X-Forwarded-For header

Hello,

You can use the following :

when HTTP_REQUEST {
  if {[HTTP::header exists X-Forwarded-For]}{
      HTTP::header replace X-Forwarded-For "[HTTP::header X-Forwarded-For], [IP::client_addr]"
  } else {  
      HTTP::header insert X-Forwarded-For [IP::client_addr]
  }
}