What This Port Is
Port 3562 sits in the registered port range (1024–49151), the middle band of the port number space. These ports are assigned by IANA on request to specific services, distinguishing them from the well-known ports below 1024 (reserved for core protocols like HTTP, SSH, and DNS) and the ephemeral ports above 49151 (used temporarily by clients for outgoing connections).
The registered range is large — over 48,000 ports — and a significant fraction of them hold registrations like this one: old, obscure, and functionally abandoned.
The SDBProxy Registration
IANA records show port 3562 assigned to SDBProxy, registered in August 2002.1 The description: a database middleware proxy. The registrant: Eric Grange.
That's nearly everything documented about it.
SDBProxy doesn't have a surviving website, a public repository, a Wikipedia entry, or meaningful forum discussion. It existed in an era when database middleware was a legitimate architectural problem — applications needed connection pooling, query routing, and load balancing across database servers, and solutions like SDBProxy were emerging to fill that gap. MySQL Proxy, ProxySQL, and PgBouncer eventually became the answers the industry converged on. SDBProxy apparently did not.
The registration persists because IANA port assignments don't expire. Once claimed, a port holds its name indefinitely, whether the software behind it thrives or disappears. Port 3562 is a permanent record of a problem someone cared about solving in 2002.
What You Might Actually Find Here
In practice, port 3562 is unoccupied on virtually every system. If something is listening on it, it's one of:
- A development tool or local service that chose this port to avoid conflicts
- Custom application configuration
- A network scanner or intrusion detection system flag worth investigating
No known malware families are associated with port 3562, and no common software defaults to it.
Checking What's Listening
macOS / Linux:
Windows:
Cross-platform (with nmap):
If you find something listening here unexpectedly, the lsof or netstat output will give you the process ID (PID), which you can use to identify the responsible application.
Why Unassigned-in-Practice Ports Matter
The registered port range was designed to be a reservation system. Register your service, get a number, tell the world. In theory, any given registered port points to one known thing.
In practice, the range is full of registrations like SDBProxy's — technically claimed, functionally vacant. This creates a minor coordination problem: software that wants to pick a port for internal use has to navigate around a minefield of names, some active, some ghost. Port scanners flag everything; administrators have to trace each one.
It's a reminder that the port registry is a historical record as much as a live directory. Port 3562 tells you something about what people were building in 2002. It tells you almost nothing about what's running in your network today.
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