Reference Guide

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. Dell has chosen not to support SNMP Set operations for this reason.
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/openmanagemanuals.
NOTE: As of iDRAC7 firmware release r1.30.30, iDRAC7 supports SNMP query operations (GET,
GETNEXT, GETBULK) via the SNMPv3 protocol, in addition to supporting query operations via the
SNMP v1 and SNMP v2c protocols. More specifically, iDRAC7 now supports the SNMP User Security
Model (USM).
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.
Two drawbacks to SNMP traps are that they are sent using UDP, which is not a guaranteed delivery
mechanism, and that they are not acknowledged by the receiver.
An SNMP trap message contains the trap’s enterprise OID, the agent IP address, a generic trap ID, the
specific trap ID, a time stamp, and zero or more variable bindings (varbinds). The combination of an
enterprise OID and a specific trap ID uniquely identifies each Server Administrator-defined trap. A varbind
consists of an OID and its value and provides additional information about the trap.
In order for a management system to receive SNMP traps from a managed system, the node must be
configured to send traps to the management system. Trap destination configuration is dependent on the
operating system. When this configuration is done, a management application on the management
system can wait for traps and act on them when received.
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