12 }

tcpInErrs OBJECT-TYPE

  SYNTAX     Counter32
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The total number of segments received in error (e.g., bad
          TCP checksums).
          Discontinuities in the value of this counter are
          indicated via discontinuities in the value of sysUpTime."
  ::= { tcp 14 }

tcpOutRsts OBJECT-TYPE

  SYNTAX     Counter32
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The number of TCP segments sent containing the RST flag.
          Discontinuities in the value of this counter are
          indicated via discontinuities in the value of sysUpTime."
  ::= { tcp 15 }

– { tcp 16 } was used to represent the ipv6TcpConnTable in RFC 2452, – which has since been obsoleted. It MUST not be used.

tcpHCInSegs OBJECT-TYPE

  SYNTAX     Counter64
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The total number of segments received, including those
          received in error.  This count includes segments received

Raghunarayan Standards Track [Page 8] RFC 4022 MIB for TCP March 2005

          on currently established connections.  This object is
          the 64-bit equivalent of tcpInSegs.
          Discontinuities in the value of this counter are
          indicated via discontinuities in the value of sysUpTime."
  ::= { tcp 17 }

tcpHCOutSegs OBJECT-TYPE

  SYNTAX     Counter64
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The total number of segments sent, including those on
          current connections but excluding those containing only
          retransmitted octets.  This object is the 64-bit
          equivalent of tcpOutSegs.
          Discontinuities in the value of this counter are
          indicated via discontinuities in the value of sysUpTime."
  ::= { tcp 18 }

– The TCP Connection table

tcpConnectionTable OBJECT-TYPE

  SYNTAX     SEQUENCE OF TcpConnectionEntry
  MAX-ACCESS not-accessible
  STATUS     current
  DESCRIPTION
         "A table containing information about existing TCP
          connections.  Note that unlike earlier TCP MIBs, there
          is a separate table for connections in the LISTEN state."
  ::= { tcp 19 }

tcpConnectionEntry OBJECT-TYPE

  SYNTAX     TcpConnectionEntry
  MAX-ACCESS not-accessible
  STATUS     current
  DESCRIPTION
         "A conceptual row of the tcpConnectionTable containing
          information about a particular current TCP connection.
          Each row of this table is transient in that it ceases to
          exist when (or soon after) the connection makes the
          transition to the CLOSED state."
  INDEX   { tcpConnectionLocalAddressType,
            tcpConnectionLocalAddress,
            tcpConnectionLocalPort,
            tcpConnectionRemAddressType,

Raghunarayan Standards Track [Page 9] RFC 4022 MIB for TCP March 2005

            tcpConnectionRemAddress,
            tcpConnectionRemPort }
  ::= { tcpConnectionTable 1 }

TcpConnectionEntry ::= SEQUENCE {

      tcpConnectionLocalAddressType   InetAddressType,
      tcpConnectionLocalAddress       InetAddress,
      tcpConnectionLocalPort          InetPortNumber,
      tcpConnectionRemAddressType     InetAddressType,
      tcpConnectionRemAddress         InetAddress,
      tcpConnectionRemPort            InetPortNumber,
      tcpConnectionState              INTEGER,
      tcpConnectionProcess            Unsigned32
  }

tcpConnectionLocalAddressType OBJECT-TYPE

  SYNTAX     InetAddressType
  MAX-ACCESS not-accessible
  STATUS     current
  DESCRIPTION
         "The address type of tcpConnectionLocalAddress."
  ::= { tcpConnectionEntry 1 }

tcpConnectionLocalAddress OBJECT-TYPE

  SYNTAX     InetAddress
  MAX-ACCESS not-accessible
  STATUS     current
  DESCRIPTION
         "The local IP address for this TCP connection.  The type
          of this address is determined by the value of
          tcpConnectionLocalAddressType.
          As this object is used in the index for the
          tcpConnectionTable, implementors should be
          careful not to create entries that would result in OIDs
          with more than 128 subidentifiers; otherwise the information
          cannot be accessed by using SNMPv1, SNMPv2c, or SNMPv3."
  ::= { tcpConnectionEntry 2 }

