What This Port Is
Port 3406 sits in the registered ports range (1024–49151). Unlike the well-known ports below 1024, registered ports don't require elevated privileges to open. They are meant to be claimed by specific applications and registered with IANA so that different software doesn't accidentally step on each other.
IANA's records show port 3406 assigned to nokia-ann-ch2 — "Nokia Announcement Channel 2" — registered in February 2002 by a Nokia engineer named Morteza Kalhour. Both TCP and UDP are listed.1
What Nokia Announcement Channel 2 actually did is not well-documented in any public RFC or specification. Nokia registered clusters of consecutive ports in the early 2000s for various internal and product-related services — SMS gateways, announcement systems, mobile infrastructure. Those products came and went. The IANA registration stayed.
The MySQL NDB Cluster Connection
In MySQL Cluster documentation, port 3406 appears as the PortNumberStats parameter for ndb_mgmd — the NDB Cluster Management Server daemon. This is a separate endpoint from the main management port (1186) and is used specifically for retrieving statistical information from the cluster management node.2
This is not an official IANA assignment for MySQL. It's a default value baked into MySQL Cluster's configuration, and it happens to land on a port that was already quietly claimed. In practice, if you're running MySQL NDB Cluster and see traffic on 3406, that's almost certainly what it is.
What to Do If You See It
If port 3406 shows up on a system you're investigating, check what's actually listening:
macOS/Linux:
Windows:
If you see ndb_mgmd in the output, you're looking at a MySQL NDB Cluster statistics endpoint. If you see something else entirely, you're in the territory of ad hoc usage — software that picked a port and happened to land here.
Why Registered-but-Dormant Ports Matter
The registered ports range contains thousands of entries like this one: claimed for a product or service that later shrank, pivoted, or disappeared, but never formally released. IANA registrations don't expire automatically.
This creates a practical problem. Developers looking for a "free" port to use for a new application might see 3406 listed in IANA's registry and correctly avoid it — even though nothing has used it in the Nokia sense for years. The registration acts as a soft reservation, keeping the port in a kind of permanent holding pattern.
It's a reminder that the port space has history. Every number has a story, even when the story is "a company that doesn't quite exist this way anymore registered this and never let go."
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