title: Vagrant ssh prompts 'no kex alg' and I'm unable to connect to the virtual machine
body: <p>I'm trying to connect to a vagrant with a command <code>vagrant ssh</code> as instructed in the official vagrant documentation. Earlier I used older ubuntu as a virtual machine: <code>config.vm.box = "hashicorp/precise32"</code>. During that time, issuing a command <code>vagrant ssh</code> did let me connect to the machine with just a username and password.</p>
  
  <p>Now I changed the vagrant box to a newer one because I wanted newer <code>nodejs</code>. Currently, the box is: <code>config.vm.box = "ubuntu/vivid32"</code>. Now with this box, if I run the vagrant, and try to connect to the machine with vagrant <code>ssh</code>, it does not let me, but instead it will prompt <code>no kex alg</code>. I read somewhere it has to do with authentication using keys. How could I connect to the new ubuntu with vagrant ssh? One option could be to just regularly connect to the box.</p>