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.