Thanks for the prompt response. It is very useful. I was playing external_acl_type to understand how it works. a couple of questions - when a request did not pass external acl , I got a HTTP 403. How can I make it to return 401 instead? - how do I write an external acl program to support concurrency? I followed some example on the internet. The program basically parses stdio for input parameters, and writes out the result to stdout? Thanks -- View this message in context: http://squid-web-proxy-cache.1019090.n4.nabble.com/Squid-and-Splash-page-tp3473302p4238930.html Sent from the Squid - Users mailing list archive at Nabble.com.