之前的安装步骤省略，请参考http://laravelacademy.org/post/8671.html
使用vagrant up命令之后，如果有以下报错，
请更改private_key文件的权限
C:\Users\ilaptop\Homestead\.vagrant\machines\homestead-7\virtualbox\private_key
解决步骤：
权限更改后，再次使用vagrant up和vagrant ssh，可以看到已经成功了
报错信息：
ilaptop@ilaptop MINGW64 ~/Homestead ((v7.6.0))
$ vagrant up
Bringing machine 'homestead-7' up with 'virtualbox' provider...
==> homestead-7: Checking if box 'laravel/homestead' is up to date...
==> homestead-7: Clearing any previously set forwarded ports...
==> homestead-7: Clearing any previously set network interfaces...
==> homestead-7: Preparing network interfaces based on configuration...
homestead-7: Adapter 1: nat
homestead-7: Adapter 2: hostonly
==> homestead-7: Forwarding ports...
homestead-7: 80 (guest) => 8000 (host) (adapter 1)
homestead-7: 443 (guest) => 44300 (host) (adapter 1)
homestead-7: 3306 (guest) => 33060 (host) (adapter 1)
homestead-7: 4040 (guest) => 4040 (host) (adapter 1)
homestead-7: 5432 (guest) => 54320 (host) (adapter 1)
homestead-7: 8025 (guest) => 8025 (host) (adapter 1)
homestead-7: 27017 (guest) => 27017 (host) (adapter 1)
homestead-7: 22 (guest) => 2222 (host) (adapter 1)
==> homestead-7: Running 'pre-boot' VM customizations...
==> homestead-7: Booting VM...
==> homestead-7: Waiting for machine to boot. This may take a few minutes...
homestead-7: SSH address: 127.0.0.1:2222
homestead-7: SSH username: vagrant
homestead-7: SSH auth method: private key
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...
homestead-7: Warning: Remote connection disconnect. Retrying...解决图：
