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Just like you can bridge two wired ethernet interfaces, you can bridge between an ethernet interface and a wireless interface. However, most Access Points (APs) will reject frames that have a source address that didn’t authenticate with the AP.

The above comes from the Debian wiki's article on bridge network connections, and I'm trying to understand the details of why exactly this is the case. Would the following be an accurate explanation?

Suppose the following set up: one physical router which sets up an access point, one host machine with a WiFi NIC, a virtual bridge within that host, and a guest VM. The host machine and the guest VM connect to the virtual bridge. The problem is that a packet sent from the guest VM, that goes to the virtual bridge, then gets sent out by the WiFi NIC, and then reaches the access point on the router, has a source IP that is not the WiFi NIC's, correct? (Does anyone have reading suggestions delving into these topics in depth?)

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Would the following be an accurate explanation?

… The problem is that a packet sent from the guest VM, that goes to the virtual bridge, then gets sent out by the WiFi NIC, and then reaches the access point on the router, has a source IP that is not the WiFi NIC's, correct?

No that's not correct. The "source address" in question here refers to an Ethernet address, not IP.

Also, it's not NICs that have IP addresses, that's something that only manifests further up - on the IP layer, which the card is not concerned with.

It's not inherently a problem, it's just not how WiFi works: a link in a Wi-Fi (wpa) network is between two devices with fixed MAC addresses. No switching at that level is supposed to happen on the station side. You'd need your bridging host to implement a forwarding service for specific management communications; I'm trying to remember its name, but it's not coming. Anyways, you asked about what the problem is, not for the solution, and that is the problem.

Ah yes: you need relayd or something similar for relaying arp and DHCP (v4) along with IPv6 RAs and similar. Alternatively, you could instead of using a bridge device, rely on 802.11s, which defines how to properly interconnect separate Ethernet segments like your bridge and your AP's network. But you need support for 802.11s "mesh" on the access point, and by your wireless NIC's driver (but that's more the rule than the exception these days).

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