Therfor, again as usual, I wanted to be able to unencrypt the device using SSH. As many times before I followed the instructions on this page. When I tried to recreate the initrd, all I got was an “error 72″ along with a note, that this all was deprecated — and a hint where to find more, which I ignored…

As Google couldn’t help much, I decided to read the information: Debian now supports this feature natively and it’s damn easy to configure:

[edit 2010-12-29 17:00] A small word of warning: As I just found out, this isn’t that easily working with Ubuntu. According to bug report 595648 on launchpad Plymouth is responsible for problems unencrypting the device. Comment #5 provides a workaround. However, I haven’t tested this. [/edit]

All you need to do is installing dropbear (a tiny SSH server) and BusyBox (a tiny shell, usually already installed) using apt-get. The initrd will be recreated automatically. Then reboot your computer. Don’t worry: If you can’t login via SSH you can still do by using the keyboard. It’s absolutley(?) fail-safe.

There’s also a public/private key pair being created automatically when dropbear is installed. For later public key authentication you can either use the private key provided in /etc/initramfs-tools/root/.ssh/id_rsa (copy to your own machine and use it when logging into the server specifying “-i”, see below) or just add your usual (public) key to /etc/initramfs-tools/root/.ssh/authorized_keys. (cat your_pubkey.pub >> …authorized_keys and recreate the initrd with update-initramfs)

The final command (for logging into your booting server only) looks then something like:

ssh -o "UserKnownHostsFile=~/.ssh/known_hosts.initramfs" \
-i "your_public_key"

“-o” specifies a different known_hosts. This is necessarry, because your server will (going this easy way) have two separate fingerprints: One during the boot process offered by dropbear and one afterwards offered by your usual SSH server. This would cause a lot of inconvnience and warnings as changed fingerprints can indicate something nasty going on — as the warning will tell you.
“-i” specifies the private key to use and is only needed if you copied the one being created by dropbear. If you copied your regular one over this can be omitted.

As you probably don’t want to do too much on your server in this state, it’s comfortable to pass the command for decrypting the harddrive directly:

ssh -o "UserKnownHostsFile=~/.ssh/known_hosts.initramfs" \
 -i "~/.ssh/id_rsa.initramfs" root@10.0.0.103 \
 "echo -ne \"encryptionpassphrase\" >/lib/cryptsetup/passfifo"

Yes, that’s right: The password to decrypt the device is in plain here…

As you can see, this is really easy: Install dropbear, copy dropbear’s private key and use it to login. Three short steps and almost fool proof.

Quite a time ago when I read how easy Truecrypt would offer complete system encryption, I decided to do some benchmarks. As I was especially afraid of performance loss in Games I looked around for some benchmark demos. These results do NOT represent the games I play

Atto Disk Benchmark 2.46

Drive C unencrypted

Drive C encrypted

Based on the results of these benchmarks, you can see mainly two things:

• I’ve got pretty old and slow hardware.
• There is no performance loss. Not even in games.

After having done these benchmarks, there was only one single question remaining: What is the reason for my desktop to still be unencrypted, if a) there is no disadvantage and b) the encryption is that easy? Right, there was no reason, and so I encrypted my whole system drive.

This is what I want you to do now, too. But let me start explaining, why you should even think about encrypting your computer: You don’t have anything to hide? Really? Okay, go! Really. I don’t wan’t to explain everything to you. Maybe you really don’t have to encrypt your Desktop system (as long as you do not fear the police or your family). However, an unencrypted laptop is an absolute no go.

If you loose it, you do not only loose a device, but also valuable data. What data? For example your stored WiFi passwords, maybe even more passwords stored in your browser. What about your private documents? Do you want everybody to be able to read them? What about sensitive data from your company (that shouldn’t reside on your private laptop!)?

If you still don’t care, it’s okay. It’s not my problem. Otherwise, here’s what to do:

First of all: Make some backups. There shouldn’t be any problems and I didn’t experience any, but there *could* be some. And backups are always good (when did you make your last?)

