I also don't have first hand knowledge of possible consequences of doing this. If you really think it's a bad thing I'll rethink posting links on how to do it. It's not good to contribute to a potentially bad situation either and I believe you know what you're talking about on this subject. What is the worst that can happen?
using DMZ with just only the PS3 online there isn't much that can be done,but if you have another device as most people do connected to your router then it can be easily accessed by someone using a JB console with them running it through their own pc and gain access to your computer along with other devices..
this used to not be possible very easily but there is so many script kiddies out there running these silly tools, as now Sony can't even ban a JB console anymore as they have spoof tools to mask their real console id/MAC...
i personally have even found a way using wireshark alongside of net tools 5 to gain these hackers ip addresses on GTA4 and then i can flood their connection so they get disconnected,and i do it all on the pc and the PS3 has nothing to do with it but just give me their IP as the packet crosses my network switch...
i only do this to the hackers so in a way i am just helping Sony out for free and to give us players a real game to play.
so my main point is,it is best to always use the most secured connection you can because these noobs take advantage of people when the oppurtunity arises.
i have read and not positive if it really works but supposedly some of these people can decrypt certain things in these packets and actually get a legit players console banned...not sure it really works but in theory it makes sense and this was a few years ago and other measures i would hope would be put in place.
so in other words,most of the time your most likely to be ok but it only takes one person who really knows their **bleep** to really foul things up for someone because they took the easy way out by opening all kinds of ports that aren't needed or using DMZ..
This has nothing to do with putting your PS3 in the DMZ. If it is setup correctly there is nothing that can be done through the PS3.
You getting their WAN IP address is something completely different and you flooding their connection is something completely different than the PS3 being in the DMZ.
Now if you had a Windows machine somehow get that IP address for the DMZ then yes there can be some issues. Someone could access your drive through services that are provided in Windows. The PS3 does not have this capability.
And IF you get caught flooding someone, say a DDOS, you are committing a federal crime. You should never be admitting to this!!
Reading this thread is like pulling teeth... the OP needs to be more forthcoming. And false claims about the dangers of a game console in a DMZ configuration needs to stop... it's simply not true.
ISP: Cable, DSL or FiOS
DMZ configuration: before the adoption of UPnP puting the fixed IP(static IP) of your PS3 in a DMZ was a quick way of not having to deal with configuring and maintaning Port Forward settings. This is much different than putting a PC in a DMZ, a PC's OS has multiple attack surfaces to take advatage of. The OS of the PS3 is a closed system... no attack surface from an external source. It's that simple.
UPnP solves the headache of configuring Port Forwarding. UPnP lets the PS3 change ports opening/closing dynamically on the router based on the needs of the application/game. That's why you use UPnP.