- A port on a switch is configured as port mirroring (SPAN) for the purpose of analyzing network traffic.
- Due to the characteristics of the switch and its configuration the flow to be analyzed provided by the SPAN port is
802.1quntagged in one direction and tagged in the other. - The data flow coming from the switch should be merged into a single flow (
802.1quntagged). It should also not be redirected back to the switch.
- IDS host recieves port mirrored flow on port
ens1f0: RX tagged flow + TX untagged. - The interface
ens1f0.40gets only the tagget flow (RX) and untags it. - Bridge
br1joins all three network flows: RX tagged flow + TX untagged +ens1f0.40(same RX flow but untagged). - ebtables drop all the
802.1qtagged frames onbr1.