FTP doesn't work with csf installed

This usually means that your server does not correctly support FTP connection tracking (e.g. the Virtuozzo VPS kernel doesn't), or you're attempting to use FTP over SSL/TLS.

To work around this:

1. You need to follow the instructions in the FTP section in the csf readme.txt, i.e. open up a port range in TCP_IN in csf and open up the same passive port range in your FTP server

2. Users should use Passive (PASV) mode in their FTP clients

3. You cannot use FTP over SSL/TLS unless you open up the port range as above (see csf readme.txt) regardless of whether you're using a monolithic kernel or not

4. Remember to restart csf and your FTP server before testing

If FTP still doesn't work, then there's likely a problem with the iptables module installation with the kernel that your server is running.