Port 3606: Unassigned — An Empty Address in a Registered Range

What Range This Port Belongs To

Port 3606 falls in the registered port range (1024–49151). IANA manages this range, and organizations can formally request assignments for their applications. Port 3606 has no such assignment — it is listed as unassigned in the IANA Service Name and Transport Protocol Port Number Registry.¹

This doesn't mean the port is inactive on any given system. Registered ports can be used by any software without conflict resolution — they're just unclaimed addresses. An application can bind to port 3606 without registering it anywhere, and many do.

The "Splitlock Server" Label

Several community port databases list port 3606 as "Splitlock Server" on both TCP and UDP.² This label has no traceable origin: no RFC, no vendor documentation, no active project. It appears to be a phantom entry — copied from database to database until it gained the appearance of legitimacy through repetition.

The MySQL NDB Cluster management node claim that sometimes accompanies port 3606 online is also incorrect. MySQL NDB's management node defaults to port 1186, not 3606.³

There is no evidence of a "Splitlock Server" product in active use. Treat the label as noise.

What Might Actually Be Here

Because port 3606 is unassigned, anything could be listening on it on a given host. Common scenarios:

• Development servers that needed a port and grabbed one arbitrarily
• Internal tooling that picked a number and stuck with it
• Gaming servers, proxies, or custom daemons with no formal registration
• Malware — unassigned ports in the registered range are occasionally used because they're less likely to be blocked by default firewall rules

How to Check What's Listening

On Linux or macOS:

# Show what process is bound to port 3606
ss -tlnp sport = :3606

# Or with lsof
lsof -i :3606

On Windows:

# Show listening ports with process IDs
netstat -ano | findstr :3606

# Match the PID to a process name
tasklist /FI "PID eq <pid>"

If nothing is returned, nothing is listening. If something is, the process name will tell you what.

Why Unassigned Ports Exist

The registered port range has 48,128 slots. Far fewer than that have formal assignments. The gaps are intentional — IANA doesn't pre-fill them speculatively. A port gets assigned when someone builds something, registers it, and IANA approves the registration.

The unassigned space is the Internet's available real estate. Some of it gets claimed properly. Some gets squatted on. Some stays empty. Port 3606 is, for now, in the empty category.