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rfc:rfc2452

Network Working Group M. Daniele Request for Comments: 2452 Compaq Computer Corporation Category: Standards Track December 1998

             IP Version 6 Management Information Base
               for the Transmission Control Protocol

Status of this Memo

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

Copyright Notice

 Copyright (C) The Internet Society (1998).  All Rights Reserved.

Abstract

 This document is one in the series of documents that define various
 MIB objects for IPv6.  Specifically, this document is the MIB module
 which defines managed objects for implementations of the Transmission
 Control Protocol (TCP) over IP Version 6 (IPv6).
 This document also recommends a specific policy with respect to the
 applicability of RFC 2012 for implementations of IPv6.  Namely, that
 most of managed objects defined in RFC 2012 are independent of which
 IP versions underlie TCP, and only the TCP connection information is
 IP version-specific.
 This memo defines an experimental portion of the Management
 Information Base (MIB) for use with network management protocols in
 IPv6-based internets.

1. Introduction

 A management system contains: several (potentially many) nodes, each
 with a processing entity, termed an agent, which has access to
 management instrumentation; at least one management station; and, a
 management protocol, used to convey management information between
 the agents and management stations.  Operations of the protocol are
 carried out under an administrative framework which defines
 authentication, authorization, access control, and privacy policies.

Daniele Standards Track [Page 1] RFC 2452 TCP MIB for IPv6 December 1998

 Management stations execute management applications which monitor and
 control managed elements.  Managed elements are devices such as
 hosts, routers, terminal servers, etc., which are monitored and
 controlled via access to their management information.
 Management information is viewed as a collection of managed objects,
 residing in a virtual information store, termed the Management
 Information Base (MIB).  Collections of related objects are defined
 in MIB modules.  These modules are written using a subset of OSI's
 Abstract Syntax Notation One (ASN.1) [1], termed the Structure of
 Management Information (SMI) [2].

2. Overview

 This document is one in the series of documents that define various
 MIB objects, and statements of conformance, for IPv6.  This document
 defines the required instrumentation for implementations of TCP over
 IPv6.

3. Transparency of IP versions to TCP

 The fact that a particular TCP connection uses IPv6 as opposed to
 IPv4, is largely invisible to a TCP implementation.  A "TCPng" did
 not need to be defined, implementations simply need to support IPv6
 addresses.
 As such, the managed objects already defined in [TCP MIB] are
 sufficient for managing TCP in the presence of IPv6.  These objects
 are equally applicable whether the managed node supports IPv4 only,
 IPv6 only, or both IPv4 and IPv6.
 For example, tcpActiveOpens counts "The number of times TCP
 connections have made a direct transition to the SYN-SENT state from
 the CLOSED state", regardless of which version of IP is used between
 the connection endpoints.
 Stated differently, TCP implementations don't need separate counters
 for IPv4 and for IPv6.

4. Representing TCP Connections

 The exception to the statements in section 3 is the tcpConnTable.
 Since IPv6 addresses cannot be represented with the IpAddress syntax,
 not all TCP connections can be represented in the tcpConnTable
 defined in [TCP MIB].

Daniele Standards Track [Page 2] RFC 2452 TCP MIB for IPv6 December 1998

 This memo defines a new, separate table to represent only those TCP
 connections between IPv6 endpoints.  TCP connections between IPv4
 endpoints continue to be represented in tcpConnTable [TCP MIB].  (It
 is not possible to establish a TCP connection between an IPv4
  endpoint and an IPv6 endpoint.)
 A different approach would have been to define a new table to
 represent all TCP connections regardless of IP version.  This would
 require changes to [TCP MIB] and hence to existing (IPv4-only) TCP
 implementations.  The approach suggested in this memo has the
 advantage of leaving IPv4-only implementations intact.
 It is assumed that the objects defined in this memo will eventually
 be defined in an update to [TCP MIB].  For this reason, the module
 identity is assigned under the experimental portion of the MIB.

