Pacote linux-headers não encontrado pelo aptitude mas instalado e em uso pelo sistema?

Question

Eu sinto que não entendo o que está acontecendo. Vamos ver meus comandos:

root@cms:~# sudo apt-get install virtualbox-5.1
  Reading package lists... Done
  Building dependency tree
  Reading state information... Done
  virtualbox-5.1 is already the newest version.
  0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

root@cms:~# /etc/init.d/vboxdrv status
  VirtualBox kernel module is not loaded.

root@cms:~# /etc/init.d/vboxdrv setup
  vboxdrv.sh: Stopping VirtualBox services.
  vboxdrv.sh: Building VirtualBox kernel modules.
  This system is not currently set up to build kernel modules (system extensions).
  Running the following commands should set the system up correctly:
  apt-get install linux-headers-3.2.0-23-virtual
  (The last command may fail if your system is not fully updated.)
  apt-get install linux-headers-virtual
  vboxdrv.sh: failed: Look at /var/log/vbox-install.log to find out what went wrong.

root@cms:~# apt-get install linux-headers-3.2.0-23-virtual
  Reading package lists... Done
  Building dependency tree
  Reading state information... Done
  E: Unable to locate package linux-headers-3.2.0-23-virtual
  E: Couldn't find any package by regex 'linux-headers-3.2.0-23-virtual'

root@cms:~# apt-get install linux-headers-virtual
  Reading package lists... Done
  Building dependency tree
  Reading state information... Done
  linux-headers-virtual is already the newest version.
  0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

Então, eu não entendo porque o virtualbox diz que eu preciso do linux-headers-3.2.0.23-virtual e o Linux diz que ele já está instalado no sistema.

Se eu listar cabeçalhos em / boot /, tenho apenas 3.2.0.23 arquivos.

Estou no Ubnutu 14.04.5 LTS (atualizado há algumas semanas em 12.04 LTS).

EDIT 1

root@cms:~# apt-cache policy linux-headers-virtual
  linux-headers-virtual:
  Installed: 3.13.0.129.138
  Candidate: 3.13.0.129.138
  Version table:
  *** 3.13.0.129.138 0
    500 http://archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
    500 http://security.ubuntu.com/ubuntu/ trusty-security/main amd64 Packages
    100 /var/lib/dpkg/status
 3.13.0.24.28 0
    500 http://archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages

EDIT 2

root@cms:/tmp# apt-cache policy linux-virtual linux-image-virtual linux-generic linux-image-generic
  linux-virtual:
    Installed: (none)
    Candidate: 3.13.0.129.138
    Version table:
      3.13.0.129.138 0
        500 http://archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu/ trusty-security/main amd64 Packages
      3.13.0.24.28 0
        500 http://archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
  linux-image-virtual:
    Installed: 3.13.0.129.138
    Candidate: 3.13.0.129.138
    Version table:
      *** 3.13.0.129.138 0
        500 http://archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu/ trusty-security/main amd64 Packages
        100 /var/lib/dpkg/status
      3.13.0.24.28 0
        500 http://archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
  linux-generic:
    Installed: 3.13.0.129.138
    Candidate: 3.13.0.129.138
    Version table:
      *** 3.13.0.129.138 0
        500 http://archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu/ trusty-security/main amd64 Packages
        100 /var/lib/dpkg/status
      3.13.0.24.28 0
        500 http://archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
  linux-image-generic:
    Installed: 3.13.0.129.138
    Candidate: 3.13.0.129.138
    Version table:
      *** 3.13.0.129.138 0
        500 http://archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages  
        500 http://security.ubuntu.com/ubuntu/ trusty-security/main amd64 Packages
        100 /var/lib/dpkg/status
      3.13.0.24.28 0
        500 http://archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages