Splunk > Monitor Linux system

Why Monitor Linux with Splunk?

Monitoring your Linux systems with Splunk offers several advantages:

1. Performance Optimization: Gain insights into system performance, resource utilization, and application behavior. Detect and address performance bottlenecks.
2. Security: Monitor logs for signs of security breaches, unauthorized access, and other suspicious activities. Quickly respond to security incidents.
3. Troubleshooting: Easily identify and troubleshoot system issues, errors, and faults with detailed log analysis.
4. Capacity Planning: Plan for resource scaling and optimization by tracking historical performance data.
5. Compliance: Collect and retain logs required for compliance with regulatory standards, such as HIPAA or PCI DSS.

What to Monitor in Linux with Splunk

1. System Logs:Syslog: Monitor system logs to track system events, kernel messages, and service logs.journald: For systems using systemd, capture journal logs for system-wide information and errors.
2. Authentication Logs:Secure Log (auth.log): Monitor login and authentication events. Detect unauthorized access attempts.
3. Application Logs:Apache Access and Error Logs: If you're running a web server, track web traffic and errors.Database Logs: Monitor logs for databases like MySQL or PostgreSQL for errors and queries.
4. Performance Metrics:CPU and Memory Usage: Monitor CPU and memory utilization to identify resource constraints.Disk Usage: Keep an eye on disk space and I/O activity.Network Traffic: Track network usage, bandwidth, and interface statistics.
5. Security Logs:Security Logs (e.g., /var/log/secure): Monitor for security events, including failed login attempts, privilege escalations, and authentication issues.Auditd Logs: If enabled, capture audit logs for detailed system activity monitoring.
6. Custom Logs:Capture logs generated by custom applications or scripts, tailoring the monitoring to your specific needs.

How to Set Up Linux Monitoring with Splunk

Here's a step-by-step guide to setting up Linux monitoring with Splunk:

1. Install Splunk:

• Install Splunk on a central server, known as the Splunk indexer. Ensure that you have sufficient storage and resources to store and analyze log data.

2. Install the Universal Forwarder:

• On each Linux system you want to monitor, install the Splunk Universal Forwarder. This lightweight agent collects and forwards log data to the Splunk indexer.

3. Configure Data Inputs:

• Configure the Universal Forwarder on each Linux system to send log data to the Splunk indexer. You can use various data input methods, such as syslog, files, and scripted inputs.

4. Data Parsing:

• Create parsing rules or use pre-built field extractions to transform log data into meaningful events.

5. Index and Store Data:

• Define data indexes in Splunk to organize and store log data efficiently. Ensure adequate storage capacity for historical data retention.

6. Create Dashboards and Alerts:

• Design custom dashboards and alerts to visualize and respond to important system events, performance metrics, and security incidents.

7. Automation:

• Implement automation scripts to respond to alerts and remediate issues automatically.

8. Data Retention and Compliance:

• Define data retention policies to comply with regulatory requirements. Use Splunk's features to archive and manage historical data.

9. Scalability:

• As your Linux environment grows, scale your Splunk infrastructure to handle increased log volume. Consider distributed deployments for high availability.

10. Continuous Improvement:

• Regularly review your monitoring setup, dashboards, and alerts to ensure they align with changing system requirements.

The "Splunk Add-on for Unix and Linux" is a valuable extension for Splunk that simplifies the collection, parsing, and analysis of Unix and Linux data. Here's how to use it effectively:

Step 1: Install the Splunk Add-on for Unix and Linux:

1. In your Splunk environment, log in to the Splunk Web interface.
2. Navigate to "Apps" in the top menu.
3. Click on "Browse more apps."
4. Search for "Splunk Add-on for Unix and Linux" and click "Install."

Step 2: Configure Data Inputs:

The add-on comes with predefined data inputs for various Unix and Linux data sources. You can configure these inputs to start collecting data:

1. Go to "Settings" in the top menu and select "Data Inputs."
2. Under "Local Inputs," you'll find "Splunk Add-on for Unix and Linux." Click on it to configure data inputs for the relevant data sources.
3. Set up inputs for log files, scripts, or other data sources you want to monitor. These could include system logs, authentication logs, or application logs.

Step 3: Configure Source Types and Sourcetypes:

Source types and sourcetypes help Splunk identify and categorize data. To make data more manageable and searchable, you can configure these settings:

1. Navigate to "Settings" > "Sourcetypes" or "Source types" depending on your Splunk version.
2. Define or modify sourcetypes to match the data sources you are monitoring.

