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Linux SNMP

Pack assets​

Templates​

The Monitoring Connector Linux SNMP brings a host template:

  • OS-Linux-SNMP-custom

The connector brings the following service templates (sorted by the host template they are attached to):

Service AliasService TemplateService Description
CpuOS-Linux-Cpu-SNMP-customCheck the rate of utilization of CPU for the machine. This check can give the average CPU utilization rate and the rate per CPU for multi-core CPU
LoadOS-Linux-Load-SNMP-customCheck the server load average
MemoryOS-Linux-Memory-SNMP-customCheck the rate of the utilization of memory
SwapOS-Linux-Swap-SNMP-customCheck virtual memory usage

The services listed above are created automatically when the OS-Linux-SNMP-custom host template is used.

Discovery rules​

Host discovery​

Rule nameDescription
SNMP AgentsDiscover your resource through a SNMP subnet scan. You need to install the Generic SNMP to get the discovery rule

More information about discovering hosts automatically is available on the dedicated page.

Service discovery​

Rule nameDescription
OS-Linux-SNMP-Disk-IODiscover the disk partitions and monitor space occupation
OS-Linux-SNMP-Disk-NameDiscover the disk partitions and monitor space occupation
OS-Linux-SNMP-Disk-PathDiscover the disk partitions and monitor space occupation
OS-Linux-SNMP-Inodes-NameDiscover the disk partitions and monitor inodes usage
OS-Linux-SNMP-Packet-Errors-NameDiscover network interfaces and monitor errored and discarded packets
OS-Linux-SNMP-Processes-NameDiscover processes and monitor their system usage
OS-Linux-SNMP-Traffic-NameDiscover network interfaces and monitor bandwidth utilization

More information about discovering services automatically is available on the dedicated page and in the following chapter.

Collected metrics & status​

Here is the list of services for this connector, detailing all metrics linked to each service.

Metric nameUnit
cpu.utilization.percentage%
cpu_core#core.cpu.utilization.percentage%

To obtain this new metric format, include --use-new-perfdata in the EXTRAOPTIONS service macro.

Prerequisites​

To monitor a Linux based device, the SNMP service must be installed and configured. Most of Linux distributions rely on net-snmp.

net-snmp server configuration​

A detailed documentation on how-to configure SNMP is available in the documentation of each Linux distribution.

Find below a minimalist snmpd.conf / net-snmp config file (replace my-snmp-community by the relevant value).

com2sec notConfigUser  default       my-snmp-community
group   notConfigGroup v1           notConfigUser
group   notConfigGroup v2c           notConfigUser
view centreon included .1.3.6.1
view    systemview    included   .1.3.6.1.2.1.1
view    systemview    included   .1.3.6.1.2.1.25.1.1
access notConfigGroup "" any noauth exact centreon none none
access  notConfigGroup ""      any       noauth    exact  systemview none none
includeAllDisks 10%

The SNMP server must be restarted each time the configuration is modified. Also make sure that the SNMP server is configured to automatically start on boot.

Network flow​

The target server must be reachable from the Centreon Poller on the UDP/161 SNMP port.

Installing the monitoring connector​

Pack​

  1. If the platform uses an online license, you can skip the package installation instruction below as it is not required to have the connector displayed within the Configuration > Monitoring Connector Manager menu. If the platform uses an offline license, install the package on the central server with the command corresponding to the operating system's package manager:
dnf install centreon-pack-operatingsystems-linux-snmp
  1. Whatever the license type (online or offline), install the Linux SNMP connector through the Configuration > Monitoring Connector Manager menu.

Plugin​

Since Centreon 22.04, you can benefit from the 'Automatic plugin installation' feature. When this feature is enabled, you can skip the installation part below.

You still have to manually install the plugin on the poller(s) when:

  • Automatic plugin installation is turned off
  • You want to run a discovery job from a poller that doesn't monitor any resource of this kind yet

More information in the Installing the plugin section.

Use the commands below according to your operating system's package manager:

dnf install centreon-plugin-Operatingsystems-Linux-Snmp

Using the monitoring connector​

Using a host template provided by the connector​

  1. Log into Centreon and add a new host through Configuration > Hosts.
  2. Fill the Name, Alias & IP Address/DNS fields according to your ressource settings.
  3. Apply the OS-Linux-SNMP-custom template to the host.

