Port 1515 occupies an interesting space in the port number system. It's registered with IANA under the name "ifor-protocol," but there's no RFC, no official documentation, no trail explaining what "ifor" actually means or what the protocol does.1
And then you search the actual Internet and find where it's really used.
What Port 1515 Does
Port 1515 is a registered port (in the 1024-49151 range) available for both TCP and UDP.2 The IANA registry lists it as "ifor-protocol" with no further explanation—just a name attached to a number.
But in practice, port 1515 has found a specific use: Wazuh agent enrollment.
Wazuh Agent Enrollment
Wazuh, an open-source security monitoring platform, uses port 1515/TCP for enrolling new agents with its central manager.3 When you deploy a Wazuh agent on a system, it connects to the manager on port 1515 to register itself and receive its authentication credentials.
The enrollment process works like this:
- Agent connects to manager on port 1515/TCP
- Connection is encrypted with TLS
- Agent authenticates (optionally with a shared password)
- Manager issues credentials stored in
client.keys - Agent can now report to manager on port 1514
The connection is secure by default—TLS encryption protects the enrollment process from interception.4 You can add additional security with password authentication, where agents must provide a shared password read from /var/ossec/etc/authd.pass.
Port 1515 is enabled by default in Wazuh and listens for new agent connections automatically.5
The Registered Ports Range
Port 1515 sits in the registered ports range (1024-49151). These ports are assigned by IANA but require less stringent procedures than well-known ports (0-1023). Organizations can request registration for their protocols and services.
The "ifor-protocol" registration suggests someone once submitted this port for a specific protocol, but the documentation never made it into the public record. The name remains, cryptic and unexplained.
Why Unassigned Ports Matter
Ports like 1515 demonstrate something important about how the Internet actually works: official designation matters less than actual usage.
The IANA registry provides structure and prevents conflicts, but it doesn't dictate reality. Software developers need ports for their applications. If a registered port has minimal documented use, it becomes available for new purposes—like Wazuh choosing 1515 for agent enrollment.
This is how the port space stays useful. The 48,128 registered ports aren't all actively used by their original registrants. Some registrations are ancient, some protocols are dead, some names like "ifor-protocol" lead nowhere. The ports get repurposed by software that needs them.
How to Check What's Listening on Port 1515
If you want to see whether something is listening on port 1515 on your system:
On Linux/Mac:
On Windows:
If you see Wazuh's ossec-authd process, that's agent enrollment listening. If you see something else—or nothing—then either the port is unused or another application claimed it.
The Mystery of "ifor-protocol"
What was "ifor-protocol" supposed to be? No one seems to know.
There's no RFC defining it. No documentation from the original registrant. No historical software that obviously used it. Just a name in the IANA database, attached to port 1515, with no story behind it.
This happens more often than you'd think. The port registry contains hundreds of entries like this—names without narratives, protocols without papers, registrations that outlived their purpose or never fulfilled it in the first place.
And then someone like the Wazuh developers comes along, needs a port for secure agent enrollment, sees 1515 isn't being actively used, and gives it new life.
That's the real story of port 1515: a registered port with a mysterious name that found its purpose anyway.
Frequently Asked Questions About Port 1515
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