Port 3377: Cogsys License Manager — A Ghost Assignment

What Range This Port Belongs To

Port 3377 sits in the registered port range (1024-49151). These ports are assigned by the Internet Assigned Numbers Authority (IANA) to specific services — but registration is not enforcement. A company can claim a port number, stop using it, dissolve, and the number stays on the books indefinitely. The IANA registry is a ledger, not a lock.¹

The Official Assignment: Cogsys Network License Manager

IANA assigns port 3377 (both TCP and UDP) to cogsys-lm, the Cogsys Network License Manager.² Network license managers are common in engineering and scientific software: a license server listens on a fixed port, and client machines check in to borrow a license seat before launching expensive applications.

The problem is that Cogsys, as a company, has largely disappeared from public documentation. What product ran on this port, who maintained it, when the assignment was made — none of this is clearly documented in surviving sources. The port has a registered name. The service behind it is effectively a ghost.

Who Actually Uses It

The more practically relevant use of port 3377 today is N-able Take Control, a remote desktop and managed IT service platform. Take Control uses port 443 (HTTPS) as its primary outbound connection channel, but falls back to TCP 3377 when port 443 is blocked or subject to deep packet inspection.³

If you see outbound traffic on port 3377 from a managed workstation, Take Control is the most likely explanation — not a Cogsys license server.

How to Check What's Listening

If you find port 3377 open on a machine and want to know what's using it:

On Linux or macOS:

# Show which process is listening on port 3377
sudo ss -tlnp | grep 3377

# Or with lsof
sudo lsof -i :3377

On Windows:

# Show all listening ports with process IDs
netstat -ano | findstr :3377

# Then look up the process by PID
tasklist | findstr <PID>

On any system, with nmap (from another machine):

nmap -sV -p 3377 <target-ip>

Why This Matters

Registered ports with dormant assignments create quiet gaps in the port landscape — ports that appear occupied on paper but are free in practice. Applications looking for an open, low-friction port sometimes land here by convention or coincidence.

For firewall administrators, port 3377 is worth a second look: if you're seeing unexpected outbound traffic on it, check whether Take Control or a similar remote management agent is installed. If you're seeing inbound traffic you didn't expect, the absence of a well-known active service on this port makes it worth investigating.