RFC1918 addresses to permit in for VPN?

Mon Jan 1 09:46:55 UTC 2001

On Sun, 31 Dec 2000, Stephen Stuart wrote:

> Date: Sun, 31 Dec 2000 14:15:59 -0800
> From: Stephen Stuart <stuart at mfnx.net>
> To: jlewis at jasonlewis.net
> Cc: nanog at merit.edu
> Subject: Re: RFC1918 addresses to permit in for VPN? 
> 
> 
> Only that private addressing helps ensure that your machines don't
> have access to the Internet. If you've set up a network where there is
> truly no packet path to the Internet such that it wouldn't matter if
> your back-end network was numbered in RFC1918 space or not, then it
> becomes unlikely that the network in question will be compromised *by
> an attacker arriving via the Internet*, and your security does not
> depend on RFC1918 addressing. You will have someone walking up to a
> switch and plugging in to consider (but that's more a facility
> security issue). RFC1918 gives you a place to number hosts without
> conflicting with "public" address space, that's all.
> 
Using RFC1918 space also gets you an IP range where the outside world has
no route to it -- Sorry, but no packets are not getting there, ergo no way
to hack.

Assuming various things that should be standard procedure -- dynamic NAT
as opposed to static, blocking source routing, etc.

At that point, just by use of simple routing, you've effectively
eliminated 100% of attacks from the outside, and you only have to worry
about inside.  The front door is secure, now work on the back door.

> 