[Dnsmasq-discuss] DHCP server not assigning IP to RTMU86

Kamil kamil at incmachines.com
Sat May 14 00:53:51 UTC 2022


> On 11/05/2022 12:41, Kamil via Dnsmasq-discuss wrote:
> > Hi!
> >
> > I've configured Dnsmasq with the following config:
> >
> >     interface=eth0
> >     bind-interfaces
> >     dhcp-option=3,192.168.6.1
> >     dhcp-option=6,8.8.8.8
> >     set long-lasting records.
> >     dhcp-range=192.168.6.11,192.168.6.20,255.255.255.0,12h
> >
> >
> > And most of the devices work just fine (here is the example syslog):
> >
> >     May 10 16:25:11 myhost dnsmasq-dhcp[1862]: DHCP packet received on
> >     eth0 which has no address
> >     May 10 16:25:12 myhost dhcpcd[740]: eth0: carrier acquired
> >     May 10 16:25:12 myhost kernel: [ 1598.601129] bcmgenet
> >     fd580000.ethernet eth0: Link is Up - 100Mbps/Full - flow control off
> >     May 10 16:25:12 myhost dhcpcd[740]: eth0: IAID 01:XX:XX:90
> >     May 10 16:25:12 myhost dhcpcd[740]: eth0: adding address <mac>
> >     May 10 16:25:12 myhost dhcpcd[740]: eth0: probing address
> >     192.168.6.1/24 <http://192.168.6.1/24>
> >     May 10 16:25:12 myhost avahi-daemon[384]: Joining mDNS multicast
> >     group on interface eth0.IPv6 with address fe80::XX:XX:XX:d2c.
> >     May 10 16:25:12 myhost avahi-daemon[384]: New relevant interface
> >     eth0.IPv6 for mDNS.
> >     May 10 16:25:12 myhost avahi-daemon[384]: Registering new address
> >     record for fe80::XX:XX:XX:d2c on eth0.*.
> >     May 10 16:25:12 myhost dhcpcd[740]: eth0: soliciting an IPv6 router
> >     May 10 16:25:12 myhost dnsmasq-dhcp[1862]: DHCP packet received on
> >     eth0 which has no address
> >     May 10 16:25:14 myhost dnsmasq-dhcp[1862]: DHCP packet received on
> >     eth0 which has no address
> >     May 10 16:25:16 myhost dnsmasq-dhcp[1862]: DHCP packet received on
> >     eth0 which has no address
> >     May 10 16:25:16 myhost dhcpcd[740]: eth0: using static address
> >     192.168.6.1/24 <http://192.168.6.1/24>
> >     May 10 16:25:17 myhost avahi-daemon[384]: Joining mDNS multicast
> >     group on interface eth0.IPv4 with address 192.168.6.1.
> >     May 10 16:25:17 myhost avahi-daemon[384]: New relevant interface
> >     eth0.IPv4 for mDNS.
> >     May 10 16:25:17 myhost dhcpcd[740]: eth0: adding route to
> >     192.168.6.0/24 <http://192.168.6.0/24>
> >     May 10 16:25:17 myhost avahi-daemon[384]: Registering new address
> >     record for 192.168.6.1 on eth0.IPv4.
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 available DHCP
> >     range: 192.168.6.11 -- 192.168.6.20
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464
> >     DHCPDISCOVER(eth0) <mac>
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 tags: known,
> eth0
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464
> >     DHCPOFFER(eth0) 192.168.6.15 <mac>
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 requested
> >     options: 1:netmask, 3:router, 28:broadcast, 6:dns-server
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 next server:
> >     192.168.6.1
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 sent size:  1
> >     option: 53 message-type  2
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 sent size:  4
> >     option: 54 server-identifier  192.168.6.1
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 sent size:  4
> >     option: 51 lease-time  infinite
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 sent size:  4
> >     option:  1 netmask  255.255.255.0
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 sent size:  4
> >     option: 28 broadcast  192.168.6.255
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 sent size:  4
> >     option:  3 router  192.168.6.1
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 sent size:  4
> >     option:  6 dns-server  192.168.6.1
