Failed to start guacd.service: Unit guacd.service is masked.


Si al configurar Apache Guacamole sucede el siguiente error:

root@rock64:/var/lib/tomcat8/webapps/guacamole-1.0.0# service guacd start
Failed to start guacd.service: Unit guacd.service is masked.

Se soluciona eliminando la anulación o enmascaramiento:

root@rock64:/var/lib/tomcat8/webapps/guacamole-1.0.0# systemctl unmask guacd.service
Removed /etc/systemd/system/guacd.service.



modprobe: ERROR: could not insert ‘vboxdrv’: Operation not permitted where: suplibOsInit what: 3 VERR_VM_DRIVER_NOT_INSTALLED (-1908) – The support driver is not installed. On linux, open returned ENOENT.


Cuando al ejecutar Virtualbox en Kubuntu ocurre el siguiente error:


modprobe vboxdrv
as root
where: suplibOsInit what: 3 VERR_VM_DRIVER_NOT_INSTALLED (-1908) - The support driver is not installed. On linux, open returned ENOENT.

y en consola indica lo siguiente:
modprobe: ERROR: could not insert 'vboxdrv': Operation not permitted

es necesario tener en cuenta que es debido a un error al instalar Virtuabox, concretamente al no activar permisos en BIOS como el asistente indica. Para solucionarlo,

sudo apt install linux-headers-generic
sudo apt install build-essential gcc make perl
sudo apt-get install virtualbox

y realizar el siguiente paso siguiente fielmente las instrucciones: En él se va a pedir configurar un nuevo password que posteriormente, en el siguiente reinicio de la máquina, la BIOS pedirá. En ese punto, se ha de introducir y otorgar los permisos que ésta solicite.

sudo dpkg-reconfigure virtualbox-dkms
sudo reboot

Con ello, el problema estaría solucionado.


unknown filesystem type ‘exfat’.


If trying to mount an exfat file system we get the following error:

carlos@rock64:~$ sudo mount /dev/sda1 /media/pendrive/
[sudo] password for carlos:
mount: /media/pendrive: unknown filesystem type 'exfat'.


It is just necessary to install the “exfat-fuse package:
carlos@whenIGrewUp:~$ sudo apt-get install exfat-fuse
Leyendo lista de paquetes... Hecho
Creando árbol de dependencias
Leyendo la información de estado... Hecho
El paquete indicado a continuación se instaló de forma automática y ya no es necesario.
Utilice «sudo apt autoremove» para eliminarlo.
Se instalarán los siguientes paquetes adicionales:
Se instalarán los siguientes paquetes NUEVOS:
exfat-fuse exfat-utils
0 actualizados, 2 nuevos se instalarán, 0 para eliminar y 22 no actualizados.
Se necesita descargar 64,4 kB de archivos.
Se utilizarán 273 kB de espacio de disco adicional después de esta operación.
¿Desea continuar? [S/n]
Des:1 http://es.archive.ubuntu.com/ubuntu bionic/universe amd64 exfat-fuse amd64 1.2.8-1 [24,5 kB]
Des:2 http://es.archive.ubuntu.com/ubuntu bionic/universe amd64 exfat-utils amd64 1.2.8-1 [39,9 kB]
Descargados 64,4 kB en 0s (296 kB/s)
Seleccionando el paquete exfat-fuse previamente no seleccionado.
(Leyendo la base de datos ... 231016 ficheros o directorios instalados actualmente.)
Preparando para desempaquetar .../exfat-fuse_1.2.8-1_amd64.deb ...
Desempaquetando exfat-fuse (1.2.8-1) ...
Seleccionando el paquete exfat-utils previamente no seleccionado.
Preparando para desempaquetar .../exfat-utils_1.2.8-1_amd64.deb ...
Desempaquetando exfat-utils (1.2.8-1) ...
Configurando exfat-utils (1.2.8-1) ...
Configurando exfat-fuse (1.2.8-1) ...
Procesando disparadores para man-db (2.8.3-2ubuntu0.1) ...