When using SNMP v3, use the SNMPEXTRAOPTIONS macro to add specific authentication parameters. More information in the Troubleshooting SNMP section.

MacroDescriptionDefault valueMandatory
SNMPEXTRAOPTIONSAny extra option you may want to add to every command (E.g. a --verbose flag). All options are listed here
  1. Deploy the configuration. The host appears in the list of hosts, and on the Resources Status page. The command that is sent by the connector is displayed in the details panel of the host: it shows the values of the macros.

Using a service template provided by the connector​

  1. If you have used a host template and checked Create Services linked to the Template too, the services linked to the template have been created automatically, using the corresponding service templates. Otherwise, create manually the services you want and apply a service template to them.
  2. Fill in the macros you want (e.g. to change the thresholds for the alerts). Some macros are mandatory (see the table below).
MacroDescriptionDefault valueMandatory
WARNINGWarning threshold average CPU utilization80
CRITICALCritical threshold average CPU utilization90
EXTRAOPTIONSAny extra option you may want to add to the command (E.g. a --verbose flag). All options are listed here
  1. Deploy the configuration. The service appears in the list of services, and on page Resources Status. The command that is sent by the connector is displayed in the details panel of the service: it shows the values of the macros.

How to check in the CLI that the configuration is OK and what are the main options for?​

Once the plugin is installed, log into your Centreon poller's CLI using the centreon-engine user account (su - centreon-engine). Test that the connector is able to monitor a resource using a command like this one (replace the sample values by yours):

/usr/lib/centreon/plugins/centreon_linux_snmp.pl \
    --plugin=os::linux::snmp::plugin \
    --mode=interfaces \
    --hostname=10.0.0.1 \
    --snmp-version='2c' \
    --snmp-community='my-snmp-community'  \
    --interface='.*' \
    --name \
    --add-status \
    --add-traffic \
    --critical-status='' \
    --warning-in-traffic='80' \
    --critical-in-traffic='90' \
    --warning-out-traffic='80' \
    --critical-out-traffic='90' \
    --verbose

The expected command output is shown below:

OK: All interfaces are ok | '*int*#status'=;;;;'*int*#interface.traffic.in.bitspersecond'=b/s;;;;'*int*#interface.traffic.out.bitspersecond'=b/s;;;;

Troubleshooting​

Please find the troubleshooting documentation for Centreon Plugins typical issues.

Available modes​

In most cases, a mode corresponds to a service template. The mode appears in the execution command for the connector. In the Centreon interface, you don't need to specify a mode explicitly: its use is implied when you apply a service template. However, you will need to specify the correct mode for the template if you want to test the execution command for the connector in your terminal.

All available modes can be displayed by adding the --list-mode parameter to the command:

/usr/lib/centreon/plugins/centreon_linux_snmp.pl \
    --plugin=os::linux::snmp::plugin \
    --list-mode

The plugin brings the following modes:

ModeLinked service template
arp [code]Not used in this Monitoring Connector
cpu [code]OS-Linux-Cpu-SNMP-custom
cpu-detailed [code]OS-Linux-Cpu-Detailed-SNMP-custom
disk-usage [code]Not used in this Monitoring Connector
diskio [code]OS-Linux-Disk-IO-SNMP-custom
inodes [code]OS-Linux-Inodes-Global-SNMP-custom
interfaces [code]Os-Linux-Packet-Errors-Generic-Id-SNMP-custom
Os-Linux-Packet-Errors-Generic-Name-SNMP-custom
Os-Linux-Packet-Errors-Global-SNMP-custom
OS-Linux-Traffic-Generic-Id-SNMP-custom
OS-Linux-Traffic-Generic-Name-SNMP-custom
OS-Linux-Traffic-Global-SNMP-custom
list-diskio [code]Used for service discovery
list-diskspath [code]Used for service discovery
list-interfaces [code]Used for service discovery
list-processes [code]Used for service discovery
list-storages [code]Used for service discovery
load [code]OS-Linux-Load-SNMP-custom
memory [code]OS-Linux-Memory-SNMP-custom
processcount [code]OS-Linux-Process-Generic-SNMP-custom
storage [code]OS-Linux-Disk-Generic-Id-SNMP-custom
OS-Linux-Disk-Generic-Name-SNMP-custom
OS-Linux-Disk-Global-SNMP-custom
swap [code]OS-Linux-Swap-SNMP-custom
tcpcon [code]OS-Linux-Tcpcon-Generic-SNMP-custom
time [code]OS-Linux-NTP-SNMP-custom
udpcon [code]Not used in this Monitoring Connector
uptime [code]OS-Linux-Uptime-SNMP-custom

