You can configure your linux bridge (brctl operates them) as a hub (if you want to) with setting the aging property of the bridge to 0 as below:
brctl setageing <bridge> 0
This make your bridge to behave as a hub. Most of you may not remember a network hub’s functionality that is different from switches. Hubs are dummy devices, in other words they forward every packet to every other ports. It has no look-up table to decide packets destination port. Whereas switches are smart devices. They know which device (based on mac address) is connected to its port and with the help of this information it forward packets only to the destination port. There is an exception at that procedure. If a switch lookup table is full of MAC addresses then it starts to behave as a HUB. Lots of security issues raises from this HUB-Like behavior.