What Port 2520 Does
Port 2520 is registered with IANA for the Pervasive Listener — the service name is pvsw, short for Pervasive Software. It operates on both TCP and UDP.
The listener is the front door for Pervasive.SQL (later marketed as PSQL), a database engine built specifically for embedded use in business applications. When a client application needed to connect to a Pervasive database server, it knocked on port 2520 first — the listener answered, then directed the connection to the appropriate database service.
If you see port 2520 open on a machine running accounting software from the 1990s or 2000s, Pervasive is almost certainly the explanation.
What Pervasive Software Was
Pervasive Software built something unusual: a database engine designed to be invisible. While Oracle and SQL Server competed for enterprise attention, Pervasive embedded itself inside vertical market software — point-of-sale systems, medical office management tools, accounting packages like Sage 50 (formerly Peachtree).
The underlying engine descended from Btrieve, a record manager originally built for Novell NetWare in the 1980s. Pervasive acquired it, rebuilt it, and turned it into Pervasive.SQL — a full relational database that could be installed silently alongside a host application without the end user knowing it was there.
Tens of thousands of small businesses ran Pervasive without ever hearing the name. It just worked, quietly, behind whatever software they actually knew.
Actian Corporation acquired Pervasive Software in April 2013. The product continues as Actian PSQL, though it is firmly legacy software at this point.1
Port 2520 in the Pervasive Stack
Pervasive used several ports:
- 3351 (TCP/UDP) — Btrieve record-level access (the low-level engine)
- 1583 (TCP/UDP) — ODBC/SQL interface (relational queries)
- 2520 (TCP/UDP) — Pervasive Listener (service discovery and connection routing)
Port 2520 was the entry point. Clients that didn't know the exact service port would contact the listener, which would hand them off to the right service. Think of it as the receptionist for the database.
What Range This Port Belongs To
Port 2520 sits in the registered port range (1024–49151). IANA maintains registrations in this range on a first-come, first-served basis — applications claim them, and IANA records the assignment to prevent conflicts.
Unlike the well-known ports (0–1023), registered ports don't require superuser privileges to bind, and enforcement is informal. If you see something else running on 2520 today, that's entirely possible — IANA registration is a reservation, not a lock.2
How to Check What's Listening on Port 2520
On Linux/macOS:
On Windows:
Then match the PID to a process:
If you find something listening and it isn't Pervasive/Actian PSQL, identify the process before assuming it's benign. Unrecognized listeners on any port deserve scrutiny.
Frequently Asked Questions
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