Requests for Comments (RFCs) define TCP/IP standards. RFCs are published by the Internet Engineering Task Force (IETF) and other working groups. The RFCs that are relevant to the discussion of SNMP in this chapter are:
RFC # | Title | Why relevant |
1155 | Structure and Identification of Management Information for TCP/IP-based Internets | defines SMI.MIB |
1157 | Simple Network Management Protocol (SNMP) | defines SNMP |
1213 | Management Information Base for Network Management of TCP/IP-based internets: MIB-II | defines MIB_II.MIB |
The following sections contain implementation details concerning RFCs 1157 and 1213.
Windows NT provides support for SNMP on TCP/IP and IPX networks. The security options for SNMP include a list of community names. If you remove all the community names, including the default name, Public, SNMP will respond to any community names presented.
This is expected behavior, as described in RFC 1157:
An SNMP message originated by an SNMP application entity that in fact belongs to the SNMP community named by the community component of said message is called an authentic SNMP message. The set of rules by which an SNMP message is identified as an authentic SNMP message for a particular SNMP community is called an authentication scheme. An implementation of a function that identifies authentic SNMP messages according to one or more authentication schemes is called an authentication service.
Clearly, effective management of administrative relationships among SNMP application entities requires authentication services that (by the use of encryption or other techniques) are able to identify authentic SNMP messages with a high degree of certainty. Some SNMP implementations may wish to support only a trivial authentication service that identifies all SNMP messages as authentic SNMP messages.
When there are no community names identified, Windows NT follows the behavior described in the preceding sentence.
RFC 1213 defines the Internet MIB-II. The section "MIB Object Types for Windows NT" in Appendix A contains a description of this MIB, and the Windows NT SDK CD contains the source file.
Windows NT does not implement any of the variables in the SNMP and EGP groups of MIB-II. Because Windows NT does not implement EGP, it does not implement the variables in this group.
The SNMP group was not implemented in Windows NT 3.1 because the extension mechanism only allowed a MIB DLL to register for the entire branch of the namespace. The SNMP group is part of the Internet MIB but the statistics required for the SNMP group must be maintained by the SNMP agent.
This limitation was removed in Windows NT 3.5 but the code has not been changed.