FTP Passive Port Range Checker

Verify that your FTP server’s passive mode port range is open and reachable through firewalls. Essential for diagnosing “unable to open data connection” errors.

What is passive mode?

In FTP passive mode (PASV), the server opens a random high-numbered port for data transfers and tells the client which port to connect to. If these ports are blocked by a firewall, file transfers will fail even though the control connection on port 21 works fine.

The control connection on port 21 passes through the firewall, but the second data connection to port 50000 is blocked; the server's 227 reply encodes the port as 195 x 256 + 80 — The control connection is not the one that fails - and the 227 reply tells you which port to open.

Common passive port ranges

Range	Used by
49152–65535	IANA dynamic/ephemeral range (default on many servers)
40000–40100	Common custom range (cPanel, Plesk)
30000–31000	Common custom range (FileZilla Server default)