tcpConnectionLocalPort OBJECT-TYPE

  SYNTAX     InetPortNumber
  MAX-ACCESS not-accessible
  STATUS     current
  DESCRIPTION
         "The local port number for this TCP connection."
  ::= { tcpConnectionEntry 3 }

tcpConnectionRemAddressType OBJECT-TYPE

Raghunarayan Standards Track [Page 10] RFC 4022 MIB for TCP March 2005

  SYNTAX     InetAddressType
  MAX-ACCESS not-accessible
  STATUS     current
  DESCRIPTION
         "The address type of tcpConnectionRemAddress."
  ::= { tcpConnectionEntry 4 }

tcpConnectionRemAddress OBJECT-TYPE

  SYNTAX     InetAddress
  MAX-ACCESS not-accessible
  STATUS     current
  DESCRIPTION
         "The remote IP address for this TCP connection.  The type
          of this address is determined by the value of
          tcpConnectionRemAddressType.
          As this object is used in the index for the
          tcpConnectionTable, implementors should be
          careful not to create entries that would result in OIDs
          with more than 128 subidentifiers; otherwise the information
          cannot be accessed by using SNMPv1, SNMPv2c, or SNMPv3."
  ::= { tcpConnectionEntry 5 }

tcpConnectionRemPort OBJECT-TYPE

  SYNTAX     InetPortNumber
  MAX-ACCESS not-accessible
  STATUS     current
  DESCRIPTION
         "The remote port number for this TCP connection."
  ::= { tcpConnectionEntry 6 }

tcpConnectionState OBJECT-TYPE

  SYNTAX     INTEGER {
                  closed(1),
                  listen(2),
                  synSent(3),
                  synReceived(4),
                  established(5),
                  finWait1(6),
                  finWait2(7),
                  closeWait(8),
                  lastAck(9),
                  closing(10),
                  timeWait(11),
                  deleteTCB(12)
              }
  MAX-ACCESS read-write
  STATUS     current

Raghunarayan Standards Track [Page 11] RFC 4022 MIB for TCP March 2005

  DESCRIPTION
         "The state of this TCP connection.
          The value listen(2) is included only for parallelism to the
          old tcpConnTable and should not be used.  A connection in
          LISTEN state should be present in the tcpListenerTable.
          The only value that may be set by a management station is
          deleteTCB(12).  Accordingly, it is appropriate for an agent
          to return a `badValue' response if a management station
          attempts to set this object to any other value.
          If a management station sets this object to the value
          deleteTCB(12), then the TCB (as defined in [RFC793]) of
          the corresponding connection on the managed node is
          deleted, resulting in immediate termination of the
          connection.
          As an implementation-specific option, a RST segment may be
          sent from the managed node to the other TCP endpoint (note,
          however, that RST segments are not sent reliably)."
  ::= { tcpConnectionEntry 7 }

tcpConnectionProcess OBJECT-TYPE

  SYNTAX     Unsigned32
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The system's process ID for the process associated with
          this connection, or zero if there is no such process.  This
          value is expected to be the same as HOST-RESOURCES-MIB::
          hrSWRunIndex or SYSAPPL-MIB::sysApplElmtRunIndex for some
          row in the appropriate tables."
  ::= { tcpConnectionEntry 8 }

– The TCP Listener table

tcpListenerTable OBJECT-TYPE

  SYNTAX     SEQUENCE OF TcpListenerEntry
  MAX-ACCESS not-accessible
  STATUS     current
  DESCRIPTION
         "A table containing information about TCP listeners.  A
          listening application can be represented in three
          possible ways:
          1. An application that is willing to accept both IPv4 and
             IPv6 datagrams is represented by

