A paz esteja com você:
cat /etc/yum.repos.d/SQUID.repo
[squid]
name=Squid repo for CentOS 6
baseurl=http://www1.ngtech.co.il/rpm/centos/6/x86_64 #go to "http://www1.ngtech.co.il/rpm/centos/6/" and view which architecture is right for you
failovermethod=priority
enabled=1
gpgcheck=0
yum clean all
yum repolist
yum update