What Port 3569 Is
Port 3569 sits in the registered port range (1024–49151). IANA assigned it in August 2002 to the Meinberg Control Service (mbg-ctrl), on both TCP and UDP.
Meinberg is a German company that has been making precision timing hardware since 1970: GPS receivers, radio clocks, NTP time servers, PTP grandmaster clocks. The kind of gear that data centers, power grids, and telecom networks use when "close enough" time isn't good enough. Port 3569 is the control channel — the port through which their management software (mbgsvcd, their service daemon) talks to Meinberg timing devices on the network.1
If you see port 3569 open on a server, one of two things is happening: you're looking at a Meinberg timing appliance, or you're on a network where someone set up an NTP infrastructure and didn't close unused ports.
The Unofficial Use
In 1999, Novalogic shipped Delta Force 2, a military tactical shooter that used peer-to-peer multiplayer. The game needed UDP ports 3568 and 3569 open for multiplayer sessions to work through NAT.2
Two things occupying the same number for completely unrelated reasons — this happens constantly in the registered port range. Nobody coordinates. Nobody asks. The IANA registration is a reservation, not enforcement.
What Range This Port Belongs To
The registered port range runs from 1024 to 49151. These ports:
- Require IANA registration, but registration doesn't prevent others from using them
- Are available to non-root processes on most operating systems (unlike ports below 1024)
- Outnumber well-known ports 47:1, which is why collisions and informal uses accumulate
How to Check What's Listening
If you see port 3569 active on a machine and want to know what's actually using it:
On Linux/macOS:
On Windows:
The process ID in the output maps to a running process. On Linux, ss will show the process name directly with -p. On Windows, take the PID to Task Manager or run tasklist | findstr <PID>.
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