Use this directive to customize authentication schemes presence and
order in Squid's Unauthorized and Authentication Required responses.
auth_schemes scheme1,scheme2,... [!]aclname ...
where schemeN is the name of one of the authentication schemes
configured using auth_param directives. At least one scheme name is
required. Multiple scheme names are separated by commas. Either
avoid whitespace or quote the entire schemes list.
A special "ALL" scheme name expands to all auth_param-configured
schemes in their configuration order. This directive cannot be used
to configure Squid to offer no authentication schemes at all.
The first matching auth_schemes rule determines the schemes order
for the current Authentication Required transaction. Note that the
future response is not yet available during auth_schemes evaluation.
If this directive is not used or none of its rules match, then Squid
responds with all configured authentication schemes in the order of
auth_param directives in the configuration file.
This directive does not determine when authentication is used or
how each authentication scheme authenticates clients.
The following example sends basic and negotiate authentication
schemes, in that order, when requesting authentication of HTTP
requests matching the isIE ACL (not shown) while sending all
auth_param schemes in their configuration order to other clients:
auth_schemes basic,negotiate isIE
auth_schemes ALL all # explicit default
This directive supports fast ACLs only.
See also: auth_param.