Companies using public IP space owned by others for internal routing

Mon Dec 18 02:20:44 UTC 2017

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

-----Original Message-----
From: Richard Porter [mailto:richard at pedantictheory.com] 
Sent: Sunday, December 17, 2017 8:25 PM
To: Robert Webb <rwebb at ropeguru.com>
Cc: nanog at nanog.org
Subject: Re: Companies using public IP space owned by others for internal routing

Robert,
I’ve heard of two cases recently, large companies (non carrier/ISP). One company looking to solve challenge with IPv6 and 6to4 and DNS.

Also curious how wide-spread this is? Maybe just the kick in the butt for catching the elusive IPv6 unicorn?

~Richard

> On Dec 17, 2017, at 3:30 PM, Robert Webb <rwebb at ropeguru.com> wrote:
> 
> Will anyone comment on the practice of large enterprises using non RFC1918 IP space that other entities are assigned by ARIN for internal routing?
> 
> Just curious as to how wide spread this might be. I just heard of this happening with a large ISP and never really thought about it until now.
> 
> Robert