Fail2ban scans log files like /var/log/pwdfail or /var/log/apache/error_log and bans IP that makes too many password failures. It updates firewall rules to reject the IP address.
First, we need to install Gamin so that fail2ban can detect modification to the log files. See this page. Generally, you will just have to do :
#pacman -S gamin
Then you can install fail2ban
#pacman -S fail2ban
If you want fail2ban to send an email when someone has been banned, you have to configure SSMTP (for example). You will also have to install whois to get some information about the attacker.
#pacman -S whois