This is what I have so far but I can't get the RewriteCond and RewriteRule properly.
RewriteEngine On
RewriteCond %{LA-U:REMOTE_USER} (\d{3})$
RewriteRule !^%1 http://subdomain.mydomain.com/%1 [R,L].
AuthName "My Domain Protected Area"
AuthType Basic
AuthUserFile /path/to/my/.htpasswd
Require valid-user
This is what I mean the ReWriteCond and RewriteRule
to say:
"If the REMOTE_USER has a username ending in 3 digits then capture the three digits that match and for whatever url they are trying to access if it does not start with the 3 digits captured then redirect them to the sub directory with the name equal to those captured three digits."
In other words, if a user named 'johnny202' is authenticated then if he's requesting any directory other than http://subdomain.mydomain.com/202/ then he should be redirected to http://subdomain.mydomain.com/202/
The only thing I can think of that is wrong is the first instance of '%1'.