Companies using public IP space owned by others for internal routing

Mon Dec 18 02:49:45 UTC 2017

> -----Original Message-----
> From: Mark Andrews [mailto:marka at isc.org]
> Sent: Sunday, December 17, 2017 9:35 PM
> To: Robert Webb <rwebb at ropeguru.com>
> Cc: Richard Porter <richard at pedantictheory.com>; nanog at nanog.org
> Subject: Re: Companies using public IP space owned by others for internal
> routing
> 
> 
> > On 18 Dec 2017, at 1:20 pm, Robert Webb <rwebb at ropeguru.com> wrote:
> >
> > Apologies for not responding sooner.
> >
> > This came to light with me on a forum where someone posted that they
> thought it strange that their MTA received an IP that is assigned to the DoD
> DNIC.
> >
> > Where I work I have the opposite issue. They have a lot of public IPv4
> > space and only use it internally never be advertised to the internet.
> Something I have never agreed With doing.
> >
> > Robert
> 
> Why?  This is a perfectly legitimate use of the IP addresses.  The purpose of
> assigning addresses is so that they are unique WORLD WIDE in whatever
> context you wish to use them in.
> 
> Mark

I going to guess you were talking about the use internally of public IP addresses..

But there are rules governing what to use where. So it is OK to hoard publicly addressable IPv4 IP's for internal
use that will never reach the outside world? No the way I have been taught.

Maybe I just lack that big picture..

Robert