Step 4: Customize Field Extractions:

The add-on provides field extractions to parse log data and extract meaningful information. You can customize these field extractions as needed:

1. Go to "Settings" > "Advanced search" > "Search macros."
2. Review the macros provided by the add-on and customize them to match your specific log formats and data.

Step 5: Set Up Indexing and Data Storage:

Define indexes for your Unix and Linux data to organize and store it efficiently. Ensure that you have enough storage capacity for historical data retention:

1. Go to "Settings" > "Indexes."
2. Create an index for your Unix and Linux data, specifying its retention policy.

Step 6: Data Searching and Visualization:

You can now search, analyze, and visualize your Unix and Linux data using Splunk. Create searches, dashboards, and alerts to gain insights into system performance, security events, and more:

1. Use Splunk's powerful search language to query and filter data.
2. Create dashboards and reports to visualize key metrics and events. You can use the data from the add-on to build custom dashboards.
3. Set up alerts to receive notifications when specific events or conditions are met.

Step 7: Regular Maintenance and Updates:

• Regularly review and update your data inputs, field extractions, and sourcetypes to ensure they align with changing system requirements.
• Monitor the performance of your Splunk instance and the data storage capacity to prevent issues related to data retention.
• Stay up to date with new versions of the add-on and Splunk itself to benefit from the latest features and improvements.

Searching data with the "Splunk Add-on for Unix and Linux" involves using Splunk's search language and query capabilities to extract valuable information from the data collected by the add-on. Here's a step-by-step guide on how to search data with this add-on:

Step 1: Access Splunk Web Interface:

1. Log in to the Splunk Web interface using your credentials.

Step 2: Perform a Basic Search:

1. In the Splunk Web interface, you'll see the search bar at the top. Click inside the search bar to activate it.
2. Enter a basic search query. For example, to search for system logs, you might enter:

sourcetype=linux:syslog        

Press the "Enter" key or click the "Search" button to execute the query.

Step 3: Refine and Expand Your Search:

1. After your initial search, you can refine and expand your query to narrow down the results or explore specific aspects of the data.
2. Use search operators like AND, OR, NOT, and wildcards to create more complex queries. For example:

sourcetype=linux:syslog AND error        

You can also use time-based searches to focus on specific time ranges:

sourcetype=linux:syslog AND error earliest=-1h        

Step 4: Use Field Extractions:

1. The "Splunk Add-on for Unix and Linux" includes field extractions that help you parse log data and extract meaningful information. You can reference these fields in your searches. For example:

sourcetype=linux:syslog error | table _time, host, message        

Use the table command to display specific fields from the search results.

Step 5: Create Reports and Dashboards:

1. To save and share search results, you can create reports and dashboards. Reports allow you to save search results for future reference, while dashboards provide visual representations of your data.
2. To create a report, click "Save As" in the search results view and choose "Report." Follow the prompts to save and name the report.
3. To create a dashboard, go to "Settings" > "User interface" > "Dashboards." You can create a new dashboard and add panels with visualizations based on your search results.

Step 6: Set Up Alerts:

1. You can set up alerts to be notified when specific conditions or events occur. For instance, you can create an alert to be notified when a certain error appears in your logs.
2. To set up an alert, perform a search, and then click the "Alert" button. Follow the steps in the alert creation wizard to specify alert conditions, actions, and schedules.

Step 7: Save and Share Your Searches:

1. You can save searches for future use and share them with other users in your Splunk environment.
2. Click "Save As" in the search bar and choose "Search" to save your search query. You can give it a name and add it to your saved searches for easy access.

Step 8: Learn and Experiment:

1. To become proficient in searching data in Splunk, explore Splunk documentation, tutorials, and training resources. Experiment with different search commands and functions to get the most out of your data.

By following these steps and experimenting with different search queries and commands, you can effectively search and analyze data collected by the "Splunk Add-on for Unix and Linux" to gain insights into your Unix and Linux systems.

Author

Nadir Riyani?is an accomplished and visionary Engineering Manager with a strong background in leading high-performing engineering teams. With a passion for technology and a deep understanding of software development principles, Nadir has a proven track record of delivering innovative solutions and driving engineering excellence. He possesses a comprehensive understanding of software engineering methodologies, including Agile and DevOps, and has a keen ability to align engineering practices with business objectives.