Raghunarayan Standards Track [Page 12] RFC 4022 MIB for TCP March 2005

             a tcpListenerLocalAddressType of unknown (0) and
             a tcpListenerLocalAddress of ''h (a zero-length
             octet-string).
          2. An application that is willing to accept only IPv4 or
             IPv6 datagrams is represented by a
             tcpListenerLocalAddressType of the appropriate address
             type and a tcpListenerLocalAddress of '0.0.0.0' or '::'
             respectively.
          3. An application that is listening for data destined
             only to a specific IP address, but from any remote
             system, is represented by a tcpListenerLocalAddressType
             of an appropriate address type, with
             tcpListenerLocalAddress as the specific local address.
          NOTE: The address type in this table represents the
          address type used for the communication, irrespective
          of the higher-layer abstraction.  For example, an
          application using IPv6 'sockets' to communicate via
          IPv4 between ::ffff:10.0.0.1 and ::ffff:10.0.0.2 would
          use InetAddressType ipv4(1))."
  ::= { tcp 20 }

tcpListenerEntry OBJECT-TYPE

  SYNTAX     TcpListenerEntry
  MAX-ACCESS not-accessible
  STATUS     current
  DESCRIPTION
         "A conceptual row of the tcpListenerTable containing
          information about a particular TCP listener."
  INDEX   { tcpListenerLocalAddressType,
            tcpListenerLocalAddress,
            tcpListenerLocalPort }
  ::= { tcpListenerTable 1 }

TcpListenerEntry ::= SEQUENCE {

      tcpListenerLocalAddressType       InetAddressType,
      tcpListenerLocalAddress           InetAddress,
      tcpListenerLocalPort              InetPortNumber,
      tcpListenerProcess                Unsigned32
  }

tcpListenerLocalAddressType OBJECT-TYPE

  SYNTAX     InetAddressType
  MAX-ACCESS not-accessible
  STATUS     current
  DESCRIPTION

Raghunarayan Standards Track [Page 13] RFC 4022 MIB for TCP March 2005

         "The address type of tcpListenerLocalAddress.  The value
          should be unknown (0) if connection initiations to all
          local IP addresses are accepted."
  ::= { tcpListenerEntry 1 }

tcpListenerLocalAddress OBJECT-TYPE

  SYNTAX     InetAddress
  MAX-ACCESS not-accessible
  STATUS     current
  DESCRIPTION
         "The local IP address for this TCP connection.
          The value of this object can be represented in three
          possible ways, depending on the characteristics of the
          listening application:
          1. For an application willing to accept both IPv4 and
             IPv6 datagrams, the value of this object must be
             ''h (a zero-length octet-string), with the value
             of the corresponding tcpListenerLocalAddressType
             object being unknown (0).
          2. For an application willing to accept only IPv4 or
             IPv6 datagrams, the value of this object must be
             '0.0.0.0' or '::' respectively, with
             tcpListenerLocalAddressType representing the
             appropriate address type.
          3. For an application which is listening for data
             destined only to a specific IP address, the value
             of this object is the specific local address, with
             tcpListenerLocalAddressType representing the
             appropriate address type.
          As this object is used in the index for the
          tcpListenerTable, implementors should be
          careful not to create entries that would result in OIDs
          with more than 128 subidentifiers; otherwise the information
          cannot be accessed, using SNMPv1, SNMPv2c, or SNMPv3."
  ::= { tcpListenerEntry 2 }

tcpListenerLocalPort OBJECT-TYPE

  SYNTAX     InetPortNumber
  MAX-ACCESS not-accessible
  STATUS     current
  DESCRIPTION
         "The local port number for this TCP connection."
  ::= { tcpListenerEntry 3 }

Raghunarayan Standards Track [Page 14] RFC 4022 MIB for TCP March 2005

tcpListenerProcess OBJECT-TYPE

  SYNTAX     Unsigned32
  MAX-ACCESS read-only
  STATUS     current
  DESCRIPTION
         "The system's process ID for the process associated with
          this listener, or zero if there is no such process.  This
          value is expected to be the same as HOST-RESOURCES-MIB::
          hrSWRunIndex or SYSAPPL-MIB::sysApplElmtRunIndex for some
          row in the appropriate tables."
  ::= { tcpListenerEntry 4 }

