What is SNMP Walk and How to Utilize it with Nagios XI

SNMP (Simple Network Management Protocol) is a standard protocol used to manage and monitor devices on a network, such as routers, switches, servers, printers, and more. It allows systems to query devices to retrieve data about their performance, status, and configurations.

What is SNMP Walk?

SNMP Walk is a command that allows you to retrieve multiple pieces of information from an SNMP-enabled device in one go. It works by sending a request to the device to list all available SNMP objects, which are the specific pieces of information the device can provide (e.g., CPU usage, memory usage, or interface status). The response from the device contains all the objects’ values, which you can then use for monitoring and alerting purposes.

Why Use SNMP Walk in Nagios XI?

Nagios XI is a powerful monitoring solution that enables system administrators to monitor the health and performance of various devices and systems in their infrastructure. Using SNMP as a monitoring protocol helps Nagios XI gather data from a wide range of devices, even those without direct agent support.

The SNMP Walk Wizard in Nagios XI simplifies the process of setting up SNMP-based monitoring by automatically discovering available SNMP objects from a device. By using this wizard, you can easily configure checks for SNMP-enabled devices without needing to manually input OIDs (Object Identifiers) or configure the SNMP queries from scratch.

Here are the key reasons you might want to use the SNMP Walk Wizard in Nagios XI:

1. Ease of Use: The wizard guides you through the process of configuring SNMP checks, reducing the complexity of manually entering OIDs and SNMP settings.
2. Automation: The wizard automatically discovers SNMP objects, saving time and effort in finding the correct OIDs for monitoring specific device metrics.
3. Comprehensive Monitoring: SNMP allows you to monitor a wide range of metrics, including hardware health, network interfaces, and more, giving you a comprehensive view of your network devices’ status.
4. Centralized Monitoring: With Nagios XI, you can monitor all your devices and systems from a single interface, streamlining your network management tasks.

How to Use the SNMP Walk Wizard in Nagios XI

If you do not have SNMP installed yet, you can look at our SNMP installation guides for help!

Step 1: Access the SNMP Walk Wizard

1. Log in to Nagios XI.
2. Navigate to the Run a Wizard button and Find the SNMP Walk Configuration Wizard.

Step 2: Configure SNMP Settings

1. Device Address: Enter the hostname or IP address of the device you want to monitor.
2. Device Port: This will be left at 161 unless you changed it manually.
3. SNMP Version: Choose the SNMP version that your device supports (v1, v2c, or v3). Make sure you select the correct version for your device to avoid communication issues.
4. Community String: Enter the SNMP community string for the device. This is like a password for accessing SNMP data.

SNMP Advanced Scan Settings

When using the SNMP Walk Wizard in Nagios XI, you can adjust several advanced settings for the SNMP scan. These settings are optional but can help fine-tune the scan process depending on your specific requirements. Here’s what each setting does:

1. OID (Object Identifier):
   • The OID is a unique identifier used to reference a specific SNMP object (or data point) on a device. Each SNMP object represents a particular metric, such as CPU usage, memory usage, or network interface status.
   • In the Advanced Scan Settings, the OID field allows you to specify a starting point for the SNMP walk. If you enter an OID here, the scan will begin from that OID, retrieving all related objects beneath it. This can be useful if you’re looking for a specific set of metrics, as it allows you to limit the SNMP walk to a particular subtree of objects, making the scan more efficient.
2. Timeout:
   • The Timeout setting defines how long Nagios XI will wait for a response from the device before considering the SNMP query to have failed.
   • The default timeout is typically set to 15 seconds. You may want to adjust this if you’re monitoring a device that’s known to respond slowly or if you’re querying a large number of SNMP objects, which could take longer.
   • Timeout is expressed in seconds. If the device doesn’t respond within the specified time frame, the walk will stop, and Nagios XI will report an error. Increasing the timeout value can help prevent false negatives in environments with slow or heavily loaded devices.
3. Max Results:
   • The Max Results setting controls the maximum number of SNMP objects (OIDs) that Nagios XI will retrieve during the walk.
   • The default value is typically set to 200 results. This is useful for controlling the scope of the scan, as some devices may have thousands of SNMP objects available. Limiting the results helps to prevent overwhelming the Nagios XI server with too much data and also improves the scan performance.

Step 3: Run the SNMP Walk

Once the SNMP settings are configured, click the Walk button to initiate the SNMP walk. Nagios XI will query the device for all available SNMP objects, which may take a few moments depending on the number of objects and the speed of the device.

Step 4: Select SNMP Objects to Monitor

After the SNMP walk is complete, you will see a list of available SNMP objects (OIDs) that the device can provide. You can browse through this list and select the specific OIDs you want to monitor, such as CPU usage, disk space, or network traffic.

Step 5: Configure Nagios XI to Monitor the SNMP Objects

For each selected OID, you will need to configure a check to monitor the value. This can be done by selecting a predefined Nagios XI check template or creating a custom check based on the OID’s data type.

Step 6: Save and Apply Changes

Once you’ve configured all the checks, save your settings and apply the changes. Nagios XI will now begin monitoring the selected SNMP objects and will alert you if any of them go outside the defined thresholds.

Conclusion

The SNMP Walk Wizard in Nagios XI is a valuable tool for simplifying SNMP-based monitoring, saving time and effort when discovering and configuring SNMP objects. By automating the process of discovering OIDs, it allows you to quickly set up monitoring for your SNMP-enabled devices and ensures that you have full visibility into your network’s health and performance. Whether you’re monitoring routers, servers, or printers, the SNMP Walk Wizard makes it easier to gather valuable data for effective network management.

For more articles about Nagios XI and Networking check out more of our Documentation!