I have installed Vagrant, VirtualBox and Homestead correctly, made all configurations correctly, when I try to run composer command to install Laravel on my VM using SSH I got this error :
[ErrorException]
mkdir(): Protocol error
I guess you are using VirtualBox version 5.0.4. Seems like this a bug of VirtualBox
: https://www.virtualbox.org/ticket/14563
Fixed in https://www.virtualbox.org/download/testcase/VirtualBox-5.0.5-102721-OSX.dmg
So, upgrade or downgrade your VirtualBox version.