Archive for the ‘Ubuntu’ Category

Dovecot is watching the whole server filesystem for modifications and removed or added sub filesystems. If you get errors similar to this one on your server:

Aug 30 09:10:23 server1 dovecot: master: Warning: /var/www/clients/client1/web1/log is no longer mounted. If this is intentional, remove it with doveadm mount

 (the directory path may vary), then you can fix it by excluding the path from being watched by dovecot. In my case, dovecot shall not watch my website directories as they do not contain any mailboxes

Run the following command on the shell as root user:

doveadm mount add ‘/var/www/*’ ignore

To exclude all files and folders in /var/www from deovecot monitoring.

 

Incorrent Time on Windows/Linux Dual Boot System

Monday, April 22, 2013 posted by CSch

If you work on a dual boot system you might experience that when you log off from Windows, onto Linux, and to Windows again, the time that is shown in the bottom right corner might be an hour or more off the actual time. This will correct once you refresh it by loading the time from a time server again but will remain an issue for the next logins.
This has not directly to do with daylight savings or an incorrect time zone, but most likely with Linux assuming that the BIOS time is set to UTC while it’s set to local time. So it just changes the BIOS clock according to that. Logging in to Windows with the wrong BIOS clock will result in a wrong system time.

This Linux behavior can easily be changed though, so just login to your Linux system and open a command line. First log in as root with your password:

sudo su

Then enter following to open the rcS file (note that I use vi as text editor – you can use any other you like here):

vi /etc/default/rcS

Now look for the line reading UTC = yes and change it to UTC = no. Save the file and try to boot into Windows – if every other time setting is set correct you should get the right time now.

Install Steam on Ubuntu and Linux Mint

Saturday, March 16, 2013 posted by CSch

With Steam support for Linux, there will most likely be a whole lot more games coming out for Ubuntu and its consorts. While the database of games with Linux support still grows, many titles are already available.
To install Steam on Ubuntu or Linux Mint, open a Terminal and enter the following commands:

sudo apt-key adv –keyserver keyserver.ubuntu.com –recv-keys B05498B7
sudo sh -c ‘echo “deb http://repo.steampowered.com/steam/ precise steam” >>
/etc/apt/sources.list.d/steam.list’

 

sudo apt-get update
sudo apt-get install steam

Afterwards start it with

steam

Screenshot at 2013-03-12 12:16:05

If you get error messages from amavisd similar to the one posted below on a server which is virtualized with OpenVZ:

Mar  5 09:09:02 v100 amavis[17378]: (17378-14) (!!)TROUBLE in process_request: Error writing a SMTP response to the socket: Broken pipe at (eval 100) line 987, <GEN44> line 31.

then the issue can be caused by the NUMTCPSOCK value in the openvz limits. Even if the barrier of this limit was never met in /proc/user_beancounters, the above error occurs when more then 25% of all TCP sockets were used. The solution is to set the NUMTCPSOCK barrier and limit to a high value in the openvz container configuration file. Here a value that worked for me on a moderately used mailserver:

NUMTCPSOCK=”2000:2000″

Finally restart the OpenVZ VM to apply the new limit value.

 

Apache mod_security settings for WordPress and ModX

Monday, January 7, 2013 posted by Till

If you use the apache mod_security module on your apache server, you might encounter wrong 403 errors for several URL’s of the cms systems. Here are some exception rules to avoid that:

For WordPress Blogs

<locationmatch "/wp-admin/admin-ajax.php">
SecRuleRemoveById 300013
SecRuleRemoveById 300015
SecRuleRemoveById 300016
SecRuleRemoveById 300017
</locationmatch>

<locationmatch "/wp-admin/page.php">
SecRuleRemoveById 300013
SecRuleRemoveById 300015
SecRuleRemoveById 300016
SecRuleRemoveById 300017
</locationmatch>

<locationmatch "/wp-admin/post.php">
SecRuleRemoveById 300013
SecRuleRemoveById 300015
SecRuleRemoveById 300016
SecRuleRemoveById 300017
</locationmatch>

For the ModX CMS

<LocationMatch "/manager/index.php">
SecRuleRemoveById 300016
</LocationMatch>

<LocationMatch “/connectors/resource/index.php”>
SecRuleRemoveById 300013 300014 300015 300016
</LocationMatch>

<LocationMatch “/connectors/element/tv.php”>
SecRuleRemoveById 300013 300016
</LocationMatch>

Add these rules inside the vhost file of the website. If you use ISPConfig to manage the server, then add the rules in the apache directives field of the website settings in ispconfig.

Many thanks to PlanetFox for providing the rules.

