::= { docsSubMgtGroups 1 }
END
5. Acknowledgements
This document is based on work by Michael St. Johns, then at
Excite@Home. Thanks to Guenter Roeck and Julie McGray for reviewing
earlier versions. Thanks to Bert Wijnen, Mike Heard, and Harrie
Hazewinkel for extensive later review. Thanks to the working group
chairs, Richard Woundy and Jean-Francois Mule, for their extensive
support.
6. IANA Considerations
The MIB module defined in this document uses the following IANA-
assigned OBJECT IDENTIFIER value recorded in the SMI Numbers
registry:
Descriptor OBJECT IDENTIFIER value
---------- -----------------------
docsSubMgt { mib-2 125}
7. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[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.
[ITU-T-J122] Second-Generation Transmission Systems for Interactive
Cable Television Services, J.122, ITU-T, December, 2002.
[RFC2670] St. Johns, M., "Radio Frequency (RF) Interface
Management Information Base for MCNS/DOCSIS compliant RF
interfaces", RFC 2670, August 1999.
[RFC3289] Baker, F., Chan, K., and A. Smith, "Management
Information Base for the Differentiated Services
Architecture", RFC 3289, May 2002.
[RFC4001] Daniele, M., Haberman, B., Routhier, S., and J.
Schoenwaelder, "Textual Conventions for Internet Network
Addresses", RFC 4001, February 2005.
8. Informative References
[RFC1858] Ziemba, G., Reed, D., and P. Traina, "Security
Considerations for IP Fragment Filtering", RFC 1858,
October 1995.
[RFC2669] St. Johns, M., "DOCSIS Cable Device MIB Cable Device
Management Information Base for DOCSIS compliant Cable
Modems and Cable Modem Termination Systems", RFC 2669,
August 1999.
[RFC3128] Miller, I., "Protection Against a Variant of the Tiny
Fragment Attack (RFC 1858)", RFC 3128, June 2001.
[RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart,
"Introduction and Applicability Statements for
Internet-Standard Management Framework", RFC 3410,
December 2002.
[DOCSBPI] "Data-Over-Cable Service Interface Specifications:
Baseline Privacy Plus Interface Specification SP-BPI+-
I11-040407", DOCSIS, April 2004, available at
http://www.cablemodem.com/ and at
http://www.cablelabs.com/specifications/archives.
9. Security Considerations
This MIB is intended to limit certain kinds of network behavior by
subscriber hosts attached to cable modems, including, for example, IP
spoofing. These limitations may be compromised, however, if the
cable modem’s identity or registration process is spoofed. The
DOCSIS RFI and privacy specifications [ITU-T-J122] and [DOCSBPI]
define a number of mechanisms for assuring modem identity.
For network filtering of TCP traffic to be effective, implementors
MUST follow the recommendations in section 3.4.
There are a number of management objects defined in this MIB that
have a MAX-ACCESS clause of read-write and/or read-create. These
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.
Unauthorized SETs to this MIB can permit two major security problems
with public cable network operation: IP address spoofing, and defeat
of operator-defined packet filtering.
The following objects, if SET maliciously, would evade controls on
address spoofing:
docsSubMgtCpeControlMaxCpeIp
docsSubMgtCpeControlActive
docsSubMgtCpeControlLearnable
docsSubMgtCpeControlReset
docsSubMgtCpeMaxIpDefault
docsSubMgtCpeActiveDefault
docsSubMgtCpeLearnableDefault
The following objects could also permit packet filtering to be
defeated:
docsSubMgtCmFilterSubDownstream
docsSubMgtCmFilterSubUpstream
docsSubMgtCmFilterCmDownstream
docsSubMgtCmFilterCmUpstream
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 access to these objects and possibly even to encrypt
the values of these objects when they are sent over the network via
SNMP. The most sensitive is docsSubMgtCpeIpAddr within
docsSubMgtCpeIpTable. Although docsSubMgtCpeIpTable is intended to
control address spoofing, it includes information about the current
subscriber address pool. This information may in itself be valuable
to would-be spoofers.
SNMP versions prior to SNMPv3 did not include adequate security.
Even if the network itself is secure (for example by using IPSec),
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) who have legitimate
rights to GET or SET (change/create/delete) them.
Author’s Address
Wilson Sawyer
50 Kelly Brook Lane
East Hampstead NH 03826
Phone: +1 603 382 7080
EMail: wsawyer@ieee.org
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.