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Linux NRPE4

Pack assets

Templates

The Monitoring Connector Linux NRPE4 brings a host template:

  • OS-Linux-NRPE4-custom

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

Service AliasService TemplateService Description
CpuOS-Linux-Cpu-NRPE4-customCheck the rate of utilization of CPUs for the machine. This check can give the average CPU utilization rate and the rate per CPU for multi-core CPUs
LoadOS-Linux-Load-NRPE4-customCheck the server load average
MemoryOS-Linux-Memory-NRPE4-customCheck the rate of the utilization of memory
NtpOS-Linux-Ntp-NRPE4-customCheck system time synchronization with NTP server
Protocol-NRPE4OS-Linux-Protocol-NRPE4-customControl test to make sure the NRPE v4 protocol is configured correctly.
SwapOS-Linux-Swap-NRPE4-customCheck virtual memory usage
UptimeOS-Linux-Uptime-NRPE4-customTime since the server has been working and available

The services listed above are created automatically when the OS-Linux-NRPE4-custom host template is used.

Discovery rules

Service discovery

Rule nameDescription
OS-Linux-NRPE4-Disk-NameDiscover the disk partitions and monitor space occupation
OS-Linux-NRPE4-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
command.exit.code.countcount

Prerequisites

The prerequisites below have to be applied to the Linux servers to be monitored.

Network flow

The NRPE protocol uses the TCP port 5666.

SourceDestinationProtocolePort
PollerHôte superviséTCP5666

System prerequisites

  1. Install the agent.
dnf -y install epel-release
dnf -y install nrpe
dnf -y config-manager --set-enabled 'powertools'
mkdir -p /var/lib/centreon/centplugins/
chown nrpe: /var/lib/centreon/centplugins/
  1. Change the IP address for theallowed_hosts parameter in /etc/nagios/nrpe.cfg (replace POLLER_IP_ADDRESS with the IP address of the poller that will monitor the host).
sed -i 's/dont_blame_nrpe=0/dont_blame_nrpe=1/'  /etc/nagios/nrpe.cfg
sed -i 's/allowed_hosts=127.0.0.1,::1/allowed_hosts=POLLER_IP_ADDRESS/' /etc/nagios/nrpe.cfg
  1. Add the definition of the check_centreon_plugins command:
cat >/etc/nrpe.d/centreon-commands.cfg <<'EOF'
command[check_centreon_plugins]=/usr/lib/centreon/plugins/centreon_linux_local.pl --plugin=$ARG1$ --mode=$ARG2$ $ARG3$
EOF
  1. Restart the service to apply the new configuration:
systemctl restart nrpe
systemctl enable nrpe
  1. To monitor systemd-journal, run the following commands:
usermod -a -G systemd-journal nrpe
systemctl restart nrpe
  1. To monitor systemctl-sc and traffic, run the following commands:
setenforce Permissive
sed -i 's/SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config
reboot
  1. Add the Centreon plugins' repository:
cat >/etc/yum.repos.d/centreon-plugins.repo <<'EOF'
[centreon-plugins-stable]
name=Centreon plugins repository.
baseurl=https://packages.centreon.com/rpm-plugins/el8/stable/$basearch/
enabled=1
gpgcheck=1
gpgkey=https://yum-gpg.centreon.com/RPM-GPG-KEY-CES
module_hotfixes=1

[centreon-plugins-stable-noarch]
name=Centreon plugins repository.
baseurl=https://packages.centreon.com/rpm-plugins/el8/stable/noarch/
enabled=1
gpgcheck=1
gpgkey=https://yum-gpg.centreon.com/RPM-GPG-KEY-CES
module_hotfixes=1

[centreon-plugins-testing]
name=Centreon plugins repository. (UNSUPPORTED)
baseurl=https://packages.centreon.com/rpm-plugins/el8/testing/$basearch/
enabled=0
gpgcheck=1
gpgkey=https://yum-gpg.centreon.com/RPM-GPG-KEY-CES
module_hotfixes=1