5. Conformance

 This memo contains conformance statements to define conformance to
 this MIB for TCP over IPv6 implementations.

6. Definitions

IPV6-TCP-MIB DEFINITIONS ::= BEGIN

IMPORTS

 MODULE-COMPLIANCE, OBJECT-GROUP      FROM SNMPv2-CONF
 MODULE-IDENTITY, OBJECT-TYPE,
 mib-2, experimental                  FROM SNMPv2-SMI
 Ipv6Address, Ipv6IfIndexOrZero       FROM IPV6-TC;

ipv6TcpMIB MODULE-IDENTITY

 LAST-UPDATED "9801290000Z"
 ORGANIZATION "IETF IPv6 MIB Working Group"
 CONTACT-INFO
      "       Mike Daniele
              Postal: Compaq Computer Corporation
                      110 Spitbrook Rd
                      Nashua, NH 03062.
                      US
              Phone:  +1 603 884 1423
              Email:  daniele@zk3.dec.com"
 DESCRIPTION
      "The MIB module for entities implementing TCP over IPv6."
 ::= { experimental 86 }

Daniele Standards Track [Page 3] RFC 2452 TCP MIB for IPv6 December 1998

– objects specific to TCP for IPv6

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

– the TCP over IPv6 Connection table

– This connection table contains information about this – entity's existing TCP connections between IPv6 endpoints. – Only connections between IPv6 addresses are contained in – this table. This entity's connections between IPv4 – endpoints are contained in tcpConnTable.

ipv6TcpConnTable OBJECT-TYPE

 SYNTAX      SEQUENCE OF Ipv6TcpConnEntry
 MAX-ACCESS  not-accessible
 STATUS      current
 DESCRIPTION
      "A table containing TCP connection-specific information,
       for only those connections whose endpoints are IPv6 addresses."
 ::= { tcp 16 }

ipv6TcpConnEntry OBJECT-TYPE

 SYNTAX      Ipv6TcpConnEntry
 MAX-ACCESS  not-accessible
 STATUS      current
 DESCRIPTION
      "A conceptual row of the ipv6TcpConnTable 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.
       Note that conceptual rows in this table require an additional
       index object compared to tcpConnTable, since IPv6 addresses
       are not guaranteed to be unique on the managed node."
 INDEX   { ipv6TcpConnLocalAddress,
           ipv6TcpConnLocalPort,
           ipv6TcpConnRemAddress,
           ipv6TcpConnRemPort,
           ipv6TcpConnIfIndex }
 ::= { ipv6TcpConnTable 1 }

Ipv6TcpConnEntry ::=

 SEQUENCE { ipv6TcpConnLocalAddress    Ipv6Address,
            ipv6TcpConnLocalPort       INTEGER (0..65535),
            ipv6TcpConnRemAddress      Ipv6Address,
            ipv6TcpConnRemPort         INTEGER (0..65535),
            ipv6TcpConnIfIndex         Ipv6IfIndexOrZero,

Daniele Standards Track [Page 4] RFC 2452 TCP MIB for IPv6 December 1998

            ipv6TcpConnState           INTEGER }

ipv6TcpConnLocalAddress OBJECT-TYPE

 SYNTAX     Ipv6Address
 MAX-ACCESS not-accessible
 STATUS     current
 DESCRIPTION
      "The local IPv6 address for this TCP connection. In
       the case of a connection in the listen state which
       is willing to accept connections for any IPv6
       address associated with the managed node, the value
       ::0 is used."
 ::= { ipv6TcpConnEntry 1 }

ipv6TcpConnLocalPort OBJECT-TYPE

 SYNTAX     INTEGER (0..65535)
 MAX-ACCESS not-accessible
 STATUS     current
 DESCRIPTION
      "The local port number for this TCP connection."
 ::= { ipv6TcpConnEntry 2 }

