nanog mailing list archives

Re: Arguing against using public IP space


From: Valdis.Kletnieks () vt edu
Date: Tue, 15 Nov 2011 09:17:20 -0500

On Tue, 15 Nov 2011 10:57:32 GMT, Leigh Porter said:

Well this is not quite true, is it.. If your firewall is not working and you
have private space internally then you are a lot better off then if you have
public space internally! So if your firewall is not working then having private
space on one side is a hell of a lot more secure!

By the same token, if your firewall fails closed rather than fails open, you're
more secure.

And this is totally overlooking the fact that the vast majority of *actual*
attacks these days are web-based drive-bys and similar things that most
firewalls are configured to pass through.  Think about it - if a NAT'ed
firewall provides any real protection against real attacks, why are there still
so many zombied systems out there?  I mean, Windows Firewall has been shipping
with inbound "default deny" since XP SP2 or so. How many years ago was that?
And what *real* security over and above that host-based firewall are you
getting from that appliance?

Or as Dr Phil would say "FIrewalls - how is that working out for you?"

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