The X-Forward-For header is in the http protocol as a result. This header is use to transmit the IP address of the user when it tries to connect through a proxy or load balancer to the web server. Since Apache does not take this header into account by default, the configuration of the Apache HTTP server has to be adapted.
Learn how to change the protocol settings of Apache considering the X-Forwarded-For header using the instructions below:
Below is an example of a LogFormat directive (named "proxy");
In the following example, Apache is instructed to log the calls with the log format "proxy" in the file access.log using domain-tld: