Port 2790: PLG Proxy — A Registered Ghost

What Port 2790 Is

Port 2790 sits in the registered port range (1024–49151), the middle tier of the port numbering system. Well-known ports (0–1023) are reserved for foundational protocols — HTTP, SSH, DNS. Dynamic/ephemeral ports (49152–65535) are assigned on the fly for temporary connections. The registered range is where applications and services claim a permanent home.

IANA's registry lists port 2790 as assigned to PLG Proxy (service name: plgproxy) over both TCP and UDP, with a contact named Charlie Hava.¹ That's the entirety of the official record.

The Problem: No One Knows What PLG Proxy Is

No public documentation explains what PLG Proxy does or why it needed port 2790. No open source project carries the name. No RFC describes its protocol. The IANA registration is the only artifact.

This happens more than you'd expect. The registered port range contains thousands of entries submitted by developers, companies, and researchers who registered a port and then — for whatever reason — never shipped the software, never published the documentation, or simply let the project die. The registration outlives the intent.

Port 2790 appears to be one of these: a legitimate registration with no surviving context.

What Range This Port Lives In

The registered port range (1024–49151) requires no special system privileges to use. Any process running under a normal user account can bind to port 2790. This makes registered ports the natural habitat for application servers, databases, game servers, and custom services.

Unlike well-known ports, registered ports aren't strictly enforced. Software can and does use ports that don't match its registered assignment. The registry is a coordination mechanism, not a lock.

How to Check What's Listening on Port 2790

If you're seeing traffic on port 2790 and want to know what's behind it:

On Linux/macOS:

# Show what process is bound to port 2790
ss -tlnp | grep 2790
# or
lsof -i :2790

On Windows:

netstat -ano | findstr :2790
# Then check the PID against Task Manager

If something is listening on this port on your system, it isn't PLG Proxy — it's whatever your software chose to run there. Unassigned and ghost-assigned ports get reused constantly by application defaults, development servers, and custom services.

Why Ghost Assignments Exist

IANA's registration process has historically been relatively easy to complete and doesn't require the service to be publicly released or even functional. Developers register ports during design phases, startups register ports before they ship, and occasionally registrations are simply abandoned.

The registry doesn't expire. An assignment made decades ago by a developer who has since moved on remains in the official record indefinitely. Port 2790 is one result of this: a permanent placeholder for something that never quite arrived.