SnmpMonitor

The SNMP monitor gives a generic possibility to monitor states and results from SNMP agents. This monitor has two basic operation modes:

Test the response value of one specific OID (scalar object identifier);
Test multiple values in a whole table.

To decide which mode should be used, the walk and match-all parameters are used.

See the Operating mode selection'' and Monitor specific parameters for the SnmpMonitor'' tables below for more information about these operation modes.

Table 1. Operating mode selection
walk	match-all	Operating mode
`true`	`true`	tabular, all values must match
	`false`	tabular, any value must match
	`count`	specifies that the value of at least minimum and at most maximum objects encountered in
`false`	`true`	scalar
	`false`	scalar
	`count`	tabular, between `minimum` and `maximum` values must match

Monitor Facts

Class Name

org.opennms.netmgt.poller.monitors.SnmpMonitor

Remote Enabled

false

When the monitor is configured to persist the response time, it will count the total amount of time spent until a successful response is obtained, including the retries. It won’t store the time spent during the last successful attempt.

Configuration and Use

Table 2. Monitor specific parameters for the SnmpMonitor
Parameter	Description	Required	Default value
`hex`	Specifies that the value monitored should be compared against its hexadecimal representation. Useful when the monitored value is a string containing non-printable characters.	optional	`false`
`match-all`	Can be set to: `count`: specifies that the value of at least minimum and at most maximum objects encountered in the walk must match the criteria specified by `operand` and `operator`. `true` and `walk` is set to `true`: specifies that the value of every object encountered in the walk must match the criteria specified by the `operand` and `operator` parameters. `false` and `walk` is set to `true`: specifies that the value of any object encountered in the walk must match the criteria specified by the `operand` and `operator` parameters.	optional	`true`
`maximum`	Valid only when `match-all` is set to `count`, otherwise ignored. Should be used in conjunction with the `minimum` parameter. Specifies that the value of at most `maximum` objects encountered in the walk must meet the criteria specified by the `operand` and `operator` parameters.	optional	`0`
`minimum`	Valid only when `match-all` is set to `count`, otherwise ignored. Should be used in conjunction with the `maximum` parameter. Specifies that the value of at least `minimum` objects encountered in the walk must meet the criteria specified by the `operand` and `operator` parameters.	optional	`0`
`oid`	The object identifier of the MIB object to monitor. If no other parameters are present, the monitor asserts that the agent’s response for this object must include a valid value (as opposed to an error, no-such-name, or end-of-view condition) that is non-null.	optional	`.1.3.6.1.2.1.1.2.0` (SNMPv2-MIB::SysObjectID)
`operand`	The value to be compared against the observed value of the monitored object. Note: Comparison will always succeed if either the `operand` or `operator` parameter isn’t set and the monitored value is non-null.	optional	`-`
`operator`	The operator to be used for comparing the monitored object against the `operand` parameter. Must be one of the following symbolic operators: `<` (<): Less than. Both operand and observed object value must be numeric. `>` (>): Greater than. Both operand and observed object value must be numeric. `<=` (⇐): Less than or equal to. Both operand and observed object value must be numeric. `>=` (>=): Greater than or equal to. Both operand and observed object value must be numeric. `=`: Equal to. Applied in numeric context if both operand and observed object value are numeric, otherwise in string context as a case-sensitive exact match. `!=`: Not equal to. Applied in numeric context if both operand and observed object value are numeric, otherwise in string context as a case-sensitive exact match. `~`: Regular expression match. Always applied in string context. Note: Comparison will always succeed if either the `operand` or `operator` parameter isn’t set and the monitored value is non-null. Keep in mind that you need to escape all < and > characters as XML entities (`<` and `>` respectively)	optional	`-`
`port`	Destination port where the SNMP requests shall be sent.	optional	from `snmp-config.xml`
`reason-template`	A user-provided template used for the monitor’s reason code if the service is unvailable. Defaults to a reasonable value if unset. See below for an explanation of the possible template parameters.	optional	depends on operation mode
`retries`	Deprecated Same as `retry`. Parameter `retry` takes precedence if both are set.	optional	from `snmp-config.xml`
`walk`	`false`: Sets the monitor to poll for a scalar object unless if the `match-all` parameter is set to `count`, in which case the `match-all` parameter takes precedence. `true`: Sets the monitor to poll for a tabular object where the `match-all` parameter defines how the tabular object’s values must match the criteria defined by the `operator` and `operand` parameters. See also the `match-all`, `minimum`, and `maximum` parameters.	optional	`false`

This monitor implements the Common Configuration Parameters.

