Have you ever searched where the virtual host of a website is defined in the apache config files? There is a handy option of the apache2ctl script which might help then. When you run the command:

apache2ctl -S

~# apache2ctl -S
VirtualHost configuration:
wildcard NameVirtualHosts and _default_ servers:
*:8080                 is a NameVirtualHost
default server ispconfig.local (/etc/apache2/sites-enabled/000-ispconfig.vhost:10)
port 8080 namevhost ispconfig.local (/etc/apache2/sites-enabled/000-ispconfig.vhost:10)
*:8081                 is a NameVirtualHost
default server ispconfig.local (/etc/apache2/sites-enabled/000-apps.vhost:10)
port 8081 namevhost ispconfig.local (/etc/apache2/sites-enabled/000-apps.vhost:10)
*:80                   is a NameVirtualHost
default server ispconfig.local (/etc/apache2/sites-enabled/000-default:1)
port 80 namevhost ispconfig.local (/etc/apache2/sites-enabled/000-default:1)
port 80 namevhost example.com (/etc/apache2/sites-enabled/example.com.vhost:7)
Syntax OK

If you use mod_security on your server you might encounter that a website script is not compatible with mod_security. To disable mod_security (v2) for a website, add the following code into the apache directives field:

<IfModule mod_security2.c>
SecRuleEngine Off
</IfModule>

For the older mod_security 1 version, use these configuration directives:

<IfModule mod_security.c>
SecFilterEngine Off
</IfModule>

When you install the latest java runtime enviroment, it gets installed beside your existing java installation. With every java update, more space is used on the harddisk. To remove old java versions, there is a tool named JavaRa which can be downloaded here:

https://sourceforge.net/projects/javara/files/javara/JavaRa/JavaRa.zip/download

Unpack the JavaRa.zip file and double click on the JavaRa.exe to start JavaRa. Select the language:

and click on “Remove older versions”.

Maybe you had this problem already: you use Debian or Ubuntu Linux and a software package that you like to install is only available in RPM format. The solution is a handy tool called alien, which converts .rpm files to .deb.  Installing alien:

apt-get install alien

Converting a rpm package to debian format:

alien --to-deb /tmp/mysoftwarefile.rpm

Conversions from .deb to rpm are also possible:

alien --to-rpm /tmp/mysoftwarefile.deb

If you use a squid reverse proxy in front of your apache webserver to reduce the load, it might happen that pages are not cached correctly because the website script running on the apache webserver sends wrong caching headers. I had this problem with a wordpress install, wordpress had always send pragma no-cache headers with the pages so squid reported a cache miss for every page request. A simple solution for this is to use apache mod_headers to delete the no chache header and replace it with a header for 10 minute cache period.

First, ensure that mod_herders is enabled. To do this in Debian and Ubuntu, run the command:

a2enmod headers

Header unset Pragma
Header set Cache-Control "must-revalidate, max-age=0, s-maxage=600"
Header set Vary "Accept-Encoding"

The ISPConfig update script is a easy way to update a ISPConfig 3 installation. If you want to backup the installation before, take a look at the instructions at the end of the article.

To update ISPConfig 3, login as root user on the shell of your server and run the command:

ispconfig_update.sh

Please choose the update method. For production systems select 'stable'.
The update from svn is only for development systems and may break your current setup.

Select update method (stable,svn) [stable]:

The updater will then check the version of your system, download the latest update and starts the update process. In the next step, enter the mysql root password:

This application will update ISPConfig 3 on your server.
MySQL root password []:

Reconfigure Services? (yes,no) [yes]:

ISPConfig Port [8080]:

Reconfigure Crontab? (yes,no) [yes]:

Backup before updates

Before you update a software, it is always a good idea to backup all relevant data. This enables you to restore the software version that you had before in case of an error. The steps to create a backup of the ispconfig software and settings are:

Create a backup folder:

mkdir /home/backup
chmod 700 /home/backup
cd /home/backup

mysqldump -u root -p dbispconfig > dbispconfig.sql

tar pcfz ispconfig_software.tar.gz /usr/local/ispconfig

tar pcfz etc.tar.gz /etc

Have you ever executed a command on the shell and noticed the that you had to run it with sudo? Instead of typing the command again with “sudo” in front of it, just run:

sudo !!

To update the spamassassin rules regularily on your ISPConfig 3 server, add the following line to the root crontab by running:

crontab -e

23 4 */2 * * /usr/bin/sa-update --no-gpg &> /dev/null

which sa-update

If a process is shown with process state “D” in tools like ps or top, then its a zombie process. Example:

ps axl | grep D

F   UID   PID  PPID PRI  NI    VSZ   RSS WCHAN  STAT TTY        TIME COMMAND
4   104  2579  9109  20   0   5024  2116 refrig D    ?          0:00 cleanup -z -t unix -u -c

Sometimes you need to know which debian package contains a specific file e.g. because you deleted a system file accidently or you try to install a new software that requires this file. The apt package management utility which is used in Debian and Ubuntu comes with a handy tool called apt-file which allows a saerch for filenames in the package database.

Install apt-file

apt-get install apt-file

apt-file update

apt-file search /bin/bash

apt-file search /bin/bash
bash: /bin/bash
bash: /usr/bin/bashbug
bash-minimal: /bin/bash-minimal
bash-static: /bin/bash-static
bashdb: /usr/bin/bashdb
mybashburn: /usr/bin/bashburn