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.

The spamassassin installation on a ISPConfig 2 server is normally updated together with ISPConfig. Here are the steps iIf you want to update spamassassin manually without updating ISPConfig 2:

Download the latest Spamassassin sources and unpack the tar.gz file

cd /tmp
wget http://ftp.fernuni-hagen.de/ftp-dir/pub/mirrors/\
www.apache.org/spamassassin/source/Mail-SpamAssassin-3.3.1.tar.gz
tar xfz Mail-SpamAssassin-3.3.1.tar.gz

cd Mail-SpamAssassin-3.3.1
perl Makefile.PL PREFIX=/home/admispconfig/ispconfig/tools/\
spamassassin/usr SYSCONFDIR=/home/admispconfig/ispconfig/\
tools/spamassassin/etc
make
make install

cd ..
rm -f Mail-SpamAssassin-3.3.1.tar.gz
rm -rf Mail-SpamAssassin-3.3.1

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

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

Since january 1 2010, spamassassin is falsely marking non spam emails as spam due to an error in the regular expression of the FH_DATE_PAST_20XX rule.

Description of the bug:

https://secure.grepular.com/blog/index.php/2010/01/01/spamassassin-2010-bug/

To fix this, run the following command on the shell as root user:

sa-update

/home/admispconfig/ispconfig/tools/spamassassin/usr/bin/sa-update

More and more internet access providers are closing port 25 to reduce spam except for connections to their own mailservers. If you run your own mailserver and have problems to connect to it on port 25, you can enable port 465 (smtps) in postfix as a workaround. Edit the /etc/postfix/master.cf file:

vi /etc/postfix/master.cf

and remove the # in front of the smtps line. Example for Debain 5, change the line:

#smtps     inet  n       -       -       -       -       smtpd

to:

smtps     inet  n       -       -       -       -       smtpd

and restart postfix:

/etc/init.d/postfix restart

The following steps describe the procedure to reset the mysql root password on Linux.

1) Stop the mysql server

/etc/init.d/mysql stop

2) Start the mysql server manually without permission tables which allows us to login as root user without password:

mysqld_safe --skip-grant-tables &

3) Login into mysql as root user without a password and switch to the “mysql” database:

mysql -u root mysql

Then execute this SQL query to set a new password for the mysql root user:

update user set Password=PASSWORD('mynewpassword') WHERE User='root';

(Replace “mynewpassword” with the new root password in the above command).

Then logout from the mysql prompt by typing:

exit

4) Now bring back the running mysql instance into the foreground by typing:

fg

and then press [ctrl] + c to kill the mysql process.

5) Start the mysql server again:

/etc/init.d/mysql start