The following error may occur while reloading CSF (csf -r) :
*WARNING* Binary location for [HOST] [/usr/bin/host] in /etc/csf/csf.conf is either incorrect, is not installed or is not executable
*WARNING* Missing or incorrect binary locations will break csf and lfd functionality
In this particular case, CSF was installed on a CentOS 7 server and there wasn’t any “host” executable under /usr/bin.
To resolve this issue, just install the missing package which is provided by Bind Utilities (bind-utils) :
yum install bind-utils