Should proxy have one interface or two

["Gleb Paharenko" <gpaharenko () gmail com>]

Hi, list.

In many network designs web proxy server has two interfaces. One is
for internal clients, second is outgoing interface for proxy.
Why it is not use one interface both for incoming requests from users
and for outgoing requests from proxy? Of course this interface should
be in separate subnet with firewalled control on it and it should be
SNATed as well. Hope I clearly describe my question, of why it is
better to
have two interfaces in different subnets for web-proxy.


-- 
Best regards.
Gleb Pakharenko.
http://gpaharenko.livejournal.com
http://www.linkedin.com/in/gpaharenko