I've got a server farm set up in IIS 8.5. When I inspect the HTTP_X_FORWARDED_FOR
header in my application code, it gives me the correct IP address but it contains a colon and a port number.
E.g.
HTTP_X_FORWARDED_FOR 127.0.0.1:64031
I know that HTTP_X_FORWARDED_FOR
can contain a comma-separated list of IPs, but I've never heard of it containing port numbers.
I've not explicitly configured 64031
to be a port number anywhere in my setup. Also, the number seems to change randomly which leads me to believe it's some kind of internal port number selected by IIS to communicate between the web farm "front-end" proxy and the back-end physical website.
I've not seen this documented anywhere on the web. Is this standard behaviour? Is it Microsoft Magic? Is it something peculiar to my setup? What exactly is that port number all about?