[squid-users] auth acl, combining and matching

From: Eugene M. Zheganin <eugene_at_zhegan.in>
Date: Tue, 14 Aug 2012 14:32:20 +0600


Since I always receive comprehensive answers here I decided to ask about
one more long existed problem.

I use squids in corporate environment along with traffic quotas and
custom deny info pages. Yeah, flatrated internet came long ago in Russia
too, but my supervisors think that limiting the traffic is still an
effective way of fighting slackers.

So, the goal is to show a page 'you're not authorized' to unauthorized
users (bad username/password pair, or no username, or intercepted
traffic), 'this is denied' page on some restricted URLs, and mostly -
'you're out of traffic' to users with no traffic left. Here I step on
one thing that is keeping me away from that. Imagine I have similar config:

acl unauthorized proxy_auth -
acl no-traffic-left external self-written-script
acl allowed-users external some-LDAP-checking
acl some-other-users external some-LDAP-checking

http_access deny unauthorized
http_access deny no-traffic-left
http_access allow allowed-users
http_access deny all

deny_info NOTRAFFIC no-traffic-left
deny_info UNAUTHORIZED unauthorized
deny_info NOACCESS all

So, to the actual point. I will simply describe how it does work from my
experience. So, imagine user 'foobar' is trying to get the access. It
matches both the no-traffic-left and the allowed-users ACLs. Futhermore,
allowed-users is a group of users. In a configuration above, when squid
will receive the 'foobar' username on the 'http_access deny
no-traffic-left' line, it won't block the foobar user, but instead it
will reprompt for the credentials. So, in order to actually block users
like foobar, I need to say something about src, like this:

http_access deny unauthorized all

This way squid will immidiately block such users. But, here the problem
comes: last matching ACL will be 'all', so I'm unable to tell users with
no traffic why exaclty they are blocked. I tried the way

http_access deny all unauthorized

But it works the same way as the line without 'all', - it keeps
reprompting for the passwords. It looks like 'hey, do you know some
other password, so I can grant you an access ?'. Is there any
possibility of ... in the term of packet filters, say to squid 'block it
immidiately' ? The way 'quick' works in pf, or, if you prefer, the same
way the 'L' flag works in apache's mod_rewrite ? I mean, I need a
mechanism of saying that this rule should actually be the last if it
matches. And the other question - I have a feeling that this happens
only if a username matches more that one proxy_auth ACL. For example
this doesn't happen to the user '-', or any other fake user (I was using
for a long time the fake username to represent the entity without

Received on Tue Aug 14 2012 - 08:32:37 MDT

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