This is an updated version of the original sshblack tool found at http://www.pettingers.org/code/sshblack.html
Please refer to that page, and release 2.8.1 in this Git repository, for background information and design.
The sshblack-install.txt may be useful.
In RHEL/CentOS 7 and 8 the firewall functionality is replaced by Firewalld.
The CLI command firewall-cmd is now used to administer the firewall.
This version of sshblack replaces the iptables firewall used in the obsolete RHEL/CentOS 6.
The files in this folder are installed to EL8 orEL9 systems using the script install.sh.
The script install.sh-el7 should be used on CentOS7/EL7 systems.
In addition, this crontab job is useful for getting E-mail alerts:
0 8 * * * /bin/grep user=root /var/log/secure; /bin/grep Evil /var/log/messages