Port 2870: Daishi — Registered, Named, and Unknown

What Is Port 2870?

Port 2870 sits in the registered ports range (1024–49151). These ports are managed by IANA, the Internet Assigned Numbers Authority, which maintains a registry of service names and port assignments. Unlike the well-known ports below 1024, registered ports don't require root privileges to open, and they're claimed on a first-come basis by anyone willing to submit a registration request.¹

Port 2870 is registered. IANA lists it under the service name "daishi", assigned to both TCP and UDP, with a contact named Patrick Chipman.²

That is the entirety of publicly available information about daishi.

The Problem with "Daishi"

There is no RFC for daishi. There is no public specification. There is no software project, documentation, or archived mailing list discussion that explains what the protocol does, what problem it solves, or why it needed its own port number.

The name itself — "daishi" (大師 in Japanese, meaning "great teacher" or "great master," used as a posthumous title for Buddhist monks) — offers no technical hints. It could be a personal project, an internal enterprise tool, or a proprietary protocol for software that never shipped. Whoever registered it did so and then, as far as the public record is concerned, disappeared.

This is not unusual. The registered ports range contains hundreds of names like this: claimed in the 1990s or early 2000s for software that never reached critical mass, leaving ghost entries in the IANA table.

What to Do If You See Port 2870

If you notice traffic on port 2870, it is almost certainly not "daishi" — it's whatever application on your specific system chose this port, either by configuration or coincidence.

To check what's using it:

On Linux or macOS:

# Show which process is listening on port 2870
ss -tlnp | grep 2870
# or
lsof -i :2870

On Windows:

# Show listening processes with port 2870
netstat -ano | findstr :2870
# Then match the PID to a process:
tasklist | findstr <PID>

These commands show you the truth: the process name, its PID, and whether it's listening or connected.

Why Unassigned-in-Practice Ports Matter

Ports like 2870 illustrate something real about the port system: registration and usage are different things. A port can be "taken" in the registry while being entirely unused in practice, and a port can be heavily used by real software while appearing unassigned.

When applications need a port and don't have a strong reason to pick a specific number, they often land in the registered range somewhat arbitrarily. Your database tool, your game server, your VPN — any of them might pick 2870 with no knowledge of daishi and no conflict in practice, because daishi is nowhere to be found.

The registered range is large enough (nearly 48,000 ports) that collisions are rare. But the ghost entries — registered names attached to nothing — are a reminder that the port registry is a historical document as much as a technical one.