Port 3435: Pacom Security User Port — Physical Security Systems

What Port 3435 Is

Port 3435 is registered with IANA to Pacom Systems as the "Pacom Security User Port," registered in March 2002. Pacom builds integrated physical security platforms — access control systems, intrusion alarms, video surveillance, elevator control, and building management — primarily for enterprise deployments like banks, utility companies, and large campuses.

This is a door-lock-and-alarm company, not a software vendor. Port 3435 is used by Pacom's GMS (Global Management System) platform for communication between its security controllers and management software.

If you're not running Pacom hardware on your network, you should not see this port open.

The Registered Port Range

Port 3435 sits in the registered port range (1024–49151). Here's what that means:

• Well-known ports (0–1023) are reserved for universal protocols: HTTP on 80, HTTPS on 443, SSH on 22. The IANA guards these carefully.
• Registered ports (1024–49151) are where vendors and projects register their software. Anyone can apply. IANA records the claim, but enforcement is minimal — it's a registry, not a bouncer.
• Dynamic/ephemeral ports (49152–65535) are unregistered and used temporarily by your OS for outbound connections.

The registered range holds over 48,000 ports. Most are claimed by software you've never heard of. Pacom's claim on 3435 is legitimate but narrow — it matters on networks running their hardware and nowhere else.

How to Check What's Listening on This Port

If you see activity on port 3435 and you're not running Pacom systems, investigate:

Linux / macOS:

# Show what process is listening on port 3435
ss -tlnp | grep 3435

# Or with netstat
netstat -tlnp | grep 3435

# Or check all connections involving this port
lsof -i :3435

Windows:

netstat -aon | findstr :3435

The PID in the output can be cross-referenced in Task Manager or with tasklist /fi "PID eq [pid]" to identify the owning process.

Why Unassigned and Niche Ports Matter

The port registry is a map of intent. Most of those 48,000 registered ports are quiet — registered once, used by specific enterprise hardware, and invisible to ordinary traffic. But that quietness is also why an unexpected open port stands out.

Security scanners flag unexpected open ports precisely because legitimacy here is about context. Port 443 being open is expected on a web server. Port 3435 being open is a question: do you actually have Pacom physical security hardware talking to a management system, or is something else going on?

Unassigned and niche ports are the dark matter of the port space — most of them are nothing, but the one that isn't nothing is worth knowing about.