– The deprecated TCP Connection table

tcpConnTable OBJECT-TYPE

  SYNTAX     SEQUENCE OF TcpConnEntry
  MAX-ACCESS not-accessible
  STATUS     deprecated
  DESCRIPTION
         "A table containing information about existing IPv4-specific
          TCP connections or listeners.  This table has been
          deprecated in favor of the version neutral
          tcpConnectionTable."
  ::= { tcp 13 }

tcpConnEntry OBJECT-TYPE

  SYNTAX     TcpConnEntry
  MAX-ACCESS not-accessible
  STATUS     deprecated
  DESCRIPTION
         "A conceptual row of the tcpConnTable containing information
          about a particular current IPv4 TCP connection.  Each row
          of this table is transient in that it ceases to exist when
          (or soon after) the connection makes the transition to the
          CLOSED state."
  INDEX   { tcpConnLocalAddress,
            tcpConnLocalPort,
            tcpConnRemAddress,
            tcpConnRemPort }
  ::= { tcpConnTable 1 }

TcpConnEntry ::= SEQUENCE {

      tcpConnState         INTEGER,
      tcpConnLocalAddress  IpAddress,
      tcpConnLocalPort     Integer32,
      tcpConnRemAddress    IpAddress,
      tcpConnRemPort       Integer32

Raghunarayan Standards Track [Page 15] RFC 4022 MIB for TCP March 2005

  }

tcpConnState OBJECT-TYPE

  SYNTAX     INTEGER {
                  closed(1),
                  listen(2),
                  synSent(3),
                  synReceived(4),
                  established(5),
                  finWait1(6),
                  finWait2(7),
                  closeWait(8),
                  lastAck(9),
                  closing(10),
                  timeWait(11),
                  deleteTCB(12)
              }
  MAX-ACCESS read-write
  STATUS     deprecated
  DESCRIPTION
         "The state of this TCP connection.
          The only value that may be set by a management station is
          deleteTCB(12).  Accordingly, it is appropriate for an agent
          to return a `badValue' response if a management station
          attempts to set this object to any other value.
          If a management station sets this object to the value
          deleteTCB(12), then the TCB (as defined in [RFC793]) of
          the corresponding connection on the managed node is
          deleted, resulting in immediate termination of the
          connection.
          As an implementation-specific option, a RST segment may be
          sent from the managed node to the other TCP endpoint (note,
          however, that RST segments are not sent reliably)."
  ::= { tcpConnEntry 1 }

tcpConnLocalAddress OBJECT-TYPE

  SYNTAX     IpAddress
  MAX-ACCESS read-only
  STATUS     deprecated
  DESCRIPTION
         "The local IP address for this TCP connection.  In the case
          of a connection in the listen state willing to
          accept connections for any IP interface associated with the
          node, the value 0.0.0.0 is used."
  ::= { tcpConnEntry 2 }

Raghunarayan Standards Track [Page 16] RFC 4022 MIB for TCP March 2005

tcpConnLocalPort OBJECT-TYPE

  SYNTAX     Integer32 (0..65535)
  MAX-ACCESS read-only
  STATUS     deprecated
  DESCRIPTION
         "The local port number for this TCP connection."
  ::= { tcpConnEntry 3 }

tcpConnRemAddress OBJECT-TYPE

  SYNTAX     IpAddress
  MAX-ACCESS read-only
  STATUS     deprecated
  DESCRIPTION
         "The remote IP address for this TCP connection."
  ::= { tcpConnEntry 4 }

tcpConnRemPort OBJECT-TYPE

  SYNTAX     Integer32 (0..65535)
  MAX-ACCESS read-only
  STATUS     deprecated
  DESCRIPTION
         "The remote port number for this TCP connection."
  ::= { tcpConnEntry 5 }

– conformance information

tcpMIBConformance OBJECT IDENTIFIER ::= { tcpMIB 2 }

tcpMIBCompliances OBJECT IDENTIFIER ::= { tcpMIBConformance 1 } tcpMIBGroups OBJECT IDENTIFIER ::= { tcpMIBConformance 2 }

