SNMP Reference Guide

ENTERPRISES(

DELL (674)

SNMPv2(6)

In the preceding example, the OID prefix for the Dell enterprise would be 1.3.6.1.4.1.674.

The numbers in boldface type show the categories and numbers that apply to Server Administrator. All Server

Administrator-defined OIDs consist of 1.3.6.1.4.1.674 followed by additional component values.

SNMP Security

SNMP version 1 has a very limited security mechanism. SNMP agents support the use of a community string, which is

configured at each SNMP agent and is passed as a part of all SNMP request messages. There is no verification that the

requester is actually a member of the specified community. As most system and network management data is not

confidential, this limited security is acceptable for Get types of requests. On the other hand, this security is not

acceptable for Set types of operations where an SNMP request could power off a system, reconfigure a redundant

array of independent disks (RAID) card, and so on. Some vendors have chosen not to support SNMP Set operations for

this reason. Server Administrator is able to support SNMP Set operations because its SNMP agents implement a hash/

digest mechanism to prevent unauthorized SNMP Set operations. One limitation of this practice is that only server

administrator-developed SNMP management applications have the capability to support the hash/digest mechanism.

NOTE: The default SNMP agent configuration usually includes a SNMP community name such as public. For

security reasons, change the SNMP community names from their default values. For information about changing

SNMP community names, see the

Dell OpenManage Server Administrator User’s Guide

available on the Dell

Support website at dell.com/support/manuals. For additional guidelines, see the Securing an SNMP Environment

article, dated May 2003, in the Dell Power Solutions magazine. This magazine is also available at dell.com/

powersolutions .

NOTE: Server Administrator provides support to enable or disable SNMP Set operations. For more information on

enabling or disabling SNMP Set operations in Server Administrator, see the

Dell OpenManage Server

Administrator User’s Guide

or the

Dell OpenManage Server Administrator Command Line Interface User's Guide

the Dell Support web site at dell.com/support/manuals.

Management Actions

Management actions can be performed using the SNMP Set command. These actions can consist of configuring a

phone number for the system’s owner, rebooting a system, or changing the asset tag of the system. See the previous

section, Security, for limitations on Set operations.

SNMP Traps

SNMP is frequently used to monitor systems for fault conditions such as temperature violations, hard drive failures, and

so on. Management applications can monitor for these conditions by polling the appropriate OIDs with the Get command

and analyzing the returned data. This method has its drawbacks. If it is done frequently, significant amounts of network

bandwidth can be consumed. If it is done infrequently, the response to the fault condition may not occur in a timely

fashion. SNMP traps avoid these limitations of the polling method.

An SNMP trap is an asynchronous event indicating that something significant has occurred. This is analogous to a

pager receiving an important message, except that the SNMP trap frequently contains all the information needed to

diagnose a fault.