Port 2908: mao — Registered, Undocumented, Forgotten

What This Port Is

Port 2908 sits in the registered port range (1024–49151). These ports are assigned by IANA — the Internet Assigned Numbers Authority — to specific services upon request. Unlike the well-known ports below 1024, you don't need root privileges to bind to them. Anyone can request a registered port number for a service they're building.

Port 2908 is registered. Its assigned service name is mao.

That's about where the documentation ends.

The Ghost Registration

According to the IANA Service Name and Transport Protocol Port Number Registry, port 2908 (both TCP and UDP) is assigned to "mao," with Marc Baudoin listed as the point of contact at babafou@babafou.eu.org. Marc Baudoin is a French IT trainer and UNIX systems administrator with a long career in infrastructure computing.¹

What "mao" does? The IANA record provides no description. There is no RFC, no public specification, no open-source project, no trace of this protocol in common use. The registration exists. The protocol, publicly at least, does not.

This is more common than it sounds. The registered port range was designed to accommodate private and commercial services, and many entries in the registry are similarly sparse — registered years ago for a project that never shipped publicly, or for internal tooling that never needed external documentation.

What Might Be Listening Here

If you see traffic on port 2908 on your network, it is almost certainly not the "mao" service. It's more likely:

• Application-specific traffic — some software picks ports in this range for internal communication
• Custom services — developers sometimes bind internal APIs and microservices to ports in the registered range for convenience
• Scanning traffic — automated scanners probe ports across the full registered range

How to Check What's Listening

On Linux or macOS:

# Show what process is bound to port 2908
ss -tlnp sport = :2908

# Or with lsof
lsof -i :2908

On Windows:

netstat -ano | findstr :2908

If something is listening and you didn't put it there, look up the process ID to identify the application.

Why Registered Ports Matter

The registered port range exists to prevent two services from accidentally colliding. If you're building a service that needs to receive inbound connections, registering a port number tells the rest of the Internet: this number is taken. Don't use it for something else.

The system depends on entries being meaningful. Ghost registrations like "mao" are a small failure mode of the registry — the name is claimed, but the knowledge of what it does lives only with the person who claimed it.²