How can you use syslog for centralized logging and monitoring of IT systems?

1 What is syslog?

Syslog is a protocol that defines how log messages are formatted, transmitted, and received over a network. Syslog messages consist of a header and a payload, which contain information such as the timestamp, the hostname, the severity, the facility, and the message text. Syslog messages can be sent over UDP, TCP, or TLS, depending on the reliability and security requirements. Syslog servers are applications that listen for syslog messages on a specific port and store them in files, databases, or other destinations.

3 How to set up a syslog server?

In order to set up a syslog server, you must install and configure a syslog daemon on a dedicated machine or virtual machine. There are multiple syslog daemons available, such as rsyslog, syslog-ng, and Kiwi Syslog Server. The steps to set up a syslog server vary depending on the daemon chosen, but typically include starting the service, configuring the daemon to listen for syslog messages on the desired port and protocol, and configuring it to store the messages in the desired destination. Additionally, you can configure the daemon to filter, parse, transform, or enrich the messages according to your needs. Finally, you should test the server by sending some test messages from a source system and verifying that they are received and stored correctly.

4 How to configure syslog sources?

To configure syslog sources, you need to enable and configure the syslog client on each device or application that you want to send logs to the syslog server. A syslog client is a program or feature that generates and sends syslog messages over the network, and the steps for configuration may vary depending on the type and vendor of the device or application. Generally, you'll need to enable the syslog client on the device or application, specify the syslog server's IP address and port, configure the severity and facility levels of log messages, format them according to the syslog protocol, and add any custom fields, tags, labels, or metadata if needed. Finally, you can test your syslog source by generating some log messages and verifying that they are sent and received by the syslog server.

5 How to use syslog for monitoring and alerting?

In order to use syslog for monitoring and alerting, you need to utilize a tool or service that can analyze, visualize, and alert on the syslog messages stored in the syslog server. There are many tools and services available for this purpose, such as Logstash, Elasticsearch, Kibana, Grafana, Nagios, Zabbix, and more. The steps to use syslog for monitoring and alerting may differ depending on the tool or service selected; however, they usually involve connecting the tool or service to the syslog server and importing the syslog messages into its database or index. Additionally, creating dashboards or charts to identify patterns, trends, anomalies, or issues is essential. Furthermore, creating queries, filters, rules, or policies to extract relevant information or insights from the syslog messages is necessary. Lastly, setting up alerts, notifications, or actions to trigger when certain conditions are met in the syslog messages and notify the relevant stakeholders is required.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?