On 2/22/26 12:45 PM, Matthias Andree via Dnsmasq-discuss wrote:
Am 22.02.26 um 11:33 schrieb Colin Finnis:
I have been running dnsmasq for some time on a Raspberry PI. I had no
problems until about 18 months ago when the DNS would suddenly stop
working. I found these types of entries in the syslog.
Feb 21 16:14:07 pilot dnsmasq-dhcp[2061]: DHCPACK(eth0) 192.168.0.242
02:ef:dd:91:3a:f3 Wild-s-S21
Feb 21 16:14:09 pilot dnsmasq-dhcp[2061]: DHCPREQUEST(eth0)
192.168.0.242 02:ef:dd:91:3a:f3
Feb 21 16:14:09 pilot dnsmasq-dhcp[2061]: DHCPACK(eth0) 192.168.0.242
02:ef:dd:91:3a:f3 Wild-s-S21
Feb 21 16:14:09 pilot dhcpcd[377]: eth0: hardware address
02:ef:dd:91:3a:f3 claims 192.168.0.8
Feb 21 16:14:10 pilot dhcpcd[377]: eth0: hardware address
02:ef:dd:91:3a:f3 claims 192.168.0.8
Feb 21 16:14:10 pilot dhcpcd[377]: eth0: 10 second defence failed for
192.168.0.8
Feb 21 16:14:10 pilot dhcpcd[377]: eth0: deleting route to 192.168.0.0/24
Feb 21 16:14:10 pilot dhcpcd[377]: eth0: deleting default route via
192.168.0.1
Feb 21 16:14:10 pilot avahi-daemon[279]: Withdrawing address record
for 192.168.0.8 on eth0.
The problem always seems to be associated with Samsung phones and
appears to have started after an update to the phone around 18 months
ago. I have found what purports to be a solution which requires a
setting change on the phone. This is fine for my phone but visitors to
my house can cause the same problem and its difficult to get them all
to change before the damage is done. It dosnt always happens when the
phone is brought into the house, I think it occur when the phone is
close to the property and the signal is poor.
As you can see the request is made for an address and the DNS
responds. The request is made a second time and immediately the device
seems to take over the IP address of the DNS box. DHCPD then goes into
some sort of defence mode and avahi withdraws the statically assigned
address. I have tried changing the address of the DNS server in case
it was just the phone using a random address but that made no
difference. I cant run a network monitor on the traffic so I cant see
what is happen during this event. It just sems strange behaviour for
the phone to suddenly decide its going to usurp the DNS’s IP address.
Im technically savvy having worked in the IT industry for 40 years but
cant work out away to either prevent this or stop it happening. The
only way at the moment is to reboot the PI. Any help would be
appreciated.
Colin Finnis
Colin,
you're not reporting your dnsmasq version, and what's utterly unclear to
me is how the MAC address is both for Wild-s-S21 and dhcpcd? What is the
setting for the Samsung phone that would prevent this? Give the phone a
static address?
How come dhcpcd concludes that the shown hardware address is for
192.168.0.8 if dnsmasq handed out 192.168.0.242 for what appears to be a
Samsung S21 phone?
Newer phones have, per default, random MAC turned on, if you want to
assign a static lease to your phone you might want to stop that from
happening.
--
John Doe
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