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
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:
 - 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].
 - 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.
 - 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.
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.
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
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 }
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."
 ::= { 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."
 ::= { 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
 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,
 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
 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
 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
 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
 "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 }
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
 }
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 }
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:
 -- OBJECT tcpConnectionLocalAddressType
 -- SYNTAX InetAddressType { ipv4(1), ipv6(2) }
 -- DESCRIPTION
 -- This MIB requires support for only global IPv4
 -- and IPv6 address types.
 --
 -- OBJECT tcpConnectionRemAddressType
 -- SYNTAX InetAddressType { ipv4(1), ipv6(2) }
 -- DESCRIPTION
 -- This MIB requires support for only global IPv4
 -- and IPv6 address types.
 --
 -- OBJECT tcpListenerLocalAddressType
 -- SYNTAX InetAddressType { unknown(0), ipv4(1),
 -- ipv6(2) }
 -- DESCRIPTION
 -- This MIB requires support for only global IPv4
 -- and IPv6 address types. The type unknown also
 -- needs to be supported to identify a special
 -- case in the listener table: a listen using
 -- both IPv4 and IPv6 addresses on the device.
 --
 "
 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."
 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 }
 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.
 [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
 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.
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
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