Port 4840

opcua-tcp and opcua-udp · TCP/UDP

RangeRegistered port (1024–49151)
ProtocolTCP/UDP
Serviceopcua-tcp and opcua-udp
Registered2006-09
Modified2018-01-04

Frequently asked questions

What is port 4840 used for?

Port 4840 is registered with the IANA for opcua-tcp and opcua-udp (TCP/UDP). Description: OPC UA Connection Protocol; OPC UA Multicast Datagram Protocol.

Is port 4840 a well-known port?

No. Port 4840 is in the range 1024–49151 (registered or user ports). Ordinary programs may open it without root privileges.

How do I check whether port 4840 is open?

Locally on Linux with ss -tulpn | grep ':4840\b', on Windows with netstat -ano | findstr :4840. To test a remote host use Test-NetConnection <host> -Port 4840 in PowerShell or nc -zv <host> 4840 on Linux/macOS.

How do I open port 4840 in the firewall?

Ubuntu/Debian (ufw): sudo ufw allow 4840/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=4840/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 4840" -Direction Inbound -Protocol TCP -LocalPort 4840 -Action Allow.

IANA registry entries

ProtocolServiceDescription (IANA)
TCPopcua-tcpOPC UA Connection Protocol
UDPopcua-udpOPC UA Multicast Datagram Protocol

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