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// IoT & industrial (ICS)

Port 34964: PROFInet Context Manager

Port 34964 is assigned by IANA to profinet-cm (PROFInet Context Manager).

34964

How profinet-cm works

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

A controller sends commands to an industrial device on port 34964, 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 34964 dangerous?

We have no specific security note for port 34964. 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 34964

ServicePortTransportDescriptionReferenceUpdated
profinet-cm 34964 TCP, UDP PROFInet Context Manager - 2026-03-16

// source: IANA service name and port number registry

03 Check it

Which program uses port 34964, and is it reachable?

Linux

sudo ss -ltnup 'sport = :34964'      # process listening on 34964
sudo lsof -nP -i :34964

macOS

sudo lsof -nP -i :34964

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 34964 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 34964
netstat -ano | findstr :34964

From another machine

nmap -p 34964 -sV <host>
sudo nmap -sU -p 34964 <host>
nc -zv <host> 34964

Block it in the firewall

sudo ufw deny 34964/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 34964" -Direction Inbound -LocalPort 34964 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 34964 used for?

Port 34964 is assigned by IANA to profinet-cm (PROFInet Context Manager).

Is port 34964 TCP or UDP?

Port 34964 is registered for TCP and UDP.

Is it safe to open port 34964?

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 34964 is open?

On Linux run "ss -ltnup 'sport = :34964'", on macOS "lsof -nP -i :34964", and on Windows "netstat -ano | findstr :34964" to see the local process. From another machine, "nmap -p 34964 <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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