If you run a firewall on your Linux server and want to use passive FTP connections, you have to define the passive port range in pure-ftpd and your firewall to ensure that the connections don’t get blocked.
♦ vi /etc/pure-ftpd.conf
search for passive port range in pure-ftpd.conf file and add the range.
PassivePortRange 30000 50000
In cPanel servers we usually have the PassivePortRange in between 30000 50000