TT: Uni-directional file synchronization between different hosts with Unison
When you work with at least two computers on the same project on a daily basis you might have a problem. You need to get changed files from host A to host B and vice versa. The problem getting bigger when you work in addition on different operation systems or use more than two hosts. On UNIX/Linux the preferred tool for such a task is Rsync. Unfortunately Rsync synchronize only in one direction, it doesn't work very well when more than two hosts are involved (and it isn't really comfortable to set up on Windows) and can't use a secure communication channel. Another approach is to check-in changed source files into a version control system, like CVS. On host A you check it in and on host B you check it out afterwards. But this means you always need a more or less stable variant of your code, so that other developer can, at least compile, or much better use it. That is not always the case (especially when you leave the office at 11:00 p.m.) and it also doesn't cover files which aren't handled by a version control system. Luckily there is a solution for all the problems mentioned which is called Unison. So here comes the second post in the ToolTips series, which covers an easy and portable way for file synchronization.
TT: Console navigation the easy way with Apparix
Today I will start a new series where I present small tools which I use on a daily basis and considered very useful. These tools haven't to be killer applications, but doing the task they are written for, very well. Therefor also the name of this series: TT, which stands for ToolTips. Most of this applications are open source, so I will take the opportunity to say "Thank you" to all the people out there, which create such cool stuff in there free time.
Installing Linux on a USB hard disk for the MacBook Pro
One of the features of Mac OS X I love, is the possibility to install Mac OS X on any attached removable media, like a FireWire or USB hard disk. This makes it really easy for me to test VirtualBox on the several versions of Mac OS X we support (formerly Tiger, now Leopard and Snow Leopard). The advantage of this setup is that I don't waste disk space for operation systems I usually don't use very often. Currently I have a 150GB hard disk in my MacBook Pro which is really not that much if you deal in the virtualization business. There are several test VM's of any kind of guest operation systems and of course the ISO's to install them. The second main OS, I do much of my work, is Linux. For this I have a standard PC with Gentoo on it, which have all that I need. Unfortunately this doesn't really help when I on travel. As I soon be away for some time, I decided I need, at least for testing, the same flexibility mentioned above for a Linux installation. And here the problems start to arise. Of course Apple didn't really support installing other OS's than Mac OS X on Apple hardware. Yes, there is Boot Camp, but this is mainly for Windows, is very inflexible and doesn't really help if you try to install something on another place than the integrated hard disk. There are projects like rEFIt, which even makes Boot Camp superfluous, but this project has really bad USB boot support. In the following I will explain how it is even possible to install Ubuntu 9.10 on a USB hard disk.
FRITZ!Box tuning part 2: Access your home network with OpenVPN
AVM has built a VPN server into the FRITZ!Box, why should I use some other software for this job, you may ask. The reason is quite simple: the build in one is a piece of closed source software written by AVM and there is only one official client which could be used to connect to it, the FRITZ!VPN software. This client software is only available for the Windows operation system family and so by no means anything useful to me. I'm pretty sure they are using some official protocol like IPSec, so it might be possible to connect to the FRITZ!Box with other clients as well, but that's something I didn't want to try. OpenVPN on the other side is a rock solid open source software which could be used from many popular OS's these days. Even graphical clients, like TunnelBlick for Mac OS X, are available. So here comes the second article of the FRITZ!Box tuning series, which will explain how to convert your FRITZ!Box into a OpenVPN server, where any number of clients can concurrently be connected. I highly recommend to read the first part of this series, because this post is build on top of the stuff done there. This count especially for the filesystem layout on the usbstick and the way additional software is started. Also in the following it will be helpful to have ssh access to the FRITZ!Box all the time. As already written in the first part, there is no guarantee that the information presented here will work on your side or that I'm responsible for anything happen to your FRITZ!Box. In preparation of the following you need access to a second OpenVPN installation which will be used to create all necessary certificates and keys and which could be used to test the installation afterward. I'm using a Gentoo Linux host where you could install OpenVPN simply by executing emerge openvpn. Make sure you have the examples USE flag set to get all the helper scripts which make the life much more easier.