Table 3. Variables which can be used in the reason-template parameter
Variable	Description
`${hex}`	Value of the `hex` parameter.
`${ipaddr}`	IP address polled.
`${matchall}`	Value of the `match-all` parameter.
`${matchcount}`	When `match-all` is set to `count`, contains the number of matching instances encountered.
`${maximum}`	Value of the `maximum` parameter.
`${minimum}`	Value of the `minimum` paramater.
`${observedvalue}`	Polled value that made the monitor succeed or fail.
`${oid}`	Value of the `oid` parameter.
`${operand}`	Value of the `operand` parameter.
`${operator}`	Value of the `operator` parameter.
`${port}`	Value of the `port` parameter.
`${retry}`	Value of the `retry` parameter.
`${timeout}`	Value of the `timeout` parameter.
`${walk}`	Value of the `walk` parameter.

Example for monitoring scalar object

As a working example we want to monitor the thermal system fan status which is provided as a scalar object ID.

cpqHeThermalSystemFanStatus .1.3.6.1.4.1.232.6.2.6.4.0

The manufacturer MIB gives the following information:

Description of the cpqHeThermalSystemFanStatus from CPQHLTH-MIB

SYNTAX 	INTEGER  {
    other    (1),
    ok       (2),
    degraded (3),
    failed   (4)
}
ACCESS 	read-only
DESCRIPTION
"The status of the fan(s) in the system.

This value will be one of the following:
other(1)
Fan status detection is not supported by this system or driver.

ok(2)
All fans are operating properly.

degraded(3)
A non-required fan is not operating properly.

failed(4)
A required fan is not operating properly.

If the cpqHeThermalDegradedAction is set to shutdown(3) the
system will be shutdown if the failed(4) condition occurs."

The SnmpMonitor is configured to test if the fan status returns ok(2). If so, the service is marked as up. Any other value indicates a problem with the thermal fan status and marks the service down.

Example SnmpMonitor as HP InsightManager fan monitor in poller-configuration.xml

<service name="HP-Insight-Fan-System" interval="300000" user-defined="false" status="on">
    <parameter key="oid" value=".1.3.6.1.4.1.232.6.2.6.4.0"/>(1)
    <parameter key="operator" value="="/>(2)
    <parameter key="operand" value="2"/>(3)
    <parameter key="reason-template" value="System fan status is not ok. The state should be ok($\{operand}) the observed value is $\{observedvalue}. Please check your HP Insight Manager. Syntax: other(1), ok(2), degraded(3), failed(4)"/>(4)
</service>

<monitor service="HP-Insight-Fan-System" class-name="org.opennms.netmgt.poller.monitors.SnmpMonitor" />

1	Scalar object ID to test
2	Operator for testing the response value
3	Integer 2 as operand for the test
4	Encode MIB status in the reason code to give more detailed information if the service goes down

Example test SNMP table with all matching values

The second mode shows how to monitor values of a whole SNMP table. As a practical use case the status of a set of physical drives is monitored. This example configuration shows the status monitoring from the CPQIDA-MIB.

