nanog mailing list archives

Re: AWS issues with 172.0.0.0/12


From: Matt Palmer <mpalmer () hezmatt org>
Date: Wed, 2 Oct 2019 07:39:03 +1000

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.

- Matt


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