[centreon-plugins-testing-noarch]
name=Centreon plugins repository. (UNSUPPORTED)
baseurl=https://packages.centreon.com/rpm-plugins/el8/testing/noarch/
enabled=0
gpgcheck=1
gpgkey=https://yum-gpg.centreon.com/RPM-GPG-KEY-CES
module_hotfixes=1

[centreon-plugins-unstable]
name=Centreon plugins repository. (UNSUPPORTED)
baseurl=https://packages.centreon.com/rpm-plugins/el8/unstable/$basearch/
enabled=0
gpgcheck=1
gpgkey=https://yum-gpg.centreon.com/RPM-GPG-KEY-CES
module_hotfixes=1

[centreon-plugins-unstable-noarch]
name=Centreon plugins repository. (UNSUPPORTED)
baseurl=https://packages.centreon.com/rpm-plugins/el8/unstable/noarch/
enabled=0
gpgcheck=1
gpgkey=https://yum-gpg.centreon.com/RPM-GPG-KEY-CES
module_hotfixes=1
EOF
  1. Install the plugin :
dnf install -y centreon-plugin-Operatingsystems-Linux-Local.noarch https://packages.centreon.com/artifactory/rpm-standard/23.04/el8/stable/noarch/RPMS/perl-cpan-libraries/perl-JSON-Path-0.5-2.el8.noarch.rpm

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-nrpe4
  1. Whatever the license type (online or offline), install the Linux NRPE4 connector through the Configuration > Monitoring Connector Manager menu.

Plugin

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

dnf install nagios-plugins-nrpe

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 in the Name, Alias & IP Address/DNS fields according to your resource's settings.
  3. Apply the OS-Linux-NRPE4-custom template to the host. A list of macros appears. Macros allow you to define how the connector will connect to the resource, and to customize the connector's behavior.
  4. Fill in the macros you want. Some macros are mandatory.
MacroDescriptionDefault valueMandatory
NRPEPORT5666
NRPECLIENTcheck_nrpe
NRPESTATEFILEDIRDefine the cache directory (default: '/var/lib/centreon/centplugins')/var/lib/centreon/centplugins/
NRPETIMEOUT5
NRPEEXTRAOPTIONSAny extra option you may want to add to every command (a --verbose flag for example). 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
COMMANDCommand to test (default: none). You can use 'sh' to use '&&' or '||'X
COMMANDOPTIONSCommand options (default: none)
THRESHOLDSSet action according command exit code. Example: %(code) == 0,OK,File xxx exist#%(code) == 1,CRITICAL,File xxx not exist#,UNKNOWN,Command problemX
EXTRAOPTIONSAny extra option you may want to add to the command (a --verbose flag for example). All options are listed here.
  1. Deploy the configuration. The service appears in the list of services, and on the Resources Status page. 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/lib64/nagios/plugins//check_nrpe -H 10.0.0.1 -p 5666 -t 5  -c check_centreon_plugins -a 'os::linux::local::plugin' 'traffic'  ' \
--filter-interface="" \
--warning-in="" \
--critical-in="" \
--warning-out="" \
--critical-out="" \
--filter-state="RU" \
--speed="" \
--statefile-dir=/var/lib/centreon/centplugins/ rn '

The expected command output is shown below:

OK: All interfaces are ok | '*interface*#interface.traffic.in.bitspersecond'=b/s;;;;'*interface*#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/lib64/nagios/plugins//check_nrpe -H 10.0.0.1 -p 5666 -t 5  -c check_centreon_plugins -a 'os::linux::local::plugin' 'traffic'  ' \
--filter-interface="" \
--list-mode

The plugin brings the following modes:

