How to Enable passive mode in FTP server with CSF firewall

If you running a FTP server (Pureftp/Proftp) with a CSF firewall (very importantly in VPS or virtuozzo etc), it is very important to to enable passive mode,  because this mode, works best for ftp clients protected by firewall since the client initiates the connection. If you dont enable this mode in VPS you might encounter problems like ftp server will be unresponsive or hang.

Along with FTP server running Pure-ftp  or Proftp, just follow the below steps:

1. Add Passive Port range 30000-350000 to your Pureftp or Proftp configuration file

Pureftpd

open /etc/pure-ftpd.conf, and change this line to:

PassivePortRange    30000 35000

ProFTP

Open /etc/proftpd.conf, and add this line:

PassivePorts    30000 35000

2. Open the ports from 30000 – 35000 in your CSF firewall configuration file under TCP_IN

Open /etc/csf/csf.conf

# Allow incoming TCP ports
TCP_IN = "20,21,22,25,53,80,110,30000:35000"

3. Restart firewall and ftp server

service csf restart
service pureftpd restart (or)
service proftpd restart

Once this is done, open your ftp client and try connecting to ftp server. It should be able to work in passive mode.