Facing this issue while installing Jenkins over a centos server: Downloading packages: warning: /var/cache/yum/x86_64/7/jenkins/packages/jenkins-2.440.3-1.1.noarch.rpm: Header V4 RSA/SHA512 Signature, key ID ef5975ca: NOKEY Public key for jenkins-2.440

[abhi.nick16]

[al1]

Did you follow the link to the Jenkins Installation Docs?