Port 217: dBASE Unix — The Reserved Seat Nobody Claims

Port 217 sits in an unusual category: officially assigned but functionally abandoned. IANA records list it as the designated port for "dBASE Unix," a database management system that needed network communication capabilities back when Unix systems were learning to share data across networks.¹

The service it was meant to serve no longer exists in any meaningful way.

What dBASE Unix Was

dBASE was a database management system that became popular in the 1980s and early 1990s. The Unix variant needed a way for database clients to communicate with database servers over TCP/IP networks. Someone at IANA assigned port 217 for this purpose—both TCP and UDP variants.²

The protocol was meant to handle database operations: queries, updates, record retrieval. Standard database communication for its era.

The Well-Known Port Range

Port 217 falls in the well-known port range (0-1023), also called system ports. These ports are assigned by IANA through formal procedures—"IETF Review" or "IESG Approval."³ Getting a port number in this range meant something in the early Internet. It signaled that your service was significant enough to warrant protection from conflicts.

Ports in this range require root privileges to bind on Unix-like systems. This restriction exists because these ports were meant for system services, not casual applications.

Current Reality

Port 217 appears in the official IANA registry. The assignment is still there. But dBASE Unix as a networked database service is gone. The ecosystem that would use this port disappeared years ago.

The port isn't reassigned because IANA doesn't recycle well-known port numbers easily. Once assigned, they tend to stay assigned, even when the service dies. The Internet has hundreds of these fossil ports—officially claimed but practically empty.

What This Means

If you see traffic on port 217 today, it's almost certainly not dBASE Unix. It could be:

• A custom application using an "available" port (not checking IANA records)
• Port scanning or security probing
• Misconfigured software
• Someone deliberately using an obscure assigned port, assuming it won't conflict with anything

To check what's listening on port 217 on your system:

# On Linux/Unix/macOS:
sudo lsof -i :217
sudo netstat -tulpn | grep :217

# On Windows:
netstat -ano | findstr :217

Why Unassigned (or Effectively Unassigned) Ports Matter

The Internet has 65,535 ports per protocol (TCP and UDP). Only 1,024 are in the privileged well-known range. The rest are split between registered ports (1024-49151) and dynamic/ephemeral ports (49152-65535).

Ports like 217 show the tension between official assignment and practical use. The bureaucracy says "claimed." Reality says "empty." This gap matters because:

• Developers might use these ports thinking they're free
• Security tools may not know what to expect on these ports
• Network documentation becomes archaeological—describing services that no longer exist

Port 217 is a reserved seat at a table where nobody shows up anymore. The reservation stands, but the guest never arrives.

Related Ports

Other database services claimed well-known ports in the same era:

• Port 3306: MySQL (still actively used)
• Port 5432: PostgreSQL (still actively used)
• Port 1521: Oracle (still actively used)

The difference: those services survived. dBASE Unix didn't.