Visit the Ebtables project page for more details on this project. Many wireless Access Points ship with support for multiple SSIDs (for e.g. one for guest and one for corporate). For security reasons, it is important to mark these packets so that upstream switches can handle them differently. The following implements the ebt_vnat module that can be instructed to add a VLAN tag so that these traffic classes can be handled differently.

Unfortunately I have lost the original patch files and I was able to dig this out from my email messages to Bart: