Port 625DEC DLM

Historic TCP/UDP assignment for the DEC Distributed Lock Manager service.

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

Technical Details

what runs on :625

DEC DLM uses port 625 over both TCP and UDP for proprietary binary inter-node lock-management traffic. It is a cluster-internal service rather than a request/response protocol intended for ordinary applications, and implementations are generally tied to DEC/OpenVMS clustering. The IANA entry is an alias for dec-dlm and is now historic; there is no broadly applicable modern handshake or framing specification for identifying arbitrary listeners on this port.

Security Information

exposure of :625

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 1,604 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

tcp · udp

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

security overview

A listener should normally be reachable only from authenticated or otherwise trusted cluster peers on a management or cluster network. The protocol is not generally deployed with encryption by default, and exposing it to the Internet could disclose cluster activity or provide an attack surface in legacy systems, although the service is obscure and rarely encountered in current scans.

Record

iana registry entry

port: :625
service: DEC DLM
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 2/10safe
category: Network Services System
usage: This port is associated with the DEC Distributed Lock Manager (DLM), a cluster coordination service used primarily by OpenVMS systems. It is normally encountered only between trusted nodes in legacy DEC or OpenVMS cluster environments, not as a general client-facing service.
lookups: 0rank 993
added: 2026-09-16
updated: 2026-09-22
references: IANA service name registry — port 625

Something wrong?

This record is maintained by the engineers who use port 625. 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 2026-09-22.

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 :625DEC DLM

Technical Details

Security Information

Related Ports

Port 625DEC DLM