ipv6TcpConnRemAddress OBJECT-TYPE

 SYNTAX     Ipv6Address
 MAX-ACCESS not-accessible
 STATUS     current
 DESCRIPTION
      "The remote IPv6 address for this TCP connection."
 ::= { ipv6TcpConnEntry 3 }

ipv6TcpConnRemPort OBJECT-TYPE

 SYNTAX     INTEGER (0..65535)
 MAX-ACCESS not-accessible
 STATUS     current
 DESCRIPTION
      "The remote port number for this TCP connection."
 ::= { ipv6TcpConnEntry 4 }

ipv6TcpConnIfIndex OBJECT-TYPE

 SYNTAX     Ipv6IfIndexOrZero
 MAX-ACCESS not-accessible
 STATUS     current
 DESCRIPTION
      "An index object used to disambiguate conceptual rows in
       the table, since the connection 4-tuple may not be unique.
       If the connection's remote address (ipv6TcpConnRemAddress)
       is a link-local address and the connection's local address

Daniele Standards Track [Page 5] RFC 2452 TCP MIB for IPv6 December 1998

       (ipv6TcpConnLocalAddress) is not a link-local address, this
       object identifies a local interface on the same link as
       the connection's remote link-local address.
       Otherwise, this object identifies the local interface that
       is associated with the ipv6TcpConnLocalAddress for this
       TCP connection.  If such a local interface cannot be determined,
       this object should take on the value 0.  (A possible example
       of this would be if the value of ipv6TcpConnLocalAddress is ::0.)
       The interface identified by a particular non-0 value of this
       index is the same interface as identified by the same value
       of ipv6IfIndex.
       The value of this object must remain constant during the life
       of the TCP connection."
 ::= { ipv6TcpConnEntry 5 }

ipv6TcpConnState 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 only value which may be set by a management station is
       deleteTCB(12).  Accordingly, it is appropriate for an agent
       to return an error response (`badValue' for SNMPv1, 'wrongValue'
       for SNMPv2) 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 this has the effect of deleting the TCB
       (as defined in RFC 793) of the corresponding connection on
       the managed node, resulting in immediate termination of the
       connection.

Daniele Standards Track [Page 6] RFC 2452 TCP MIB for IPv6 December 1998

       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)."
 ::= { ipv6TcpConnEntry 6 }

– – conformance information –

ipv6TcpConformance OBJECT IDENTIFIER ::= { ipv6TcpMIB 2 }

ipv6TcpCompliances OBJECT IDENTIFIER ::= { ipv6TcpConformance 1 } ipv6TcpGroups OBJECT IDENTIFIER ::= { ipv6TcpConformance 2 }

– compliance statements

ipv6TcpCompliance MODULE-COMPLIANCE

 STATUS  current
 DESCRIPTION
      "The compliance statement for SNMPv2 entities which
       implement TCP over IPv6."
 MODULE  -- this module
 MANDATORY-GROUPS { ipv6TcpGroup }
 ::= { ipv6TcpCompliances 1 }

ipv6TcpGroup OBJECT-GROUP

 OBJECTS   { -- these are defined in this module
             -- ipv6TcpConnLocalAddress (not-accessible)
             -- ipv6TcpConnLocalPort (not-accessible)
             -- ipv6TcpConnRemAddress (not-accessible)
             -- ipv6TcpConnRemPort (not-accessible)
             -- ipv6TcpConnIfIndex (not-accessible)
             ipv6TcpConnState }
 STATUS    current
 DESCRIPTION
      "The group of objects providing management of
       TCP over IPv6."
 ::= { ipv6TcpGroups 1 }

END

Daniele Standards Track [Page 7] RFC 2452 TCP MIB for IPv6 December 1998

7. Acknowledgments

 This memo is a product of the IPng work group, and benefited
 especially from the contributions of the following working group
 members:
    Dimitry Haskin          Bay Networks
    Margaret Forsythe       Epilogue
    Tim Hartrick            Mentat
    Frank Solensky          FTP
    Jack McCann             DEC

