Syslog
is a standard protocol that is widely used for logging system events and messages in IT systems, including servers, network devices, and other computer systems.
It provides a centralized repository for log data that can be used to analyse system behavior and performance, detect security threats, and diagnose problems.
Syslog works by sending log messages from a device or system to a central log server.
The log server collects and stores these log messages, which can then be analyzed and processed to gain insights into system behavior.
The log messages sent by a device or system include information such as the time and date of the event, the severity of the event, and a description of the event. This information can be used to identify patterns, track changes over time, and alert administrators to potential issues.
The default port used by the syslog protocol is UDP port 514. This is the standard port for syslog transmission, and is typically used by most syslog implementations.
In Syslog, each message is assigned a severity level, which indicates the type of event or message being recorded. The Syslog message levels are:
0 - Emergency: The system is in an unusable state.
1 - Alert: Action must be taken immediately.
2 - Critical: Critical conditions.
3 - Error: Error conditions.
4 - Warning: Warning conditions.
5 - Notice: Normal but significant conditions.
6 - Informational: Informational messages.
7 - Debug: Debug-level messages.
These levels allow administrators to categorize and prioritize the messages, making it easier to identify and address critical issues.
Syslog Facility Level
Syslog is a standard for message logging and is widely used for log management in computer systems. In Syslog, each message is assigned a facility level, which indicates the source of the message. The Syslog facility levels are:
0 - kernel messages 1 - user-level messages
2 - mail system
3 - system daemons
4 - security/authorization messages
5 - messages generated internally by syslog
6 - line printer subsystem
7 - network news subsystem
8 - UUCP subsystem
9 - clock daemon
10 - security/authorization messages
11 - FTP daemon
12 - NTP subsystem
13 - log audit
14 - log alert
15 - clock daemon (note 2)
16-23 - reserved for local use
These levels allow administrators to categorize and filter messages based on the source, making it easier to manage the logs and identify issues.
Syslog provides many benefits to IT professionals and organizations, including:
: Syslog provides a centralized repository for log data, making it easier to manage and analyze log data from multiple sources. This can help to reduce the time and effort required to troubleshoot problems and improve overall system performance.
Syslog can help to detect security threats by logging system events and messages that may indicate an attack. This information can be used to prevent and mitigate security incidents.
Syslog provides detailed information about system behavior and performance, allowing IT professionals to monitor their systems more effectively and detect any potential issues before they become major problems.
Syslog can help organizations to meet various compliance requirements, such as those related to data privacy, security, and audit.
: Syslog is a simple and straightforward protocol that is easy to implement and use. IT professionals can quickly and easily set up a syslog server and start collecting log data from their systems.
Rsyslog: A powerful and flexible syslog server that can be used for both centralized logging and log analysis.
Syslog-ng: A high-performance syslog server that supports advanced log processing and routing capabilities.
Graylog: A fully-featured log management platform that includes a syslog server, log analysis, and alerting capabilities.
Fluentd: An open-source data collector and log management tool that supports syslog input and output.
Logrotate: A log rotation utility that can be used to manage the size and retention of log files generated by syslog.
In addition to open-source options, there are also commercial syslog servers available, such as SolarWinds® Log Manager for SolarWinds, which offers advanced features such as real-time log analysis and alerting. The choice of syslog server will depend on the specific needs and requirements of an organization.