Port 1505 is registered to "funkproxy," a protocol from Funk Software, Inc. that hasn't been actively used in over a decade. The port sits in IANA's registry like a tombstone—official, permanent, and pointing to something that no longer exists.
What Funkproxy Was
In the 1990s, Funk Software created Proxy, a remote control system that let administrators manage computers from across the network. Port 1505 was where the Proxy Host listened for connections from the Proxy Master.1
The software added TCP/IP support in version 4.1, making it possible to initiate remote control sessions over TCP port 1505.2 For its time, it was a useful tool in an era when remote administration meant Telnet or proprietary protocols.
What Happened to Funk Software
Funk Software was founded in 1982 in Cambridge, Massachusetts. The company started with utilities like Sideways (which printed wide spreadsheets on dot matrix printers), then shifted to network security in the late 1990s, becoming an early pioneer in RADIUS and AAA authentication.3
Juniper Networks acquired Funk Software in 2005 for $122 million.4 In 2014, Juniper sold the legacy Funk Software business unit to Siris Capital, which created Pulse Secure.5 Through these acquisitions and transitions, the original Proxy software was discontinued.
The company is gone. The software is gone. The port registration remains.
The Registered Range
Port 1505 sits in the registered port range (1024-49151). These ports are assigned by IANA to specific services upon request. Companies submit applications, IANA approves them, and the port becomes officially associated with that protocol.
The problem: nothing forces companies to maintain their registrations. When a company is acquired, when software is discontinued, when protocols become obsolete—the port assignments stay. IANA doesn't revoke them. The registry accumulates history like sediment.
What Uses Port 1505 Now
Unofficially, port 1505 has been observed in use by Microsoft Active Directory Federation Services (ADFS) for communication between ADFS servers and Web Application Proxy servers.6 This is not an official assignment—Microsoft didn't register it with IANA. But when you need a port and you find one that's technically registered but practically unused, you take it.
This is how ports get reused in practice. The official registry says one thing. The actual network says another.
Why This Matters
Most ports in the registered range tell the same story. Claimed by companies that have since been acquired, merged, or dissolved. Registered for protocols that nobody remembers. The IANA registry is part technical specification, part archaeological record.
When you see an unfamiliar port in your firewall logs, chances are decent it's one of these ghosts—officially assigned to something obsolete, actually used for something entirely different, or just scanning noise looking for vulnerabilities in software that hasn't existed in fifteen years.
How to Check What's Actually Using Port 1505
On Linux or macOS:
On Windows:
If you find something listening on port 1505, it's almost certainly not funkproxy. It might be ADFS. It might be something else entirely. The port number tells you what it was supposed to be, not what it actually is.
Frequently Asked Questions About Port 1505
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