Dear Gurus,

I have Linux Squid Proxy server. It is blocked for all sites but allow only one or two sites like http://www.rediffmail.com & http://www.hotmail.com.

I assign DNS address in my all user computer.

When i remove Proxy setting from Internet Explorer or other Browser, at that time they are able to access internet ( all sites ).

How can i protect it??

DNS address is required for mail communication.

Thanking you

Regards

Pranav

In you need a firewall like iptables on the server connecting the lan to the internet and block all port 80

below is a description of squid iptables installation (squid uses port 3128 )

http://www.brandonhutchinson.com/squ..._firewall.html

You need to configure your Squid box to be transparent.

Since you already have a working Squid configuration, all you need to do is follow steps 4 & 5 from this article:

Transparent Proxy With Squid

...but this is assuming 2 things:

1.) Your Squid box is on the default gateway itself...if not; if your Squid box is on a DMZ, then follow steps 4 & 6 instead.
2.) You are using iptables on the default gateway

You might also wish to configure the default gateway to block all OUTGOING requests on port 8080 and port 3128...this way, you users can't cheat and use an external proxy.