Port 4840OPC UA PubSub over UDP

OPC UA PubSub UADP datagrams carried over UDP multicast for industrial telemetry and control.

transport: udp
in transit: cleartext
assignment: official
risk: 4/10
lookups: 0

also known as opcua-udp, UADP, OPC UA UDP Multicast

1 other service is registered on port 4840. compare all 2 →

Technical Details

what runs on :4840

OPC UA PubSub over UDP uses connectionless multicast datagrams, so there is no TCP-style handshake or persistent session. Messages use the OPC UA UADP NetworkMessage format and may include publisher identifiers, dataset metadata, sequence information, and payload fields; multicast addresses, ports, and message layout are configured by the deployment. UDP port 4840 is assigned for this multicast datagram service, while TCP port 4840 is separately used by the OPC UA binary client/server protocol.

Security Information

exposure of :4840

risk score

4/ 10caution

worth attention. how exposed you are depends on configuration — don't leave it reachable from the internet without a reason.

network services averages 3.0 across 983 ports — this one sits 1.0 above.

in transit

cleartext

credentials and payloads are readable by anyone on path

assignment

official

registered with iana for this service — scanners fingerprint it by number

reachable over

udp

udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite

security overview

This traffic is generally intended for a controlled local or industrial network, not direct Internet exposure. Without configured OPC UA PubSub security, multicast datagrams can be observed or spoofed and may disclose or influence process data; signed and encrypted security groups can provide integrity, authenticity, and confidentiality, but availability remains vulnerable to UDP or multicast disruption.

Record

iana registry entry

port: :4840
service: OPC UA PubSub over UDP
transport: UDP
encryption: cleartext
assignment: iana registered
risk: 4/10caution
category: Network Services
usage: This port carries OPC UA PubSub UADP NetworkMessages over UDP multicast between industrial publishers and subscribers. Engineers typically encounter it on local automation networks, where controllers, sensors, gateways, and monitoring systems exchange telemetry or commands.
lookups: 0rank 994
added: 2026-09-06
updated: 2026-09-06
references: IANA service name registry — port 4840

Something wrong?

This record is maintained by the engineers who use port 4840. Every field on it is editable — change what's wrong, say how you know, and a reviewer publishes it, usually within a minute. Last touched 2026-09-06.

01edit any field on a page of its own
02a model checks it for accuracy and spam
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edit this record →back to the registry

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all 983 in network services →

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risk mix of the 8 listed

caution100%

0 of 8 encrypted

Port :4840OPC UA PubSub over UDP

Technical Details

Security Information

Related Ports

Port 4840OPC UA PubSub over UDP