We use as a scalar object id the physical drive status given by the following tabular OID:

cpqDaPhyDrvStatus .1.3.6.1.4.1.232.3.2.5.1.1.6

Description of the cpqDaPhyDrvStatus object id from CPQIDA-MIB

SYNTAX 	INTEGER  {
    other             (1),
    ok                (2),
    failed            (3),
    predictiveFailure (4)
}
ACCESS 	read-only
DESCRIPTION
Physical Drive Status.
This shows the status of the physical drive.
The following values are valid for the physical drive status:

other (1)
 Indicates that the instrument agent does not recognize
 the drive.  You may need to upgrade your instrument agent
 and/or driver software.

ok (2)
 Indicates the drive is functioning properly.

failed (3)
 Indicates that the drive is no longer operating and
 should be replaced.

predictiveFailure(4)
 Indicates that the drive has a predictive failure error and
 should be replaced.

The configuration in our monitor will test all physical drives for status ok(2).

Example SnmpMonitor as HP Insight physical drive monitor in poller-configuration.xml

<service name="HP-Insight-Drive-Physical" interval="300000" user-defined="false" status="on">
    <parameter key="oid" value=".1.3.6.1.4.1.232.3.2.5.1.1.6"/>(1)
    <parameter key="walk" value="true"/>(2)
    <parameter key="operator" value="="/>(3)
    <parameter key="operand" value="2"/>(4)
    <parameter key="match-all" value="true"/>(5)
    <parameter key="reason-template" value="One or more physical drives are not ok. The state should be ok($\{operand}) the observed value is $\{observedvalue}. Please check your HP Insight Manager. Syntax: other(1), ok(2), failed(3), predictiveFailure(4), erasing(5), eraseDone(6), eraseQueued(7)"/>(6)
</service>

<monitor service="HP-Insight-Drive-Physical" class-name="org.opennms.netmgt.poller.monitors.SnmpMonitor" />

1	OID for SNMP table with all physical drive states
2	Enable walk mode to test every entry in the table against the test criteria
3	Test operator for integer
4	Integer `2` as operand for the test
5	Test in walk mode has to be passed for every entry in the table
6	Encode MIB status in the reason code to give more detailed information if the service goes down

Example test SNMP table with all matching values

This example shows how to use the SnmpMonitor to test if the number of static routes are within a given boundary. The service is marked as up if at least 3 and at maxium 10 static routes are set on a network device. This status can be monitored by polling the table ipRouteProto from the RFC1213-MIB2.

ipRouteProto 1.3.6.1.2.1.4.21.1.9

The MIB description gives us the following information:

SYNTAX 	INTEGER  {
    other(1),
    local(2),
    netmgmt(3),
    icmp(4),
    egp(5),
    ggp(6),
    hello(7),
    rip(8),
    is-is(9),
    es-is(10),
    ciscoIgrp(11),
    bbnSpfIgp(12),
    ospf(13),
    bgp(14)}
}
ACCESS 	read-only
DESCRIPTION
"The routing mechanism via which this route was learned.
Inclusion of values for gateway routing protocols is not
intended to imply that hosts should support those protocols."

To monitor only local routes, the test should be applied only on entries in the ipRouteProto table with value 2. The number of entries in the whole ipRouteProto table has to be counted and the boundaries on the number has to be applied.

Example SnmpMonitor used to test if the number of local static route entries are between 3 or 10.

<service name="All-Static-Routes" interval="300000" user-defined="false" status="on">
 <parameter key="oid" value=".1.3.6.1.2.1.4.21.1.9" />(1)
 <parameter key="walk" value="true" />(2)
 <parameter key="operator" value="=" />(3)
 <parameter key="operand" value="2" />(4)
 <parameter key="match-all" value="count" />(5)
 <parameter key="minimum" value="3" />(6)
 <parameter key="maximum" value="10" />(7)
</service>

<monitor service="All-Static-Routes" class-name="org.opennms.netmgt.poller.monitors.SnmpMonitor" />

1	OID for SNMP table ipRouteProto
2	Enable walk mode to test every entry in the table against the test criteria
3	Test operator for integer
4	Integer `2` as operand for testing local route entries
5	Test in walk mode has is set to `count` to get the number of entries in the table regarding `operator` and `operand`
6	Lower count boundary set to `3`
7	High count boundary is set to `10`