我正在尝试在我的 Ubuntu 系统上安装 OpenSSH 客户端，因为仍然收到以下错误消息：
Reading package lists ... Done
Building the dependency tree
Reading status information ... Done
Openssh-client package is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: 'openssh-client' package has no installation candidate
我查看了几个论坛，认为是更新系统时出现的问题。所以我尝试更新，但收到一条消息，提示某些软件包无法安装。我不知道该怎么办。以下是答案：
Err http://sunsite.rediris.es xenial Release.gpg
Can not resolve "sunsite.rediris.es"
Err http://sunsite.rediris.es xenial-updates Release.gpg
Can not resolve "sunsite.rediris.es"
Err http://sunsite.rediris.es xenial-backports Release.gpg
Can not resolve "sunsite.rediris.es"
Err http://sunsite.rediris.es xenial-security Release.gpg
Can not resolve "sunsite.rediris.es"
W: Can not retrieve http://sunsite.rediris.es/mirror/ubuntu-archive/dists/xenial/InRelease
W: The download of some index files failed, they were skipped, or the old ones were used instead.
答案1
您需要不同的镜像。此镜像不再存在。选择新镜像 - 我不会在这里详细介绍，这超出了这个问题的范围。看看我怎样才能使用靠近我的镜像，或者选择更快的镜像？。
选择您的镜像并打开终端。运行：
sudo apt-get update
然后你就可以安装了openssh-client。
sudo apt-get install openssh-client