1. Anonymizer. This generally deletes any personnal info in the
HTTP headers (cookies) so that the destination server knows
less about the user. This doesn't bypass your firewall.
2. redirection. An http packet is formed of 3 things. A request line
("get http://foo.blah.example/index.html HTTP/1.1"), a set of headers
and a body that contains data.
When you surf, the URL you visit is normally in the request line.
So filters can check it and see whether it is allowed or not.
But if the user connects to a proxy that allows him to enter the URL
in a form, then this URL will be in the body of the request seen
by your FW, and it won't be checked against the rules.
If this is not clear, here is an example:
Imagine that Bob leaves in the US and wants to send a letter to Alice
who lives in Cuba, and imagine that the US Post Office prohibits any
relation with Cuba. So Bob puts his letter in another letter that he sends
to Carla in Spain, and Carla sends the included letter to Alice.
cheers,
mouss
At 02:21 28/06/01 -0700, Sudipto basu wrote:
>Hi all,
>since I am a bewbie to firewall concepts and my
>project requires a through knowledge of the concepts
>i need your help in understanding a few concepts.
>
>As we know there are some sites like silentsurf.com
>who offers Anonymous Access to any site. I wanted know
>how they work. How they bypass our proxies and
>firewalls which prevent one from accessing some sites
>which these type of sites provides access to?
>
>I want to know the details.
>Thanks for reading and helping.
>Sudipto Basu
>IGSI India,
>[EMAIL PROTECTED]
>
>=====
>
>The most I can do for my friend is.
>Simply to be his friend.
>
>
>
>
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