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Howto: Squid proxy authentication using ncsa_auth helper
For fine control you may need to use Squid proxy server authentication. This will only allow authorized users to use proxy server.
You need to use proxy_auth ACLs to configure ncsa_auth module. Browsers send the user's authentication in the Authorization request header. If Squid gets a request and the http_access rule list gets to a proxy_auth ACL, Squid looks for the Authorization header. If the header is present, Squid decodes it and extracts a username and password.
However squid is not equipped with password authentication. You need to take help of authentication helpers. Following are included by default in most squid and most Linux distros:
You need to use proxy_auth ACLs to configure ncsa_auth module. Browsers send the user's authentication in the Authorization request header. If Squid gets a request and the http_access rule list gets to a proxy_auth ACL, Squid looks for the Authorization header. If the header is present, Squid decodes it and extracts a username and password.
However squid is not equipped with password authentication. You need to take help of authentication helpers. Following are included by default in most squid and most Linux distros:

