[Dnsmasq-discuss] Problem with VM and dnsmasq

[mario]

Hello, Albert.

On 10/07/2015 09:09 PM, Albert ARIBAUD wrote:
> Hi again mario,
>
> Le Wed, 7 Oct 2015 19:06:15 +0200, Albert ARIBAUD
> <albert.aribaud at free.fr> a écrit :
>
>> Stupid question BTW: how does yor host get its eth and wlan IPs? Does
>> it ask another DHCP server on the segment, or are they fixed? In the
>> end, does it get the same or different addresses on both I/Fs?

The whole LAN is served by the single dnsmasq we are discussing, both 
DHCP and DNS.
The different NICs are dished distinct IP addresses, except for the few 
with reserved addresses.


> Also: when your VM switches between host eth tand host wlan for its
> bridge, does it do it while off or is it still on? What if both the
> host and VM boot on wlan and never switch to eth?


The VM is brought down completely, powered off. I then
disconnect the host, count to 5 ;-)  re-connect the host thru the other 
NIC,
change guest setup as regards to network configuration,  then I
bring up the VM.

It is as fresh a start as I can concoct, short of bringing the whole 
host down.

I do not know what you mean by

.... What if VM boot[s] on wlan and never switch[es] to eth?

The VM does not have access to a wifi connection. It has a single 
ethernet NIC;
as per VirtualBox (or any Hypervisor) it is connected either to wired or 
to the
wifi NIC of the host. I never switch the guest while it is up and running.
When I want to switch the host's connection, I bring the VM down (=powered
off), reconnect the host, change the VM network configuration so that it 
hooks up
now with the new alive NIC, then bring it up.

When the host is conneted via wifi, the VM never receives a reply to its 
BOOTP/DHCP
request: I can see, in the tcpdump records, hundreds of requests, dnsmasq
makes hundred of replies, not a single one of them leaves the gateway: 
the VM
never gets a DHCP reply. If the host is connected via ethernet, the same 
occurs except
the reply occurs in a couple of seconds, and that's the end of the DHCP 
process:
the VM is served a proper IP address in a matter of seconds.



>
>> Anyway: the only difference I see between the requests is the broadcast
>> flag present for the WLAN packet and absent in the ETH packet, but I
>> don't see how this could affect dnsmasq.
>>
>>> Cheers,
>>>
>>> Mario
> Amicalement,
Cheers, and thanks for your help,

Mario