Install CSF Firewall

For non cpanel server, install perl modules

yum install -y perl perl-libwww-perl perl-Time-HiRes unzip bind-utils

On Ubuntu

apt-get install libwww-perl

Once we have requirments installed, install csf with

cd /usr/local/src
wget https://download.configserver.com/csf.tgz
tar -xzf csf.tgz
cd csf
sh install.sh

sed -i "s/RESTRICT_SYSLOG = \"0\"/RESTRICT_SYSLOG = \"1\"/g" /etc/csf/csf.conf

See csf