rick at linuxmafia.com
Sun Aug 19 18:49:51 PDT 2007
Quoting Alex Kleider (a_kleider at yahoo.com):
> I thought I was getting the 2nd edition but what I have makes no
> mention if which edition it is so I assume it is the first (copyright
> Topology schematic on page 87
That would seem to refer to Figure 4.1 in chapter 4, in the first
edition. Section 4.2 starts out:
"We have used three general application gateway configurations. They are
shown in Figure 4.1. [...]"
There you have it: _application_ gateways. The authors are talking,
here, about network proxy services operating at the application layer of
the standard OSI networking model. As I mentioned, the standard
commodity example of an application-level proxy gateway is "SOCKS".
So, a network application on the inside of the gateway would submit its
request to the proxy for that network service. The proxy would generate
a corresponding service request on the public network side of the
gateway. And so on.
Chapter 3 described how such things (application gateways) work, and
distinguished them from packet filtering and from circuit gateways.
You may not ever encounter (or _know_ you've encountered) an
application-level proxy gateway, let alone construct one, but it might
repay your effort to learn how they work.
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