Port 1974: DRP — A registered port no one talks about

What Range This Port Belongs To

Port 1974 falls in the registered port range (1024-49151). These ports are registered with IANA — the Internet Assigned Numbers Authority — which means someone at some point submitted a request claiming this port for a specific service. Registration doesn't guarantee the protocol is widely used, actively maintained, or even that the software still exists.

Unlike the well-known ports below 1024 (which require root/administrator privileges to bind on most systems), registered ports can be claimed by any process. The registration is a courtesy — a way of saying "we use this, please don't."

The IANA Assignment

IANA lists port 1974 as assigned to DRP — Datagram Relay Protocol on both TCP and UDP. No RFC governs it. No major documentation exists for it. It's the kind of entry that suggests a protocol was registered, used internally by one organization, and quietly faded.

If you've stumbled onto port 1974 and were hoping to find a rich protocol history behind it, there isn't one to find.

The One Thing That Shows Up: xArrow SCADA

The real-world appearance of port 1974 is associated with xArrow, a SCADA (Supervisory Control and Data Acquisition) system used in industrial control environments. SCADA systems monitor and control physical infrastructure — water treatment plants, electrical grids, manufacturing equipment.

xArrow used port 1974 for its server communications. That would be a footnote, except for what CISA (the U.S. Cybersecurity and Infrastructure Security Agency) published about it:

• Multiple integer overflow vulnerabilities in xArrow's server allowed remote attackers to execute arbitrary code by sending specially crafted packets to UDP port 1974.¹
• Denial-of-service conditions could be triggered through the same port.
• xArrow versions 7.2 and prior carried multiple additional vulnerabilities, including cross-site scripting and unvalidated registry key execution.²
• CISA noted that xArrow did not respond to requests to work on mitigating the issues.

A SCADA system with unpatched remote code execution vulnerabilities, sitting on a quiet registered port, is exactly the kind of thing that makes security researchers nervous. Industrial control systems don't reboot easily.

If you're running xArrow or see traffic on port 1974 in an industrial environment, treat it as a priority to investigate.

How to Check What's Listening on Port 1974

On Linux or macOS:

# Show processes listening on port 1974
ss -tlnp sport = :1974

# Or with lsof
lsof -i :1974

On Windows:

netstat -ano | findstr :1974

The output will show the process ID. From there, use Task Manager or tasklist to identify what's running.

If nothing is listening, the port is closed. If something unexpected is listening, that's worth investigating.

Why Unassigned and Obscure Ports Matter

The registered range contains thousands of ports like this one — technically claimed, minimally documented, associated with software that may or may not still be in use. They matter for two reasons:

Inventory: If a port is open on your system, you should know why. An open port is an attack surface. "I don't know what that is" is not an acceptable answer in a security audit.

Detection: Attackers sometimes use obscure registered ports deliberately — they're less likely to be flagged by rules targeting well-known ports. Traffic on port 1974 in an environment that doesn't run xArrow or any DRP implementation deserves scrutiny.

The registered port range is the Internet's middle ground: not the chaos of ephemeral ports, not the structured clarity of well-known ports. Just tens of thousands of claims, some maintained, many forgotten.