sudo sed -i 's|mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os|#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os|g' /etc/yum.repos.d/CentOS-Base.repo

sudo sed -i 's|#baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/|baseurl=http://vault.centos.org/7.9.2009/os/$basearch/|g' /etc/yum.repos.d/CentOS-Base.repo

sudo sed -i 's|mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates|#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates|g' /etc/yum.repos.d/CentOS-Base.repo

sudo sed -i 's|#baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/|baseurl=http://vault.centos.org/7.9.2009/updates/$basearch/|g' /etc/yum.repos.d/CentOS-Base.repo

sudo sed -i 's|mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras|#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras|g' /etc/yum.repos.d/CentOS-Base.repo

sudo sed -i 's|#baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/|baseurl=http://vault.centos.org/7.9.2009/extras/$basearch/|g' /etc/yum.repos.d/CentOS-Base.repo

sudo sed -i 's|mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus|#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus|g' /etc/yum.repos.d/CentOS-Base.repo

sudo sed -i 's|#baseurl=http://mirror.centos.org/centos/$releasever/centosplus/$basearch/|baseurl=http://vault.centos.org/7.9.2009/centosplus/$basearch/|g' /etc/yum.repos.d/CentOS-Base.repo

sudo yum clean all

sudo yum makecache