Available options​

Generic options​

All generic options are listed here:

OptionDescription
--modeDefine the mode in which you want the plugin to be executed (see--list-mode).
--dyn-modeSpecify a mode with the module's path (advanced).
--list-modeList all available modes.
--mode-versionCheck minimal version of mode. If not, unknown error.
--versionReturn the version of the plugin.
--pass-managerDefine the password manager you want to use. Supported managers are: environment, file, keepass, hashicorpvault and teampass.
--verboseDisplay extended status information (long output).
--debugDisplay debug messages.
--filter-perfdataFilter perfdata that match the regexp. Eg: adding --filter-perfdata='avg' will remove all metrics that do not contain 'avg' from performance data.
--filter-perfdata-advFilter perfdata based on a "if" condition using the following variables: label, value, unit, warning, critical, min, max. Variables must be written either %{variable} or %(variable). Eg: adding --filter-perfdata-adv='not (%(value) == 0 and %(max) eq "")' will remove all metrics whose value equals 0 and that don't have a maximum value.
--explode-perfdata-maxCreate a new metric for each metric that comes with a maximum limit. The new metric will be named identically with a '_max' suffix). Eg: it will split 'used_prct'=26.93%;0:80;0:90;0;100 into 'used_prct'=26.93%;0:80;0:90;0;100 'used_prct_max'=100%;;;;
--change-perfdata --extend-perfdataChange or extend perfdata. Syntax: --extend-perfdata=searchlabel,newlabel,target[,[newuom],[min],[m ax]] Common examples: Convert storage free perfdata into used: --change-perfdata=free,used,invert() Convert storage free perfdata into used: --change-perfdata=used,free,invert() Scale traffic values automatically: --change-perfdata=traffic,,scale(auto) Scale traffic values in Mbps: --change-perfdata=traffic_in,,scale(Mbps),mbps Change traffic values in percent: --change-perfdata=traffic_in,,percent()
--extend-perfdata-groupAdd new aggregated metrics (min, max, average or sum) for groups of metrics defined by a regex match on the metrics' names. Syntax: --extend-perfdata-group=regex,namesofnewmetrics,calculation[,[ne wuom],[min],[max]] regex: regular expression namesofnewmetrics: how the new metrics' names are composed (can use $1, $2... for groups defined by () in regex). calculation: how the values of the new metrics should be calculated newuom (optional): unit of measure for the new metrics min (optional): lowest value the metrics can reach max (optional): highest value the metrics can reach Common examples: Sum wrong packets from all interfaces (with interface need --units-errors=absolute): --extend-perfdata-group=',packets_wrong,sum(packets_(discard |error)_(in|out))' Sum traffic by interface: --extend-perfdata-group='traffic_in_(.*),traffic_$1,sum(traf fic_(in|out)_$1)'
--change-short-output --change-long-outputModify the short/long output that is returned by the plugin. Syntax: --change-short-output=pattern~replacement~modifier Most commonly used modifiers are i (case insensitive) and g (replace all occurrences). Eg: adding --change-short-output='OK~Up~gi' will replace all occurrences of 'OK', 'ok', 'Ok' or 'oK' with 'Up'
--change-exitReplace an exit code with one of your choice. Eg: adding --change-exit=unknown=critical will result in a CRITICAL state instead of an UNKNOWN state.
--range-perfdataRewrite the ranges displayed in the perfdata. Accepted values: 0: nothing is changed. 1: if the lower value of the range is equal to 0, it is removed. 2: remove the thresholds from the perfdata.
--filter-uomMask the units when they don't match the given regular expression.
--opt-exitReplace the exit code in case of an execution error (i.e. wrong option provided, SSH connection refused, timeout, etc). Default: unknown.
--output-ignore-perfdataRemove all the metrics from the service. The service will still have a status and an output.
--output-ignore-labelRemove the status label ("OK:", "WARNING:", "UNKNOWN:", CRITICAL:") from the beginning of the output. Eg: 'OK: Ram Total:...' will become 'Ram Total:...'
--output-xmlReturn the output in XML format (to send to an XML API).
--output-jsonReturn the output in JSON format (to send to a JSON API).
