llsjk wrote:

>  >> As far as I have it: on the firewall on port 3128 is Dansguardian
>>>  listening which should automatically forward the request to Squid on
>>>  port 8080 who talks to the outside world.  That is why I expect to get
>>>  the same message, whether the browser uses proxy or not, due to the
>>>  redirection.  Or am I missing something somewhere?
>>>    
>>
>>  Yes, you are missing something !
>>
>>  Going direct, there are several things that can happen when your
>>  client makes a request :
>>
>>  1) It gets a page returned
>>  2) It gets an error response from the server (eg 404 page not found)
>>  3) The connections attempt is rejected (eg there is no web server
>>  running on that machine, or a firewall configured to reject inbound
>>  connections)
>>  4) The connection attempt is ignored with no response (eg there is no
>>  machine at that address, or a firewall configured to drop, not
>>  reject, inbound packets).
>>
>>  When you go via the proxy, it's always there, so options 3&4 are
>>  unlikely to happen. Even if the end server you are attempting to get
>>  pages from doesn't exist, you will still be able to establish a tcp
>>  connection to the proxy - and will eventually receive an error
>>  message generated BY THE PROXY to say it couldn't connect.
>>
>>
>>  So:
>>
>>  Going direct you may get messages to the effect that the browser
>>  couldn't connect to the server.
>>
>>  Going via the proxy you will NOT get these errors FROM THE BROWSER
>>  but may well get them from the proxy.
>>
>>
>>  Does this make sense ? It's nothing to do with Shorewall or the proxy
>  > - it's just basic networking.


>Thanks Simon, but I thought that through Redirection one would make sure
>that no one could go directly.  I thought the redirection will always
>take the browser through port 3128.


As Tom has already said - IT DOES.

Now please read my previous message again - it explains why going via 
a proxy (whether by a redirection on a network device, or by proxy 
settings in the browser) may well produce different results than 
having the web browser go direct to the website.

The difference is that with a proxy involved, the browser machine 
should never get "no response at all" (packets dropped by firewall) 
or "connection rejected" (connection rejected by firewall or server 
without service running).

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