7.5. Probes

Now that the Red Hat Network Monitoring Daemon has been installed and notification methods have been created, you may begin installing probes on your Monitoring-entitled systems. If a system is entitled to Monitoring, a Probes tab appears within its System Details page. This is where you will conduct most probe-related work.

7.5.1. Managing Probes

To add a probe to a system, the system must be entitled to Monitoring. Further, you must have access to the system itself, either as the system's root user, through the System Group Administrator role, or as the Organization Administrator. Then:

  1. Log into the RHN website as either an Organization Administrator or the System Group Administrator for the system.

  2. Navigate to the System Details ⇒ Probes tab and click create new probe.

  3. On the System Probe Creation page, complete all required fields. First, select the Probe Command Group. This alters the list of available probes and other fields and requirements. Refer to Appendix C Probes for the complete list of probes by command group. Remember that some probes require the Red Hat Network Monitoring Daemon to be installed on the client system.

  4. Select the desired Probe Command and the Monitoring Scout, typically RHN Monitoring Satellite but possibly an RHN Proxy Server. Enter a brief but unique description for the probe.

  5. Select the Probe Notifications checkbox to receive notifications when the probe changes state. Use the Probe Check Interval pulldown menu to determine how often notifications should be sent. Selecting 1 minute (and the Probe Notification checkbox) means you will receive notifications every minute the probe surpasses its CRITICAL or WARNING thresholds. Refer to Section 7.4 Notifications to find out how to create notification methods and acknowledge their messages.

  6. Use the RHNMD User and RHNMD Port fields, if they appear, to force the probe to communicate via sshd, rather than the Red Hat Network Monitoring Daemon. Refer to Section 7.2.3 Configuring SSH for details. Otherwise, accept the default values of nocpulse and 4545, respectively.

  7. If the Timeout field appears, review the default value and adjust to meet your needs. Most but not all timeouts result in an UNKNOWN state. If the probe's metrics are time-based, ensure the timeout is not less than the time alloted to thresholds. Otherwise, the metrics serve no purpose, as the probe will time out before any thresholds are crossed.

  8. Use the remaining fields to establish the probe's alert thresholds, if applicable. These CRITICAL and WARNING values determine at what point the probe has changed state. Refer to Section 7.5.2 Establishing Thresholds for best practices regarding these thresholds.

  9. When finished, click Create Probe. Remember, you must commit your Monitoring configuration change on the Scout Config Push page for this to take effect.

To delete a probe, navigate to its Current State page (by clicking the name of the probe from the System Details ⇒ Probes tab), and click delete probe. Finally, confirm the deletion.

7.5.2. Establishing Thresholds

Many of the probes offered by RHN contain alert thresholds that, when crossed, indicate a change in state for the probe. For instance, the Linux::CPU Usage probe allows you to set CRITICAL and WARNING thresholds for the percent of CPU used. If the monitored system reports 75 percent of its CPU used, and the WARNING threshold is set to 70 percent, the probe will go into a WARNING state. Some probes offer a multitude of such thresholds.

In order to get the most out of your Monitoring entitlement and avoid false notifications, Red Hat recommends running your probes without notifications for a time to establish baseline performance for each of your systems. Although the default values provided for probes may suit you, every organization has a different environment that may require altering thresholds.

7.5.3. Monitoring the RHN Server

In addition to monitoring all of your client systems, you may also use RHN to monitor your RHN Server, whether that be an RHN Satellite Server a RHN Proxy Server. To monitor your RHN Server, find a system monitored by the server, and go to that system's System Details ⇒ Probes tab.

Click create new probe and select the Satellite Probe Command Group. Next, complete the remaining fields as you would for any other probe. Refer to Section 7.5.1 Managing Probes for instructions.

Although the RHN Server appears to be monitored by the client system, the probe is actually run from the server on itself. Thresholds and notifications work normally.


Any probes that require Red Hat Network Monitoring Daemon connections cannot be used against a RHN Satellite Server or RHN Proxy Server on which Monitoring software is running. This includes most probes in the Linux command group as well as the Log Agent probes and the Remote Program probes. Use the Satellite command group probes to monitor RHN Satellite Servers and RHN Proxy Servers. In the case of Proxy scouts, the probes are listed under the system for which they are reporting data.