hi ,
i have a squid linux server with authentication . whenever a user needs to browse an authentication login opens up . my default squid proxy port is 3128 . but when i change d port to 80 the browser opens up without any authentication and user is able to browse the internet . is there a way to block port 80 . i tried removing acl line in squid.conf file acl Safe_ports port 80 # http . but the problem persists.
can any 1 help me with this problem.

thanks regrds dolreich

You mean like configuring the client as if though the proxy was actually running on port 80 instead of 3128? Wierd.

But when this happens, is it happening through Squid? Or is there indications that they are getting routed through with SNAT? You can check by typing an invalid URL and seeing if you get a Squid error page.

The thing is, unless you're doing some kind of routing, there really isn't any need to. A side-effect of having routing disabled and having the proxy listening only on one internal port is that changing the port number on the client would keep them offline. I'm starting to get the impression that perhaps you are indeed doing SNAT, and the clients are able to bypass the proxy by simply choosing not to use it - is that the case? Your "when I change the port to 80" comment makes it sound otherwise.