Port 1090: The unassigned port tracking aircraft worldwide

Port Number: 1090
Transport Protocols: TCP, UDP
Official Assignment: Unassigned
Port Range: Registered ports (1024-49151)

What Port 1090 Does

Port 1090 is officially unassigned by the Internet Assigned Numbers Authority (IANA)¹. It has no designated service or protocol. This doesn't mean the port is unused—it means anyone can use it for anything, and several applications have.

The most notable use is in aviation tracking software. While aircraft broadcast ADS-B signals on the 1090 MHz radio frequency, software like dump1090 (used by FlightAware's PiAware) processes this data and makes it available over network ports, including port 1090 in some configurations². Thousands of hobbyists run these systems on Raspberry Pi devices, feeding data to flight tracking networks that monitor roughly 90,000 unique aircraft daily³.

Beyond aviation, port 1090 appears in enterprise systems. Cisco's Unified Communications Manager uses TCP 1090 for the AON Management Console (AMC) Service, providing real-time monitoring, data collection, and alerting⁴. Some implementations of FF Fieldbus Message Specification also reference this port⁵.

Occasionally, web proxies and VPN services use port 1090 as an alternate port when standard ports are blocked or unavailable⁶.

The Registered Ports Range

Port 1090 belongs to the registered ports range (1024-49151). IANA assigns these ports to specific services upon application, but registration isn't mandatory. Developers can use unassigned ports freely, which is why you'll find port 1090 serving different purposes across different systems.

The lack of official assignment creates flexibility but also ambiguity. If you see traffic on port 1090, you can't immediately know what it is—you have to look at the specific software running on that system.

Security Considerations

Unassigned ports carry inherent risk. Because port 1090 has no official owner, malware and trojans have occasionally used it for command and control communication⁷. If you see unexpected traffic on this port, investigate it.

The presence of traffic on port 1090 doesn't mean anything is wrong—it could be legitimate aircraft tracking software, enterprise management tools, or an authorized proxy. But it could also be something you didn't install. Check what's listening before assuming.

How to Check What's Listening

On Linux or macOS:

# See what's listening on port 1090
sudo lsof -i :1090

# Or using netstat
netstat -an | grep 1090

On Windows:

# See what's using port 1090
netstat -ano | findstr :1090

The output shows you the process ID and program name. If you recognize the software (dump1090, piaware, a Cisco service), you're fine. If you don't recognize it, investigate further.

Why Unassigned Ports Matter

The Internet has 65,535 ports per protocol (TCP and UDP). Only a fraction have official assignments. The rest—including port 1090—exist as open territory for developers to use as needed.

This flexibility enables innovation. FlightAware didn't need IANA permission to build a global aircraft tracking network. They just needed software that could listen on available ports and volunteers willing to run it. Port 1090 and ports like it make this possible.

But the same flexibility that enables hobbyist aircraft tracking also enables less benign uses. Unassigned ports are doors without official locks. Anything can walk through them. That's why monitoring network traffic matters—not to lock down every port, but to know what's actually using them.

Related Ports

• Port 30005 — Beast-format raw ADS-B data output used by dump1090²
• Port 30104 — Multilateration results data used in aircraft tracking systems²
• Port 8080 — Common alternate HTTP port, another example of unofficial standard use