SFTP being blocked by IPTables


Jan 16, 2015
cPanel Access Level
Root Administrator
Every so often, I don't know what triggers it the FTP user will be presented this through FileZilla log:

Command: PASS ************
Response: 530 Login authentication failed
Error: Critical error
Error: Could not connect to server

I've been redundantly using iptables -F which allow the SFTP to work again for a certain amount of time and then I must do it again.

Linux version 2.6.32-504.3.3.el6.x86_64
WHM 11.46.1 (build 4)
CENTOS 6.6 x86_64

I'm using pureftpd and I require the use of 'require explicit FTP over TLS'.
I believe it has something to do with iptables blocking passive ports.
version: iptables-1.4.7-14.el6.x86_64

It's been a while but I've tried a few times to search the forums and google for a resolution. I modified the /etc/pureftpd file to include:

PassivePortRange 49152 65534

I've also tried to add this port range to iptables. I don't really know much about iptables to troubleshoot this issue. So i've just been using iptables -F. It's starting to get to the point of inconvenience and would like to fix it asap. Any direction would be appreciated.


Staff member
Apr 11, 2011
Hello :)

I suggest using a firewall management tool such as CSF to manage your firewall rules. This should address the issue.

CSF Firewall

Thank you.