What This Port Is
Port 3674 is registered with IANA under the service name wininstall-ipc — the inter-process communication port for WinINSTALL, a Windows software deployment and package management tool. The registration was filed by Bill Somerville on August 13, 2008, and covers both TCP and UDP.1
It sits in the registered port range (1024–49151), which means it went through a formal process to claim its number. It is not unassigned. It just belongs to something most people no longer use.
What WinINSTALL Was
Before Microsoft Configuration Manager (SCCM) and Intune were household names in IT departments, administrators needed ways to push software to hundreds of Windows machines without walking to each desk. WinINSTALL was one of those tools.
WinINSTALL LE — the free version — worked by taking a "before" snapshot of a system, letting you run an installer, then taking an "after" snapshot. The difference became an MSI package you could deploy silently across your network via Group Policy or scripted installs. For nearly two decades it was one of the most downloaded free tools in the sysadmin world.
Port 3674 was used for the IPC channel — the communication pipe between WinINSTALL components talking to each other during deployment operations. It's the kind of port that opens quietly during a software push and closes when the job is done. Not glamorous. Essential when it mattered.
Who Encounters This Port Today
Almost nobody. WinINSTALL is largely a legacy product. Modern Windows environments use SCCM, Intune, Ansible, or similar tools. If you see traffic on port 3674 today, it is likely one of three things:
- An older enterprise environment still running WinINSTALL infrastructure
- A scanner or security tool probing the port out of habit
- Something else entirely using the port informally, since port squatting on obscure registered numbers is not unheard of
If you see something unexpected on this port, verify what's actually listening — don't assume it's WinINSTALL.
How to Check What's Using Port 3674
On Linux or macOS:
On Windows:
Then take the PID from the last column and look it up:
If something is listening on this port and you don't recognize it, that's worth investigating.
Why Registered Ports Like This Matter
The registered port range exists so that software can claim a number and others can avoid it. When WinINSTALL registered port 3674, it was staking out territory: "this is ours, don't use it for something else."
The system works reasonably well when software is in active use. It gets strange when software fades. The registration stays in the IANA database indefinitely. Port 3674 will say wininstall-ipc long after the last WinINSTALL server is decommissioned — a placeholder for infrastructure that largely moved on.2
That's not a criticism. It's just how port registrations work. Permanence is a feature, not a bug. The alternative — constantly recycling port numbers — would create more confusion than it solved.
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