RewriteEngine On
RewriteBase /
 
RewriteCond %{QUERY_STRING} ^(.*)$
RewriteRule ^([a-z0-9_\-]+)/([a-z0-9_\-]+)/([a-z0-9_\-]+)$ index.php?mod=$1&action=$2&do=$3&%1
RewriteRule login.html index.php?mod=user&action=main&do=login