If I don't want to add other repository (EPEL for example) than the official ones that are coming with a fresh CentOS install, is there a more official alternative than fail2ban?
Does it exist a fail2ban alternative in official Centos repository?
centos;ssh;fail2ban
No, there is not. EPEL is maintained by community around Fedora and RHEL so it is the most official source you can get fail2ban from.