On Wed, 7 May 2025, at 13:15, Nick Owens wrote:
> On Wed, May 7, 2025 at 2:30 AM Thomas <exnih...@fastmail.org> wrote:
>
>> Hello everyone,
>>
>> For some reasons dhcpleased has stopped functioning yesterday, without any
>> changes on my setup. The error message is: "wrong
>> DHO_DHCP_CLIENT_IDENTIFIER", more details below.
>>
>
> the dhcp client identifier is sent by dhcpleased, and seems to expect the
> server to send it back. the message indicates it didn't match. perhaps if
> you run "tcpdump -s 1024 -n -tt -vv -e -i bse0 udp port 68" or so, you can
> look at the "CID" field in the DHCP request and response frames and see
> what the server sent you back.
>
Thanks for this, I had tried tcpdump before but did not know what to look for.
See below:
$MAC_OBSD ff:ff:ff:ff:ff:ff 0800 342: 0.0.0.0.68 > 255.255.255.255.67: [udp sum
ok] xid:0xb648d41a vend-rfc1048 DHCP:DISCOVER HN:"hostname" CID:1.$MAC_OBSD
PR:SM+DG+NS+HN+DN+BR+119+121 [tos 0x10] (ttl 128, id 0, len 328)
$MAC_ROUTER $MAC_OBSD 0800 393: 192.168.0.254.67 > 192.168.0.22.68: [udp sum
ok] xid:0xb648d41a Y:192.168.0.22 S:192.168.0.254 vend-rfc1048 DHCP:OFFER
SID:192.168.0.254 LT:86400 RN:43200 RB:75600 CID:1.81.128.58.4.0.0
SM:255.255.255.0 NS:192.168.0.254 DN:"home" BR:192.168.0.255 DG:192.168.0.254
T125:0,3561,9476,1591,17218,14131,13061,4146,11831,18225,14133,12614,12343,12343
,12601,13062,2387,18226,11598,20525,12336 (ttl 64, id 0, len 379)
Looking at this, CID in the response is indeed different. I tried to set up
manually the CID send client id in /etc/dhcpleased which worked when later
using dhcpleased -vvd
interface bse0 {
ignore dns
send client id "01:51:80:3A:04:00:00" # this is 1.81.128.58.4.0.0
}
So I have 2 possible solutions, setting up the address and default route in
/etc/hostname.bse0 or sending the client id that the router keeps sending back
as above. This makes for some odd results on the router side though as it then
attributes a MAC of 51:80:3A:04:00:00 to my Raspberry and shows another device
with the normal MAC behind that device or some sort of weird wifi bridge.
I have no idea where 1.81.128.58.4.0.0 / 51:80:3A:04:00:00 (also not sure what
the prefix 51:80:3A is). I also no idea why this seem to have changed very
recently apart from an update of the router from the ISP or that being somehow
linked to the upgrade to 7.7 or both or neither...
Rebooting the router gets dhcpleased to work without "hack" the first time
around (acquiring an IP address with ifconfig bse0 up autoconf; dhcpleased
-vvd). Later killing it and running dhcpleased -vvd again shows the same issue
with the identifier.
So although I do have a functional setup back and understand where the issue
is, I'm still at a loss as to why this started to be buggy and why this happens.
Thomas
