Port 1746 has no officially assigned service. IANA's registry lists it as unassigned — no protocol, no application, no RFC. It's a blank space on the map.
That's not unusual. The registered port range (1024-49151) contains thousands of unassigned numbers. Not every port is spoken for.
What the Registered Range Means
Ports are divided into three ranges:
- Well-known ports (0-1023): Reserved for core Internet services. HTTP, HTTPS, SSH, DNS, SMTP. These require special privileges to open on most operating systems.
- Registered ports (1024-49151): Applications can register with IANA to claim a port number for their service. Port 1746 sits here, unclaimed.
- Dynamic/ephemeral ports (49152-65535): Used temporarily by clients when making outbound connections. Never registered to anything.
Being in the registered range means port 1746 could be claimed by an application that registered with IANA. It just hasn't been.
No Known Unofficial Uses
Some unassigned ports pick up informal uses over time — applications that never bothered registering, internal tools at large organizations, proprietary protocols that spread without standardization. Port 1746 has none of this in any documented form.
One thing worth noting: Rockwell Automation's Allen-Bradley hardware line includes a 1746 series (SLC 500 I/O modules). The number is a product model number, not a port assignment — the two are unrelated.
The Security Angle
Some port databases flag 1746 as a "trojan port," meaning malware has been observed using it. This sounds alarming until you understand the logic: attackers often pick unassigned ports specifically because nothing legitimate is supposed to be there. Traffic on an unknown port is easier to hide than traffic on port 80.
An unassigned port appearing in your network traffic isn't automatically a red flag. But it's worth investigating.
How to Check What's Listening
If you see activity on port 1746 and want to know what's behind it:
On Linux/macOS:
On Windows:
The process ID in the output can be matched against Task Manager or tasklist to identify the application.
Why Unassigned Ports Exist
The port numbering system was designed for growth. IANA doesn't pre-assign ports to hypothetical future protocols — it waits for something real to need a number. The gaps between assigned ports are intentional, leaving room for new services as they emerge.
Port 1746 is one of those gaps. It hasn't been claimed yet. That's not a flaw — it's the system working as designed.
Frequently Asked Questions
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