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  1. #1
    Untangle Ninja Jim.Alles's Avatar
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    Default dnsmasq hostname is * /Android

    So what does the asterisk mean in the DHCP leases hostname?
    In a word - duplicate.

    The reason that asterisks show up is because that only one lease can own a name. When the next device takes a lease claiming to be the same hostname it steals the name from the first, and the first gets a *

    This makes sense to me when I have a laptop that has an Ethernet port and Wi-Fi. Both of those will use the same hostname. I keep my Wi-Fi on a separate sub-net from the wired, so I don't have to fool around with trying to force the same IP address; yet I can still use DHCP reservations.

    But I am getting stars all over the place in the hosts table???

    Well, it turns out there is this:
    Since Android 8 - when android_id became unique to apps - net.hostname is no more set, so a null is sent in DHCPREQUEST. See Android 8 Privacy Changes and Security Enhancements:

    net.hostname is now empty and the dhcp client no longer sends a hostname

    So the WiFi routers show no host names for Android 8+, neither we can set / unset / change it.
    From: https://android.stackexchange.com/a/217171

    All up-to-date Android devices are going to have the identical hostname of '<null>'. To me, this seems like a great way to screw up the integrity of a database.

    So it seems the best thing for me to keep a little sanity is to add a hostname at the lowest level, (dnsmasq) with the dhcp-host option for those devices that I own and are 'shooting blanks'.

    YMMV
    Last edited by Jim.Alles; 09-17-2020 at 02:58 PM.

  2. #2
    Untangle Ninja Jim.Alles's Avatar
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    Default

    And to add to this headache: Android devices may, by default, rotate their random mac addresses.
    So action needs to be taken to nail that down, if possible.

    I don't see where NGFW examines the client-ID

    The client-ID is used as the computer's
    unique-ID in preference to the MAC address, if it's available. Some DHCP
    clients provide it, and some don't. The ones that do normally derive it
    from the MAC address unless explicity configured, but it could be
    something like a serial number, which would protect a computer from
    losing its identify if the network interface were replaced.

  3. #3
    Untangle Ninja sky-knight's Avatar
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    The android devices are supposed to keep the same MAC address on a per SSID basis. I can make mine change when I jump networks by adding / removing SSID's to my WAPs, but when I jump back on the original networks, it goes right back to what it was.

    I'm sure there's some sort of internal limit, but I've never found it.
    Rob Sandling, BS:SWE, MCP
    NexgenAppliances.com
    Phone: 866-794-8879 x201
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  4. #4
    Untangle Ninja Jim.Alles's Avatar
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    Quote Originally Posted by sky-knight View Post
    The android devices are supposed to keep the same MAC address on a per SSID basis. I can make mine change when I jump networks by adding / removing SSID's to my WAPs, but when I jump back on the original networks, it goes right back to what it was.

    I'm sure there's some sort of internal limit, but I've never found it.
    yup. after some version (I have been messing with 4, 7, 9, 10 and the Pixel-2 just updated to 11)
    each network (SSID) has an advanced option to use the <device MAC> or the <random MAC>. I have been setting/verifying the home networks to <device MAC>, and a few oft-used outside ones to randomized. It looks like you have more experience with the random bit, I haven't been watching that (yet). There are a lot more settings now under each Wi-Fi network.

    What I saw after the update was that existing networks had <device MAC> set with no interaction on my part, and <random MAC> on any newly added Wi-Fi networks as default.

    So with some network management attention paid, I have my devices presenting DHCP with stable MAC addresses, and the newer android devices with blank hostnames I am entering dhcp-host entries with my choice of hostname.

    Androids with the long number for a hostname I am setting a more descriptive hostname on top of that in the devices table.

    I now have one phantom device in the hosts table that I can't get rid of. In addition, it picked up a user name from God knows where.
    Last edited by Jim.Alles; 09-17-2020 at 09:16 PM.

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