PlayStationNetwork blocking of CGNAT public addresses

Mike Hammett nanog at
Fri Sep 16 13:28:21 UTC 2016

A network that doesn't support IPv6, yet discriminates against CGNAT? That seems like a promising future. 

Mike Hammett 
Intelligent Computing Solutions 

Midwest Internet Exchange 

The Brothers WISP 

----- Original Message -----

From: "Simon Lockhart" <simon at> 
To: nanog at 
Sent: Friday, September 16, 2016 8:12:46 AM 
Subject: PlayStationNetwork blocking of CGNAT public addresses 


We operate an access network with several hundred thousand users. Increasingly 
we're putting the users behind CGNAT in order to continue to give them an IPv4 
service (we're all dual-stack, so they all get public IPv6 too). Due to the 
demographic of our users, many of them are gamers. 

We're hitting a problem with PlayStationNetwork 'randomly' blocking some of our 
CGNAT outside addresses, because they claim to have received anomalous, or 
'attack' traffic from that IP. This obviously causes problems for the other 
legitimate users who end up behind the same public IPv4 address. 

Despite numerous attempts to engage with PSN, they are unwilling to give us 
any additional information which would allow us to identify the 'rogue' users 
on our network, or to identify the 'unwanted' traffic so that we could either 
block it, or use it to identify the rogue users ourselves. 

Has anyone else come up against the problem, and/or have any suggestions on 
how best to resolve it? 

Many thanks in advance, 


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