How to compile Truecrypt from source

A few days ago my new USB hard drive arrived. My idea was to connect the hard drive to my Raspberry Pi so that everyone in the network can read the data on that drive. But all the data stored on that drive should be encrypted. The problem was that I also wanted to use the hard drive to copy files from a computer of a friend. Not everyone uses Linux, so I could not encrypt the hard drive with LUKS.
But I had an idea to encrypt the hard drive with Truecrypt, which is available for Windows, Mac OS X and Linux. I created a little partition (about 100MB) which is not encrypted and download the Truecrypt installer for each OS to that partition. The advantage is that you don’t need an internet connection to download the installer. The rest of the hard drive is encrypted with Truecrypt.

The main problem was the installation of Truecrypt on my Pi because there is no ARM binary. I’ve no X-Server on my Pi so I had to install Truecrypt as console-only version. Here are the steps I’ve done to install Truecrypt on my Pi.

How to install Privoxy and combine it with Tor

In this post I’ll show you how you can improve your privacy and anonymity while you are browsing on some websites. For this purpose I’ll use Privoxy and Tor. Privoxy is a non-caching web-proxy with filtering capabilities for enhancing privacy. Tor uses an overlay network of volunteers and relays your traffic through the Tor network to it’s destination. It also encrypts your data, so no Tor node (except the exit node) can read your data.

This is not a high-security setup, but it should improve your privacy and anonymity.

1. Privoxy
2. Tor
3. Combine Privoxy and Tor
4. Appendix

How to set up a stateful firewall with iptables

My old post to set up a small rules set for iptables is deprecated so I decided to update this post and improve some rules.
This time I tested this iptables setup on my Raspberry Pi. I connected to my Pi via SSH and the first time I tested the rules order I locked myself out and I had to connect the monitor and keyboard to fix this. The rule order in this post worked for me to set everything up via SSH.

I also tried this setup on a virtual machine and made a screencast of it. You can find the video at the end of this post.

1. Kernel modules
2. Important Rules
3. Chain Policies
4. Port Rules
5. Logging
6. Saving Rules
7. Appendix (Script and video)

How to install a CalDav and CardDav server using Radicale

During my time at the university I had lots of meetings, events and I couldn’t remember all these events, so I had to write them down. But we’re living in a digital world, so I wanted to keep all my appointments digitally. I tried Thunderbird Lightning and it is a great Add On. But I also wanted to synchronize all these events with my smartphone without using an external cloud, e.g. Google Calendar.

I wanted a small program with minimal dependencies to act as a server which is able to run on a Raspberry Pi. It doesn’t have to provide a web interface, because I can use Thunderbird or my smartphone to add, change or delete events. I found Radicale which is written in Python and has no dependencies. It supports the CalDav and CardDav protocol. That’s all I wanted so I gave it a try. My first impression was very good and it works great. Here are all steps I did to set up my own CalDav server with Radicale.

1. Installation of Radicale
2. Adding bcrypt support to Radicale (optional step)
3. Configure Radicale
4. Configure Thunderbird Lightning
5. Configure Android Calendar

How to make daily backups with rsync and cronjobs

It’s always a good idea to make backups of important data (documents, images, music, etc.), e.g. the worst case for students is to lose data of written reports or theses.
I wanted to make backups of my documents and source codes every day. The backup should be stored on a usb flash drive. But I also wanted to keep deleted files for a couple of days, in case of accidentally deleted files. There are many ways to complete this task, but I decided to use rsync and cronjobs for this purpose. Both tools make the backup process very flexible. It’s very easy to manage the time of the backup process with cronjobs and rsync makes it easy to change the destination (e.g. another folder, device or remote host).
My idea was to add a cronjob to start a bash script which uses rsync to copy the directories and files to the flash drive. But the device names of flash drives changes, if you plug them in a different order. To avoid this problem, I added a udev rule to create a symbolic link every time the flash drive is plugged.

How to install Slackware ARM on a Raspberry Pi

A few days ago I got my Raspberry Pi and I had to decide which OS I install. I like Slackware and decided to give Slackware ARM (formerly ArmedSlack) a try. It was surprisingly easy to install it.
The first step was to download the Slackware ARM installer and copy it to the SD card.
Download installer:

$ wget http://www.daves-collective.co.uk/raspi/images/raspi-slack-installer_01Aug12.img.xz

Write the installer to SD card:

$ xz -dc raspi-slack-installer_01Aug12.img.xz | dd of=[device] bs=65536


How to mount LUKS encrypted partitions manually

In the last days I played a bit with Slackware Linux on my netbook. But I play a bit too much and I had to recover some important files from my home folder but it is encrypted. The system wasn’t able to boot successfully. I had to boot from an usb-stick. But the problem was to decrypt the partition with my home folder.

How to disable the monitor sleep mode

A week ago I changed the linux distribution from Ubuntu to Slackware. I also changed my windowmanager from Gnome 3 to XFCE. But whatever I set in the power manager XFCE puts the monitor to sleep every 10 minutes. Here is a fix that worked for me.