Port 3005: The Former Plex Companion Port

What Range This Port Belongs To

Port 3005 is a registered port — part of the range from 1024 to 49151. These ports are managed by IANA, and anyone can apply to have a service officially assigned to one. Unlike well-known ports (0–1023), registered ports don't require elevated privileges to open, which makes them popular with application developers.

IANA lists no active, well-known assignment for port 3005. It appears in various port databases under names like "Miralix TimeOut" (telephony session management) and "Genius License Manager," but neither has established widespread real-world presence. In practice, port 3005 is effectively unassigned.

The Plex Chapter

Port 3005 has its most notable history with Plex Media Server. Plex used this port for TCP connections enabling local control of Plex Home Theater via the Plex Companion feature — the mechanism that let you throw media from a phone to a TV.

That official designation is gone. Plex's current support documentation no longer lists port 3005 as a required or recommended port. ¹ The docker-plex maintainers removed it from their container documentation after users noticed it had quietly disappeared from Plex's own specs. ²

The result: thousands of home users and self-hosters opened port 3005 in their firewalls based on guides that cited outdated Plex documentation. Many of those ports remain open today, no longer serving any purpose — or serving whatever else decided to listen there.

A Security Note Worth Knowing

CVE-2022-24396 involved a vulnerability on port 3005 in SAP's Simple Diagnostics Agent (versions 1.0–1.57). The agent exposed administrative functionality on this port without any authentication checks, even when accessed via localhost. It's a reminder that listening on a port — any port — without authentication is a meaningful security decision. ³

What's Actually Listening Here

If port 3005 shows up open on your system, these are the most likely explanations:

1. An old Plex installation configured when 3005 was still part of Plex's spec
2. A development server — Node.js developers frequently use ports 3000–3010 for local apps
3. Enterprise telephony software (Miralix or similar)
4. Something you didn't intentionally configure

To find out exactly what's using it:

macOS / Linux:

lsof -i :3005
# or
ss -tlnp | grep 3005

Windows:

netstat -ano | findstr :3005

These commands show you the process ID and name. If nothing shows up, the port isn't actively in use — though a firewall rule may still exist opening it to inbound traffic.

Why Unassigned Ports Matter

The port registry exists to create order. When applications claim ports unofficially — or claim them and then abandon them — they leave behind confusion: firewall rules that no longer serve their purpose, guides that cite outdated behavior, systems left half-open.

Port 3005 is a small case study in port drift. A legitimate application used it, documentation spread, and then the application moved on while the documentation didn't. The port is fine. The inherited configurations are the problem.