[Winpcap-users] can not get any captured package when

[Lin George]

Thanks Bryan,
1.
> If *something* sets the proxy address and port in the browser (not
> necessarily the user), then it's not a transparent proxy.  (For
> instance, there are ways to set the proxy via a central policy in a lot
> of browsers.  You won't have to set it on each individual machine, but
> the proxy will still be used explicitly, and the full URL will be sent
> to it, so it's not transparent.)

My sample of using IE to check proxy setting is not good. Actually my question is, on Windows platform how to check whether a proxy is transparent or not? What is the rule?
2.
> No.  An explicit proxy (non-transparent) will always do the DNS
> resolution for the client.  A transparent proxy may or may not do the
> DNS lookup; it depends on how the proxy was set up.

Is there any ways to check whether a proxy resolves DNS address or not from client side? I am very interested in how could we setup proxy to resolve DNS -- what is the underlying mysterious tricks are used? :-)
regards and have a good weekend,
George


----- Original Message ----
From: Bryan Kadzban <bryan at kadzban.is-a-geek.net>
To: Lin George <george4academic at yahoo.com>
Cc: winpcap-users at winpcap.org
Sent: Thursday, August 14, 2008 11:18:49 PM
Subject: Re: [Winpcap-users] can not get any captured package when

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Lin George wrote:
> I am interested in your reply regarding to proxy and transparent 
> proxy. In my understanding if we do not need to set explicitly in IE 
> or Windows Registry the proxy address and port, the proxy will be 
> used transparently and in this situation the proxy is called 
> transparent proxy.

(You use IE?  I'm sorry...  ;-) )

If *something* sets the proxy address and port in the browser (not
necessarily the user), then it's not a transparent proxy.  (For
instance, there are ways to set the proxy via a central policy in a lot
of browsers.  You won't have to set it on each individual machine, but
the proxy will still be used explicitly, and the full URL will be sent
to it, so it's not transparent.)

> What is the correct understanding of whether a proxy is transparent
> or not?

If your browser has its proxy address set to something, then it's not
transparent.  Otherwise (if there is actually a proxy in use!) it is.

> For gateway, I think there is also transparent and non-transparent, 
> from "end user" (not network admin) point of view, how do we know 
> whether of the 4 following situations are used?

I have no idea what you mean by "gateway"; the default route is never
transparent.  But we're so off topic now that you don't have to explain.

> Is it correct understanding that all transparent proxy will do DNS 
> resolution and non-transparent proxy will not do DNS resolution?

No.  An explicit proxy (non-transparent) will always do the DNS
resolution for the client.  A transparent proxy may or may not do the
DNS lookup; it depends on how the proxy was set up.
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