As for year 2025 there is no more updates for CentOS 7.9.2009. Moreover you need to adjust repository file as network locations changed a little bit. So edit /etc/yum.repos.d/CentOS-Base.repo as follows: Then recreate yum cache: And if necessary: Now you are good to go with packages installation. If installing rkhunter, remember to install epel-release and then in case you did no enable EPEL to be enable by default which is the most probably situation.