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charset="utf-8" Hi Julian, Thank you! Your point is spot-on: in a shared-key Wi-Fi network, an attacker can simply broadcast a forged GARP reply (sip == tip == gateway_ip) to poison the gateway MAC for all peers. Giving GARP an exemption indeed leaves a door open. We verified the Android / mobile use case and confirmed that completely disallowing neighbor learning from L2 BMC is safe: - Gateway validation: Android relies on NUD (Neighbor Unreachability Detection) unicast probes and unicast replies (PACKET_HOST), never on broadcast replies. - Wi-Fi Roaming: Roaming clients *send* GARP to notify the AP/switch; they do not need to receive broadcast GARP. - Router failover: NUD naturally detects stale neighbor state and re-probes via unicast, recovering within seconds. For v6, following your guidance: 1. L2 BMC ARP Replies: Drop all of them unconditionally (including GARP) with SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST. 2. L2 BMC ARP Requests: Process and send replies as usual, but suppress updating/creating neighbor cache entries. Does this match your vision for v6? If so, I will prepare the patch accordingly. Best regards, Star Chang