authentication before rewrite

I have written an external redirection program in which I 'm dependent to username/passwd from basic auth.

Unfortunately Apache first processes the redirection and thereafter the authentication.

Is there a way to change this?

Show us your code.

ok, my code in httpd.conf:

------snip------

<VirtualHost URL>

<Location />
AuthType Basic
AuthName "Authtest"
AuthUserFile /usr/local/httpd/access/users
require valid-user
</Location>

ServerName URL
DocumentRoot /usr/local/httpd/htdocs/
ErrorLog /var/log/httpd/xxxxx-error_log
CustomLog /var/log/httpd/xxxxx-access_log combined

RewriteEngine on
RewriteLog /var/log/httpd/rewrite.log
RewriteLogLevel 9

RewriteMap auth-map prg:/tmp/redirection
RewriteRule ^/(.*)$ URL${auth-map:$1:%{LA-U:REMOTE_USER}:%{HTTP_COOKIE}} [P]

</VirtualHost>

------snap------

Apache every time first proceed the rewrite and thereafter ask me for username/passwd.

Into my external program I compare username and cookie-key with a database and give a url of an error page back when they not correspond.

Can I change the sequence of the processes or do you have another idea, as I could solve this problem.

Thanks in advance.

What do you have for <Directory "/usr/local/httpd/htdocs"> ?

You should move your Rewrite* lines to within that <Directory> block.

Also, why don't you use internal redirection instead?