--output-openmetricsReturn the output in OpenMetrics format (to send to a tool expecting this format).
--output-fileWrite output in file (can be combined with json, xml and openmetrics options). E.g.: --output-file=/tmp/output.txt will write the output in /tmp/output.txt.
--disco-formatApplies only to modes beginning with 'list-'. Returns the list of available macros to configure a service discovery rule (formatted in XML).
--disco-showApplies only to modes beginning with 'list-'. Returns the list of discovered objects (formatted in XML) for service discovery.
--float-precisionDefine the float precision for thresholds (default: 8).
--source-encodingDefine the character encoding of the response sent by the monitored resource Default: 'UTF-8'.
--hostnameName or address of the host to monitor (mandatory).
--snmp-communitySNMP community (default value: public). It is recommended to use a read-only community.
--snmp-versionVersion of the SNMP protocol. 1 for SNMP v1 (default), 2 for SNMP v2c, 3 for SNMP v3.
--snmp-portUDP port to send the SNMP request to (default: 161).
--snmp-timeoutTime to wait before sending the request again if no reply has been received, in seconds (default: 1). See also --snmp-retries.
--snmp-retriesMaximum number of retries (default: 5).
--maxrepetitionsMax repetitions value (default: 50) (only for SNMP v2 and v3).
--subsetleefHow many OID values per SNMP request (default: 50) (for get_leef method. Be cautious when you set it. Prefer to let the default value).
--snmp-autoreduceProgressively reduce the number of requested OIDs in bulk mode. Use it in case of SNMP errors (By default, the number is divided by 2).
--snmp-force-getnextUse SNMP getnext function in SNMP v2c and v3. This will request one OID at a time.
--snmp-cache-fileUse SNMP cache file.
--snmp-usernameSNMP v3 only: User name (securityName).
--authpassphraseSNMP v3 only: Pass phrase hashed using the authentication protocol defined in the --authprotocol option.
--authprotocolSNMP v3 only: Authentication protocol: MD5|SHA. Since net-snmp 5.9.1: SHA224|SHA256|SHA384|SHA512.
--privpassphraseSNMP v3 only: Privacy pass phrase (privPassword) to encrypt messages using the protocol defined in the --privprotocol option.
--privprotocolSNMP v3 only: Privacy protocol (privProtocol) used to encrypt messages. Supported protocols are: DES|AES and since net-snmp 5.9.1: AES192|AES192C|AES256|AES256C.
--contextnameSNMP v3 only: Context name (contextName), if relevant for the monitored host.
--contextengineidSNMP v3 only: Context engine ID (contextEngineID), if relevant for the monitored host, given as a hexadecimal string.
--securityengineidSNMP v3 only: Security engine ID, given as a hexadecimal string.
--snmp-errors-exitExpected status in case of SNMP error or timeout. Possible values are warning, critical and unknown (default).
--snmp-tls-transportTransport protocol for TLS communication (can be: 'dtlsudp', 'tlstcp').
--snmp-tls-our-identityX.509 certificate to identify ourselves. Can be the path to the certificate file or its contents.
--snmp-tls-their-identityX.509 certificate to identify the remote host. Can be the path to the certificate file or its contents. This option is unnecessary if the certificate is already trusted by your system.
--snmp-tls-their-hostnameCommon Name (CN) expected in the certificate sent by the host if it differs from the value of the --hostname parameter.
--snmp-tls-trust-certA trusted CA certificate used to verify a remote host's certificate. If you use this option, you must also define --snmp-tls-their-hostname.

Modes options​

All available options for each service template are listed below:

OptionDescription
--use-ucdUse UCD mib for cpu average.
--warning-averageWarning threshold average CPU utilization.
--critical-averageCritical threshold average CPU utilization.
--warning-coreWarning thresholds for each CPU core
--critical-coreCritical thresholds for each CPU core

All available options for a given mode can be displayed by adding the --help parameter to the command:

/usr/lib/centreon/plugins/centreon_linux_snmp.pl \
    --plugin=os::linux::snmp::plugin \
    --mode=interfaces \
    --help