Internet-Security.com TCP port 3493 details

TCP port 3493 is the default port for Network UPS Tools (NUT) upsd, the daemon that serves UPS status and control to clients.
It’s used on many NAS systems and appliances, including Synology DSM (UPS Server), QNAP QTS, TrueNAS/FreeNAS, and OpenMediaVault.
Firewall/router and server platforms also expose it when running NUT, such as pfSense with the NUT package and standard Linux distributions running nut-server.
Client software like upsmon/upsc, Home Assistant’s NUT integration, Nagios/Checkmk/Cacti plugins, and other monitoring tools connect to 3493 to query or manage UPS devices.
Docker containers for NUT typically listen on 3493 as well.

TCP 3493