Port 3568 has no official assignment. IANA — the organization that manages the global port registry — lists it as unassigned.1 No protocol was formally registered here, no RFC defines it, no service owns it.
But ports don't need official owners to see traffic. They just need applications that pick them.
The Range It Belongs To
Port 3568 sits in the registered ports range (1024–49151), sometimes called the user ports range.2 This middle tier sits between the well-known ports (0–1023, reserved for foundational protocols like HTTP, SSH, and DNS) and the ephemeral ports (49152–65535, used temporarily by your OS when making outbound connections).
Registered ports are supposed to be claimed. Applications apply to IANA, get assigned a number, and that number becomes theirs — listed in the global registry, associated with a service name. Tens of thousands of ports in this range are formally assigned to specific protocols.
Port 3568 was never one of them.
Two Games, One Port
In 1999, two tactical PC games chose port 3568 for their multiplayer traffic — apparently without coordination.
Dark Reign 2, a real-time strategy game from Pandemic Studios, used TCP and UDP 3568 alongside a handful of other ports for its online multiplayer.3 Delta Force 2, a tactical shooter from Novalogic, used UDP 3568 and 3569 to connect players across servers.4
Both games are from the era when PC multiplayer meant opening specific ports on your router — assuming you had a router, and assuming you understood what a router was. The dedicated portforwarding guides that still exist for these games are archaeological artifacts from a time when "firewall" was a novel word in household vocabulary.
Neither game is in active use today. The multiplayer servers are long dark. Port 3568 is quiet again.
How to Check What's Using It
If port 3568 shows up active on your system, check it:
macOS / Linux:
Windows:
This shows the process ID (PID) holding the port. On macOS and Linux, lsof gives you the process name directly. On Windows, take the PID to Task Manager to identify the application.
If something is actively listening on port 3568 and you don't recognize it, that's worth investigating. Unassigned ports are occasionally used by malware precisely because they're unremarkable and unlikely to be blocked by default firewall rules.
Why Unassigned Ports Exist
IANA can't anticipate every application. The registered ports range contains 48,127 possible ports, and only a fraction are formally claimed. The rest sit available — not forbidden, just unnamed.
When a developer needs a port, they can apply to IANA for a formal assignment, or they can simply pick an unused number and ship. Many do the latter. The application works, the port is used informally, and the registry stays silent about it.
This is fine until two applications pick the same unassigned port, or until a port scan flags unusual traffic on a number with no known legitimate use. The registry exists to prevent those collisions and to give network defenders a baseline for what's expected.
Port 3568 is a small example of what happens in the gaps — a number that slipped through without a name, briefly claimed by nostalgia, now waiting again.
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