Network Working Group M. St. Johns Request for Comments: 1414 US Department of Defense M. Rose Dover Beach Consulting, Inc. February 1993
Identification MIB
Status of this Memo
This RFCspecifies an IAB standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "IAB Official Protocol Standards" for the standardization state and status of this protocol. Distribution of this memo is unlimited.
Abstract
This memo defines a MIB for use with identifying the users associated with TCP connections. It provides functionality approximately equivalent to that provided by the protocol defined in RFC1413 [1]. This document is a product of the TCP Client Identity Protocol Working Group of the Internet Engineering Task Force (IETF).
Table of Contents
1. The Network Management Framework ....................... 2 2. Identification MIB ..................................... 3 3. Definitions ............................................ 3 3.1 Conformance Groups .................................... 3 3.2 Textual Conventions ................................... 3 3.3 The Ident information Group ........................... 3 4. Security Considerations ................................ 6 5. References ............................................. 6 6. Authors' Addresses ..................................... 7
1. The Network Management Framework
The Internet-standard Network Management Framework consists of three components. They are:
STD 16/RFC1155 [2] which defines the SMI, the mechanisms used for describing and naming objects for the purpose of management. STD 16/RFC1212 [3] defines a more concise description mechanism, which is wholly consistent with the SMI.
STD 17/RFC1213 [4] which defines MIB-II, the core set of managed objects for the Internet suite of protocols.
STD 15/RFC1157 [5] which defines the SNMP, the protocol used for network access to managed objects.
The Framework permits new objects to be defined for the purpose of experimentation and evaluation.
Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. Within a given MIB module, objects are defined using RFC1212's OBJECT-TYPE macro. At a minimum, each object has a name, a syntax, an access-level, and an implementation-status.
The name is an object identifier, an administratively assigned name, which specifies an object type. The object type together with an object instance serves to uniquely identify a specific instantiation of the object. For human convenience, we often use a textual string, termed the object descriptor, to also refer to the object type.
The syntax of an object type defines the abstract data structure corresponding to that object type. The ASN.1 [6] language is used for this purpose. However, RFC1155 purposely restricts the ASN.1 constructs which may be used. These restrictions are explicitly made for simplicity.
The access-level of an object type defines whether it makes "protocol sense" to read and/or write the value of an instance of the object type. (This access-level is independent of any administrative authorization policy.)
The implementation-status of an object type indicates whether the object is mandatory, optional, obsolete, or deprecated.
2. Identification MIB
The Identification MIB defines a uniform set of objects useful for identifying users associated with TCP connections. End-systems which support TCP may, at their option, implement this MIB. However, administrators should read Section 4 ("Security Considerations") before enabling these MIB objects.
3. Definitions
RFC1414-MIB DEFINITIONS ::= BEGIN
IMPORTS OBJECT-TYPE FROM RFC-1212 tcpConnLocalAddress, tcpConnLocalPort, tcpConnRemAddress, tcpConnRemPort FROM RFC1213-MIB;
ident OBJECT IDENTIFIER ::= { mib-2 24 }
-- conformance groups
identInfo OBJECT IDENTIFIER ::= { ident 1 }
-- textual conventions
-- none
-- the ident information system group -- -- implementation of this group is mandatory
identTable OBJECT-TYPE SYNTAX SEQUENCE OF IdentEntry ACCESS not-accessible STATUS mandatory DESCRIPTION "A table containing user information for TCP connections.
Note that this table contains entries for all TCP connections on a managed system. The corresponding instance of tcpConnState (defined in MIB-II) indicates the state of a particular
connection." ::= { identInfo 1 }
identEntry OBJECT-TYPE SYNTAX IdentEntry ACCESS not-accessible STATUS mandatory DESCRIPTION "User information about a particular TCP connection." INDEX { tcpConnLocalAddress, tcpConnLocalPort, tcpConnRemAddress, tcpConnRemPort } ::= { identTable 1 }
identStatus OBJECT-TYPE SYNTAX INTEGER { noError(1), unknownError(2) } ACCESS read-only STATUS mandatory DESCRIPTION "Indicates whether user information for the associated TCP connection can be determined. A value of `noError(1)' indicates that user information is available. A value of `unknownError(2)' indicates that user information is not available." ::= { identEntry 1 }
identOpSys OBJECT-TYPE SYNTAX OCTET STRING (SIZE(0..40)) ACCESS read-only STATUS mandatory DESCRIPTION "Indicates the type of operating system in use. In addition to identifying an operating system, each assignment made for this purpose also (implicitly) identifies the textual format and
maximum size of the corresponding identUserid and identMisc objects.