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 available DHCP
> >     range: 192.168.6.11 -- 192.168.6.20
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464
> >     DHCPREQUEST(eth0) 192.168.6.15 <mac>
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 tags: known,
> eth0
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 DHCPACK(eth0)
> >     192.168.6.15 <mac>
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 requested
> >     options: 1:netmask, 3:router, 28:broadcast, 6:dns-server
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 next server:
> >     192.168.6.1
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 sent size:  1
> >     option: 53 message-type  5
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 sent size:  4
> >     option: 54 server-identifier  192.168.6.1
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 sent size:  4
> >     option: 51 lease-time  infinite
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 sent size:  4
> >     option:  1 netmask  255.255.255.0
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 sent size:  4
> >     option: 28 broadcast  192.168.6.255
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 sent size:  4
> >     option:  3 router  192.168.6.1
> >     May 10 16:25:20 myhost dnsmasq-dhcp[1862]: 1567457464 sent size:  4
> >     option:  6 dns-server  192.168.6.1
> >     May 10 16:25:26 myhost dhcpcd[740]: eth0: no IPv6 Routers available
> >
> >
> > Except one - the RTMU86 NFC reader to which Dnsmasq doesn't assign the
> > IP address. Here syslog shows:
> >
> >     May 10 16:26:15 myhost dhcpcd[740]: eth0: carrier acquired
> >     May 10 16:26:15 myhost kernel: [ 1661.024489] bcmgenet
> >     fd580000.ethernet eth0: Link is Up - 100Mbps/Full - flow control off
> >     May 10 16:26:15 myhost dhcpcd[740]: eth0: IAID 01:XX:XX:90
> >     May 10 16:26:15 myhost dhcpcd[740]: eth0: adding address
> >     fe80::XX:XX:XX:d2c
> >     May 10 16:26:15 myhost dhcpcd[740]: eth0: probing address
> >     192.168.6.1/24 <http://192.168.6.1/24>
> >     May 10 16:26:15 myhost avahi-daemon[384]: Joining mDNS multicast
> >     group on interface eth0.IPv6 with address fe80::XX:XX:XX:d2c.
> >     May 10 16:26:15 myhost avahi-daemon[384]: New relevant interface
> >     eth0.IPv6 for mDNS.
> >     May 10 16:26:15 myhost avahi-daemon[384]: Registering new address
> >     record for fe80::XX:XX:XX:d2c on eth0.*.
> >     May 10 16:26:15 myhost dhcpcd[740]: eth0: soliciting an IPv6 router
> >     May 10 16:26:17 myhost dnsmasq-dhcp[1862]: DHCP packet received on
> >     eth0 which has no address
> >     May 10 16:26:20 myhost dhcpcd[740]: eth0: using static address
> >     192.168.6.1/24 <http://192.168.6.1/24>
> >     May 10 16:26:20 myhost avahi-daemon[384]: Joining mDNS multicast
> >     group on interface eth0.IPv4 with address 192.168.6.1.
> >     May 10 16:26:20 myhost avahi-daemon[384]: New relevant interface
> >     eth0.IPv4 for mDNS.
> >     May 10 16:26:20 myhost avahi-daemon[384]: Registering new address
> >     record for 192.168.6.1 on eth0.IPv4.
> >     May 10 16:26:20 myhost dhcpcd[740]: eth0: adding route to
> >     192.168.6.0/24 <http://192.168.6.0/24>
> >     May 10 16:26:28 myhost dhcpcd[740]: eth0: no IPv6 Routers available
> >     May 10 16:26:35 myhost dhcpcd[740]: eth0: carrier lost
> >     May 10 16:26:35 myhost kernel: [ 1681.494492] bcmgenet
> >     fd580000.ethernet eth0: Link is Down
> >     May 10 16:26:35 myhost dhcpcd[740]: eth0: deleting address
> >     fe80::XX:XX:XX:d2c
> >     May 10 16:26:35 myhost avahi-daemon[384]: Withdrawing address record
> >     for fe80::XX:XX:XX:d2c on eth0.
> >     May 10 16:26:35 myhost avahi-daemon[384]: Leaving mDNS multicast
> >     group on interface eth0.IPv6 with address fe80::XX:XX:XX:d2c.
> >     May 10 16:26:35 myhost avahi-daemon[384]: Interface eth0.IPv6 no