8. References

 [1]           Information processing systems - Open Systems
               Interconnection - Specification of Abstract Syntax
               Notation One (ASN.1), International Organization for
               Standardization.  International Standard 8824,
               (December, 1987).
 [2]           McCloghrie, K., Editor, "Structure of Management
               Information for version 2 of the Simple Network
               Management Protocol (SNMPv2)", RFC 1902, January 1996.
 [TCP MIB]     SNMPv2 Working Group, McCloghrie, K., Editor, "SNMPv2
               Management Information Base for the Transmission
               Control Protocol using SMIv2", RFC 2012, November 1996.
 [IPV6 MIB TC] Haskin, D., and S. Onishi, "Management Information
               Base for IP Version 6: Textual Conventions and General
               Group", RFC 2465, December 1998.
 [IPV6]        Deering, S., and R. Hinden, "Internet Protocol, Version
               6 (IPv6) Specification", RFC 2460, December 1998.
 [RFC2274]     Blumenthal, U., and B. Wijnen, "The User-Based Security
               Model for Version 3 of the Simple Network Management
               Protocol (SNMPv3)", RFC 2274, January 1998.
 [RFC2275]     Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based
               Access Control Model for the Simple Network Management
               Protocol (SNMP)", RFC 2275, January 1998.

9. Security Considerations

 This MIB contains a management object that has a MAX-ACCESS clause of
 read-write and/or read-create.  In particular, it is possible to
 delete individual TCP control blocks (i.e., connections).

Daniele Standards Track [Page 8] RFC 2452 TCP MIB for IPv6 December 1998

 Consequently, anyone having the ability to issue a SET on this object
 can impact the operation of the node.
 There are a number of managed objects in this MIB that may be
 considered to contain sensitive information in some environments.
 For example, the MIB identifies the active TCP connections on the
 node.  Although this information might be considered sensitive in
 some environments (i.e., to identify ports on which to launch
 denial-of-service or other attacks), there are already other ways of
 obtaining similar information.  For example, sending a random TCP
 packet to an unused port prompts the generation of a TCP reset
 message.
 Therefore, it may be important in some environments to control read
 and/or write access to these objects and possibly to even encrypt the
 values of these object when sending them over the network via SNMP.
 Not all versions of SNMP provide features for such a secure
 environment.  SNMPv1 by itself does not provide encryption or strong
 authentication.
 It is recommended that the implementors consider the security
 features as provided by the SNMPv3 framework.  Specifically, the use
 of the User-based Security Model [RFC2274] and the View-based Access
 Control Model [RFC2275] is recommended.
 It is then a customer/user responsibility to ensure that the SNMP
 entity giving access to an instance of this MIB, is properly
 configured to give access to those objects only to those principals
 (users) that have legitimate rights to access them.

10. Author's Address

 Mike Daniele
 Compaq Computer Corporation
 110 Spit Brook Rd
 Nashua, NH 03062
 Phone: +1-603-884-1423
 EMail: daniele@zk3.dec.com

Daniele Standards Track [Page 9] RFC 2452 TCP MIB for IPv6 December 1998

11. Full Copyright Statement

 Copyright (C) The Internet Society (1998).  All Rights Reserved.
 This document and translations of it may be copied and furnished to
 others, and derivative works that comment on or otherwise explain it
 or assist in its implementation may be prepared, copied, published
 and distributed, in whole or in part, without restriction of any
 kind, provided that the above copyright notice and this paragraph are
 included on all such copies and derivative works.  However, this
 document itself may not be modified in any way, such as by removing
 the copyright notice or references to the Internet Society or other
 Internet organizations, except as needed for the purpose of
 developing Internet standards in which case the procedures for
 copyrights defined in the Internet Standards process must be
 followed, or as required to translate it into languages other than
 English.
 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.
 This document and the information contained herein is provided on an
 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 TASK FORCE DISCLAIMS 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.

Daniele Standards Track [Page 10]

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