Redirect with REMOTE_USER in a custom server variable

Hi,

I have a case that I need redirect all requests from "server A" to "server B" and rewriting a custom server variable using the REMOTE_USER variable (mycustomservervariable = {REMOTE_USER}). "Server A" uses windows authentication, but REMOTE_USER is always empty in url rewrite rule.

I've spent some time searching a solution, but could not come up with anything. Does anyone have any tips or ever needed to do something like this?

I really appreciate any help,

Marcelo Palladino