The legal values for the `indentOpSys' strings are those listed in the SYSTEM NAMES section of the most recent edition of the ASSIGNED NUMBERS RFC[8]." ::= { identEntry 2 }
identCharset OBJECT-TYPE SYNTAX OCTET STRING (SIZE(0..40)) ACCESS read-only STATUS mandatory DESCRIPTION "Indicates the repertoire of the corresponding identUserid and identMisc objects.
The legal values for the `identCharset' strings are those listed in the CHARACTER SET section of the most recent edition of the ASSIGNED NUMBERS RFC[8]." ::= { identEntry 3 }
identUserid OBJECT-TYPE SYNTAX OCTET STRING (SIZE (0..255)) ACCESS read-only STATUS mandatory DESCRIPTION "Indicates the user's identity. Interpretation of this object requires examination of the corresponding value of the identOpSys and identCharset objects." ::= { identEntry 4 }
identMisc OBJECT-TYPE SYNTAX OCTET STRING (SIZE (0..255)) ACCESS read-only STATUS mandatory DESCRIPTION "Indicates miscellaneous information about the user. Interpretation of this object requires examination of the corresponding value of the identOpSys and identCharset objects." ::= { identEntry 5 }
END
4. Security Considerations
The information available through this MIB is at most as trustworthy as the host providing it OR the organization operating the host. For example, a PC in an open lab has few if any controls on it to prevent a user from having an SNMP query return any identifier the user wants. Likewise, if the host has been compromised the information returned may be completely erroneous and misleading.
This portion of the MIB space should only be used to gain hints as to who "owns" a particular TCP connection -- information returned should NOT be considered authoritative for at least the reasons described above. At best, this MIB provides some additional auditing information with respect to TCP connections. At worse it can provide misleading, incorrect or maliciously incorrect information.
The use of the information contained in this MIB for other than auditing or normal network management functions is strongly discouraged. Specifically, using information from this MIB space to make access control decisions - either as the primary method (i.e., no other checks) or as an adjunct to other methods may result in a weakening of normal system security.
This MIB provides access to information about users, entities, objects or processes which some systems might normally consider private. The information accessible through this MIB is a rough analog of the CallerID services provided by some phone companies and many of the same privacy consideration and arguments that apply to CallerID service apply to this MIB space. If you wouldn't run a "finger" server [7] due to privacy considerations, you might not want to provide access to this MIB space on a general basis. Access to this portion of the MIB tree may be controlled under the normal methods available through SNMP agent implementations.
7. References
[1] St. Johns, M., "Identification Protocol", RFC1413, US Department of Defense, February 1993.
[2] Rose M., and K. McCloghrie, "Structure and Identification of Management Information for TCP/IP-based internets", STD 16, RFC 1155, Performance Systems International, Hughes LAN Systems, May 1990.
[3] Rose, M., and K. McCloghrie, Editors, "Concise MIB Definitions", STD 16, RFC1212, Performance Systems International, Hughes LAN Systems, March 1991.
[4] McCloghrie K., and M. Rose, Editors, "Management Information Base for Network Management of TCP/IP-based internets", STD 17, RFC 1213, Performance Systems International, March 1991.
[5] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple Network Management Protocol", STD 15, RFC1157, SNMP Research, Performance Systems International, Performance Systems International, MIT Laboratory for Computer Science, May 1990.
[6] Information processing systems - Open Systems Interconnection - Specification of Abstract Syntax Notation One (ASN.1), International Organization for Standardization, International Standard 8824, December 1987.
[7] Zimmerman, D., "The Finger User Information Protocol", RFC1288, Center for Discrete Mathematics and Theoretical Computer Science, December 1991.
[8] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2, RFC1340, USC/Information Sciences Institute, July 1992.
8. Authors' Addresses
Michael C. St. Johns U.S. Department of Defense DARPA/CSTO 3701 N. Fairfax Dr Arlington, VA 22203
Phone: (703) 696-2271 EMail: stjohns@DARPA.MIL
Marshall T. Rose Dover Beach Consulting, Inc. 420 Whisman Court Mountain View, CA 94043-2186
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