What are the steps to install whois information for fail2ban

[mark_nl (Mark Verlinde)]

here it is:

Add Whois information to fail2ban reports

short recap of linked post run which whois or To check if you got bit by misleading feed back. problem in linked post was: Hope it helps

Could you go trough the suggested steps?

EDIT:
Most important check on the command line if whois is installed: which whois

If it is missing it is safe to install : yum install whois