Essential SNMP

Chapter 7. Configuring SNMP Agents

By this time you should understand what an SNMP agent is: it’s nothing more than software that lives on the device you want to monitor. It responds to requests from the NMS and generates traps. This chapter discusses how to configure agents. It starts by defining some standard configuration parameters that are common to all SNMP agents, then goes into some advanced parameters you might run into when configuring your equipment. The bulk of this chapter walks through the configuration for a number of common devices, paying attention to security issues.

Parameter Settings

All SNMP devices share the following common configurable parameters:

• sysLocation

• sysContact

• sysName

• Read-write and read-only access community strings (and frequently, a trap community string)

• Trap destination

sysLocation is the physical location for the device being monitored. Its definition in RFC 1213 is:

sysLocation OBJECT-TYPE
    SYNTAX  DisplayString (SIZE (0..255))
    ACCESS  read-write
    STATUS  mandatory
    DESCRIPTION
        "The physical location of this node (e.g., 'telephone closet,
         3rd floor')."
    ::= { system 6 }

As you can see, its SYNTAX is DisplayString, which means it can be an ASCII string of characters; its size is declared to be at most 255 characters. This particular object is useful for determining where a device is located. This kind of practical information is essential in a large network, particularly if it’s spread over a wide area. If you have a misbehaving switch, it’s ...