Невозможно использовать yum на RHEL 7.2

В настоящее время я использую RHEL Server 7.2, и каждый раз, когда я запускаю команду yum (даже такие базовые вещи, как update, install, localinstall и т. Д.), Я получаю следующую ошибку:

One of the configured repositories failed (Unknown),  and yum doesn't have enough cached data to continue. At this point the only safe thing yum can do is fail. There are a few ways to work "fix" this:  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  Cannot retrieve metalink for repository: epel/x86_64. Please verify its path and try again 

Я читал, что способ исправить это состоял в том, чтобы изменить все экземпляры «https» на «http» в /etc/yum.repos.d/epel.repo, но это не сработало для меня. Я также попытался обновить SSL-сертификаты, но безуспешно. Какие-нибудь мысли? Спасибо!

-Эдит Это терминал в моей школе (Penn State Berks). Это один из немногих Linux-боксов, установленных на территории кампуса, так что практически нет поддержки. Он создан для моего исследовательского проекта, так что я и профессор - единственные, кто им пользуется. Все настройки сети, включая настройки DNS, были настроены школой ранее.

-Edit Я попытался запустить команду yum update, но с отключенным репо epel, и это было результатом:

773 physics10 -- /home/student/Desktop/tmux-x86_64-rhel6>yum update --disablerepo=epel/x86_64 Loaded plugins: langpacks, product-id, rhnplugin, search-disabled-repos, subscription-manager This system is receiving updates from RHN Classic or Red Hat Satellite.   Error getting repository data for epel/x86_64, repository not found 774 physics10 -- /home/student/Desktop/tmux-x86_64-rhel6>yum update --disablerepo=epel Loaded plugins: langpacks, product-id, rhnplugin, search-disabled-repos, subscription-manager This system is receiving updates from RHN Classic or Red Hat Satellite. http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') Trying other mirror. http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') Trying other mirror. http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') Trying other mirror. http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') Trying other mirror. http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') Trying other mirror. http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') Trying other mirror. http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') Trying other mirror. http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') Trying other mirror. http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') Trying other mirror. http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') Trying other mirror.  One of the configured repositories failed (Nux.Ro RPMs for general desktop use), and yum doesn't have enough cached data to continue. At this point the only safe thing yum can do is fail. There are a few ways to work "fix" this:  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 nux-dextop  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=nux-dextop.skip_if_unavailable=true  failure: repodata/repomd.xml from nux-dextop: [Errno 256] No more mirrors to try. http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://li.nux.ro/download/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: [Errno 12] Timeout on http://mirror.li.nux.ro/li.nux.ro/nux/dextop/el7/x86_64/repodata/repomd.xml: (28, 'Connection timed out after 30001 milliseconds') 775 physics10 -- /home/student/Desktop/tmux-x86_64-rhel6>