Port 955: Unassigned — A Reserved but Unclaimed Well-Known Port

Port 955 is unassigned. It exists in the well-known port range (0-1023), but no protocol has ever claimed it as home.

What "Unassigned" Means

The well-known port range (0-1023) is controlled by IANA—the Internet Assigned Numbers Authority. These ports are supposed to be assigned to fundamental Internet services. Port 22 is SSH. Port 80 is HTTP. Port 443 is HTTPS.

Port 955 is... nothing. Officially.

IANA has reserved it, but no RFC has ever defined a service for it. No protocol has planted a flag. It's an empty lot in a valuable neighborhood.

The Unassigned Block

Port 955 isn't alone. It sits in the middle of an unusually large unassigned block: ports 954-988. That's 35 consecutive ports with no official assignment.¹

This is rare. In the well-known range, most ports have been claimed. Finding 35 consecutive empty ports is like finding an undeveloped city block in Manhattan.

Why hasn't anyone claimed this space? Maybe nobody needs it. Maybe the protocols that would have used these ports evolved to use dynamic ports instead. Maybe they're just waiting for the right service to come along.

What Might Be Listening

Just because a port is unassigned doesn't mean nothing uses it. Software developers can—and do—use any port they want. Your system might have something listening on port 955 right now.

Check what's using this port:

# Linux/macOS - show what's listening on port 955
sudo lsof -i :955

# Linux - alternative using netstat
sudo netstat -tulpn | grep :955

# Windows - show process using port 955
netstat -ano | findstr :955

If something appears, it's a custom application or service. Not a standard protocol.

Why Unassigned Ports Matter

The existence of unassigned ports tells you something about Internet architecture: it was designed with room to grow.

When the well-known port system was created, the designers didn't try to fill every slot. They left gaps. They reserved space for future protocols that didn't exist yet.

Some of those protocols arrived. Many didn't. Port 955 is still waiting.

Security Considerations

Unassigned ports are neutral. They're not inherently dangerous or safe. The risk depends entirely on what's using them.

If you see unexpected traffic on port 955:

• Investigate what's listening — Use the commands above to identify the process
• Verify the application — Unknown processes deserve scrutiny
• Check your firewall — Unassigned ports are often blocked by default, which is fine

According to SANS Internet Storm Center, port 955 shows minimal attack activity in their monitoring systems.² This makes sense—attackers target ports with known services. An unassigned port is an unknown, and unknowns are harder to exploit systematically.

The Empty Spaces

The Internet has thousands of assigned ports. Port 80 carries the web. Port 25 carries email. Port 53 answers DNS queries.

Port 955 carries nothing. It's reserved but unclaimed. A number in a registry with no story attached.

Maybe that will change. Maybe someday an RFC will assign port 955 to some new protocol, and this empty space will finally have a purpose.

Until then, it waits.