For June, 2016

VirtualBox fails on startup

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Result Code: NS_ERROR_FAILURE (0x80004005) / Kernel driver not installed (rc=-1908) are the errors displayed when the kernel driver needs to be recompiled. It usually happens when updates to Ubuntu are installed.

The kernel driver can be recompiled by issuing one the following commands:

sudo /etc/init.d/vboxdrv setup


sudo /sbin/rcvboxdrv setup

The former one works for Ubuntu versions prior to Ubuntu 16.04. If the first one is not found on your system, try the second one.

Port forwarding using SSH

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SSH port forwarding let you connect to a server using another server a relay.

For example, if you host a web server in a DMZ behind your office router, you will not be able to access it using its public URL if your workstation is behind the same router.

You can easily implement a workaround if you have access to a server on the Internet. Issue this command on one of the machines connected on the same network as your workstation.

ssh -fN -t -C -D


  • is the address of the machine that will accept connections from your LAN on port 2080.
  • is the machine on the Internet that will establish connections to the final destination

You may need to add the port number on which listen to using the -p option. If SSH listens to port 8787 on, the command would be:

ssh -p 8787 -fN -t -C -D

You may also need to supply a user name to connect to The command would then look like:

ssh -p 8787 -fN -t -C -D

You can use this setup with a browser if you configure it to use a proxy to connect to the Internet. For example, access the proxy configuration of Firefox: preferences >> advanced >> network >> settings. Choose Manual proxy configuration and fill-out the SOCKS host parameters.

SSH Port Forwarding

The result will be that Firefox will open the URLs you type-in using the server

Reset Unity Top Menu Bar Widget Panel

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Sometimes, widget disappears from the Top Menu Bar Widget Panel of Unity. The Widget Panel can be reset using the following command:

killall unity-panel-service

Make Linux use the hardware clock set to local time

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Ubuntu sometimes assumes that the hardware clock of the computer is set to GMT. If the hardware clock is set to local time, set UTC=no in /etc/default/rcS.

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