I am using Arch Linux. I followed a tutorial to change /etc/iptables/iptables.rules to allow only the basic ports for my web server. I also used /etc/modules-load.d/nf_conntrack_ftp.conf to enable that module, and changed the default FTP port that I use in /etc/modprobe.d/ip_conntrack_ftp.conf. I have two problems. FTP is not working since I am getting a 500 Illegal Port Command, and an ERRCONNREFUSED. If I use active mode instead and over plain FTP, it owrks. So it's something wrong with iptables. Also, iptables is not allowing IPv6 connections even though I allow them. Do I have to change another file? Thanks you. Here's a screenshot of iptables.rules: Of course, I changed the FTP port before I posted this.
Changing IPTables to Allow FTP over TLS Using Passive Ports
arch linux;iptables;ftp;ssl