Port 2350: Pharos Booking Server — The University Print Queue Port

Port 2350 sits in the registered port range (1024-49151) without an official IANA service assignment. In practice, it has one well-known informal tenant: the Pharos Booking Server (psbserver), software that manages reservations for shared computing resources in universities and libraries.

What the Registered Port Range Means

Ports 1024-49151 are "registered" ports. IANA maintains a registry of which services claim which numbers, but registration isn't mandatory. Companies and projects can — and regularly do — pick a port in this range, use it consistently across installations, and never formally register it.

Port 2350 is one of those. The Pharos Booking Server has used it for years across thousands of institutional deployments without ever appearing in IANA's official registry.¹

What Runs Here: Pharos Booking Server

Pharos Systems makes software for managing shared resources in institutional environments — primarily printers and computer workstations. Their Pharos Uniprint and related products include a booking component that lets students reserve computer lab time, print quotas, and shared devices.

The psbserver process listens on port 2350/TCP. When a student opens the Pharos client and checks whether the library's color printer is available, that query goes to this port. When they make a reservation, modify it, or cancel it, the same port handles the transaction.²

The protocol is proprietary. It communicates between:

• Pharos Popup / Web Release (the client applications students use)
• Pharos Booking Server (the backend managing availability, quotas, and scheduling)

The server typically talks to a Microsoft SQL Server database to store booking state.

Security Note

Traffic on port 2350 is not encrypted by default in older Pharos deployments. User credentials and booking details can travel in plaintext. If you're administering a Pharos installation, verify that your deployment uses a secured transport layer — particularly relevant on university networks where packet capture is trivially easy.³

How to Check What's Using This Port

If you see port 2350 open on a machine:

# Linux/macOS — show process using port 2350
sudo lsof -i :2350
sudo ss -tlnp | grep 2350

# Windows — show process using port 2350
netstat -ano | findstr :2350

On an institutional machine, you'll likely find a Pharos process. On a personal machine, this port should not normally be open. If it is and you don't recognize the process, investigate.

Why Unassigned Ports Matter

The port registry isn't just administrative bookkeeping — it's the difference between "this is expected" and "what is that?" When a port has a known assignment, network administrators can confidently allow or block it. When a port is unassigned, every instance of traffic on it requires investigation to determine whether it's legitimate software or something unexpected.

Port 2350 illustrates the gap between the registry and reality. Thousands of universities run Pharos on this port. None of them needed IANA's blessing, and none of their students know the port exists. The infrastructure just works — quietly, in the background, making sure someone else's print job doesn't eat your quota.