I don't need no stinking firewall!

Mark Smith nanog at 85d5b20a518b8f6864949bd940457dc124746ddc.nosense.org
Tue Jan 5 22:49:30 UTC 2010

On Tue, 5 Jan 2010 14:16:58 -0600
"Brian Johnson" <bjohnson at drtel.com> wrote:

> Security Gurus, et al,
> I have my own idea of what a firewall is and what it does. I also
> understand what statefull packet inspection is and what it does. Given
> this information, and not prejudging any responses, exactly what is a
> firewall for and when is statefull inspection useful?

First thing to work out is your threat model. Once you've worked out
what you're trying to protect, who you're trying to protect it from,
and what techniques they're likely use to break that protection, you
can then work out if a firewall is the right tool, then work out how
many to have and where (network perimeter only, network perimeter +
hosts, network perimeter + hosts + in application protection (e.g.
authentication like in ssh - remember, it's people that are your real
threat, not machines and their IP addresses - those are just the tools
people use).

The trap is to think technology like firewalls are only thing you
need to worry about. Unfortunately they won't stop the building
cleaners from lifting things out of the bins under desks.

> Please respond on-list as I want to have some useful discourse and
> discussion in the clear. Flamers and Trolls will be disregarded. :)
> Thank you.
>  - Brian
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