Sysadmin (3)

Monday, 13 January 2014 14:24

Dealing with Ubuntu Unity freezes

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Ubuntu is not my preferred Linux distribution but somehow this is what we currently use at work. For some reason the Unity GUI keeps on freezing several times a day. The Linux base system seems not to be affected by this because I can log into the Ctrl-Alt-1 console to restart the X server. I have no 3rd party graphic drivers installed which I could blame for this.

The hangup seems to be related to the OpenGL-Composition and Windowmanagement system (compiz) upon which Unity is based. If I kill compiz from the command line the hangup is resolved but I experienced crashes of programs like gedit. This is very bad especially if this happens during coding.Depending on the Ubuntu version you might be able to resolve the freeze with either „unity –reset“ or „dconf reset -f /org/compiz/

However for work I do not need a fancy 3d desktop and I noticed that you can use the Unity 2d desktop without compiz. Therefore from the log in screen click on the Ubuntu icon next to your name and select Ubuntu 2d.

This might prevent your system from hanging.

Tuesday, 02 July 2013 14:04

Free ubuntu disk space by uninstalling the big guys

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If you install a Ubuntu Linux it tends to install a big chuck of packages that you probably never need. I think that a useful command to find this big guys is dpigs from the debian-goodies package. This command lists the ten biggest packages installed. Make sure the packages displayed are really necessary or throw them out.

Wednesday, 09 January 2013 13:45

Create your own secure and easy to remember password now !

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Create your own secure and easy to remember password now. Well, I though that’s obvious and everyone knows this information already, but it seems it isn’t. What is a good password anyway ? A good password is a word that is easy to remember for humans but difficult to guess for computers.

Computers can guess passwords in different ways, one very common way is to use dictionary words as passwords. This words are often modified with common number combinations. For example a computer program would try the word „emperor“ from a dictionary but it might try as well „emperor1″, „emperor123″ or other combinations. Thuy, using words from dictionaries is a bad idea. Also number combinations, like „43256465“ which are hard to memorize for human beings can be guessed by a computer within a very short period of time by simply trying all number and letter combinations in a brute force manner.

It seems people tend to use passwords in a way that they feel its cryptic. But what seems cryptic to humans is not cryptic to computers. It is exactly the other way around.

So let us assume we are looking for a new password for a website with the Title. „Outer space box – connect now with all your outer space friends.“. Our own user name to this site is Megan.

The first thing to create our new password now is we think of a sentence that is easy to remember. The tite or the topic of the web site can be used as a hint to this sentence.

First comes to my mind:
I need a powerful password for Megan in Outer space which is easy to remember.

This is obviously to long for a password but I think it is easy to remember. The next step is to think of a mechanism to extract the password from the sentence. E.g. by using every second character of each word. Or, like I do now by using every first character of every word.

That gives me:

A good password does not only contain letters but it mixes lower case letters, upper case letters, numbers and if possible special characters.

So in the third step we mix in some characters that might look similar to the ones we replace.


That gives me:

This is what I call a strong password and all you have to remember is the sentence „I need a powerful password for Megan in Outer space which is easy to remember.“

P.S. never ever use passwords that have been posted as an example on any website :-)