– compliance statements

tcpMIBCompliance2 MODULE-COMPLIANCE

  STATUS     current
  DESCRIPTION
         "The compliance statement for systems that implement TCP.
          A number of INDEX objects cannot be
          represented in the form of OBJECT clauses in SMIv2 but
          have the following compliance requirements,
          expressed in OBJECT clause form in this description
          clause:
  1. - OBJECT tcpConnectionLocalAddressType
  2. - SYNTAX InetAddressType { ipv4(1), ipv6(2) }
  3. - DESCRIPTION
  4. - This MIB requires support for only global IPv4

Raghunarayan Standards Track [Page 17] RFC 4022 MIB for TCP March 2005

  1. - and IPv6 address types.
  2. -
  3. - OBJECT tcpConnectionRemAddressType
  4. - SYNTAX InetAddressType { ipv4(1), ipv6(2) }
  5. - DESCRIPTION
  6. - This MIB requires support for only global IPv4
  7. - and IPv6 address types.
  8. -
  9. - OBJECT tcpListenerLocalAddressType
  10. - SYNTAX InetAddressType { unknown(0), ipv4(1),
  11. - ipv6(2) }
  12. - DESCRIPTION
  13. - This MIB requires support for only global IPv4
  14. - and IPv6 address types. The type unknown also
  15. - needs to be supported to identify a special
  16. - case in the listener table: a listen using
  17. - both IPv4 and IPv6 addresses on the device.
  18. -

"

  MODULE  -- this module
      MANDATORY-GROUPS { tcpBaseGroup, tcpConnectionGroup,
                         tcpListenerGroup }
      GROUP       tcpHCGroup
      DESCRIPTION
         "This group is mandatory for systems that are capable
          of receiving or transmitting more than 1 million TCP
          segments per second.  1 million segments per second will
          cause a Counter32 to wrap in just over an hour."
      OBJECT      tcpConnectionState
      SYNTAX      INTEGER { closed(1), listen(2), synSent(3),
                            synReceived(4), established(5),
                            finWait1(6), finWait2(7), closeWait(8),
                            lastAck(9), closing(10), timeWait(11) }
      MIN-ACCESS  read-only
      DESCRIPTION
         "Write access is not required, nor is support for the value
          deleteTCB (12)."
  ::= { tcpMIBCompliances 2 }

tcpMIBCompliance MODULE-COMPLIANCE

  STATUS     deprecated
  DESCRIPTION
         "The compliance statement for IPv4-only systems that
          implement TCP.  In order to be IP version independent, this
          compliance statement is deprecated in favor of
          tcpMIBCompliance2.  However, agents are still encouraged
          to implement these objects in order to interoperate with
          the deployed base of managers."

Raghunarayan Standards Track [Page 18] RFC 4022 MIB for TCP March 2005

  MODULE  -- this module
      MANDATORY-GROUPS { tcpGroup }
      OBJECT      tcpConnState
      MIN-ACCESS  read-only
      DESCRIPTION
         "Write access is not required."
  ::= { tcpMIBCompliances 1 }

– units of conformance

tcpGroup OBJECT-GROUP

  OBJECTS   { tcpRtoAlgorithm, tcpRtoMin, tcpRtoMax,
              tcpMaxConn, tcpActiveOpens,
              tcpPassiveOpens, tcpAttemptFails,
              tcpEstabResets, tcpCurrEstab, tcpInSegs,
              tcpOutSegs, tcpRetransSegs, tcpConnState,
              tcpConnLocalAddress, tcpConnLocalPort,
              tcpConnRemAddress, tcpConnRemPort,
              tcpInErrs, tcpOutRsts }
  STATUS     deprecated
  DESCRIPTION
         "The tcp group of objects providing for management of TCP
          entities."
  ::= { tcpMIBGroups 1 }

