<b>Apache webserver and rewrite rules</b>

Here are some rewrite codes I sometimes use. Rewrite is a very powerful Apache
module and so almost everything is possible. Some examples.

To rewrite your http://www.oldsite.org/something to the new URL
http://www.newsite.org/something, you can use the next code:

  RewriteCond %{HTTP_HOST} ^www\.oldsite.org [NC]
  RewriteRule ^ http://www.newsite.org%{REQUEST_URI} [L,R=301]

To do an action when the user don't have a special cookie, for example to force
somebody to the login page or redirect him to a welcome page. Take a look at the
second rule. This one prevents looping over these rule again and again.

  RewriteCond %{HTTP_COOKIE} !logincookie
  RewriteCond %{QUERY_STRING} !page=login
  RewriteRule ^(.*)$ %{REQUEST_URI}?page=login [L,R]

To rewrite a request if it's a search result from google.

  RewriteCond %{HTTP_REFERER} ^http://www\.google [NC]
  RewriteRule ^ http://www.somewhere.com/something.gif [R]

To simple forward your request to your internal server2 on port 8080:

  RewriteEngine On
  RewriteRule ^/app/(.*)$ http://server2:8080/app1/$1 [P]

The website semalt.com is spamming us with referers that actually don't exsists.
To clean you statistics and send the basterts back to where they came from: 

  # Block semalt.com referer
  RewriteEngine on
  RewriteCond %{HTTP_REFERER} semalt\.com [NC,OR]
  RewriteCond %{HTTP_REFERER} ^http://([^.]+\.)*semalt\.com [NC,OR]
  RewriteCond %{HTTP_REFERER} ^http://([^.]+\.)*kambasoft\.com [NC,OR]
  RewriteCond %{HTTP_REFERER} youtube-downloader\.savetubevideo\.com [NC]
  RewriteRule (.*) http://www.semalt.com [R=301,L]