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Is NAT can provide some kind of protection?
>
> That's simply not true. Every end user running NAT is running a stateful firewall with a default inbound deny.
Really? I just tested this with 8 different router models from 5
different manufacturers and in all cases the default behavior was the
same. Put a public IP on a PC behind the router, tell the router how to
connect (DHCP in this case), and leaving everything else as default
meant that all traffic to the public IP was allowed through unless I
configured rules. One of the Netgear models (IIRC) did block ICMP but
any TCP or UDP traffic was allowed through. Now, this certainly isn't
an exhaustive test, but it tested the devices we needed checked. If
someone knows of a model that does block incoming (non-established TCP)
traffic by default I'd like to know about it. That's especially true of
combo DSL modem routers.
--
Scott Helms
Vice President of Technology
ISP Alliance, Inc. DBA ZCorum
(678) 507-5000
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