1.2. RFCs and SNMP Versions
The
Internet Engineering Task Force(IETF) is responsible for defining the standard protocols
that govern Internet traffic, including SNMP. The IETF publishes
Requests for Comments(RFCs), which are specifications for many protocols that
exist in the IP realm. Documents enter the standards track first as
proposed standards, then move to
draft status. When a final draft is eventually
approved, the RFC is given standard
status -- although there are fewer completely approved standards
than you might think. Two other standards-track designations,
historical and
experimental, define (respectively) a document
that has been replaced by a newer RFC and a document that is not yet
ready to become a standard. The following list includes all the
current SNMP versions and the IETF status of each (see Appendix D, "SNMP RFCs" for a full list of the SNMP RFCs):
-
SNMP Version
1 (SNMPv1) is the current standard version of the SNMP
protocol. It's defined in RFC 1157 and is a full IETF standard.
SNMPv1's security is based on
communities, which are nothing more than
passwords: plain-text strings that allow any SNMP-based application
that knows the strings to gain access to a device's management
information. There are typically three communities in SNMPv1:
read-only, read-write, and
trap.
-
SNMP
Version 2 (SNMPv2) is often referred to as community
string-based SNMPv2. This version of SNMP is technically called
SNMPv2c, but we will refer to it throughout this book simply as
SNMPv2. It's defined in RFC 1905, RFC 1906, and RFC 1907, and
is an experimental IETF. Even though it's experimental, some
vendors have started supporting it in practice.
-
SNMP Version 3
(SNMPv3) will be the next version of the protocol to reach full IETF
status. It's currently a proposed standard, defined in RFC
1905, RFC 1906, RFC 1907, RFC 2571, RFC 2572, RFC 2573, RFC 2574, and
RFC 2575. It adds support for strong authentication and private
communication between managed entities. Appendix F, "SNMPv3" provides an
introduction to SNMPv3 and goes through the SNMPv3 agent
configuration for Net-SNMP and Cisco. The information in this
appendix provides any system or network administrator with the
practical knowledge needed to begin using SNMPv3 as it gains
acceptance in the network-management world.
The official site for RFCs is http://www.ietf.org/rfc.html. One of the
biggest problems with RFCs, however, is finding the one you want. It
is a little easier to navigate the RFC index at Ohio State University
(http://www.cis.ohio-state.edu/services/rfc/index.html
).
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