Updated Configuration (markdown)

Configuration.md

@@ -64,6 +64,10 @@ Size limit per paste and comment in bytes, defaults to 2 Mibibytes (2097152 byte
 
 In the section `[traffic]` you can add a rate `limit` in seconds. This is the time limit between creating pastes or comments from the same IP address in seconds. Set this to 0 to disable rate limiting.
 
+If your site runs behind a reverse proxy or a load balancer, the traffic limiter will see its IP instead of the visitors. Therefore the traffic limit would be global and not per IP. You can set the HTTP `header` to use instead. In most cases this is "X_FORWARDED_FOR", but check your proxy settings to be sure.
+
+Note that malicious visitors may set a different header in every request, so only enable this in a proxy installation and set it to the header you know your proxy sets or these visitors would circumvent the traffic limiter.
+
 The option `dir` controls where the lock file is stored. Note that this directory needs to be writable for the process running PHP (i.e. your webserver, FPM or CGI process).
 
 ### base64version