In case you are still using Windows XP or 2003: TrueCrypt cannot handle logical partitions. So you can either only encrypt your System Partition or get rid of those partitions. In Windows Vista/7 there is no such limitation any more.

For almost every click you do, TrueCrypt provides detailed information on what you are about to do. Make sure you understand them, before proceeding. I do NOT take responsibility for any damage occurring from following this tutorial. Asking stupid questions beforehand is better than asking stupid questions afterwards And there are no stupid questions anyway…

Open TrueCrypt and select System->Encrypt System Partition/Drive

You don't want a hidden OS for now

No bit will remain unencrypted

A little warning for XP/2k3 users: TrueCrypt doesn't support logical paritions for those OS

Read the text. If you have such tools, you should probably select "No" here

Usually these defaults are a good choice. Select "Benchmark" to test the algorithms

You probably want to go for AES. Especially if you own a more recent Intel CPU offering hardware acceleration

Choose your password. It should be hard to guess. However, you shouldn't forget it!

Depending on your paranoia you can select here how to overwrite old data

A rescue disk is created. You can either burn it or mount it with Daemon-Tools to let TrueCrypt verify it. The disk is needed in case you need to unencrypt the device without booting Windows. However, this is NOT a way to get into the system without password.

Before anything is encrypted, TrueCrypt performs a pretest where your system is rebooted.

After rebooting Windows and starting TrueCrypt, TrueCrypt asks to encrypt the device. My 250 gig drive took about 3 hours.

Finished! I hope you still remember your password?!

My system has been encrypted for a few months now and I had no problems yet. Just the shock, when I saw the password prompt after the first night when I had problems remembering the password Moreover, it’s even more convenient as I don’t forget to mount the data partition any more…

The only real limitation I experienced is a little more CPU load during large copy actions which however is obvious and not that bad. For most of the data I’ve had this before on my encrypted partition, anyway.

One last advise: DO IT!

GET /search?hl=en&source=hp&q=Foobar&aq=f&aqi=g10&aql=&oq=&gs_rfai=

to everyone in between you and Google’s server (e.g. your admin, your ISP, the script-kiddie abusing your unencrypted WiFi), but rather something like:

C955C288BA1F561B841074546CBFA3D9723B1F2097E07FB8...

Of course, SSL can be defeated in several ways, but nonetheless, this is a very easy way to enhance your privacy…

Uh, wait? Did I just mention “privacy” while talking about Google? Well, yes. Despite all the encryption stuff, Google still knows, what you are looking for. Obvious? Yes. Inevitable? No. There is a way to use Google’s search algorithm (which is probably one of the best) without revealing your identity to Google.

This is done by using a proxy service like Scroogle. Instead of sending your queries directly to Google, you ask Scroogle to do that. Scroogle then forwards your request to Google’s servers, but drops information about you (things like your browser, your location, &c.). It then returns the results of the search to your computer, but does not save any other data like cookies to later identify you again. Google only sees a lot of requests from Scroogle, but doesn’t know, who is *really* searching anything — pretty cool, isn’t it?

Furthermore, Scroogle also offers an SSL encrypted service. By using POST instead of GET for the search it also avoids website owners to see with which search terms you found their site: Instead of a log entry like

http://www.scroogle.org/cgi-bin/nbbw.cgi?Gw=Foobar

they only see that you came from Scroogle, not knowing your exact search terms:

http://www.scroogle.org/cgi-bin/nbbw.cgi

If you want to tell them, what you were looking for, or you simply want to bookmark a search, you can use the GET version of Scroogle (at the bottom). For more detailed information about POST and GET have a look at Scroogle’s Explanation.

Unfortunately, I was about to get an important message… and was offline at that time. Therefore, I was searching for a (stupid^^) way to upgrade Pidgin — withouth adding the repositories of 9.10.

