Port 1661 sits in the registered ports range (1024-49151), officially assigned to IBM's NetView AIX monitoring service. But registration doesn't mean exclusive use. This port illustrates the gap between official assignments and actual practice.
What Lives Here Officially
Port 1661 is registered with IANA for netview-aix-1, part of IBM's NetView family of network management tools for AIX systems.1 NetView was IBM's answer to managing complex enterprise networks—the kind that connected mainframes and non-SNA devices in large organizations.
The registration covers both TCP and UDP. It's actually part of a block: ports 1661-1672 are assigned to netview-aix-1 through netview-aix-12, each handling different aspects of the monitoring system.2
What Actually Uses It
The registered ports range (1024-49151) works differently than well-known ports. IANA records assignments, but applications aren't required to ask permission. Port 1661 shows up in unofficial use by Axis network cameras for video streaming and camera management.3
This isn't a conflict in the traditional sense. NetView AIX deployments are increasingly rare. Modern IP cameras need ports. The same number can serve both purposes on different networks without issue.
Why Registration Matters (And Doesn't)
Registered ports create a record, not a reservation. When IBM registered 1661 for NetView, they were saying "we're using this" not "nobody else can."
The value is collision avoidance within an organization. If you're running NetView AIX on port 1661, you probably shouldn't also configure your Axis cameras to use it. But most networks will never run NetView AIX.
The Registered Range
Ports 1024-49151 are registered ports. Organizations and developers can register them with IANA for specific services.4 The registration provides:
- Documentation — A central record of what services claim which ports
- Collision awareness — Developers can check before choosing a port
- No enforcement — Nothing prevents two applications from using the same port
This is fundamentally different from well-known ports (0-1023), which require root privileges to bind on Unix-like systems. Registered ports can be bound by any process.
Checking What's Listening
On Linux or macOS:
On Windows:
If you see something listening on 1661, it could be NetView, an Axis camera service, or something else entirely. The port number alone doesn't tell you what's actually running.
The Real Story
Port 1661 was registered in an era when network management meant watching mainframes, not IP cameras streaming video to your phone. The official assignment remains, but the world moved on.
This is how the port system actually works. Official registrations create a historical record. Actual usage follows need. The two overlap sometimes, diverge other times, and both keep the Internet running.
Frequently Asked Questions About Port 1661
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