The one-liner above should be:
cp /etc/csf/csf.conf{,.backup} && csf -u && sed -i 's/MESSENGER = "0"/MESSENGER = "1"/g' /etc/csf/csf.conf ; sed -i 's/MESSENGERV2 = "0"/MESSENGERV2 = "1"/g' /etc/csf/csf.conf ; sed -i 's/MESSENGER_HTTPS_IN = ""/MESSENGER_HTTPS_IN = "443"/g' /etc/csf/csf.conf ; useradd csf -s /bin/false ; csf -ra
And here it is as multiple lines:
cp /etc/csf/csf.conf{,.backup}
csf -u
sed -i 's/MESSENGER = "0"/MESSENGER = "1"/g' /etc/csf/csf.conf
sed -i 's/MESSENGERV2 = "0"/MESSENGERV2 = "1"/g' /etc/csf/csf.conf
sed -i 's/MESSENGER_HTTPS_IN = ""/MESSENGER_HTTPS_IN = "443"/g' /etc/csf/csf.conf
useradd csf -s /bin/false
csf -ra