Internet-Security.com UDP port 34963 details

UDP port 34963 is used by PROFINET I/O Real-Time (RT) multicast traffic.
It appears on industrial Ethernet networks connecting PLCs and field devices—for example, Siemens SIMATIC S7‑1200/1500 controllers with ET 200 I/O racks, Siemens SINAMICS drives, and PROFINET‑enabled devices from vendors like WAGO, Phoenix Contact, and Festo.
You’ll see UDP/34963 carrying cyclic I/O data and alarms between controllers and devices in PROFINET RT deployments.
Wireshark identifies this as PROFINET RT multicast, and many ICS monitoring tools rely on this port to observe PROFINET traffic.
Security note: when exposed beyond the OT network, unauthenticated PROFINET traffic can aid reconnaissance or be abused for disruption (e.g., crafted RT/DCP packets causing device or network instability), so it should be isolated and filtered.

UDP 34963