> >     longer relevant for mDNS.
> >     May 10 16:26:35 myhost avahi-daemon[384]: Withdrawing address record
> >     for 192.168.6.1 on eth0.
> >     May 10 16:26:35 myhost avahi-daemon[384]: Leaving mDNS multicast
> >     group on interface eth0.IPv4 with address 192.168.6.1.
> >     May 10 16:26:35 myhost avahi-daemon[384]: Interface eth0.IPv4 no
> >     longer relevant for mDNS.
> >     May 10 16:26:35 myhost dhcpcd[740]: eth0: deleting route to
> >     192.168.6.0/24 <http://192.168.6.0/24>
> >     May 10 16:26:38 myhost dhcpcd[740]: eth0: carrier acquired
> >     May 10 16:26:38 myhost kernel: [ 1684.565026] bcmgenet
> >     fd580000.ethernet eth0: Link is Up - 100Mbps/Full - flow control off
> >     May 10 16:26:38 myhost dhcpcd[740]: eth0: IAID 01:79:77:90
> >     May 10 16:26:38 myhost dhcpcd[740]: eth0: adding address
> >     fe80::XX:XX:XX:d2c
> >     May 10 16:26:38 myhost dhcpcd[740]: eth0: probing address
> >     192.168.6.1/24 <http://192.168.6.1/24>
> >     May 10 16:26:38 myhost avahi-daemon[384]: Joining mDNS multicast
> >     group on interface eth0.IPv6 with address fe80::XX:XX:XX:d2c.
> >     May 10 16:26:38 myhost avahi-daemon[384]: New relevant interface
> >     eth0.IPv6 for mDNS.
> >     May 10 16:26:38 myhost avahi-daemon[384]: Registering new address
> >     record for fe80::XX:XX:XX:d2c on eth0.*.
> >     May 10 16:26:38 myhost dnsmasq-dhcp[1862]: DHCP packet received on
> >     eth0 which has no address
> >     May 10 16:26:39 myhost dhcpcd[740]: eth0: soliciting an IPv6 router
> >     May 10 16:26:41 myhost dnsmasq-dhcp[1862]: DHCP packet received on
> >     eth0 which has no address
> >     May 10 16:26:42 myhost dhcpcd[740]: eth0: using static address
> >     192.168.6.1/24 <http://192.168.6.1/24>
> >     May 10 16:26:42 myhost dhcpcd[740]: eth0: adding route to
> >     192.168.6.0/24 <http://192.168.6.0/24>
> >     May 10 16:26:42 myhost avahi-daemon[384]: Joining mDNS multicast
> >     group on interface eth0.IPv4 with address 192.168.6.1.
> >     May 10 16:26:42 myhost avahi-daemon[384]: New relevant interface
> >     eth0.IPv4 for mDNS.
> >     May 10 16:26:42 myhost avahi-daemon[384]: Registering new address
> >     record for 192.168.6.1 on eth0.IPv4.
> >     May 10 16:26:52 myhost dhcpcd[740]: eth0: no IPv6 Routers available
> >
> >
> > But when I used isc-dhcp-server with following config:
> >
> >     subnet 192.168.6.0 netmask 255.255.255.0 {
> >              interface eth0;
> >              ddns-update-style none;
> >              default-lease-time 600;
> >              max-lease-time 3600;
> >              authorative;
> >              range 192.168.6.11 192.168.6.20;
> >              option subnet-mask 255.255.255.0;
> >              option routers 192.168.6.1;
> >              option domain-name-servers 8.8.8.8;
> >              get-lease-hostnames true;
> >              use-host-decl-names true;
> >
> >     }
> > DHCP packet received on
> >     eth0 which has no address
> >
> > then isc-dhcp-server assigns correct IP to RTMU86.
> > Why doesn't Dnsmasq want to assign IP to RTMU86?
>
> In the first log, dnsmasq starts off NOT assigning addresses because
> eth0 doesn't have an IP address, then eth0 gets an IP address via dhcpcd
> and it all starts to work. In the second log, it looks like all the DHCP
> requests happen before the address gets assigned to eth0, so none work.
>
> I don't think this is a specific problem with the RTMU86, it's that your
> configuration is intermittently broken.
>
>
> Simon.
>
>

It's the same configuration.
1. I plug one device - it works.
2. I unplug it and plug the RTMU86 - doesn't work.
3. I Unplug RTMU86 and plug any other device - it works.

Nothing changes in the network, nothing changes in the config.

The same config in isc-dhcp-server works fine in both cases.
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