SNMP Polling is a
well-defined and well understood method of monitoring within the IT monitoring
industry. SNMP stands for Simple Network Management Protocol, and is a standard
way of monitoring hardware and software from nearly every vendor on the planet;
such as Cisco, VMware, Juniper, Microsoft, Linux operating systems and more.
There are two parts to
SNMP – a Network Management Station (NMS) and a Management Agent
(MA).The NMS, Opsview Monitor in this case,
communicates with the management agent running
on the hardware/software in question, using SNMP.
The management agent
that runs on the hardware / software collects information about the
aforementioned hardware/software and presents it in a logical fashion, allowing
for it to be polled by the management station (Opsview Monitor).
fashion’ uses two key concepts; OIDs (Object Identifier) and MIBs (Management
Information Base). SNMP works by querying Objects, where an object is something
containing data about a specific item within the hardware/software in question,
i.e. temperature of a chip, etc.
Objects like this with an Object Identifier (OID).
OID’s are very
structured and take a numbered, hierarchical tree structure. Most of the time, OID's are translated into a more readable format, but you still might encounter situations where you will need to use the raw numbers - to
find out more see the Guide here: link.
Tied closely to OID’s
are the Management Information Bases or MIBs. A MIB is like a translator that
helps your network management station (NMS) to understand the ‘numbers’ within
the OID. This means that instead of seeing ‘126.96.36.199.4.1.311: 44.03’ the MIB
will translate and allows Opsview Monitor to display ‘CPU0 Temperature: 44.03’.
In essence, the MIB makes SNMP objects usable.
MIB’s can be
downloaded from the hardware/software vendor and loaded into Opsview Monitor by installing them into your distribution's designated MIB directories.
Note: If you are using SNMP Traps, ensure that you copy your custom MIBs to
In the example below, the first group of text is missing a MIB file and is not able to fully translate the OID's into a human-readable format (you can see the .188.8.131.52.1.4.4, for example.) The second group of text is able to fully translate the OID's using a MIB.
There are three versions of the SNMP
protocol supported in Opsview Monitor:
SNMP v1 and SNMP v2c are very similar in their configuration; an
administrator configures a field known as the community string which is the authentication string (password,
essentially) that the NMS needs to get the data from the MA (i.e. how Opsview
Monitor can log in to the router to get the information about it).
SNMP v3 is more secure in that it allows an administrator to set a
username, an authentication algorithm, an authentication password, a privacy
algorithm AND a privacy password – all of which must be entered correctly
within Opsview Monitor in order to allow access to the router/devices
In the screen below, both SNMP v1/v2c and v3 are configured:
configuration on a Draytek router
These credentials must be entered
into Opsview Monitor in order to allow the monitoring of the Host in question.