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What is Syslog?

Syslog, also known as system logging protocol, is used for gathering and archiving log information from computer systems and devices. This versatile protocol enables the logging of a wide range of events, encompassing system messages, application errors, and even security incidents. Syslog messages are formatted in a standard way, which makes them easy to parse and analyze. This protocol is an efficient solution to obtain telemetry data from small-scale devices.

What is a Syslog Source?

A Syslog source is a system or device that generates and sends informational messages, about events or activities within a network. These messages are transmitted to a centralized syslog server or log management system for analysis and monitoring purposes. Syslog sources include devices, applications, and servers, contributing to the collection and storage of log data.

A Syslog Source generates by default the following eight fields:

  • Timestamp (_time): The time and date the message was received.
  • Application (Appname): The name of the application that generated the message.
  • Facility (facilityName and facility): The type of system or device that generated the message, such as kernel, mail, or user.
  • Host: IP address of the device sending the incoming message.
  • Priority (severityName and severity): The severity of the event, such as emergency, alert, or informational.

How Does Syslog Work?

Specific syslog implementations can vary but generally, there are three standard layers: Transport, Application, and Content layer. Let’s briefly break down what role each layer plays:

Transport layer
This layer facilitates the transmission of event messages from devices to a centralized server, ensuring reliable communication through protocols like UDP or TCP. These protocols help to establish a strong and stable connection, allowing for efficient data transfer and minimizing the chances of any disruptions or loss of information.

Application layer
At the Application layer, received syslog messages undergo interpretation, routing, and storage. This layer plays a critical role in processing the content of messages. It involves tasks such as filtering, categorization, and determining appropriate destinations for the logs.

Content layer
The content layer in syslog messages is vital for giving detailed information about system events, errors, and other activities. This layer is valuable for troubleshooting and analysis, helping companies understand their systems better and make informed decisions.

Together, the three layers form a structured approach that improves the centralized logging of diverse system activities across a network.

Syslog Benefits

Syslog offers numerous benefits that enhance various systems and protocols. Let’s dive deeper into the most important ones:

Centralized Logging
This simplifies log management by aggregating data from different sources into a single repository. This centralized approach enhances administrative efficiency and ensures that critical log files are not scattered across multiple devices or applications.

Real-time Storage Device Monitoring
Syslog messages are generated in real-time, providing instant visibility into network activities and events. This monitoring capability allows administrators to identify and address issues promptly, improving system reliability and minimizing downtime. Storing syslog data over an extended period facilitates historical analysis. ITOps can analyze past log records to identify trends, diagnose recurring problems, and make informed decisions to improve system performance and security.

Syslog integration with Security Information and Event Management (SIEM) systems strengthens security postures across various devices and use cases. By correlating syslog data with other security events, companies can detect and respond to security threats more effectively. This ensures a robust defense against cyber threats.

Top 3 Most Common Syslog Challenges
Want to learn more?

Read how Sally Beauty swaps LogStash and Syslog-ng with Cribl.Cloud for a resilient security and observability pipeline.


Check out our 3-part Syslog blog series:

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