I used the Vagrant image for 13.04 from http://cloud-images.ubuntu.com/vagrant/raring/current/raring-server-cloudimg-i386-vagrant-disk1.box to create a new virtual machine and tried to connect to it using ssh. However, the SSH always disconnected immediately, without even getting to the stage where it tried to authenticate.

I opened the VM in the VirtualBox GUI and looked at the SSH log file (auth.log). It was full of lines like this:

Jul 25 17:57:02 vagrant-ubuntu-raring-32 sshd[898]: error: Could not load host key: /etc/ssh/ssh_host_rsa_key

Jul 25 17:57:02 vagrant-ubuntu-raring-32 sshd[898]: error: Could not load host key: /etc/ssh/ssh_host_dsa_key

Jul 25 17:57:02 vagrant-ubuntu-raring-32 sshd[898]: error: Could not load host key: /etc/ssh/ssh_host_ecdsa_key

Jul 25 17:57:02 vagrant-ubuntu-raring-32 sshd[898]: fatal: No supported key exchange algorithms [preauth]

The problem was solved by executing the following commands:

sudo ssh-keygen -f /etc/ssh/ssh_host_ecdsa_key -N '' -t ecdsa

sudo ssh-keygen -f /etc/ssh/ssh_host_dsa_key -N '' -t dsa

sudo ssh-keygen -f /etc/ssh/ssh_host_rsa_key -N '' -t rsa

I would assume that these should run automatically at some point, especially given that (a) I did not have to run them myself when I installed Ubuntu from an ISO image, and (b) because Vagrant is supposed to be designed that after you run vagrant up you can immediately use the VM without any additional configuration.

I may need to create a large number of Virtual Machines in the near future and I was hoping that I could use Vagrant to do it, but I can't do it if I'm going to have to manually fix SSH on each one.

Does anyone know why this happens and what can be done to fix it? Should I report it as a bug?