If you get the error “/dev/zero: No space left on device” in the apache error.log on a OpenVZ virtual machine, then the shared memory size in the xcache.ini is too high or the xcache.mm_path is set wrong.

Edit the file /etc/php5/conf.d/xcache.ini

vi /etc/php5/conf.d/xcache.ini

xcache.mmap_path = "/tmp/xcache"

/etc/init.d/apache2 restart

If the roor still occurs after some time, you will have to reduce the xcache.size.

Edite the xcache.ini file:

vi /etc/php5/conf.d/xcache.ini

xcache.size  =                8M

/etc/init.d/apache2 restart

The /tmp and /dev/shm directories of a OpenVZ virtual machine shall be mounted without suid and exec permissions. To achieve this, create a a shell script on the host server for every virtual machine which contains the commands to remount the directories. This script will be started automatically by openvz when the VM is started.

I will use VPSID as placeholder for the ID of the virtual machine in the commands and the script. Replace VPSID with the id of the virtual machine that you want to create the script for, e.g. replace VPSID with 101.

Create the script:

vi /etc/vz/conf/VPSID.mount

#!/bin/bash
mount -n --bind -onosuid,noexec /vz/vps/VPSID/tmp /vz/root/VPSID/tmp
mount -n --bind -onosuid,noexec /vz/vps/VPSID/shm /vz/root/VPSID/dev/shm
exit ${?}

chmod 700 /etc/vz/conf/VPSID.mount

In case you plan to virtualize your server infrastructure and migrate physical servers to OpenVZ virtual machines, you may find this tutorial helpful:

http://wiki.openvz.org/Physical_to_container

I used this to migrate a ISPConfig Debian system to OpenVZ successfully.

If you use a mailserver wil very low ram (< 500 MB) and a slow CPU then it might be nescessary to disable the spam- and antivirus filter functions in ISPConfig 3 as amavisd and clamav might be too heavy for your server hardware. The steps to disable clamav and amavisd are:

Edit postfix main.cf file

vi /etc/postfix/main.cf

# content_filter = amavis:[127.0.0.1]:10024
# receive_override_options = no_address_mappings

/etc/init.d/postfix restart

/etc/init.d/clamav-daemon stop
/etc/init.d/clamav-freshclam stop
/etc/init.d/amavis stop

update-rc.d -f clamav-daemon remove
update-rc.d -f clamav-freshclam remove
update-rc.d -f amavis remove

The changes in postfix main.cf will get overwitten by a ispconfig software update when you select to reconfigure services during upadte, so you should comment out the lines again after you install a ispconfig update.

The pure-ftpd package that comes with Debian 5.0 (Lenny) does not start in a OpenVZ virtual machine as it is compiled with “capabilities”. This tutorial describes the steps to build a pure-ftpd Debian package with capabilities disabled:

Make a temporary directory

mkdir /usr/src/pure-ftpd
cd /usr/src/pure-ftpd

apt-get source pure-ftpd
apt-get build-dep pure-ftpd

cd pure-ftpd-1.0.21/debian
nano rules

optflags=--with-everything --with-largefile --with-pam --with-privsep --with-tls

optflags=--with-everything --with-largefile --with-pam --with-privsep --with-tls --without-capabilities

cd ..
dpkg-buildpackage -uc -b

cd ..
dpkg -i pure-ftpd-common_1.0.21-11.4_all.deb pure-ftpd-mysql_1.0.21-11.4_i386.deb
/etc/init.d/pure-ftpd-mysql restart

echo 'pure-ftpd-common hold' | dpkg --set-selections
echo 'pure-ftpd-mysql hold' | dpkg --set-selections

Some internet access providers have port 25 disabled in their routers to prevent spam. If you run your own mailserver in a datacenter, you might have to enable the submission port (587) in postfix to be able to send emails from your local email client to your own mailserver.

To enable port 587, edit the file /etc/postfix/master.cf

vi /etc/postfix/master.cf

#submission inet n      -       n       -       -       smtpd

submission inet n      -       n       -       -       smtpd

/etc/init.d/postfix restart

As of today, all ClamAV 0.94 or older installs will stop working. The Debian project has not released updates for their current stable release (5.0) yet to solve this, but there is a workaround. The Debain volatile project provides newer clamav versions. The installation steps to install ClamAV 0.95.3 on Debian lenny are:

1) Add the debian volatile repository to the sources list:

echo "deb http://volatile.debian.org/debian-volatile lenny/volatile main contrib non-free" >> /etc/apt/sources.list

apt-get update
apt-get install clamav
apt-get -u upgrade

/etc/init.d/amavis restart

Many webmasters want to redirect users that access their websites with “domain.tld” automatically to “www.domain.tld”. If you use the Apache web server, you can do this by using Apache rewrite rules.

Add a .htaccess file with the following content in the root directory of the website:

Options +FollowSymlinks
RewriteEngine On
RewriteCond %{HTTP_HOST}//s%{HTTPS} ^[^w][^w][^w][^.].*//((s)on¦s.*) [NC]
RewriteRule ^ http%2://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Thanks to “extras” from webmasterworld for this useful rewrite rule.

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>