Unless you live in a densely populated city, you probably struggle to make the most of the 3DS' StreetPass feature -- it's why Nintendo implemented a StreetPass Relay program earlier this month. Now, less than a week after the Mii-sharing setup launched, the gaming community has found a way to exploit it. Users on the GBATemp forums have discovered that spoofing the MAC address of a known Nintendo Zone router while broadcasting the correct SSID creates a homemade relay that pulls the latest StreetPass data from Nintendo's servers. This trick allows gamers to remotely share StreetPass data from the comfort of their own home.
It's not a gateway to unlimited passes, however -- just like with local 3DS systems, the relay stations will only share data with an individual handheld once every eight hours, requiring die-hard "homepassers" to manually change their spoofed MAC for each additional StreetPass they want to collect. There is also some concern that Nintendo will notice this remote StreetPass setup and block the known MAC addresses (or worse, infringing handhelds) in an attempt to combat exploitation. Convoluted? Sure, but it's still pretty impressive. If you're feeling bold, check out the adjacent source links to get started; the community has created tutorials for Android, Linux, OSX and Windows, complete with a spreadsheet of viable MAC addresses.
Source: Google Docs, GBATemp (1), (2)