What Is Syslog? Syslog Server vs. Event Log Explained + Recommended Syslog Management Tool

By dnsstuff on May 22, 2020

Network devices such as servers, firewalls, and routers generate logs about events and statuses, and trying to track all that information is challenging. Using syslog, in tandem with a syslog server such as SolarWinds® Kiwi Syslog® Server, provides a way to easily review and manage those logs.

This guide will go into more detail about syslog and the difference between syslog and event logs.

What Is Syslog?

The syslog protocol has been in use for decades as a way to transport messages from network devices to a logging server, typically known as a syslog server. Due to its longevity and popularity, the syslog protocol has support on most major operating systems, including macOS, Linux, and Unix. Syslog can also be supported on Microsoft Windows via third-party tools.

what is syslog

Syslog has three layers as part of the standard definition:

  • Syslog content: The information in the event message
  • Syslog application: The layer that generates, routes, interprets, and stores the message
  • Syslog transport: The layer that transmits the message

What Does Syslog Do?

Syslog provides a way for network devices to send messages and log events. For this to work, Syslog has a standard format all applications and devices can use. A syslog message contains the following elements:

  • Header
  • Structured data
  • Message

The header includes information about the version, time stamp, host name, priority, application, process ID, and message ID. The structured data comprises data blocks in a specific format, which is followed by the log message.

Log messages should be encoded using the 8-bit Unicode Transformation Format (UTF-8), but apart from that, the messages can be configured based on individual needs. The flexibility of the message content is part of what makes syslog so popular and effective.

The severity levels for syslog messages range from 0, which signals an emergency, to 5, which constitutes a warning. There are additional options for informational messages (level 6) and debugging (level 7).

While this information is advantageous, you can’t use syslog to gather information from devices the way you can with Simple Network Management Protocol (SNMP). Syslog only supports sending messages to a defined location when certain events happen.

Syslog vs. Event Log

In contrast to syslog, an event log is a more basic resource that stores different types of information based on specific events. These events include:

  • Failed password attempts
  • Locked accounts
  • Network login sessions
  • Application errors
  • Unexpected application closures

Event logs can be used to troubleshoot problems with security management, application installations, and more. The Windows event log includes the following information for each entry:

  • Date: Date when the event occurred
  • Time: Time when the event occurred
  • User: User logged in when the event occurred
  • Computer: Name of the computer used
  • Event ID: An identification number from Windows indicating the event type
  • Source: Component or program that caused the event
  • Type: Type of event

When thinking about syslog vs. event log, it helps to remember an event log is a subset of what might be tracked in syslog. Syslog servers capture information from multiple logs and store it in a central location.

What Is Syslog Server?

Syslog servers are used to collect syslog messages in a single location. A syslog server might be a physical server, a standalone virtual machine, or a software-based service.

To make it possible for syslog servers to receive, interpret, and store the messages, they usually have a couple of common components:

  • Syslog Listener: This allows the server to receive messages by gathering Syslog data.
  • Database: This is important for larger networks to be able to store syslog data for easy reference.

A good syslog server allows you to both collect the syslog messages and view and filter them from one location. This should include syslog messages from all devices and operating systems, with the ability to log in from any location through a secure portal.

Automation is also important. With the right syslog server, you can configure alerts to notify you of problems coming through syslog. You can also set up other types of responses to messages, such as running scripts, forwarding messages, and logging to a file.

Another way to view information is with reports. Syslog servers may allow you to schedule reports to run at certain times and be delivered to your email, so you can easily review graphs of statistics.

Advanced functionality may also support:

  • Filtering messages based on priority, host IP address, host name, or time
  • Buffering messages, so your system or inbox doesn’t get overwhelmed during heavy loads

While you won’t want to keep all logs active for long periods, compliance frameworks have specific requirements for log retention. A good syslog server will support archiving log data to comply with HIPAA, SOX, and more.

Why Use Syslog?

With so much complex information produced by multiple applications and systems, administrators need a way to review the details, so they can understand the cause of problems or plan appropriately for the future.

Logs collected in syslog support this by:

  • Providing information needed to return the system to a prior status after a failure
  • Containing details of individual applications to allow teams to understand trends and troubleshoot problem areas
  • Monitoring applications without impacting performance by writing the information to external devices or services

Syslog has a few weak spots. The flexibility of the message component is useful, but not having a standard format can sometimes be challenging. Syslog also employs User Datagram Protocol (UDP) to transport information, which means log messages could be lost if there’s network congestion. Finally, syslog does not include any authentication processes to prevent a machine from impersonating another.

The drawbacks are minor, though, compared to the benefits. Syslog provides a way to gather and retain important messages using a widely recognized and standardized protocol. It makes the job of administrators much easier, especially with the right syslog server.

Syslog Management Is Key

Once you know what syslog is, it’s clear it does more than an event log. Syslog is a comprehensive tool to gather information from multiple sources to make it easier to manage large networks.

Handling all that data can be a challenge, which is why a syslog server is critical. A good option with a free trial is SolarWinds Kiwi® Syslog Server. This dedicated log software offers the ability to view and filter messages, create reports, configure alerts, and more.

Kiwi Syslog free log monitoring system

Whatever solution you use, taking advantage of syslog is key to effectively managing all the devices on your network and keeping operations running smoothly.

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