Seems like theres been success?!
Can anyone explain whats been happening?
I'm confused... ha ha.
At first I thought we were talking about making streetpass packet replays and streetpass darknets but that seems to have fallen by the wayside in favour of streetpass access point spoofing and abusing official replays.
Streetpass -- a function of the 3ds that allows 3ds that are in the vicinity of one another to exchange miis and messages. Tied to this are also various bonuses for various micro games on the menu itself.
Way back in the DS era Nintendo did a deal with various wifi sharing companies (fon, the cloud and whatnot) to allow the DS to use bandwidth for free (the DS is fairly identifiable by the mac address of it which led to a few interesting discussions in places, more on mac addresses later). Typically they are found in places like mcdonalds, at events and other such things.
http://www.3dbrew.org/wiki/Nintendo_Zone has some more on that.
Sliding forward a tiny bit said access points can be used to send something out into the world (or more accurately Nintendo's servers somewhere) and then anybody that connects to the same access point will get a streetpass hit like they were there at the same time. It works it seems by having the 3ds send the SSID of the wifi network (the list from a moment ago having a lot of them) and seemingly the mac address of the wifi access point to Nintendo's servers somewhere, someone else comes along and sends the same data and down comes the streetpass hit. The mac address should be unique or nearly unique to the router itself and not be broadcast outside the local network so Nintendo has seemingly relied upon that to ensure uniqueness.
Here people are changing their SSID to that of one on the list and a mac address which they then share.
The mac address is the stumbling point for a lot of people though -- typically it is hardcoded into the wifi card of whatever device is using it. However you can change it in various ways on the device itself (things like the original xbox actually took this from the EEPROM and 360 something similar hence why you could not share them between hacked xboxes and there were similar things on the PSP), in software on the PC (linux can do it easily hence a lot of people looking to that, windows typically locks down a lot of network functionality mainly as its only use is for hacking, getting data out of compromised PCs and no "legit" stuff though earlier versions like XP do OK at it, SignZ linked up what looks like a nice tool
http://devices.natetrue.com/macshift/ though you can go manual if you want) and if you are lucky on software on the device itself.
The device itself is an interesting one, on your basic home router it is not that likely to happen (again there are few truly legit regions in home network environments to do this -- if you need it you need professional network gear which of course they are happy to sell you for 10x the price) but there are hacked firmwares for routers (DD-wrt being the most notable of these and the basis for a lot more) which will then allow you to actually change this as said hacked firmwares allow you most of the fun of professional gear but without the price tag. Beyond that a lot of people have noticed that Android being fairly open, being known to be used to set up access points and being linux based can set up as a router and change the mac address, similarly being largely linux based/friendly and quite customisable I saw someone mention the raspberry pi (they come with a LAN port but many will have added wifi too).
The trouble for most "normal" people is that they do not have a massive abundance of wifi gear available to them and will probably use their wifi card to access the internet or have wired internet only it causes trouble as this relies on the internet/access to Nintendo's servers to work for obvious reasons (data does not tend to transmit halfway around the world by itself after all). Laptops are pretty good for this as they often have wifi and network so you can wire it in for this, set up an appropriate access point on your laptop and get it done.
Nintendo could frustrate a lot of this if they want to but you can cross that bridge when you/they come to it.