Port 2071: ACP — The Quiet Port Behind Broadcast Infrastructure

What Port 2071 Is

Port 2071 sits in the registered port range (1024–49151). These are ports that can be formally claimed by organizations through IANA, but aren't reserved for system-level services the way ports below 1024 are.

IANA's official registry lists port 2071 as unassigned. But several port reference databases and, more tellingly, actual product documentation from Axon Digital Design associate it with ACP — the Axon Control Protocol, used for managing professional broadcast video equipment.¹²

The Axon Control Protocol

Axon Digital Design makes signal processing equipment for broadcast television: frame synchronizers, embedders, converters, the hardware that keeps live TV coherent as it moves through a facility. Their equipment communicates over a proprietary protocol called ACP, and the port it listens on is 2071.¹

The Axon ACP Frame Manager — a connector used in broadcast monitoring platforms like DataMiner — polls and configures Axon frames and their installed cards over TCP port 2071. Both the primary management connection and the broadcast notification connection use this same port.¹

This is the kind of protocol that doesn't show up in consumer networking guides. It lives in rack rooms at television studios and broadcast facilities, moving configuration and status data between control systems and signal processing hardware.

What "Unassigned" Actually Means

The gap between IANA's "unassigned" label and the real-world use of port 2071 is instructive.

IANA doesn't monitor every port in use on the Internet. Organizations can and do pick ports for proprietary protocols without filing a formal registration. Sometimes they register later. Sometimes they don't. The registered range is large enough (48,128 ports) that most of it goes unclaimed in the official registry, even as individual ports accumulate real-world uses over decades.

Port 2071 appears to be one of those: a port with genuine use in a specialized industry, but without the formal paperwork to match.

Security Observations

SANS Internet Storm Center logs scanning activity against port 2071, as it does for most ports. The scans appear opportunistic rather than targeted — scanners sweeping ranges looking for anything open, not specifically hunting for Axon equipment.³

If you see port 2071 open on a general-purpose server with no broadcast equipment attached, that's worth investigating.

How to Check What's Listening

Linux/macOS:

ss -tlnp | grep 2071
# or
lsof -i :2071

Windows:

netstat -ano | findstr :2071

With nmap (from another machine):

nmap -sV -p 2071 <target-ip>

The -sV flag asks nmap to probe the port and try to identify the service — useful when you need more than just "something is open."