http://ftp.scientificlinux.org/linux/scientific/

http://www.rpmfind.net/linux/rpm2html/search.php?query=gcc

http://elrepo.org/linux/kernel/el6/x86_64/RPMS/

https://people.centos.org/tru/devtools-2/6/x86_64/RPMS/

RPM 包下载 GCC 4.8安装