Port 977: Unassigned — A gap in the well-known ports

Port 977 belongs to the well-known ports range (0-1023), the addresses reserved by IANA for essential Internet services. But unlike its neighbors—DNS on 53, HTTP on 80, HTTPS on 443—port 977 has no official assignment.

According to IANA, port 977 falls within the unassigned block spanning ports 954-988.¹ It's an empty lot in a prestigious neighborhood.

What Does Unassigned Mean?

Unassigned doesn't mean unused. It means:

• No official service — IANA hasn't registered a protocol or service for this port
• Available for assignment — Someone could apply to IANA to claim this port number for a standardized service
• Possibly occupied anyway — Any application can listen on any port. Just because there's no official tenant doesn't mean the address is empty

Why Well-Known Ports Have Gaps

The well-known ports range (0-1023) was designed when the Internet was much smaller. Ports were assigned as protocols were created—telnet got 23, SMTP got 25, HTTP got 80. But not every number got claimed.

Some ports in this range were reserved for services that never became widely adopted. Others were simply skipped. Port 977 is one of the gaps—neither assigned nor explicitly reserved.

What Could Be Listening Here?

Even though port 977 has no official assignment, anything could be using it:

• Custom applications — Developers choose arbitrary ports for internal services all the time
• Malware — Backdoors and trojans sometimes pick obscure unassigned ports to avoid detection
• Research projects — Academic or experimental protocols might use unassigned ports during development
• Nothing at all — Most likely, nothing is listening on port 977 on your machine

Checking What's Actually There

On Linux or macOS:

# See if anything is listening on port 977
sudo lsof -i :977

# Or using netstat
sudo netstat -tuln | grep :977

On Windows:

# Check for listeners on port 977
netstat -ano | findstr :977

If something appears, investigate what process owns it. Unassigned ports in the well-known range shouldn't normally have listeners unless you're running custom software.

Why Unassigned Ports Matter

The existence of unassigned ports tells you something about the Internet's architecture: not everything was planned from the beginning. The well-known ports range has gaps because we couldn't predict every protocol we'd need.

Port 977 is evidence that the Internet grew organically. Some addresses got claimed early and became essential infrastructure. Others—like this one—are still waiting for their purpose.

Not every port number has a story. Sometimes the story is just the absence of one.