Port 788: Unassigned — An empty door in the well-known range

Port 788 has no official service. It belongs to the well-known ports range (0-1023)—addresses reserved by the Internet Assigned Numbers Authority (IANA) for fundamental Internet services—but nobody ever claimed it.¹

What "Unassigned" Means

The well-known ports were supposed to be carefully stewarded. Ports 0-1023 require special privileges to use on most systems, a protection meant to ensure only trusted services could bind to these addresses.

But not every port got assigned. Port 788 is one of hundreds that remain officially unassigned—available for assignment if someone requests it through IANA's formal process, but sitting empty for now.²

Why This Port Sits Empty

The early Internet assigned ports as protocols were invented. SSH got port 22. SMTP got port 25. HTTP got port 80. But by the time we reached the 700s, most of the fundamental protocols already had their addresses. The urgency to fill every slot faded.

Port 788 sits in a range (788-799) that's almost entirely unassigned. These are the numbered seats at a table where nobody ever showed up.

Security Considerations

Unassigned doesn't mean unused. Any program can try to listen on port 788 if it has the right permissions. Malware sometimes binds to unassigned well-known ports precisely because they're unexpected—system administrators don't know what should be there.

If you see port 788 open on your system and don't know why, investigate:

# Linux/macOS - see what's listening on port 788
sudo lsof -i :788

# Windows - see what's listening on port 788
netstat -ano | findstr :788

An open port 788 isn't necessarily malicious. But if you didn't intentionally run something on it, find out what did.

The Broader Picture

The well-known ports range contains 1,024 addresses. Not all of them needed to be filled. Port 788 represents the gaps—the reserved space that turned out to be unnecessary, the addresses that wait in case someone someday needs them.

The Internet works fine with empty ports. They're not a problem. They're just a reminder that careful planning sometimes means setting aside space you might never use.

Related Ports

• Ports 788-799 — Almost entirely unassigned range in the well-known ports
• Ports 0-1023 — The well-known ports range, reserved for system services
• Ports 49152-65535 — Dynamic/ephemeral ports, where your system assigns temporary ports for outbound connections