Set HTTP_CF_CONNECTING_IP in Apache Server Config

Setting the HTTP_CF_CONNECTING_IP header in an Apache HTTP server configuration involves using the mod_headers module to set or modify the header value. The HTTP_CF_CONNECTING_IP header is typically used with Cloudflare to pass the original client IP address to your server.

Here’s how you can configure it:

1. Enable the mod_headers Module:
   Ensure that the mod_headers module is enabled. You can enable it by running the following command:

   sudo a2enmod headers

Then, restart Apache to apply the changes:

   sudo systemctl restart apache2

2. Configure the Header in Your Apache Configuration File:
   You need to add the configuration to your Apache virtual host configuration file, which is usually located in /etc/apache2/sites-available/ for Debian-based distributions or /etc/httpd/conf.d/ for Red Hat-based distributions. Open your virtual host configuration file, for example:

   sudo nano /etc/apache2/sites-available/000-default.conf

Add the following lines inside the <VirtualHost> block:

   <VirtualHost *:80>
       ServerName yourdomain.com

       # Other configurations...

       # Set HTTP_CF_CONNECTING_IP header
       <IfModule mod_headers.c>
           RequestHeader set HTTP_CF_CONNECTING_IP "%{HTTP:X-Forwarded-For}e"
       </IfModule>

       # Other configurations...
   </VirtualHost>

If you are using HTTPS, make sure to update the configuration in the corresponding SSL virtual host file, typically named something like default-ssl.conf.

3. Restart Apache:
   After making these changes, restart Apache to apply the new configuration:

   sudo systemctl restart apache2

Explanation:

• RequestHeader set: This directive is used to set the value of the HTTP_CF_CONNECTING_IP header.
• “%{HTTP:X-Forwarded-For}e”: This extracts the X-Forwarded-For header, which is set by Cloudflare and contains the original client IP address.

Example with SSL:

If you are using HTTPS, you should update your SSL virtual host configuration file as well, for example:

sudo nano /etc/apache2/sites-available/default-ssl.conf

And add:

<VirtualHost *:443>
    ServerName yourdomain.com

    # Other configurations...

    # Set HTTP_CF_CONNECTING_IP header
    <IfModule mod_headers.c>
        RequestHeader set HTTP_CF_CONNECTING_IP "%{HTTP:X-Forwarded-For}e"
    </IfModule>

    # Other configurations...
</VirtualHost>

After making these changes, restart Apache again:

sudo systemctl restart apache2

By following these steps, you can set the HTTP_CF_CONNECTING_IP header in your Apache HTTP server configuration, allowing you to correctly pass and use the original client IP address provided by Cloudflare.