Port 3630: cs-remote-db — The Named Ghost

What Port 3630 Is

Port 3630 sits in the registered ports range (1024–49151) with an official IANA entry: service name cs-remote-db, description "C&S Remote Database Port," assigned on both TCP and UDP.¹

That's where the trail ends.

No RFC. No protocol documentation. No open-source implementation. No vendor page. "C&S" likely refers to a company — Computers & Structures, perhaps, or something else entirely — but whoever registered this port left no forwarding address. The registration exists; the software, if it ever shipped, does not appear to be in public use.

The Registered Ports Range

Ports 1024–49151 are called registered ports (sometimes "user ports"). Unlike the well-known ports below 1024 — which require root/administrator privileges to bind and carry protocols that everyone uses — registered ports are assigned by IANA on a first-come, first-served basis upon application.²

The bar is low. An organization fills out a form, proposes a service name, and IANA adds it to the registry. There's no requirement that the software ever ship publicly, that the protocol be documented, or that anyone besides the registrant ever use the port. The registry is a reservation system, not a hall of fame.

The result: thousands of ports like 3630, carrying names that answer no questions.

What You'll Actually Find on Port 3630

If you see traffic on port 3630 in your environment, it isn't cs-remote-db. It's something else — an internal tool, a development service, or occasionally malware that chose this port precisely because it's obscure enough to evade basic port-based firewall rules.

Check what's actually listening:

Linux / macOS:

# Show the process listening on port 3630
ss -tlnp | grep 3630
# or
lsof -i :3630

Windows:

netstat -ano | findstr :3630

With nmap (remote host):

nmap -sV -p 3630 <target>

Why Ghost Registrations Matter

The IANA registry works because everyone agrees to honor it. When a protocol like HTTP claims port 80, other software stays off port 80. The system depends on registrants actually using their ports — or releasing them when they don't.

Port 3630 is one of many registrations that occupy space without serving anyone. The port isn't dangerous, isn't blocked by default, and carries no particular history. It's just a name in a list, waiting for a service that may never come.

If you need a port for internal development and 3630 happens to be convenient, you'll find no one camping there.