Archive for the ‘Webserver’ Category
How to solve the PHP XCache error: /dev/zero: No space left on device
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
and check the mm_path. On a OpenVZ virtual machine it should be set to “/tmp/xcache” as /dev/zero might not work correctly in a virtual machine:
xcache.mmap_path = "/tmp/xcache"
Then restart apache2:
/etc/init.d/apache2 restart
and check if the error has been resolved.
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
and set xcache.size to e.g. 8 MB
xcache.size = 8M
Then restart apache2:
/etc/init.d/apache2 restart
How to enable the new multisite feature in WordPress 3.0
If you recently updated to or installed WordPress 3.0, you might wonder where the menu for Multisite feature is. By default, these new functions are disabled after a WordPress update, to enable them, edit the file wp-config.php and add the line
define(‘WP_ALLOW_MULTISITE’, true);
On your next login, you will see a new menu labeled “Super Admin” which contains the functions to add new sites to wordpress.
How to redirect requests for domain names without www to www.domain.tld
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]
If you use ISPConfig as hosting control panel, you can add these rules also in the Apache directives field of the website.
Thanks to “extras” from webmasterworld for this useful rewrite rule.
Get a list of all virtual hosts which are defined in all apache configuration files
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
on the shell, you will get a list of all virtual hosts and default servers incl. the line number where it is defined. Example:
~# 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
Thanks to Planetfox for this tipp.
How to disable Apache mod_security for a website in ISPConfig 3.
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>
Thanks to Planetfox for this tipp.
How to force caching headers with apache and squid reverse proxy
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
Then create a .htaccess file in the website root directoyr which contains the following lines:
Header unset Pragma Header set Cache-Control "must-revalidate, max-age=0, s-maxage=600" Header set Vary "Accept-Encoding"
How to use a custom php.ini with suphp
To use a custom php.ini file with SuPHP for a website, you can define the path to the php.ini file in a .htaccess file or in the apache vhost like this:
suPHP_ConfigPath /home/websites/domain.tld/
Then add a php.ini file in the directory /home/websites/domain.tld/ which may be a copy of the global php.ini were you just changed a few settings or an empty file were you add only the settings that shall be overridden in the global PHP configuration.
If you use ISPConfig 2 or 3, you can add the suPHP_ConfigPath setting also in the apache directives field of the website in ISPConfig.
Redirect a subdomain with apache mod_rewrite and keep the URL in the address bar
If you want to redirect a subdomain like sub.domain.tld into a subdirectory of the website and keep the original URL in the browser location bar, you may use the following apache directives.
RewriteEngine on
RewriteCond %{HTTP_HOST} ^sub.domain.tld [NC]
RewriteRule ^/(.*)$ /sub/$1 [L]
This rewrite rule can be added into a .htaccess file in the website root or inside the vhost file. If you use ISPConfig 2 or 3, you can add this also into the apache directives field in the website settings.
Replace sub.domain.tld with the subdomain that shall be redirected and /sub/ with the path to the directory were the pages for this subdomain are located.
Redirect domains without www (e.g. domain.com) to www.domain.com with apache rewrite rules
If all your visitors shall access your website with a URL like www.domain.com and not without www, use the following apache rewrite rule for redirecting them.
RewriteEngine On
RewriteCond %{HTTP_HOST} !^www
RewriteRule (.*) http://www.%{HTTP_HOST}$1 [L,R]
The apache rewrite rule can be added in a .htaccess file in the website root directory or if you use ISPConfig 2 or 3, you can also add the rwrite rule into the apache directives field of the website.
How to redirect an HTTP connection to HTTPS in apache webserver
Http connections can be redirected to https with the apache mod_rewrite module, which should be available in every apache installation. Create a file with the name .htaccess in the website root directory which contains the following lines:
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}
If you use ISPConfig 2 or 3, you can add these lines also in the apache directives field of the website settings form instead of adding them to a .htaccess file. But the approach with the .htaccess file will work on ISPConfig as well.