install csf => CentOS, Debian, AlmaLinux, etc.

1. Step one => requested packages:

Debian or Debian-based OS (like Ubuntu, etc.):
apt update;apt upgrade -y;apt install -y wget libio-socket-ssl-perl git perl iptables libnet-libidn-perl libcrypt-ssleay-perl ipset libio-socket-inet6-perl libsocket6-perl sendmail dnsutils unzip zip ncdu mc lynx
Centos or other Redhat-based OS (Almalinux, etc.)
yum update -y;yum install -y epel-release;yum install -y perl-Crypt-SSLeay perl-Net-SSLeay bind-utils perl-libwww-perl.noarch perl-LWP-Protocol-https.noarch perl-GDGraph nano wget mc lsof nload tcpdump monit rsync zip unzip ipset langpacks-en glibc-all-langpacks perl-Math-BigInt-FastCalc iptables lynx
2. Step two => installing CSF itself

cd /usr/src
wget https://download.configserver.com/csf.tgz
tar -xzf csf.tgz
cd csf
sh install.sh
==
perl /usr/local/csf/bin/csftest.pl
==

perl /etc/csf/csftest.pl