syslog-ng is a free and open-source implementation of the syslog protocol for Unix and Unix-like systems.

The second is called syslog-ng Premium Edition (PE) and has additional plugins (modules) under a proprietary license.

[2] In January 2018, syslog-ng, as part of Balabit, was acquired by One Identity under the Quest Software umbrella.

This time around, syslog-ng depended on some code originally developed for lsh by Niels Möller.

In a volunteer based effort, yet another rewrite was started back in 2001, dropping lsh code and using the more widely available GLib library.

PE efforts were focused on quality, transport reliability, performance and encrypted log storage.

It allows more precise filtering and sending data with proper type information to databases and document stores.

While syslog-ng PE is based on the open-source edition, its version numbering is completely independent of it.