Problem:
error: Connection timed out after 20 seconds of inactivity
error: Error retrieving directory listing
Solution 1:
In SSH Terminal run the following:
echo ip_nat_ftp > /etc/modules-load.d/iptables.conf echo ip_conntrack_ftp >> /etc/modules-load.d/iptables.conf service xinetd restart
Source: https://unix.stackexchange.com/questions/240044/on-centos7-firewalld-overwrite-iptables-modules
Solution 2:
iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT iptables -I INPUT 2 -p tcp --match multiport --dports 49152:65535 -j ACCEPT service iptables save service xinetd restart
