[1.4.x][Ubuntu] Limit access to upstream server based on request header

[shreyas.purohit@hotmail.com]

Hello,

I want something like limit_except functionality but based on custom request
headers. Lets say I have a Request header X-Secured-Client set. In that case
only I want to allow the request to my upstream server. 

How can I achieve that without using "if" blocks? (I did search the mailing
list with no success). 

If the above requirement is possible, can I check if the header value is set
to say 1 to allow the request to upstream server else send 444 back.

Thanks for any help,
Shreyas

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,247706,247706#msg-247706