For Vagrant, if you see this error after
<code class="bash">Failed to connect to VM via SSH. Please verify the VM successfully booted
by looking at the VirtualBox GUI.```
There are three things I did to fix it.
1) Enable the :gui option and run `sudo /etc/init.d/networking restart` on the box
2) Run `sudo dhclient` on the box
3) Change the IP Address in your Vagrantfile
Then rebuild your box.