Archive

For June, 2016

VirtualBox fails on startup

No Comments

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

or

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

No Comments

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 192.168.1.50:2080 example.com

where

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

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

ssh -p 8787 -fN -t -C -D 192.168.1.50:2080 example.com

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

ssh -p 8787 -fN -t -C -D 192.168.1.50:2080 remoteuser@example.com

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 example.com.

Reset Unity Top Menu Bar Widget Panel

No Comments

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

No Comments

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.

Blue Taste Theme created by Jabox