docker-machine配置虚拟机(通过virtualbox构建)出现问题
Reference:[https://stackoverflow.com/questions/33992729/cannot-get-docker-machine-to-work-with-virtualbox-when-using-cisco-vpn-anyconnec]

This machine has been allocated an IP address, but Docker Machine could not
reach it successfully.

SSH for the machine should still work, but connecting to exposed ports, such as
the Docker daemon port (usually :2376), may not work properly.

You may need to add the route manually, or use another related workaround.

This could be due to a VPN, proxy, or host file configuration issue.

You also might want to clear any VirtualBox host only interfaces you are not using.

试了很多方法，还参考了官方文档，都没解决。尝试着输入
$ sudo ifconfig vboxnet0 down && sudo ifconfig vboxnet0 up
解决。
需要证书时添加：
docker-machine regenerate-certs [name]
即可