I finally decided, it would be the best to compile Pidgin myself… and didn’t expect the problems I was going to have:

After installing Pidgin 2.6.4, the pidgin-plugin-pack, which I need for some reasons, wasn’t working. So I spent a whole evening, installing and removing packages from the repository and from source, until I finally managed to have Pidgin 2.6.4 with a working plugin-pack — unfortunately, I couldn’t remember the way and my system was in RAM… and everything gone afterwards

As I found no way to get there again, I decided to try changing the libpurple withouth installing a newer version of Pidging — not surprisingly: It didn’t work.

However, after installing Pidgin 2.6.4 from Sources (without uninstalling anything), everything was working: Receiving offline messages as well as the plugin-pack

This is probably the worst solution ever and maybe not even worth to be called “work-around”, but I hope, it will be enough until I upgrade the system over the Christmas holidays.

Just forget about it. It’s much easier to just copy the plugins (the ones I needed were in /usr/lib/pidgin/, uninstall the plugin-pack und copy the files back. This works just as fine and has the advantage that it doesn’t screw up your package management. Thank you to my brain, which started working again -.-

The talk itself was held by Patrick H. Lauke and was absolutely brilliant. Humorous, easy to follow, interesting and peppered with examples of the “sexy features”, that are about to come. It really seemed to be a look into the future of the Web.

The presentation opened with a little movie about working at Opera Software – guess what: I got a new favorite place to do my internship… now I just need the right marks. I was a little afraid that it will be a presentation about how cool Opera is (what would have been useless, as we all know that), but was all the more surprised as Patrick’s main topic was to point out the importance of open web standards, which he did for about 90 minutes. Always telling, how these standards could help you and me as a user, but also the web designers. Only the last roughly 20 minutes he showed some of the “sexy features” (he liked that one^^) of Opera, namely their widgets as well as “Opera Unite“.

A very big thank you to Patrick and his team for coming to Furtwangen as well as to everyone else making this fantastic event happen – even though it was of limited value to me for my studies, since I’m not studying anything related to media.

Just add the line bindkey -d ^@ stuff ^? to your .screenrc and restart your screen sessions. I cannot judge the quality of this nor do I know the consequences, but it’s working.

Finally, I don’t have to look for an alternative of my terminal

As I didn’t find a properly working solution for my minimal installation (some troubles with thunar and I wanted also for the console), I decided to do a poor alternative on my own. I tried to make it almost as convenient as in GNOME (or KDE…) as I was sick of always typing “sudo mount /dev/sd?1 /mnt” which also led to some troubles when using more than one stick.

It’s no more than two small scripts combined with two rules of udev (save as /etc/udev/rules/01-YOURNAME.rules and modify the script path):
BUS=="usb", KERNEL=="sd??", ACTION=="add", RUN+="/home/flo/.scripts/udev/mount.sh %k"
BUS=="usb", KERNEL=="sd??", ACTION=="remove", RUN+="/home/flo/.scripts/udev/umount.sh %k"
These lines execute mount.sh when attaching an USB device and execute umount.sh when removing it. “%k” gives the device name (e.g. sdb1) as parameter for the script.

mount.sh:

#!/bin/bash
label=$(ls -l /dev/disk/by-label/ | grep $1)
if [ $? -eq 0 ]; then	#found the device
    label=$(echo $label | sed -e 's/.*:...//g' | sed -e 's/.->.*//g')
else
    label=$(ls -l /dev/disk/by-uuid | grep $1 | sed -e 's/.*:...//g' | sed 's/.->.*//g')
fi
mkdir /media/$label
mount /dev/$1 /media/$label -o sync,gid=46,umask=007

This script tries to find the label of the partition. If not possible it uses the UUID as a name for the mount directory, which is /media/{UUID|LABEL}. It finally mounts the device into this newly created folder, setting the “sync” option, which makes it save to remove the device without umounting it. “gid=46,umask=007″ means, that only root and members of the group “plugdev” are allowed to acces the device – this is needed for FAT formated sticks.

umount.sh:

#!/bin/bash
label=$(mount | grep $1 | sed -e 's/.*\/media\///g' | sed -e 's/.type.*//g' )
umount -l /dev/$1
rmdir /media/$label

This script umounts the device and removes the folder, that was created.

