If you are using mod_proxy_http with Touchstone then you probably want to add
the following statements to the appropriate part of your Apache HTTP configuration
local to the shibboleth configuration statements and mod_proxy_http configuration
statements. These rewrite rules essentially cause REMOTE_USER as passed by the
shibboleth configuration to be written to another temporary environment variable
and then a new environment variable REMOTE_USER is created and populated for
use by mod_proxy_http.
RewriteEngine On RewriteCond %{LA-U:REMOTE_USER} (.+) RewriteRule . - [E=RU:%1] RequestHeader add REMOTE_USER %{RU}e