Verzeichnis
Debian/Ubuntu Tips & TricksDebuntu provides tutorials for Linux Administration. It is mainly focused on Debian based distributions, but how-tos should apply to other distributions with minor changes.
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.
There were some changes in the latest kernel release (2.6.34) that prevent VMware's VMCI Socket module to compile on Ubuntu 10.10 (Maverick Meerkat).
Last Sunday (2010/07/04) Debuntu server ran into some issues and got offline for some time.
It appears that one of the Raid disk got almost dead and processes were getting stuck in IOwait state.
Anyway, data was safe and everything could be recovered from the disk.
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.
I already spoke about Terminator a while back. Since then,, quite some time has passed and lots of features were added...
In the last 7+ months, cmsj as worked a lot on getting the whole architecture re-implemented in a more object-like architecture which makes the different component of Terminator interact together more naturally.
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
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.
I was trying network-manager-openvpn plugin today on Lucid, I could import my configuration, DNS was set up correctly upon connection/disconnection, route imported correctly (almost :)).
One issue though is that it was also changing the default route to the VPN tunnel while this should not happen.
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.
Hello Guys!
Just so you know the Team of Linux+ is going to release FREE online editon of Linux+ magazine. There will be 6 monthly issues with 60 pages each available for free download. They are looking for your support!
Write to ewa.swierczewska@lpmagazine.org for more details if interested.
Thanks!
There is a few software that will use the editor command to find out what text editor to use. Example commands will be dch to add a new .deb changelog entry, revision control softwares when prompting for a commit message ...
Lately, I have been experiencing a funny network issue when using VMware Workstation VMs with NAT interface. Roughly, the IP network was working fine, but DNS resolution was not anymore. It happened intermittently, but I could see that this mainly happened when I was suspending my laptop, going to another location and resuming.
Forcing the VM to use a public DNS would solve the issue.
I have been looking around for a while for an autotune effect (pitch correction, or whatever name you care to call it) for linux. Unfortunately everything I have found either cost money or wasn't for linux, or required special setup (wine, or other nasty things). All I could find in terms of linux autotune was people also looking for autotune. However, all the answers were unsatisfactory, either because they required manual pitch recognition (Not so good for the tone-deaf among us), or people confused it with pitch shifting in general. I eventually did find that praat (it's in synaptic), a speech analysis tool, comes surprisingly close to autotune functionality. It will give you a T-pain like effect, but it requires you to manually place the notes (although it will detect the pitch for you). I am not very experienced with praat, although this is what I figured out how to do (some of it from the original mailing list post, other I read from the manual or figured out).
Although it's GUI isn't too nice, and it isn't designed for musical manipulation, it gets the job done.
This tutorial will explain how to run a mail server with virtual domains and users using a MySQL backend to store email informations.
Postfix will be our SMTP server, Dovecot will be handling IMAP (optionally one could configure POP3 also) so that users can retrieve their email.
Another tutorial will cover SPAM fighting using DSPAM based on this implementation (yet to be done).
This tutorial was done on Debian Etch using postfix 2.3.8-2etch4 and 1.0.rc15-2etch4.
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.
While doing a server migration, it happens that some traffic still go to the old machine because the DNS servers are not yet synced or simply because some people are using the IP address instead of the domain name....
By using iptables and its masquerade feature, it is possible to forward all traffic to the old server to the new IP.
This tutorial will show which command lines are required to make this possible.
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.
In introduced terminator in a previous article as multi-view terminal.
Since then, terminator as quite evolved, with plenty of new features that were highlighted in Terminator 0.9 beta 1 post.
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.
How-To: Set up a LAN gateway with DHCP, Dynamic DNS and iptables on Debian EtchSun, 29 Jun 2008 00:58:46 +0000
Linux is a perfect platform to act as a router/gateway.
In this tutorial, I will explain how to set up a Linux box to operate as a network router. The box will provide the following services:
- DHCP server to provide the ip addresses to the machines in the LAN
- DNS server to resolve domain names
- Gateway with IP tables to give access to the Internet.
- Firewall with IP tables.
The resulting machine will have quite a small footprint: about 600M, and except if your network is intensively used, a low spec computer can be recycled to do the job.
As the machine is going to operate as a router/firewall
How-To: copy files over the network and preserve file permissions and informations with ssh and rsyncFri, 20 Jun 2008 17:14:01 +0000
When copying files over the network, the files informations can be modified.
When using cp, one can avoid this issue by using the -a which will do the copy in archive mode, meaning that it will keep the links, preserve mode, ownership and timestamps and the copy is recursive.
the solution to this over the network is rsync alongside with ssh.
The Intel wireless card 4965 AGN does not work properly on ad-hoc networks since hardy and kernel 2.6.24 or around, network-manager can't get it to use the mode ad-hoc and a standard configuration like:
$ sudo iwconfig wlan0 essid myessid mode ad-hoc channel X key s:mykey13charss
$ sudo dhclient wlan0
will fail to get an ip except a long battle at dhclient'ing around.
I managed to get a process to get things working faster.
Terminator 0.9, an application that allow you to have multiple terminal within the same window, is getting close to be released. FeatureFreeze has been started since a couple of weeks.
The bugs opened against terminator milestone 0.9 are being closed.
A big bunch of new features and enhancements come shipped with this new release.
A package is available from Launchpad PPA. You can grab the .deb there. Feedback to terminator bug tracker on launchpad are welcome.
transmission, a lightweight bittorrent client version 1.22 was released on the 14th of June 2008.
A .deb package is available for Ubuntu Hardy i386 and amd64 from the debuntu repository.
transmission 1.21 is out.
Transmission is a fast, easy, and free multi-platform BitTorrent client with a focus on being lightweight yet feature-filled.
In the 2 previous articles, I explained how to set up a serial console on Ubuntu and Debian.
This tutorial will now show how to connect to those serial console using another machine using a software called minicom.
This tutorial will go over the steps to go through in order to set up a serial console on Debian Linux.
Debian uses sysvinit to handle the booting process, amongst the different task, and as such, there is a few differences between most of the tutorial that you might find on the internet regarding how to set up a serial console.
A Serial Console becomes handy when running a headless server (i.e no keyboard and screen) or if you cannot connect a a server because of a network issue.
