$ sudo apt-get install openssh-serverReading package lists... DoneBuilding dependency tree       Reading state information... DoneSome packages could not be installed. This may mean that you haverequested an impossible situation or if you are using the unstabledistribution that some required packages have not yet been createdor been moved out of Incoming.The following information may help to resolve the situation:The following packages have unmet dependencies: openssh-server : Depends: openssh-client (= 1:5.9p1-5ubuntu1)                  Recommends: xauth but it is not going to be installed                  Recommends: ssh-import-id but it is not going to be installedE: Unable to correct problems, you have held broken packages.

有人说要卸载掉 openssh-client , 但是 openssh-client 被很多包依赖, 很多的 xserver 的包都依赖它, 这该怎么办好？

搞定, 先装一个依赖的指定版本的 openssh-client (旧版)：

sudo apt-get install openssh-client=1:5.9p1-5ubuntu1

然后再装 openssh-server 就OK了。