Wifi bridging without IP address

Home Forums Discussions Support Portal Wifi bridging without IP address

This topic contains 6 replies, has 2 voices, and was last updated by  Vadim Smirnov 1 week, 3 days ago.

Viewing 7 posts - 1 through 7 (of 7 total)
  • Author
    Posts
  • #10597

    Sabo
    Participant

    Hi,

    I have the following scenario using the ebridge sample bridging a Wifi and a TAP interface:

    – Wifi interface on a host that is connected to an access point and only has WinpkFilter assigned. So it does not have an IP address.
    – TAP interface bridged to that Wifi interface.
    – TAP interface used for VM machine networking

    In this scenario the VM fails to acquire a DHCP configuration. Only if IPv4 is enabled on the Wifi interface the VM will receive a DHCP configuration, but I don’t want the Wifi connection to be available via IP on the host.

    Any solution for this?

    Thx,
    –Sabo

    • This topic was modified 3 weeks ago by  Sabo.
    • This topic was modified 3 weeks ago by  Sabo.
    #10600

    Vadim Smirnov
    Moderator

    Hmm, interesting case. I don’t have a quick answer because I have never tried this kind of setup. If I have some spare time over the weekend I will give it a try.

    #10601

    Sabo
    Participant

    I did some sniffing on the Wifi interface without IP address.

    Turns out that the interface doesn’t receive any packages at all, not even ARP replies, if there is no IP configuration active. If I assign some static fake IP without a gateway that is not on the Wifi DHCP subnet, the bridge is working fine and the VM can acquire a DHCP address through the TAP interface and access the internet as well.

    So functionality-wise this is pretty much what I want, but even though irrelevant on the local host, the fake IP on the Wifi interface could cause collisions if multiple hosts on the same subnet are using this technique.

    I understand that Wifi cards resp. drivers do not support promiscuous mode, but I would still expect the interface to receive ARP replies even if there is no IP config. Is there any way to trigger this?

    Thx,
    Sabo

    #10602

    Sabo
    Participant

    Problem solved. Sending an ARP probe packet on the Wifi interface at the start of the bridging seems to trigger the packet flow just fine.

    We will continue to evaluate your driver.

    Thx,
    Sabo

    #10603

    Vadim Smirnov
    Moderator

    Very interesting, thank you for sharing!

    #10604

    Sabo
    Participant

    Unfortunately it is not as simple as that. Turns out I still had a fake IP on the Wifi interface when testing the ARP probe. I just just thought the IP config was off.

    So any hints would still be very appreciated!

    Sabo

    #10607

    Vadim Smirnov
    Moderator

    I had some time over the weekend to play with with bridging WiFi and one of the possibilities is enabling Link Layer Discovery Protocol, with the configuration below Wi-Fi adapter without IP address was successfully bridged to the wired network:

    Wi-Fi adapter configuration

Viewing 7 posts - 1 through 7 (of 7 total)

You must be logged in to reply to this topic.