Important note: These scripts should *not* be editable by users as they are executed with root rights – and therefor might be used to “hack” the system when modified!

I have no idea, how well these lines work with hard drives containing several partitions (I don’t have one here at the moment) or with encrypted partitions. I’ll have a look at that after the exams (in roughly 2 weeks).

As always: Use with care, I’m not responsible for any harm

While rewrtiting, I “(re-)developed” the algorithm, changed the underlying programs and added a few options, so I belive it’s now ready for being used.

The whole idea behind the script is that I wanted to save money and print a usual full size (DIN A4) PDF in half size, i.e. in DIN A5, which is also more handy. In addition to that, page 2 (4, n) should be on the back of 1 (3, n-1) why it was not enough to just change the printer settings to print multiple pages. Of course, this requires duplex printing! Finally, it should be possible to cut the papers in the middle and just put one stack on the other to have the correct order.

type     | front(back) | front(back)
printer  |    1 (4)    | 2 (3)
still bad|    1 (2)    | 3 (4)    a lot of manual reordering necessary
script   |    1 (2)    | n/2+1 (n/2 +2)

In this rewritten version I also added some support for downloading and merging chapters from SpringerLink (note: SpringerLink has limited access. If you are not allowed to use the ressources, the script won’t help you!). You can now download all chapters automatically by giving only the URL of the book. If you want, you can then merge those chapters into a single PDF file by inserting blank pages (if necessary) to make the chapters start on even pages.

However, it is still not very comfortable, but works quite well and fast: Reordering a whole book now takes about 10 seconds and results in a final size of about 10MB compared to about 5 minutes and several hundred MB before. If you experience any problems, just drop me a message – or try to fix it yourself

Enjoy it

• The system is absolutely silent when the hard disk is shut down (Yep, I could have bought a SSD, but this would be too expensive)
• The system consumes less power – my battery now lasts about 6 hours (having turned WLAN off, backlight down &c. of course)
• The system is fast, the programs start real fast – although they usually also do when starting them the second time
• And, last but definitely not least: I haven’t found something like that by now (Just let me believe this^^)
• Oh, and fifth: You can play around and try some things, without destroying your system as -of course!- everything has gone after rebooting.

I found two different approaches on this, which both did not satisfy me: Modifying a Live-CD to suit your needs is the most popular one. However, this will always be a Live-CD in the end, resulting in a long boot time due to hardware detection. The other idea was more promising, copying a real (i.e. installed) system into RAM, but I wanted to improve this. Although 3GiB seems quite a lot of RAM, it becomes very small if you try to put an uncompressed System into it. As the Live-CDs contain compressed systems, I also wanted it. It thought, this would be not a problem… It took longer than I expected.

Basic idea is to create a squashFS compressed image (compression ratio is about 2-3:1) of the system (excluding as most as possible), which will be loaded into RAM by the initrd and looped as “/”. As Linux can’t deal with a whole read-only file system and squashFS is exactly that, Another UnionFS (aufs) is needed to pretend write access.

So, here in short is, what need to be done (as far as I remember):
You need to compile support for SquashFS and aufs into the kernel (This should be also work with UnionFS, but I didn’t find a patch for the kernel at the time, I did it). Keep in mind, that the SquashFS of the kernel (2.6.29.1 I used) is version 4, while the version of squashfs-tools (to create the image) is 3.x in Ubuntu 9.04, so you’ll need to manually install a newer version of the tools.

After having done that, you can prepare some files, which will be need to be modified for the usage in the RAM system:
Remove the “/” line from /etc/fstab and replace it with "none / tmpfs defaults 0 0" (after creating the image, copy back the old version.)