tcpBaseGroup OBJECT-GROUP

  OBJECTS   { tcpRtoAlgorithm, tcpRtoMin, tcpRtoMax,
              tcpMaxConn, tcpActiveOpens,
              tcpPassiveOpens, tcpAttemptFails,
              tcpEstabResets, tcpCurrEstab, tcpInSegs,
              tcpOutSegs, tcpRetransSegs,
              tcpInErrs, tcpOutRsts }
  STATUS     current
  DESCRIPTION
         "The group of counters common to TCP entities."
  ::= { tcpMIBGroups 2 }

tcpConnectionGroup OBJECT-GROUP

  OBJECTS    { tcpConnectionState, tcpConnectionProcess }
  STATUS     current
  DESCRIPTION
         "The group provides general information about TCP
          connections."
  ::= { tcpMIBGroups 3 }

tcpListenerGroup OBJECT-GROUP

  OBJECTS    { tcpListenerProcess }

Raghunarayan Standards Track [Page 19] RFC 4022 MIB for TCP March 2005

  STATUS     current
  DESCRIPTION
         "This group has objects providing general information about
          TCP listeners."
  ::= { tcpMIBGroups 4 }

tcpHCGroup OBJECT-GROUP

  OBJECTS    { tcpHCInSegs, tcpHCOutSegs }
  STATUS     current
  DESCRIPTION
         "The group of objects providing for counters of high speed
          TCP implementations."
  ::= { tcpMIBGroups 5 }

END

4. Acknowledgements

 This document contains a modified subset of RFC 1213 and updates RFC
 2012 and RFC 2452.  Acknowledgements are therefore due to the authors
 and editors of these documents for their excellent work.  Several
 useful comments regarding usability and design were also received
 from Kristine Adamson.  The authors would like to thank all these
 people for their contribution to this effort.

5. References

5.1. Normative References

 [RFC793]  Postel, J., "Transmission Control Protocol", STD 7, RFC
           793, DARPA, September 1981.
 [RFC2287] Krupczak, C. and J. Saperia, "Definitions of System-Level
           Managed Objects for Applications", RFC 2287, February 1998.
 [RFC2578] McCloghrie, K., Perkins, D., and J. Schoenwaelder,
           "Structure of Management Information Version 2 (SMIv2)",
           STD 58, RFC 2578, April 1999.
 [RFC2579] McCloghrie, K., Perkins, D., and J. Schoenwaelder, "Textual
           Conventions for SMIv2", STD 58, RFC 2579, April 1999.
 [RFC2580] McCloghrie, K., Perkins, D., and J. Schoenwaelder,
           "Conformance Statements for SMIv2", STD 58, RFC 2580, April
           1999.
 [RFC2790] Waldbusser, S. and P. Grillo, "Host Resources MIB", RFC
           2790, March 2000.

Raghunarayan Standards Track [Page 20] RFC 4022 MIB for TCP March 2005

 [RFC4001] Daniele, M., Haberman, B., Routhier, S., and J.
           Schoenwaelder, "Textual Conventions for Internet Network
           Addresses", RFC 4001, February 2005.

5.2. Informative References

 [RFC1213] McCloghrie, K. and M. Rose, "Management Information Base
           for Network Management of TCP/IP-based internets", RFC
           1213, March 1991.
 [RFC2012] McCloghrie, K., Ed., "SNMPv2 Management Information Base
           for the Transmission Control Protocol using SMIv2", RFC
           2012, November 1996.
 [RFC2452] Daniele, M., "IP Version 6 Management Information Base for
           the Transmission Control Protocol", RFC 2452, December
           1998.
 [RFC2988] Paxson, V. and M. Allman, "Computing TCP's Retransmission
           Timer", RFC 2988, November 2000.
 [RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart,
           "Introduction and Applicability Statements for Internet-
           Standard Management Framework", RFC 3410, December 2002.
 [RFC3418] Presuhn, R., Ed., "Management Information Base (MIB) for
           the Simple Network Management Protocol (SNMP)", RFC 3418,
           December 2002.
 [VANJ]    Jacobson, V., "Congestion Avoidance and Control", SIGCOMM
           1988, Stanford, California.

