We increased the harddisk to 12.5GB, which was previously set to 12GB. The following is the computed MD5 checksum, on the corresponding package.box:

0bf7b36547e38adf0424735c9c638e17

We increased the harddisk to 12GB, which was previously set to 10GB. The following is the computed MD5 checksum, on the corresponding package.box:

28f704ae302a7b11879a7d835a727e8

We installed, and configured an ubuntu 14.04 virtual machine, from a minimal iso, using suggested user definitions:

vagrant@ubuntu-14:~$ cd /home/vagrant
vagrant@ubuntu-14:~$ mkdir .ssh
vagrant@ubuntu-14:~$ chmod 700 .ssh
vagrant@ubuntu-14:~$ cd /home/vagrant/.ssh
vagrant@ubuntu-14:~/.ssh$ wget https://raw.githubusercontent.com/mitchellh/vagrant/master/keys/vagrant.pub
vagrant@ubuntu-14:~/.ssh$ mv vagrant.pub authorized_keys
vagrant@ubuntu-14:~/.ssh$ chmod 600 authorized_keys
vagrant@ubuntu-14:~/$ sudo apt-get install -y openssh-server

Then, we ensure the following lines exists within /etc/ssh/sshd_config:

Port 22
PubKeyAuthentication yes
AuthorizedKeysFile %h/.ssh/authorized_keys
PermitEmptyPasswords no

Next, we ensure the vagrant user has sudo permission by editing the /etc/sudoers:

# Allow members of group sudo to execute any command
%sudo   ALL=(ALL:ALL) ALL

# sudoless vagrant user
vagrant ALL=(ALL:ALL)    NOPASSWD:ALL

Note: the ordering of the vagrant user after the %sudo group ensures that the permission is not overridden by the group.

Once completed, proceed by installing prerequisite packages for virtualbox guest additions:

vagrant@ubuntu-14:~/$ sudo apt-get install linux-headers-$(uname -r) build-essential dkms

Then, click Devices > Insert Guest Additions CD Image... on the virtualbox menu tab, and complete the installation of guest additions within the guest machine, by running the following commands:

vagrant@ubuntu-14:~/$ mkdir /tmp/temporary
vagrant@ubuntu-14:~/$ sudo mount /dev/cdrom /tmp/temporary
vagrant@ubuntu-14:~/$ cd /tmp/temporary
vagrant@ubuntu-14:~/tmp/temporary$ sudo ./VBoxLinuxAdditions.run
vagrant@ubuntu-14:~/tmp/temporary$ reboot

Note: we can verify if the installation of guest additions by running lsmod | grep -i vbox.

Finally, we created the base box, from the host machine:

$ vagrant package --base ubuntu-14.04
==> ubuntu-14.04: Attempting graceful shutdown of VM...
    ubuntu-14.04: Guest communication could not be established! This is usually because
    ubuntu-14.04: SSH is not running, the authentication information was changed,
    ubuntu-14.04: or some other networking issue. Vagrant will force halt, if
    ubuntu-14.04: capable.
==> ubuntu-14.04: Forcing shutdown of VM...
==> ubuntu-14.04: Exporting VM...
==> ubuntu-14.04: Compressing package to: /path/to/package.box

Note: ubuntu-14.04 is the name of the virtualbox virtual machine.

Note: using a hashing tool of choice, we determined that c26da6ba1c169bdc6e9168125ddb0525, is the MD5 hash, for the corresponding package.box.