OP5 Monitor ["OP5 Monitor"]
["Technical Reference"]

# Nagios Remote plugin Executor (NRPE) plugin version 4

## Overview

Beginning OP5 Monitor 8.2.1, the `check_nrpe4` (version 4) plugin is available in addition to the `check_nrpe` (version 2) plugin.

The `check_nrpe4` plugin is located in `/opt/plugins/check_nrpe4`, and is not backward-compatible with the `check_nrpe` plugin, which remains in `/opt/plugins/check_nrpe` to avoid affecting existing check commands. For more information, see the Plugin reference.

For new installations of OP5 Monitor 8.2.1 or above, a check command `check_nrpe4` is included for you to quickly use the `check_nrpe4` plugin.

For existing installations that have updated to OP5 Monitor 8.2.1, you will have to create the check command for the `check_nrpe4` plugin manually. The following sections provide examples of how to switch to the `check_nrpe4` plugin from the `check_nrpe` plugin:

- Update existing services
- Update existing check commands

## Update existing services

To update existing services to use the new `check_nrpe4` plugin, you first need to create a new check command.

### Example scenario

In this example scenario, the host `segot01` has two services that use the `check_nrpe` plugin:

- `Total processes` uses the `check_nrpe` check command with command argument `check_total_procs`. The `check_nrpe` check command preconfigured in OP5 Monitor uses the plugin of the same name. Example output from Test this check:

    _USER1_/check_nrpe -s -H 10.0.0.81 -c check_total_procs
    Result code: OK
    PROCS OK: 80 processes | procs=80;150;200;0;

- `Logged in users` uses the `check_nrpe_users` check command, which is implicitly configured to pass the command `check_users` to the `check_nrpe` plugin. Example output from Test this check:

    _USER1_/check_nrpe -s -H 10.0.0.81 -c check_users
    Result code: OK
    USERS OK - 1 users currently logged in |users=1;5;10;0

Both services use a check command configured with the `-s` option to run `check_nrpe`, which forces an SSL connection for version 2 of the plugin. In version 4 of the plugin, the `-s` option has a different function and can be removed.

### Create a check command

In this example scenario, you will create a new check command that uses the new `check_nrpe4` plugin.

1. In OP5 Monitor, go to Manage > Configure.
2. In the Configuration page, click Commands.
3. Under Create new command:
   1. In the command_name field, enter `check_nrpe4`.
   2. In the command_line field, enter `$USER1$/check_nrpe4 -H $HOSTADDRESS$ -c $ARG1$`.
4. Click Submit.
5. On the top-right corner, click Save.
6. In the Save configuration page, click Save my changes.

Success: The new `check_nrpe4` check command can now be used for existing implementations.

After you have created the new check command, you can then edit the services to use the new `check_nrpe4` plugin:

### Edit the total processes service

In this example, you will edit the `Total processes` service to use the new `check_nrpe4` check command you have created:

1. In the Services List view, look for `Total processes` and click Configure this service under Actions.
2. Under Edit service:
   1. In the check_command field, update the value from `check_nrpe` to `check_nrpe4`.
   2. Click Test this check the verify that the new check command works:

       _USER_/check_nrpe4 -H 10.0.0.81 -c check_total_procs
       Result code: OK
       PROCS OK: 80 processes | procs=80;150;200;0;

3. Click Submit.
4. On the top-right corner, click Save.
5. In the Save configuration page, click Save my changes.

Success: The `Total processes` service now uses the new `check_nrpe4` check command.

### Edit the logged in users service

In this example, you will edit the `Logged in users` service to use the new `check_nrpe4` check command you have created:

Note: This example applies for other services that use the `check_nrpe_xyz` check commands. For example, `check_nrpe_load`, `check_nrpe_swap`, and so on.

1. In the Services List view, look for `Logged in users` and click Configure this service under Actions.
2. Under Edit service:
   1. In the check_command row, click Syntax help to display the command line of the selected check command:

       Command line of selected check command:
       $USER1$/check_nrpe -s -H $HOSTADDRESS$ -c check_users

   2. Copy the arguments after the `-c` option from the command line. In this example, it is `check_users`.
   3. In the check_command field, update the value to `check_nrpe4`.
   4. In the check_command_args field, paste the argument you copied. In this example, it is `check_users`.
   5. Click Test this check the verify that the new check command works:

       _USER1_/check_nrpe4 -H 10.0.0.81 -c check_users
       Result code: OK
       USERS OK - 1 users currently logged in |users=1;5;10;0

3. Click Submit.
4. On the top-right corner, click Save.
5. In the Save configuration page, click Save my changes.

Success: The `Logged in users` service now uses the new `check_nrpe4` check command.

## Update existing check commands

### Before you begin

When you change a check command to use a new plugin, all services using that check command are affected.

To see which services use a particular check command, use the OP5 Monitor UI to perform a filter query on your browser address bar.

For example, the following query filters out services that use the `check_nrpe_users` check command:

`https://HOST/monitor/index.php/listview/?q=%5Bservices%5D%20check_command%20%3D%20%22check_nrpe_users%22`

### Edit the check command

In this example, you will update the check command `check_nrpe_users` to use the new `check_nrpe4` plugin:

Note: This example applies for other services that use the `check_nrpe_xyz` check commands. For example, `check_nrpe_load`, `check_nrpe_swap`, and so on.

1. In OP5 Monitor, go to Manage > Configure.
2. In the Configuration page, click Commands.
3. Under Command to edit, select `check_nrpe_users` and click Go.
4. Under Edit command, update the command_line field value.
   - Old value: `$USER1$/check_nrpe -s -H $HOSTADDRESS$ -c check_users`
   - New value: `$USER1$/check_nrpe4 -H $HOSTADDRESS$ -c check_users`
5. Click Submit.
6. On the top-right corner, click Save.
7. In the Save configuration page, click Save my changes.

Success: The `check_nrpe_users` check command now uses the new `check_nrpe4` plugin.

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