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 unzip

Once we have requirements installed, install csf with

cd /usr/local/src
rm -fv csf.zip
wget https://github.com/serverok/csf-firewall/archive/refs/heads/main.zip -O csf.zip
unzip csf.zip
cd csf-firewall-main
sh install.sh

/bin/sed -i "s/RESTRICT_SYSLOG\s*=.*$/RESTRICT_SYSLOG = \"3\"/g" /etc/csf/csf.conf
/bin/sed -i "s/SYSLOG_CHECK\s*=.*$/SYSLOG_CHECK = \"3600\"/g" /etc/csf/csf.conf
/bin/sed -i "s/IGNORE_ALLOW\s*=.*/IGNORE_ALLOW = \"1\"/g" /etc/csf/csf.conf
/bin/sed -i "s/TESTING = \"1\"/TESTING = \"0\"/g" /etc/csf/csf.conf
/bin/sed -i "s/PT_USERMEM\s*=.*/PT_USERMEM = \"1024\"/g" /etc/csf/csf.conf
/bin/sed -i "s/LF_NETBLOCK_ALERT\s*=.*/LF_NETBLOCK_ALERT = \"0\"/g" /etc/csf/csf.conf
/bin/sed -i "s/LF_PERMBLOCK_ALERT\s*=.*/LF_PERMBLOCK_ALERT = \"0\"/g" /etc/csf/csf.conf
/bin/sed -i "s/PS_EMAIL_ALERT\s*=.*/PS_EMAIL_ALERT = \"0\"/g" /etc/csf/csf.conf
/bin/sed -i "s/LF_EMAIL_ALERT\s*=.*/LF_EMAIL_ALERT = \"0\"/g" /etc/csf/csf.conf

See csf