How to shrink PDFs

Sometimes a PDF document you’ve created is several megabytes in size due to high resolution images. This may cause problems when you want to send this PDF via email if the attachement’s size is limited by your email provider. There is a way you can reduce the file size of an existing PDF without having to render it again with low resolution images.

How to create a video DVD with command line tools

Maybe you know this scenario: You’ve been invited to a family get-together and you take some videos of the most memorable events. Afterwards a family member comes to you and says: “I’ve seen you recording this and that. Could you give it to me on DVD?”. As a matter of fact, you can easily create a video DVD of any video you have recorded with just a view command lines.

How to use a remote firewire port and transcode DV video locally with ffmpeg

I recently moved into another appartment and found some old VHS tapes I recorded years ago. As luck would have it, I got my hands on a VCR and a MiniDV camcorder with builtin ADC, so I can get analog video signals into the MiniDV camcorder. So all I needed was a computer with firewire or IEEE1394 port. The only computer I have that still has a firewire port is my server, so I hooked the VCR to the MiniDV and the MiniDV to my server.

How to use your iPod Shuffle in Linux

In this article I will describe the probably best way to use your first or second generation iPod Shuffle in Linux. The described method is based on a python script called rebuild_db. The script will allow you to simply copy/paste music files to your iPod like to any other regular MP3-Player. In case you have a different or newer version of the iPod, the described method may not work for you and you should try using gtkPod instead.

How to enable and use Wake on LAN

In this article I will describe how to enable Wake-on-LAN (WOL) and how to use it to start-up a system remotely. In order to use Wake-on-LAN your systems hardware and network driver needs to actually support this technology. You will also need to know the MAC address of the systems ethernet card.

How to use an SSH connection as a SOCKS proxy

In this article I will describe how to use an SSH connection as a SOCKS proxy. This basically means that you can route the network traffic of any application or even your entire systems traffic through an SSH connection.

How to trim disk images to partition size

I’ve recently been playing with my Raspberry Pi and Arch Linux when I encountered the following problem:

I’ve downloaded the Arch Linux image from the Raspberry Pi download page and used dd to copy it to a 8GB SD card.

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)