ModeLinked service template
check-plugin [code]Not used in this Monitoring Connector
cmd-return [code]OS-Linux-Cmd-Generic-NRPE4-custom
OS-Linux-Is-File-Generic-NRPE4-custom
OS-Linux-Is-Not-File-Generic-NRPE4-custom
connections [code]OS-Linux-Connections-Generic-NRPE4-custom
cpu [code]OS-Linux-Cpu-NRPE4-custom
cpu-detailed [code]OS-Linux-Cpu-Detailed-NRPE4-custom
discovery-snmp [code]Not used in this Monitoring Connector
discovery-snmpv3 [code]Not used in this Monitoring Connector
diskio [code]OS-Linux-Disk-IO-NRPE4-custom
files-date [code]OS-Linux-File-Date-Generic-NRPE4-custom
files-size [code]OS-Linux-File-Size-Generic-NRPE4-custom
inodes [code]OS-Linux-Inodes-NRPE4-custom
list-interfaces [code]Used for service discovery
list-partitions [code]Not used in this Monitoring Connector
list-storages [code]Used for service discovery
list-systemdservices [code]Not used in this Monitoring Connector
load [code]OS-Linux-Load-NRPE4-custom
lvm [code]Not used in this Monitoring Connector
memory [code]OS-Linux-Memory-NRPE4-custom
mountpoint [code]Not used in this Monitoring Connector
ntp [code]OS-Linux-Ntp-NRPE4-custom
open-files [code]OS-Linux-Open-Files-NRPE4-custom
packet-errors [code]OS-Linux-Packet-Errors-NRPE4-custom
paging [code]Not used in this Monitoring Connector
pending-updates [code]OS-Linux-Pending-Updates-NRPE4-custom
process [code]OS-Linux-Process-Generic-NRPE4-custom
quota [code]Not used in this Monitoring Connector
storage [code]OS-Linux-Disks-NRPE4-custom
swap [code]OS-Linux-Swap-NRPE4-custom
systemd-journal [code]OS-Linux-Systemd-Journal-NRPE4-custom
systemd-sc-status [code]OS-Linux-Systemd-Sc-Status-NRPE4-custom
traffic [code]OS-Linux-Traffic-NRPE4-custom
uptime [code]OS-Linux-Uptime-NRPE4-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.
--custommodeWhen a plugin offers several ways (CLI, library, etc.) to get information the desired one must be defined with this option.
--list-custommodeList all available custom modes.
--multipleMultiple custom mode objects. This may be required by some specific modes (advanced).
--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. Example: 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). Example: 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). Example: 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). Example: 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. Example: 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. Example: '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'.
--hostnameHostname to query.
--timeoutTimeout in seconds for the command (default: 45). Default value can be override by the mode.
--commandCommand to get information. Used it you have output in a file.
--command-pathCommand path.
--command-optionsCommand options.
--sudo sudo command.
--ssh-backendDefine the backend you want to use. It can be: sshcli (default), plink and libssh.
--ssh-usernameDefine the user name to log in to the host.
--ssh-passwordDefine the password associated with the user name. Cannot be used with the sshcli backend. Warning: using a password is not recommended. Use --ssh-priv-key instead.
--ssh-portDefine the TCP port on which SSH is listening.
--ssh-priv-keyDefine the private key file to use for user authentication.
--sshcli-commandssh command (default: 'ssh').
--sshcli-pathssh command path (default: none)
--sshcli-optionSpecify ssh cli options (example: --sshcli-option='-o=StrictHostKeyChecking=no').
--plink-commandplink command (default: 'plink').
--plink-pathplink command path (default: none)
--plink-optionSpecify plink options (example: --plink-option='-T').
--libssh-strict-connectConnection won't be OK even if there is a problem (server known changed or server found other) with the ssh server.

Modes options

All available options for each service template are listed below:

OptionDescription
--manage-returnsSet action according command exit code. Example: %(code) == 0,OK,File xxx exist#%(code) == 1,CRITICAL,File xxx not exist#,UNKNOWN,Command problem
--separatorSet the separator used in --manage-returns (default : #)
--exec-commandCommand to test (default: none). You can use 'sh' to use '&&' or '||'.
--exec-command-pathCommand path (default: none).
--exec-command-optionsCommand options (default: none).

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

/usr/lib64/nagios/plugins//check_nrpe -H 10.0.0.1 -p 5666 -t 5  -c check_centreon_plugins -a 'os::linux::local::plugin' 'traffic'  ' \
--filter-interface="" \
--warning-in="" \
--help