Port 2766: Unassigned — Registered but Vacant

What Range This Port Belongs To

Port 2766 falls in the registered ports range (1024–49151), sometimes called the "user ports" range. IANA manages this space: organizations can formally request a port assignment for their protocol or application, and IANA records it in the official registry.

Registered ports are not first-come-first-served like domain names. They require an application, a defined protocol, and approval. Once assigned, the port is marked in the registry with the service name, protocol (TCP/UDP), and the organization responsible.

Port 2766 has no current assignment. It is listed as unassigned in the IANA registry — vacant registered territory.

Historical Associations

Port 2766 has shown up in a few contexts over the years, none of them current:

Solaris nlps_server — On older Sun Solaris systems (2.4, 2.5, 2.5.1), a System V listener service called nlps_server used this port. A buffer overflow vulnerability in that service allowed remote code execution, making port 2766 a target for attackers against Solaris infrastructure in the late 1990s and early 2000s.¹

Compaq SCP — Compaq's SCP (Session Control Protocol) was sometimes associated with this port in legacy enterprise environments. No modern HP/Compaq product continues to use it.

W32.HLLW.Deadhat (2004) — A worm with backdoor capabilities spread through file-sharing networks and used port 2766 as part of its command-and-control mechanism.¹ The port's most notable tenant was malware. That says something about how unassigned ports work in practice: when no legitimate service claims a port, something else often tries to.

How to Check What's Listening Here

If you see traffic on port 2766 and want to know what's using it:

On Linux/macOS:

# Show process listening on port 2766
ss -tlnp | grep 2766

# Or with lsof
lsof -i :2766

On Windows:

# Show process listening on port 2766
netstat -ano | findstr :2766

# Then find the process by PID
tasklist | findstr <PID>

Unexpected activity on an unassigned port like 2766 is worth investigating. Legitimate software generally uses assigned ports or chooses from the ephemeral range (49152–65535) for temporary connections.

Why Unassigned Ports Matter

The registered port range contains 48,128 possible ports. IANA has assigned only a fraction of them. The rest — including 2766 — are unclaimed.

This vacancy matters for two reasons. First, it gives the port system room to grow: new protocols can get clean assignments without collision. Second, it creates ambiguity. When traffic appears on an unassigned port, there is no official record to consult. You cannot look up what should be there. You can only look up what is there, on your system, right now.

That ambiguity is both a design feature and a security consideration. Unassigned ports are not inherently dangerous — but they are inherently unverifiable by registry lookup alone.