Registered in 2009 for the Tofino industrial security appliance used on SCADA networks.
IANA lists 6689/tcp and 6689/udp as tsa, "Tofino Security Appliance", registered in October 2009. Tofino is an industrial firewall dropped inline in front of PLCs and other control-system gear, and the port carries its management and configuration traffic rather than plant process data. You would only see it inside an operational-technology network, next to the device it protects.
Do not expose
This is the management plane of a control-system firewall. It belongs on an isolated OT management segment with no path from the internet.
$ nc -vz TARGET 6689Seen this on your network? Beige Box scans your Wi-Fi and shows every open port on every device — and its Ports tool links straight back here.
Get Beige Box →also available as JSON · Markdown
Corrections or a missing port? Reply @rimrocksystems.