openssh-server (>= 1:6.6p1-2ubuntu1) but it is not going to be installed

执行sudo apt-get install ssh，系统提示：Depends: openssh-server (>= 1:6.6p1-2ubuntu1) but it is not going to be installed。
说依赖openssh-server。

那我就执行sudo apt-get install openssh-server。
系统又提示：openssh-server : Depends: openssh-client (= 1:6.6p1-2ubuntu1) but 1:6.6p1-2ubuntu2 is to be installed。
说依赖openssh-client (= 1:6.6p1-2ubuntu1)。

我再执行sudo apt-get install openssh-client。
又提示：
openssh-client is already the newest version.

说openssh-client 已经是最新版本了。
安装openssh-server非要openssh-client 1:6.6p1-2ubuntu1的，我机器上面已经安装了openssh-client 1:6.6p1-2ubuntu2，怎么办？

解决办法

sudo apt-get install aptitude
sudo aptitude install openssh-server