Well, this was the easy part. The next thing is to modify the scripts being executed during the boot process. In my Ubuntu this was /usr/share/initramfs-tools/scripts/local. I have uploaded a modified version with a few comments for Ubuntu. If you’re not using Ubuntu, figure out, where your hard disk is mounted and replace it by mounting, copying and unmounting like in my example (NB: I don’t know, how far this works for other distributions). Again: Just modify this file for creating the RAM system. Then you should copy the old file back again, as you won’t be able to boot your “normal” system otherwise.

I also experienced some problems when checking the file system, so I turned it off in /etc/init.d/checkroot.sh by inserting a "fastboot=yes" just before checking it.

Now, it’s time to create the initrd (you’d better not overwrite the original one!):
# mkinitramfs -o /boot/initrd.img.squashfs

I have uploaded another script to create the live system image (You can also see, how the squashFS is created). Unfortunately, due to its design, this script can only create images of systems, that are (uncompressed) not larger than your RAM size. I hope to fix this after my exams in a few weeks.
As you might recognize, there is still an option to create the tar-archive. If you want to use this (why would you?^^), please refer to the tutorial mentioned above.

Don’t forget to create a new entry in your boot loader pointing at the new kernel and initrd.

I hope, I didn’t miss a point. Nevertheless: I’m not responsible for any damage, think before you act (this is, why this isn’t a step-by-step tutorial) and have a Rescue-CD around

Ah, I still forgot: Of course, all data -if not saved somewhere else- will be lost after turning the system off. Also, sometimes (I’d guess about 5-10%), the harddisk wakes up immediately after shuting it down via “hdparm -Y”. I don’t know why this happens or how to avoid it. I believe, I have read something about a bug in hdparm, but I cannot remember

Anyway, while I really fell in love with this feature, I couldn’t get used to creating my presentations with OOo. I just wanted my LaTeX back and therefor searched for a possibility to have similar features when presenting a pdf file.

I found two ways to achieve this:

First: Create an extra wide presentation to display one part on the beamer, which contains the information for the audience, while the other half (or quarter…) contains your notes and is only being displayed on your screen.

The second one (found on mikas blog) is a bit more complex: Use Impress!ve (formerly known as keyjnote) to display your presentation with xpdf to display your notes (and previews). Impressive gives you the ability to execute a python script when entering a new slide. Combined with xpdf’s “-remote” option you can use this to display your notes. The only thing to keep in mind is, that each slide will need a associated page in your notes. Whenever you switch to another slide in Impressive, it will also go to the correct page in your notes.
Impressive also gives you the ability to turn the beamer black/white, show an overview of all slides and even some nice effects when changing slides – impressive…

I decided to use the last idea as it seemed more flexible to me concerning different screen sizes and also allows me to create my notes using OpenOffice. Furthermore, I did not only want to have the notes on my screen, but also – just as in the “original” – the current slide, a preview and the time, so the notes mustn’t take all space.

I chose to use three xpdf windows (one large one for notes, a smaller one for the current slide, an even smaller one for the next slide and one with a simple stopwatch): (screenshot coming soon)

Unfortunately, there was (and somehow still is) a minor problem: You do not see the effects of Impressive on your screen, as there is only a static pdf displayed. As a result, if you want to use the overview, you would have to turn around to see, what you are doing. You also do not see, if you turn the presentation black and just talk on…

My idea was to not display the current slide as pdf anymore, but to watch the second screen (beamer) with VNC. This worked as proof of concept, but is sometimes quite laggy – even with enabled compression…
So I’m not completely happy and would be really glad, if some of you had an idea solving this problem.

You’ll need:

• A pdf file containing your presentation
• A pdf file containing your notes (each slide <-> one page of notes)
• The info file for Impressive (I uploaded a sample)
• Impressive and xpdf
• For your (and my^^) convenience I wrote a little script to start all this and position it correctly on the screen (a 1280×800 laptop screen and a 1024×768 beamer)
• If you like: A small stop watch