In the dynamic realm of digital technology, a robust system for logging events and errors across IT infrastructure is paramount. Syslog serves this purpose. This blog post will unpack what Syslog is, delve into its working mechanism, and elucidate its importance in the context of modern IT operations.

Understanding Syslog

Originating from the phrases "system logging," Syslog is a protocol leveraged for transmitting event messages from network devices, like servers, switches, and routers, to a centralized server. This server acts as a storage and analysis hub. First brought to light in 1980 as part of the UNIX operating system, Syslog has found widespread usage in modern times.

Syslog Working Mechanism

Syslog functions by generating log messages that are transmitted over the network to a centralized Syslog server. These messages contain detailed information regarding events that transpire on a device, such as network activity, system errors, and security incidents.

A device generating a Syslog message includes crucial information such as the event's severity, the time it happened, the generating device, and a detailed event description. This message is then dispatched to the Syslog server using either the User Datagram Protocol (UDP) or the Transmission Control Protocol (TCP). The Syslog server parses and stores this data in a database for later analysis, enabling administrators to troubleshoot problems, identify trends, and enhance system performance.

The Importance of Syslog

Syslog's importance in modern IT operations cannot be overstated, and here's why:

  1. Centralized Logging: Syslog offers a centralized solution for logging events across all IT infrastructure devices, streamlining system event monitoring and troubleshooting for administrators.
  2. Enhanced Security: By providing a central repository for storing security-related events, Syslog boosts system security. Syslog data analysis allows administrators to detect security incidents and implement preventative measures for future threats.
  3. Regulatory Compliance: Compliance with regulatory requirements such as the Payment Card Industry Data Security Standard (PCI DSS) and the Health Insurance Portability and Accountability Act (HIPAA) necessitates event logging and monitoring. Syslog facilitates this by providing a centralized location for log storage and analysis.
  4. Performance Monitoring: Syslog can be harnessed for system performance monitoring, enabling early identification of issues. Administrators can optimize system performance by analyzing Syslog data to spot trends and track resource usage.

Choosing Syslog Over SNMP

It's crucial to ask why one should choose Syslog over Simple Network Management Protocol (SNMP), a protocol used by numerous network management tools. SNMP uses a polling component that queries devices for Object Identifier (OID) information, primarily for performance-based metrics. SNMP can also send TRAPS, which are alert thresholds defined within the OID values.

While SNMP is useful, it's important to note that Cisco's IOS only has 90 defined SNMP TRAPs compared to over 35,000 possible Syslog messages. Most proficient engineers and administrators opt for logs to diagnose problems, as logs usually contain detailed and useful information.

The main reason some organizations don't primarily use logging as a management tool is due to the sheer volume of messages being processed. Until recently, the data volume made it challenging to use logs effectively, and the processing requirements necessary to search across terabytes of log data were not accommodating.

Inside the Syslog Protocol

Developed in the 1980s by Eric Allman as part of the Sendmail project, Syslog is now standardized within the IETF's Syslog working group. Syslog messages, according to RFC 3164, can be sent via UDP (514) and/or TCP. While typically sent in clear text, encryption methods are available. The Syslog message contains five distinct fields: Facility, Severity, Hostname, Timestamp, and Message.

Syslog Message Facility

Syslog messages are classified based on the sources that generated them, such as the operating system, process, or application. These categories, represented as integers ranging from 0-23, are used by Cisco devices for local facility ranges 16-23 (local0 – local7).

Syslog Message Severity

The log source, such as a router, which generates the Syslog message, specifies the message's severity using single-digit integers 0–7. Most networking devices use log levels 0-6, with level 7 used for console troubleshooting.

Syslog Severities
Syslog Message Severities

Syslog Message Hostname

The hostname field comprises the host name or the IP address. In devices with multiple interfaces, Syslog uses the IP address of the interface from which the message is sent.

Syslog Message Timestamp

This is the local time of the device when the message was generated, formatted as MMM DD HH:MM:SS.

Syslog Message Text

This is the text of the syslog message, along with some additional information about the process that generated it.

Syslog plays a crucial role in contemporary IT operations, offering a centralized location for storing and analyzing event logs from network devices. By deploying Syslog in your IT infrastructure, you can improve network visibility, enhance security, and boost system performance.

July 11, 2023
LogZilla University

More from the

LogZilla University


View All