ESET's state-of-the-art scanning engine has unsurpassed scanning speed and detection rates combined with a tiny footprint that makes ESET Server Security for Linux (ESSL, formerly ESET File Security for Linux (EFS)) the ideal choice for any server on Linux.

The main functionality is covered by the On-demand scanner and On-access scanner (Real-time file system protection).

The On-demand scanner can be started by a privileged user (usually a system administrator) through the command line interface, the web interface, or the operating system's automatic scheduling tool (for example, cron). The term On-demand refers to file system objects being scanned by either user or system demand.

The On-access scanner is invoked whenever a user or operating system attempts to access file system objects. Thus a scan is triggered by any attempt to access file system objects.