Verifying archive integrity... All good.
Uncompressing VirtualBox 4.3.30 Guest Additions for Linux............
VirtualBox Guest Additions installer
Removing installed version 4.3.30 of VirtualBox Guest Additions...
Copying additional installer modules ...
Installing additional modules ...
Removing existing VirtualBox DKMS kernel modules                      done
Removing existing VirtualBox non-DKMS kernel modules                  done
Building the VirtualBox Guest Additions kernel modules                done
Doing non-kernel setup of the Guest Additions                         done
Starting the VirtualBox Guest Additions                               failed
(modprobe vboxguest failed)
Installing the Window System drivers
Installing X.Org Server 1.15 modules                                  done
Setting up the Window System to use the Guest Additions               done
You may need to restart the the Window System (or just restart the guest system)
to enable the Guest Additions.

Installing graphics libraries and desktop services components         done

redirecting to systemctl start vboxadd.service
Job for vboxadd.service failed. See "systemctl status vboxadd.service" and "journalctl -xn" for details.
redirecting to systemctl start vboxadd-service.service
Failed to start vboxadd-service.service: Unit vboxadd-service.service failed to load: No such file or directory.
redirecting to systemctl start vboxadd-x11.service

Uninstalling modules from DKMS
Attempting to install using DKMS

Creating symlink /var/lib/dkms/vboxguest/4.3.30/source ->
                 /usr/src/vboxguest-4.3.30

DKMS: add completed.

Kernel preparation unnecessary for this kernel.  Skipping...

Building module:
cleaning build area....
make KERNELRELEASE=3.12.44-52.10-default -C /lib/modules/3.12.44-52.10-default/build M=/var/lib/dkms/vboxguest/4.3.30/build............
cleaning build area....

DKMS: build completed.

vboxguest:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/3.12.44-52.10-default/updates/

vboxsf.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/3.12.44-52.10-default/updates/

vboxvideo.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/3.12.44-52.10-default/updates/
Adding any weak-modules

depmod....

DKMS: install completed.
Creating user for the Guest Additions.
Creating udev rule for the Guest Additions kernel module.

vboxadd.service - LSB: VirtualBox Linux Additions kernel modules
   Loaded: loaded (/etc/init.d/vboxadd)
   Active: failed (Result: exit-code) since Di 2015-09-01 11:25:42 CEST; 11min ago
  Process: 13406 ExecStart=/etc/init.d/vboxadd start (code=exited, status=1/FAILURE)

Sep 01 11:25:42 linux-d7s8 vboxadd[13406]: Starting the VirtualBox Guest Additions ..failed
Sep 01 11:25:42 linux-d7s8 vboxadd[13406]: (modprobe vboxguest failed)

modprobe: ERROR: module 'vboxguest' is unsupported
modprobe: ERROR: Use --allow-unsupported or set allow_unsupported_modules 1 in
modprobe: ERROR: /etc/modprobe.d/10-unsupported-modules.conf
modprobe: ERROR: could not insert 'vboxguest': Operation not permitted