Changes with nginx 0.8.17                                        28 Sep 2009
    *) Security: now "/../" are disabled in "Destination" request header 
       line.
    *) Change: now $host variable value is always low case.
    *) Feature: the $ssl_session_id variable.
    *) Bugfix: socket leak; the bug had appeared in 0.8.11.
-- 
Igor Sysoev
http://sysoev.ru/en/