Port 439 sits in the well-known port range (0-1023), officially assigned by IANA to a service called DASP. It has an owner, a purpose, documentation—everything except widespread use.
This is the story of assigned ports that became ghosts.
What Port 439 Was Assigned For
According to IANA's official registry, port 439 is assigned to "dasp" on TCP, with the contact listed as Thomas Obermair.1 The protocol name stands for either "Distributed Authenticated Service Protocol" or "Datagram Authenticated Session Protocol" depending on which era you're looking at.
The earlier version was a Distributed Authenticated Service Protocol developed by Inlab Networks in the 1990s, designed to establish authenticated connections between peers with support for encryption.2
The later incarnation was a Datagram Authenticated Session Protocol designed for low-power wireless networks and embedded devices, running over UDP to provide reliable, ordered delivery of datagrams with built-in flow control and cryptographic negotiation.3
Both protocols were real. Both were documented. Neither gained traction.
The Well-Known Range
Port 439 belongs to the well-known port range (0-1023), also called system ports. These are the prestigious addresses of the Internet—assigned by IANA for services expected to be universally recognized.4
When RFC 6335 cataloged the port landscape in 2011, approximately 76% of well-known ports were assigned.4 Port 439 is part of that 76%—technically claimed, practically unused.
This is how the Internet works: not every assignment becomes a standard. Some protocols get port numbers and fade away, leaving behind only registry entries and forgotten documentation.
What Actually Runs Here
In practice? Probably nothing.
Port 439 might occasionally appear in network scans as part of enumeration sweeps, but you won't find major services listening here. The protocols assigned to this port never achieved the adoption needed to make the port number meaningful.
To check what's listening on port 439 on your system:
Most likely, you'll find nothing. Port 439 exists in the registry, not in your network traffic.
Why Unassigned-in-Practice Ports Matter
Port 439 isn't technically unassigned—it has an official owner. But functionally, it behaves like an unassigned port: available space in a crowded namespace.
The well-known port range is finite. Only 1,024 addresses exist in this prestigious space, and once assigned, they stay assigned even when the protocol dies. Port 439 represents opportunity cost—a number that could have gone to a protocol that mattered, now locked to one that didn't.
This is the reality of protocol evolution. Some services—HTTP (80), HTTPS (443), SSH (22)—become fundamental to the Internet's operation. Others get assigned, documented, and forgotten. Port 439 is the latter: a tombstone in the registry, marking where someone tried to build something and didn't quite succeed.
The Internet is built on both the protocols that won and the ones that lost. Port 439 is a reminder that assignment doesn't guarantee relevance, and that the map of ports is as much a historical record as it is a functional directory.
Related Ports
- Port 440: sgcp (Simple Gateway Control Protocol) - Another assigned-but-obscure well-known port
- Port 438: dsfgw (IBM Datastore Gateway) - Similar story of official assignment, minimal usage
- Ports 0-1023: The well-known port range, where assignments last forever whether protocols do or not
Checking What's Listening
If you want to verify whether anything is using port 439 on your network:
Was this page helpful?