tmp]$ sudo yum --enablerepo=epll install firefox-compat 加载的插件：priorities、update-motd、upgrade-helper 无法检索镜像列表http://repo.lambda-linux.io/2018.03/epll/x86_64/os/mirror.list错误为 14：HTTP 错误 403 - 禁止
配置的存储库之一失败（未知），并且 yum 没有足够的缓存数据来继续。此时 yum 能做的唯一安全的事情就是失败。有几种方法可以“修复”这个问题：
1. Contact the upstream for the repository and get them to fix the problem.
2. Reconfigure the baseurl/etc. for the repository, to point to a working
upstream. This is most often useful if you are using a newer
distribution release than is supported by the repository (and the
packages for the previous distribution release still work).
3. Disable the repository, so yum won't use it by default. Yum will then
just ignore the repository until you permanently enable it again or use
--enablerepo for temporary usage:
yum-config-manager --disable <repoid>
4. Configure the failing repository to be skipped, if it is unavailable.
Note that yum will try to contact the repo. when it runs most commands,
so will have to try and fail each time (and thus. yum will be be much
slower). If it is a very temporary problem though, this is often a nice
compromise:
yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=true
找不到存储库的有效基本 URL：epll/2018.03/x86_64