Relative Linux newbie here. Can't install yum-security plugin. Googling says it does exist for Centos 7. What am I doing wrong? Is this just a case of changing repositories? If so, which repo has it?
maybe try yum check-update first, to ensure you have the latest package data. otherwise disable fastestmirror. set "enabled=0" in /etc/yum/pluginconf.d/fastestmirror ...