When enabling logs with HAProxy on a busy web site, hard disk space can quickly become a scarce resource.

The reason is that, most of the time, HAProxy is set to use local0 facility which tend to write logs to a bunch of files in /var/log such as messages...

Thanks to rsyslog, we will be able to canalize those logs to a more appropriate location and only once, saving a bunch of disk space.

Even though I pretty like OpenVPN, there is still some devices that might not support the TUN/TAP driver needed by OpenVPN.

Take IPhones, Android phones for instance, you need to root them in order to get that feature, assuming somebody has already cooked a ROM for your device.

L2TP is quite and old standard that allow setting up VPNs.

On the other end, it does not provide any kind of encryption mechanism, and as such, it is pretty common to get L2TP running over an IPSec link.

If like me you use MPD as a service daemon to listen to music, you might be annoyed anytime GDM start a pulseaudio process which prevents MPD from accessing the sound device.

Typically, the output of ps will produce the following output:

$ ps aux | grep pulse
gdm 1371 0.0 0.4 98180 4776 ? S<sl Jun13 0:00 /usr/bin/pulseaudio --start --log-target=syslog
gdm 1411 0.0 0.2 10748 2968 ? S Jun13 0:00 /usr/lib/pulseaudio/pulse/gconf-helper

When working in a chrooted environment, there is a few special file systems that needs to be mounted so all programs behave properly.

For instance, grub will need to access your disk devices....

While most special file systems might be mounted with:

# mount fstype -t fstype /tmp/chroot/mountpoint

Where fstype will be sysfs, proc, /dev is not following this rule.

When you hotplug a hard drive in a virtual machine, the drive do not show in fdisk -l output until you reboot your VM.
In order to get the drive to appear, the SCSI bus need to be rescanned.

this tutorial will explain how to use a MySQL backend in order to authentication users against your Apache website.

To achieve this we will use Apache2 and its auth_mysql module.

Vyatta is a Linux based distro that ease the set up of VPN, Routers, antivirus.... It has a really small footprint on your system as it only requires something like 800M to be installed and is based on Debian. On the top of that, it offers configuration wrappers to facilitate service settings.

This tutorial will explain how to set up 2 Border Gateway Protocol (BGP) boxes to route the traffic from one Autonomous System (AS) to the other using Vyatta.
Vyatta Community Edition 4.1.4 was used during this set up.

Bazaar (bzr) is a distributed version control system (VCS) sponsored by Canonical and thus bzr is widely used by the Ubuntu community.

Like any vcs, bzr will let you track the different version of your code locally and let you push the changes to a remote server.

One cool feature of bzr is that you can maintain a remote copy of your code history without having a bzr server running, nor having a copy of bzr on the remote server running and simply by using ssh to transport the data.

This tutorial will not explain how bzr works, but will show the couple few step to create your local repository, add a few files, commit the changes, push them to a remote server and copy the branch newly created to another machine.

Even though new distros installers tend to support filesystem encryption out of the box, most of the time, it might be interesting to actually understand how it works, mainly when it happens that your system fails to boot :).

Most literature found on the Internet tend to cover how to set up LVM over a partition encrypted with LUKS, this tutorial takes another approach and will explain how to create LUKS encrypted partitions over LVM. The reason for this.... I wanted to have unencrypted partitions :D.

syslogd is the Linux system logging utility that take care of filling up your files in /var/log when it is asked to.

On a standard system, logging is only done on the local drive. But syslog can be configured to receive logging from a remote client, or to send logging to a remote syslog server.

Some of the use cases could be:

• A machine which filesystem goes read-only
• Log replication

this tutorial will explain how to set up both the server, to receive message from a remote client, and the client to emit messages to a syslogd server.