官方给出的安装命令是apt-get install -y docker.io kubelet kubeadm kubectl kubernetes-cni 其中-y表示对于需要确认之处取值为y，需要确认的地方其中就有是否需要验证证书的，这里可以手工确认，貌似是可以下载到证书的。安装如下（其中没有docker，因为之前已安装）
root@ubuntu:/home/wht/Kubernetes# apt-get install kubelet kubeadm kubectl
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
kubernetes-cni socat
The following NEW packages will be installed:
kubeadm kubectl kubelet kubernetes-cni socat
0 upgraded, 5 newly installed, 0 to remove and 60 not upgraded.
Need to get 321 kB/41.2 MB of archives.
After this operation, 329 MB of additional disk space will be used.
Do you want to continue? [Y/n] Y
WARNING: The following packages cannot be authenticated!
kubernetes-cni kubelet kubectl kubeadm
Install these packages without verification? [y/N] y //取N时，因为有服务端的强制验证，因此会报错
Get:1 http://us.archive.ubuntu.com/ubuntu xenial/universe amd64 socat amd64 1.7.3.1-1 [321 kB]
Fetched 316 kB in 4s (67.6 kB/s)
Selecting previously unselected package kubernetes-cni.
(Reading database ... 58697 files and directories currently installed.)
Preparing to unpack .../kubernetes-cni_0.3.0.1-07a8a2-00_amd64.deb ...
Unpacking kubernetes-cni (0.3.0.1-07a8a2-00) ...
Selecting previously unselected package socat.
Preparing to unpack .../socat_1.7.3.1-1_amd64.deb ...
Unpacking socat (1.7.3.1-1) ...
Selecting previously unselected package kubelet.
Preparing to unpack .../kubelet_1.4.0-00_amd64.deb ...
Unpacking kubelet (1.4.0-00) ...
Selecting previously unselected package kubectl.
Preparing to unpack .../kubectl_1.4.0-00_amd64.deb ...
Unpacking kubectl (1.4.0-00) ...
Selecting previously unselected package kubeadm.
Preparing to unpack .../kubeadm_1.5.0-alpha.0-1534-gcf7301f-00_amd64.deb ...
Unpacking kubeadm (1.5.0-alpha.0-1534-gcf7301f-00) ...
Processing triggers for man-db (2.7.5-1) ...
Setting up kubernetes-cni (0.3.0.1-07a8a2-00) ...
Setting up socat (1.7.3.1-1) ...
Setting up kubelet (1.4.0-00) ...
Setting up kubectl (1.4.0-00) ...
Setting up kubeadm (1.5.0-alpha.0-1534-gcf7301f-00) ...
Note：该示例中Kubernetes的几个包已经提前下载好放在apt-get的下载目录/var/cache/apt/archives中，因此没有连接谷歌下载的过程。当有多台机器需要安装时，可以只在一台机器下载并拷贝到其他节点即可。