6. Security Considerations

 There are a number of management objects defined in this MIB module
 with a MAX-ACCESS clause of read-write.  Such objects may be
 considered sensitive or vulnerable in some network environments.  The
 support for SET operations in a non-secure environment without proper
 protection can have a negative effect on network operations.  These
 are the tables and objects and their sensitivity/vulnerability:
 o  The tcpConnectionState and tcpConnState objects have a MAX-ACCESS
    clause of read-write, which allows termination of an arbitrary
    connection.  Unauthorized access could cause a denial of service.
 Some of the readable objects in this MIB module (i.e., objects with a
 MAX-ACCESS other than not-accessible) may be considered sensitive or
 vulnerable in some network environments.  It is thus important to

Raghunarayan Standards Track [Page 21] RFC 4022 MIB for TCP March 2005

 control even GET and/or NOTIFY access to these objects and possibly
 to even encrypt the values of these objects when sending them over
 the network via SNMP.  These are the tables and objects and their
 sensitivity/vulnerability:
 o  The tcpConnectionTable and the tcpConnTable contain objects
    providing information about the active connections on the device,
    the status of these connections, and the associated processes.
    This information may be used by an attacker to launch attacks
    against known/unknown weakness in certain protocols/applications.
    In addition, access to the connection table could also have
    privacy implications, as it provides detailed information on
    active connections.
 o  The tcpListenerTable and the tcpConnTable contain objects
    providing information about listeners on an entity.  For example,
    the tcpListenerLocalPort and tcpConnLocalPort objects can be used
    to identify what ports are open on the machine and what attacks
    are likely to succeed, without the attacker having to run a port
    scanner.
 SNMP versions prior to SNMPv3 did not include adequate security.
 Even if the network itself is secure (for example by using IPSec),
 even then, there is no control as to who on the secure network is
 allowed to access and GET/SET (read/change/create/delete) the objects
 in this MIB module.
 It is RECOMMENDED that implementers consider the security features as
 provided by the SNMPv3 framework (see [RFC3410], section 8),
 including full support for the SNMPv3 cryptographic mechanisms (for
 authentication and privacy).
 Further, deployment of SNMP versions prior to SNMPv3 is NOT
 RECOMMENDED.  Instead, it is RECOMMENDED to deploy SNMPv3 and to
 enable cryptographic security.  It is then a customer/operator
 responsibility to ensure that the SNMP entity giving access to an
 instance of this MIB module is properly configured to give access to
 the objects only to those principals (users) that have legitimate
 rights to indeed GET or SET (change/create/delete) them.

Raghunarayan Standards Track [Page 22] RFC 4022 MIB for TCP March 2005

7. Contributors

 This document is an output of the IPv6 MIB revision team, and
 contributors to earlier versions of this document include:
 Bill Fenner, AT&T Labs -- Research
 EMail: fenner@research.att.com
 Brian Haberman
 EMail: brian@innovationslab.net
 Shawn A. Routhier, Wind River
 EMail: shawn.routhier@windriver.com
 Juergen Schoenwalder, TU Braunschweig
 EMail: schoenw@ibr.cs.tu-bs.de
 Dave Thaler, Microsoft
 EMail: dthaler@windows.microsoft.com
 This document updates parts of the MIBs from several documents.  RFC
 2012 has been the base document for these updates, and RFC 2452 was
 the first document to define the managed objects for implementations
 of TCP over IPv6.
 RFC 2012:
 Keith McCloghrie, Cisco Systems (Editor)
 EMail: kzm@cisco.com
 RFC 2452:
 Mike Daniele, Compaq Computer Corporation
 EMail: daniele@zk3.dec.com

Editor's Address

 Rajiv Raghunarayan
 Cisco Systems Inc.
 170 West Tasman Drive
 San Jose, CA 95134
 USA
 EMail: raraghun@cisco.com

Raghunarayan Standards Track [Page 23] RFC 4022 MIB for TCP March 2005

Full Copyright Statement

 Copyright (C) The Internet Society (2005).
 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/SHE 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 procedures with respect to rights in RFC 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.

Raghunarayan Standards Track [Page 24]

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