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Keywords: mib, internet, protocol, tcp, ipv6
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].
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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 }
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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.
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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
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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
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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]