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// IoT & industrial (ICS)

Port 34963: PROFInet RT Multicast

Port 34963 is assigned by IANA to profinet-rtm (PROFInet RT Multicast).

34963

How profinet-rtm works

IoT & industrial (ICS)
controllerPLCprofinet-rtmno authentication controllerPLCprofinet-rtmno authentication

A controller sends commands to an industrial device on port 34963, which acts on the physical process.

Transport
TCP · UDP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned1 registered service
Range
Registered (1024-49151)
Category
IoT & industrial (ICS)
01 Security

Is port 34963 dangerous?

We have no specific security note for port 34963. Its risk depends on the program actually listening on it. General advice for iot & industrial (ics) services:

  • Industrial and IoT protocols often have no authentication: never expose them to the Internet.
  • Segment OT networks from IT and use protocol-aware firewalls.
  • Monitor with an ICS-aware intrusion detection system.
02 Registry

IANA registry entries for port 34963

ServicePortTransportDescriptionReferenceUpdated
profinet-rtm 34963 TCP, UDP PROFInet RT Multicast - 2026-03-16

// source: IANA service name and port number registry

03 Check it

Which program uses port 34963, and is it reachable?

Linux

sudo ss -ltnup 'sport = :34963'      # process listening on 34963
sudo lsof -nP -i :34963

macOS

sudo lsof -nP -i :34963

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 34963 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 34963
netstat -ano | findstr :34963

From another machine

nmap -p 34963 -sV <host>
sudo nmap -sU -p 34963 <host>
nc -zv <host> 34963

Block it in the firewall

sudo ufw deny 34963/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 34963" -Direction Inbound -LocalPort 34963 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 34963 used for?

Port 34963 is assigned by IANA to profinet-rtm (PROFInet RT Multicast).

Is port 34963 TCP or UDP?

Port 34963 is registered for TCP and UDP.

Is it safe to open port 34963?

It depends on the program that listens on it. Open it only for a service you know and only to the networks that need it. Industrial and IoT protocols often have no authentication: never expose them to the Internet.

How do I check if port 34963 is open?

On Linux run "ss -ltnup 'sport = :34963'", on macOS "lsof -nP -i :34963", and on Windows "netstat -ano | findstr :34963" to see the local process. From another machine, "nmap -p 34963 <host>" shows whether it is reachable.

05 Related
:1883 MQTT tcp · udp · high risk :8883 MQTT over TLS tcp · udp · moderate risk :502 Modbus TCP tcp · udp · critical risk :102 Siemens S7 (ISO-TSAP) tcp · udp · critical risk :47808 BACnet udp · tcp · critical risk :20000 DNP3 tcp · udp · sctp · critical risk :44818 EtherNet/IP tcp · udp · critical risk :802 Modbus Application Protocol Secure tcp · udp

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