Tag Archives: linux

File Encryption using LUKS

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luks logo File Encryption using LUKSLUKS (Linux Unified Key Setup) is a part of dm-crypt which provides encryption for block devices by the Linux Kernel. It is possible to encrypt a whole hard drive or a container which can be stored in a native file system containing unencrypted files.

You will learn how to create such an encrypted container here. Some common scenarios could be to store the container on an cloud service such as (Dropbox, Google Drive, Own Cloud and co.) or to store sensible data own your own devices or at your workplace.

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Prelink – Speed up your Linux even more

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tux Prelink Speed up your Linux even moreLast week i posted an article about the application Preload and how you can use it to tune the startup of applications impressively. While researching on Preload i found another way for tuning my system even more with a similar technique. Lets talk about Prelink:

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Preload – Speed up your Linux

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tux Preload Speed up your LinuxPreadload is a daemon that runs in background of your system just as every daemon does.

This daemon creates statistics of your process and application usage. And that is all that is need for speeding up the start of applications by about 50%.

Preload is one of the applications i usually install right after setting up a new desktop distribution. Die effect on the response time of a system is clearly observable. Everything goes faster an makes much more fun icon smile Preload Speed up your Linux .

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Hard Drive Benchmark using Linux

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If you want to know how performing you hard drive is you have to install bonnie++ first.

Using Debian and it derivatives its just:

After the installation create an empty folder on the drive you want to test. Bonnie++ will create temporary random content there while the benchmark is running.

Because i am having just one drive in my notebook the decision wasn’t really hard. The Partition / is nearly full so i used /home.

Now we can let bonnie++ attack the directory icon smile Hard Drive Benchmark using Linux . For having the needed permissions i had to run bonnie++ as root.

Now this will take a bit time but you will get a lot of information. (much more then a Windows application can process). When the process is done you should get some output like that:

(Please do not rate my benchmark. It was done under load)

Well this might disturb you but: Don’t Panic!

  • Per Char 4G has been written with 620 K/sec and an CPU-Usage of 98%
  • Per Block 4G has been written with 67046 K/sec and an CPU-Usage of 11%
  • Per Rewrite 4G has been written with 36145 K/sec and an CPU-Usage of 7%
  • Sequentiell Input done with 2149 K/sec and an CPU-Usage of 9%
  • Random done with 187,5 K/sec and an CPU-Usage of 5%
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Modify Clonezilla

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At work i need to use an application that can store and restore images of an computer. I am using Clonezilla to do so. Clonezilla is an distribution of Debian(sid) which does all those jobs. The advantage is that it is very customizable. Because i am storing all the images at the same space and using the same network setup i has become contra productive to setup it again and again for every single image . Thank god Clonezilla can run a prerunscript which does this for me. If you want to do the same get the lastest version of clonezilla as .zip file and extract it. Changes need to be done in the /syslinux/syslinux.cfgfile which defines the menu is shown when booting clonezilla.

Here we have two menu entries, i replaced those i did not need. I will explain the meaning of the syntax now for you:

  • label – Defines the option just for the config an can be set with any value
  • MENU DEFAULT – This defines which option should be booted if the countdown is over (define only once in config, use # for the rest)
  • MENU HIDE - Hides the menu.
  • MENU LABEL – The Label that is shown in menu.
  • MENU PASSWD – You could ask for an password when choosing the option but it is not needed to me.
  • “kernel /live/vmlinuzappend initrd=/live/initrd.img boot=live config noswap nolocales edd=on nomodeset” – Starts clonezilla as it is.
  • ocs_prerun=”mount -t cifs -o user=administrator,domain=domain.net 172.28.64.141:/Images /home/partimag” ocs_live_run=”/opt/drbl/sbin/ocs-sr -u restoredisk ask_user sda” ocs_live_extra_param=”" ocs_live_keymap=”/usr/share/keymaps/i386/qwertz/de-latin1.kmap.gz” ocs_live_batch=”no” ocs_lang=”en_US.UTF-8″ vga=788 toram=filesystem.squashfs nosplash- Here it becomes very tricky. Do not worry i will explain it for you:
    • ocs_prerun= – Commands in this value will run before clonezilla starts.
    • mount -t cifs -o- mounts a samba share with parameters:
      • user =admin – Login as “admin”
      • domain=domain.net – name of the domain (if you don’t know leave it blank. Home spaces do not use domains icon wink Modify Clonezilla )
      • 172.28.64.141:/Images – Place where the Images are stored or should be placed
      • /home/partimag – Clonezilla mounts the images here which is the reason it does not ask for any other place to search for the images.
    • ocs_live_run=”/opt/drbl/sbin/ocs-sr -u restoredisk ask_user sda” - ocs_live_run is defined two times in my config. This one runs the restore function of Clonezilla.
    • ocs_live_run=”/opt/drbl/sbin/ocs-sr -u -q2 -z1p -i 2048 -p poweroff savedisk ask_user sda- This is the second entry which runs the store function:
      • -u - Asks the user for the image name (could be set in config too).
      • restoredisk or savedisk - Which mode to run ? store, restore, partition or hard-drive ?
      • ask_user - This would be the name of the image but “-u” requests it from user.
      • sda – Which hard-drive should be written or red.
      • -q2 – Use “partclone”. I am preferring this .
      • -z1p – Use gzip-Kompression (with multicore)
      • -i 2048 – Splitzise in megabyte (Split every 2GB a new file for the backup.)
      • -p poweroff - power off after successfully running the script.
    • toram=filesystem.squashfs – Extracts all files to a ramdisk. Therefore you can remove the stick when clonezilla is booted.

After we modified our script we can flash it to an flashdrive (e.g using UnetBootIn or something like that) and test it.

If you have any problems with this how-to feel free to ask me for help and more information.

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