Port 3358: Mp Sys Rmsvr — Fujitsu's Quiet Claim

What This Port Is

Port 3358 is registered with IANA — the Internet Assigned Numbers Authority, the organization that keeps the definitive list of who owns what port — under the service name mpsysrmsvr ("Mp Sys Rmsvr"), assigned to Fujitsu by a contact named Hiroyuki Kawabuchi.¹

It operates on both TCP and UDP.

That's the full extent of what the public record tells you. No RFC. No open-source implementation. No Stack Overflow threads asking why it's open. Just a name, a company, and a number.

What Range This Port Is In

Port 3358 sits in the registered ports range: 1024 through 49151.

The registered range is the middle tier of the port system:

• Well-known ports (0-1023): Controlled by IANA, assigned to foundational protocols. HTTP gets 80, HTTPS gets 443, SSH gets 22. These require elevated privileges to open on most operating systems.
• Registered ports (1024-49151): Applications and vendors register these with IANA to avoid collisions. You don't need root to open them, and registration doesn't mean wide adoption — it just means someone filled out the paperwork.
• Dynamic/ephemeral ports (49152-65535): Unregistered. Used temporarily by your OS for outbound connections. No one owns them.

Port 3358 has been formally claimed. That's worth noting. It's not a port someone is squatting on unofficially — Fujitsu registered it with the intent to use it for something specific inside their product ecosystem.

The Fujitsu Connection

The Fujitsu ServerView suite is an enterprise server management platform — software that monitors hardware health, manages remote access, and coordinates system operations across Fujitsu PRIMERGY servers. The "RMS" in "Mp Sys Rmsvr" almost certainly stands for Remote Management Service, consistent with the patterns in ServerView's architecture.²

Enterprise management software routinely registers ports for internal communication between agents, daemons, and management consoles. These ports are never meant to be public-facing. They're internal pipes inside a managed data center, invisible to anyone not running Fujitsu hardware with ServerView installed.

If you see port 3358 open on a system you're auditing and it's not running Fujitsu server management software, that's worth investigating.

How to Check What's Listening on This Port

On Linux or macOS:

# Show what process is listening on port 3358
ss -tlnp | grep 3358

# Or with lsof
lsof -i :3358

On Windows:

netstat -ano | findstr :3358

Then match the process ID to a name:

tasklist | findstr <PID>

If something unexpected shows up, that's your lead. An unrecognized process on a registered-but-obscure port is a reasonable thing to investigate.

Why Registered-but-Obscure Ports Matter

The registered port range holds over 48,000 port numbers. Most of them look like this: formally claimed, functionally invisible, meaningful only to the software that uses them.

This is actually how the system is supposed to work. The alternative is port chaos — applications colliding on the same numbers, debugging nightmares when two services both try to claim 3000. Registration is the handshake with the global registry that says "this is ours."

Port 3358 is registered. Fujitsu owns it. Outside of Fujitsu data centers running ServerView, you should never see it.