After this, device will be perfectly mounted:
carlos@whenIGrewUp:~$ sudo mount /dev/sdd1 /media/pendrive/
FUSE exfat 1.2.8


Fstab error message on boot: maintenance mode


If booting a Debian/Ubuntu system we get a error of fstab, asking us to enter at maintenance mode or Control-D to continue, even having a “nobootwait” flag at Fstab file, change it with “nofail” as “noboowait” has been deprecated.


UUID=1EF0-3965 /media/discoalicante vfat defaults,nobootwait 0 0

UUID=1EF0-3965 /media/discoalicante vfat defaults,nofail 0 0


Kswapd0 probem at Raspberry Pi 3 with Raspbian


If in a Raspberry Pi there is a problem of resources, going slow or even frozen, and a process named “Kswapd0” is taking a lot of CPU:

root@Shirley:~# ps uax | grep kswap
root 44 0.2 0.0 0 0 ? S 11:28 1:59 [kswapd0]

is due to any process that is consuming a lot of memory, causing the need of to do “swapping“. This is, saving RAM memory at the HD (SD card in Raspberry Pi), so the operating system (Raspbian i.e.) can allocate memory to other process.

The SD card is quite slow (about 20MB/seg), what makes hard and slow the swapping process, and this drivers the Raspberry to require minutes or hours if a process is demanding a lot of RAM memory. The main advice to avoid this problem is to assume that Raspberry PI is a machine with a lot of limitations, not designed for general purposes (Desktops, browsing the web, computing, etc).

For palliating problems, you can follow next tips:

1º) Updating the system to get the state of art kernell. If you have Raspbian, run as root:

root@Shirley:~# apt-get update
root@Shirley:~# apt-get upgrade
root@Shirley:~# apt-get dist-update
root@Shirley:~# reboot

2º) Change the microSD card for another more modern and better, like the Samsung Evo+ 32GB microSD card. A SD card class 10 is enough for Raspberry Pi 3, as the machine cannot write faster than the Samsung card supports. Anyway, you can investigate reviews and comparisons of new microSD cards for Raspberry at Internet.

3º) Booting from a USB SSD disk may help, but it is expensive and the improvement is not guaranteed, as the USB 2.0 port has a maximum speed of about 20MB/s.

4º) Check the process that demands so many RAM memory. Try to update it, tune it, check for any bug (memory leak), report the high RAM consumption to developers, or by last, look for an alternative.

5º) Update Raspberry´s firmware:

root@Shirley:~# rpi-update


Creating a POE solution for iSmartAlarm Spot


If you have a iSmartalarm Spot security camera, and you haven’t the posibility to bring electricity to it, you can use this tutorial so it will be fed with the electricity that cames by a Ethernet (network) cable. This technology is commonly named “Power Over Ethernet” (POE).

At this tutorial is needed:

  • A POE injector: 48V 1,25A. You can find it at Ebay

    Also the VDE power cable is not usually included, but you can find it easly at Ebay, Amazon…



  • A high quality CAT cable. As we are going to transport electricity and data in the same wire, and for avoiding shorcircuits, fires, electromagnetic interference or others, do not hesitate buying a premium wire for this purpose. Your time is money. Also is important to use only one wire, not plugin 2 or more, so look for one which measure can satisfy your needs. For example this IBRA® 10M Cable de red Gigabit Ethernet Lan CAT.7 at Amazon.


  • A short microusb cable. For not having plenty of meters of wires, having a short wire is the most discreet and elegant solution.

With all this items, creating the POE solution is easy:

  1. Plug the power injector to the wall, and to an end of the RJ45 cable.
  2. Plug the other end of the RJ45 wire at the rear of the wall POE plug.
  3. Plug the microusb to the wall plate.
  4. Plug the iSmartAlarm Spot camera to the microusb.

And you’re done.

Note: if you want to transport data a part of electricty using the RJ45 (what should happen in most of cases), plug the data cable in the second socket of the power injector.






How to make AWUS1900 work in Kali, Debian or Ubuntu?


To make this amazing usb wifi card work, just install the following driver:

$ sudo apt-get install realtek-rtl88xxau-dkms

and later, unplug and plug the network card.