Re: AWS issues with 172.0.0.0/12

[Jim Popovitch via NANOG <nanog () nanog org>]

On October 1, 2019 9:39:03 PM UTC, Matt Palmer <mpalmer () hezmatt org> wrote:
> On Tue, Oct 01, 2019 at 04:50:33AM -0400, Jim Popovitch via NANOG
> wrote:
> > On 10/1/2019 4:09 AM, Christopher Morrow wrote:
> > > possible that this is various AWS customers making
> iptables/firewall mistakes?
> > >    "block that pesky rfc1918 172/12 space!!"
> >
> > AWS also uses some 172/12 space on their internal network (e.g. the
> network
> > that sits between EC2 instances and the AWS external firewalls)
>
> Does AWS use 172.0.0.0/12 internally, or 172.16.0.0/12?  They're
> different
> things, after all.

I don't know their entire operations, but they do use some 172.16.0.0/12
addresses internally. And yes, that is very different than 172/12, sorry
for the confusion.

-Jim P.