acl aclname proxy_auth username ...
acl aclname proxy_auth_regex [-i] pattern ...
User authentication via external processes. proxy_auth requires an EXTERNAL authentication program to check username/password combinations (see authenticate_program ).
Usage
acl aclname proxy_auth username...
use REQUIRED instead of username to accept any valid username
Example
acl ACLAUTH proxy_auth venkatesh balu deepa
This acl is for authenticating users venkatesh, balu and deepa by externalprograms
Warning
proxy_auth can't be used in a transparent proxy. It collides with any authentication done by origin servers. It may seem like it works at first, but it doesn't. When a Proxy-Authentication header is sent but it is not needed during ACL checking the username is NOT logged in access.log