Port 4503Open Metering System (OMS) over UDP

UDP port for carrying Open Metering System (OMS) metering communications.

transport: udp
in transit: cleartext
assignment: official
risk: 2/10
lookups: 0

also known as m-bus-oms, OMS over UDP

Technical Details

what runs on :4503

IANA assigns UDP/4503 to M-Bus-OMS over UDP. UDP is connectionless, so there is no TCP-style session handshake; OMS defines the metering protocol carried by the transport. UDP itself does not provide encryption or reliable delivery, and the exact datagram encoding and security behavior depend on the applicable OMS profile and implementation.

Security Information

exposure of :4503

risk score

2/ 10safe

routine exposure. this port is rarely the way in on its own — keep it patched and logged and move on.

network services averages 2.6 across 1,548 ports — this one sits 0.6 below.

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

Avoid exposing this metering service directly to the public internet; restrict it to known devices or the metering network. Meter data can be sensitive, and UDP does not authenticate or encrypt traffic on its own, although OMS security profiles may protect the metering payload. There is no basis here to claim a known vulnerability specific to this port.

Record

iana registry entry

port: :4503
service: Open Metering System (OMS) over UDP
transport: UDP
encryption: cleartext
assignment: iana registered
risk: 2/10safe
category: Network Services IoT
usage: This assignment is for OMS, the metering interoperability system used with M-Bus devices, over UDP. Engineers are most likely to encounter it in metering equipment or gateways that exchange OMS traffic on a local or managed network.
lookups: 0rank 993
added: 2026-10-05
updated: 2026-10-05
references: IANA service name registry — port 4503

Something wrong?

This record is maintained by the engineers who use port 4503. 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 2026-10-05.

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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risk mix of the 8 listed

caution100%

0 of 8 encrypted

Port :4503Open Metering System (OMS) over UDP

Technical Details

Security Information

Related Ports

Port 4503Open Metering System (OMS) over UDP