How to limit connection bandwidth in Apache

Controlling bandwidth helps manage server resources efficiently. By limiting download speeds, no single client consumes excessive capacity, ensuring fair access and stable performance for all users. This approach is especially useful in shared hosting environments or networks with constrained throughput.

The Apache web server supports the mod_ratelimit module, which regulates outgoing traffic to prevent one client from monopolizing available bandwidth. Most Linux distributions ship this module, but it may require manual activation. Once enabled, it ensures that traffic stays within defined throughput boundaries.

Configuring mod_ratelimit involves setting thresholds for sustained data transfers and initial bursts. These parameters can be fine-tuned to create a balance between rapid content delivery and controlled resource usage. Proper testing helps confirm that the chosen rate limits align with performance goals.

1. Open the terminal.
2. Enable the mod_ratelimit module for Apache.

   $ sudo a2enmod ratelimit # Ubuntu, Debian and SUSE
   Considering dependency env for ratelimit:
   Module env already enabled
   Enabling module ratelimit.
   To activate the new configuration, you need to run:
     systemctl restart apache2

   Distribution with a2enmod support can simply run the command above without having to manually enable the required modules.

   Related: How to enable or disable Apache modules

   Options	Debian, Ubuntu	openSUSE and SLES	Fedora Core, CentOS, RHEL	macOS	homebrew	xampp
   a2enmod support	yes	yes	no	no	no	no
   Modules to install	none
   Module name	n/a		ratelimit
   Loadmodule directive	n/a		LoadModule ratelimit_module <module_locations>/mod_ratelimit.so

3. Open your Apache configuration file or virtual host file using a text editor.

   $ sudo vi /etc/apache2/sites-available/000-default.conf

4. Add mod_ratelimit options within specific Location, Directory or VirtualHost directive where you want the bandwidth to be limited.

   <VirtualHost *:80>
           # .....
           # ....
           SetOutputFilter RATE_LIMIT
           SetEnv rate-limit 512
           SetEnv rate-initial-burst 1024
   </VirtualHost>

   The above configuration limits download speed to 512 KB/s after an initial burst of 1MB. Adjust the values as required.

   Related: Location for Apache VirtualHost configuration
   Documentation: Offcial documentation for mod_ratelimit

5. Save the file and close the text editor.
6. Restart the Apache service to apply the changes.

   $ sudo systemctl restart apache2 # Ubuntu and Debian
   $ sudo systemctl restart httpd # CentOS and Red Hat

   Related: How to manage the Apache web server service

7. Test the configuration by downloading a file from the server.

   $ curl --output image.iso www.simplified.guide/image.iso
     % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                    Dload  Upload   Total   Spent    Left  Speed
     3  512M    3 19.7M    0     0   538k      0  0:16:13  0:00:37  0:15:36  508k