PlayStationNetwork blocking of CGNAT public addresses

Tom Beecher beecher at
Sun Sep 18 13:15:08 UTC 2016

This is, as many things are, a huge problem in communication.

Sony tells ISP 'Hey, you have customers abusing us. Fix it!'.
ISP says 'Oh crap, sorry, what's going on? We'll run it down.'
Sony says nothing.

Let's just stop here for a second. This is fundamentally no different then
the 'I have a problem, it's the network! complaints we've all dealt with
forever. You spend days/weeks/months working on it. Maybe you ultimately
find a goofy switchport, or maybe you discover that the server HDDs were
crapping the bed and the problem server was chugging because of that. But
you had to spend tons of time working on it because you couldn't get the
info you need because the reporter was CONVINCED they KNEW what it was.

Why should Simon have to spend hours of engineering time fishing through
traffic captures and logs when he doesn't even know what he's LOOKING for?
What does PSN consider 'abuse' here?

Does Simon have customers infected with botnets that are targeting PSN at
times? Or does PSN assume nobody will ever have more than a couple
Playstations in a house, so if they see more than N connections to PSN from
the same IP, it's malicious, since CGN is likely not something they
considered? ( If anyone wants to place beer wagers, I'm picking the later. )

I spend about 8 weeks this year going back and forth with a Very Large
Website Network who had blocked a /17 of IP space from accessing ANY of
their sites because of 'malicious traffic' from a specific /23. 5 of those
weeks, their responses consisted of 'it's malicious, you go find it, should
be obvious', 'you clearly don't know what you're doing, we're wasting our
time', etc.  Week 5, I was able to extract that it was a specific web
crawler that they said was knocking their databases over. After a
conversation with their CIO the following week, they came back and admitted
that a junior system admin made some PHP changes on a bunch of servers that
he didn't think was in production,and when we crawled THOSE servers, Bad
Things Happened for them. We were doing nothing wrong ; they just refused
to look, and found it easier to blame us.

Simon's getting screwed because he's not being given any information to try
and solve the problem, and because his customers are likely blaming him
because he's their ISP.

Sony needs to stand up and work with him here.

On Sun, Sep 18, 2016 at 8:30 AM, Tom Smyth <tom.smyth at>

> Hi Simon,
> as other responders have said it is an inherent issue with NAT in general,
> on workaround is to limit the ratio of  actual users to an external IPv4
> address, the other thing we have seen from our Abuse contact emails from
> PSN, is that malicious activity towards the PSN is often accompanied by
> other malicious activities such as SSH brute force outbound and spaming...
> I would suggest that
> 1) limit the ratio of users to an external ipv4 address as much as possible
> (which would reduce the impact of one compromised customer bringing down
> play time for other clients behind the same nat
> 2)do some "canary in the mine" monitoring for obviously malicious traffic
> (loads of SMTP traffic outbound) and lots of connection requests to SSH
> servers ...   if you see that traffic from behind your CGNAT device .. just
> temporarily block the internal ip of the user until they clean up their
> devices.
> this is the pain with NAT you have to do extra work in order prevent
> infected users interrupting internet connectivity for other innocent
> users...
> I think you can use simple firewall rules  on your edge router to identify
> multiple connections to SMTP and SSH in a short period of time..
> If you do the minimum to detect that abuse  then you cant be accused of
> invading peoples privacy...  (bear in mind obvious false positives)
> (Monitoring systems etc) ...
> Hope this helps,
> On Fri, Sep 16, 2016 at 2:12 PM, Simon Lockhart <simon at> wrote:
> > All,
> >
> > 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,
> >
> > Simon
> >
> >
> --
> Kindest regards,
> Tom Smyth
> Mobile: +353 87 6193172
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