Install Minecraft on Ubuntu 12.10 and Mint 14

Friday, December 21, 2012 posted by CSch

Minecraft provides you with really good support on Linux. To be able to play, you need to download the .jar file from the official website first (you need that from the Minecraft for Linux / Other section: http://minecraft.net/download.

After you have it, you need to check if the java runtime environment is installed: open Synaptic Package Manager and search for the openjdk-7-jre package – if it isn’t installed, install it now.

Head back to the downloaded minecraft.jar file. Right-click it and open the Properties. Go to the Permissions tab and check the Execute checkbox, close the window afterwards.

Now start minecraft by right-clicking the jar file again and selecting Open With >OpenJDK Java 7 Runtime – Enjoy Minecraft!

The following guide shows how to disable and remove mysql replication from two or more mysql servers. These steps can be used for master/slave and master/master mysql setups. The following SQL commands have to be be executed in phpmyadmin or with the mysql commandline program. It is just important that you are logged in as mysql root user. Below I will use the mysql commandline client.

Login into mysql as root user from commandline:

mysql -u root -p

the mysql command will ask for the mysql root password.

Then execute these commands if the installed mysql version is < 5.5.16:

STOP SLAVE;
RESET SLAVE;
QUIT

use the commands below instead if the mysql version is > 5.5.16

STOP SLAVE;
RESET SLAVE ALL;
QUIT

Now edit the my.cnf file (/etc/mysql/my.cnf) and add a # in front of all lines that start with “replicate-” or “master-”. Example:

# replicate-same-server-id = 0
# master-host = 192.168.0.105
# master-user = slaveuser
# master-password = akst6Wqcz2B
# master-connect-retry = 60

Then restart mysql:

/etc/init.d/mysql restart

 

Setting up email routing to gmail / google apps via ISPConfig 3

Thursday, November 29, 2012 posted by Till

The following guide describes the steps to add DNS records that route emails from a domain managed in ISPConfig 3 to google apps / gmail. The guide assumes that you have already setup the dns zone for your domain in ispconfig.

Login to ISPConfig, click on the DNS module icon in the upper navigation bar, then open the settings of the DNS zone that you want to redirect to google and click on the “records” tab. You should see a record list similar to this:

Now Delete the existing MX record and the “mail” A-Record. Then add the following new records:

CNAME Record:

Hostname: mail
Target: ghs.google.com.

MX Records:

example.com. ASPMX.L.GOOGLE.COM. 10
example.com. ALT1.ASPMX.L.GOOGLE.COM. 20
example.com. ALT2.ASPMX.L.GOOGLE.COM. 30
example.com. ASPMX2.GOOGLEMAIL.COM. 40
example.com. ASPMX3.GOOGLEMAIL.COM. 50

IMPORTANT: All full domain names like “ghs.google.com.” have to end with a dot, if the dot is missing, the name is treated as subdomain of the zone.

The resulting record list should look like this:

Rotating screen in Ubuntu and Linux Mint

Wednesday, November 7, 2012 posted by CSch

Just as in Windows you have the option to rotate your screen into any direction in Linux, too. While in Windows you only need to press some keys, a key combination is not configured in Linux by default. But as you may have figured out, there are some terminal commands that let you do the exact same thing (you can configure shortcuts for these manually later on).

First, you need to find out how the screen that you want to rotate is labeled – to do that, use the following command:

xrandr -q

Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
LVDS1 connected 1366×768+0+0 (normal left inverted right x axis y axis) 344mm x 194mm
1366×768 60.1*+
1360×768 59.8 60.0
1024×768 60.0
800×600 60.3 56.2
640×480 59.9
VGA2 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)

You will get a list of connected monitors – I have only one here which is labeled LVDS1, it says connected next to the name. Determine the one that you want to rotate here. Next, we want to turn it around. For that, we use one of the following commands:

xrandr –output LVDS1 –rotate right
xrandr –output LVDS1 –rotate left
xrandr –output LVDS1 –rotate inverted
xrandr –output LVDS1 –rotate normal

Replace LVDS1 with your monitor label in the above commands and you’ll be able to rotate the screen to your likings! This is especially helpful if you need to go through documents and can turn your physical monitor around.

Remember screen brightness settings in Ubuntu and Linux Mint

Monday, October 29, 2012 posted by CSch

Screen brightness is an attribute that is reset automatically upon rebooting your machine on Ubuntu and all its fellow distributions. Lucky you if you find the settings okay, but on notebooks and similar machines, you might want to lower the brightness, you it doesn’t suck your batteries dry.

To do that, open the following file as root via terminal:

sudo gedit /etc/rc.local

In there, enter the following line somewhere before the very last one that says “exit 0″:

echo 0 > /sys/class/backlight/acpi_video0/brightness

0 is the lowest brightness setting. You can adjust it to your likings!