How to limit connection bandwidth on Apache

Apache by default will serve files to the users as fast as the bandwidth or TCP/IP allow for. In an environment where for example you are hosting files for download and you don't want a single user to hog all your server's bandwidth, you might want to throttle the download speed for your users so that your server is able to serve more users at a time.

You can limit the download speed of your Apache users by using mod_ratelimit and specify the desired speed for each Location or VirtualHost configuration.

1. Launch your preferred terminal application.
2. Enable 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. Add relevant options in Apache configuration file for a specific Location or VirtualHost configuration where you want the bandwidth to be limited.

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

   Related: Location for Apache VirtualHost configuration

   Documentation: Offcial documentation for mod_ratelimit

4. Restart Apache service for the changes to take effect.

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

   Related: How to start, restart and stop Apache service

5. Download a file from the server to see if the bandwitdth is correctly limited.

   $ 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