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<p>Razvan,</p>
<p>I tried adding interface "br0" to both my subnets a few days ago,
there was no measurable change so I removed the lines again.</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 21/2/26 20:48, Razvan Becheriu
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:821831355.221412.1771670888014.JavaMail.zimbra@isc.org">
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<div>can you add “interface”: “br0” to each of your subnets?</div>
<div
style="font-size: 12pt; font-family: arial, helvetica, sans-serif; color: #000000;"
data-attr="forced_root_block_attrs"> </div>
<div
style="font-size: 12pt; font-family: arial, helvetica, sans-serif; color: #000000;"
data-attr="forced_root_block_attrs">set logging to DEBUG and
level 99</div>
<div
style="font-size: 12pt; font-family: arial, helvetica, sans-serif; color: #000000;"
data-attr="forced_root_block_attrs"> </div>
<div
style="font-size: 12pt; font-family: arial, helvetica, sans-serif; color: #000000;"
data-attr="forced_root_block_attrs">you can overwrite logging
temporarily by passing <span
style="font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: pre-wrap; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; caret-color: #e3e4e8; color: #e3e4e8; font-family: 'Open Sans', sans-serif; font-size: 14px; text-align: left; -webkit-tap-highlight-color: rgba(0, 0, 0, 0); -webkit-text-size-adjust: 100%; background-color: #191b1f; float: none; display: inline !important;">KEA_LOGGER_SEVERITY="DEBUG" KEA_LOGGER_DBGLEVEL=99 KEA_LOGGER_DESTINATION="stdout"</span></div>
<div> before ./kea-dhcp4 -c …</div>
<div>
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<blockquote
style="margin: 0 0 0 .8em; border-left: 1px #ccc solid; padding-left: 1em;">
<hr id="MESSAGE_DATA_MARKER"><strong>From: </strong>Stuart
<a class="moz-txt-link-rfc2396E" href="mailto:sleepygriogar@gmail.com"><sleepygriogar@gmail.com></a><br>
<strong>To: </strong>Kea <a class="moz-txt-link-rfc2396E" href="mailto:kea-users@lists.isc.org"><kea-users@lists.isc.org></a>;
Razvan <a class="moz-txt-link-rfc2396E" href="mailto:razvan@isc.org"><razvan@isc.org></a><br>
<strong>Date: </strong>Saturday, 21 February 2026 12:35
PM EET<br>
<strong>Subject: </strong>Re: [Kea-users] Kea DHCP4 not
working on newly configured bridged network<br>
<br>
<p>Razvan,</p>
<p>The secondary kea server is on a completely seperate
computer. My home network infrastructure consists of on
decent (ish) server and several, old, second hand
computers I bought cheap. One of these runs the
secondary server. It binds to the standard ethernet port
of that machine and then services the network via the
router. As I said the main server is connected to the
router through br0. It connects to the internet and to
other computers on the network (e.g. it shares files via
samba). It even contacts the secondary dhcp server to
ask it to turn off when I restart kea-dhcp4-server. It
then just doesn't offer leases. The VMs connect to the
router via the Bridged Network and then receive dhcp
DORA from the secondary server via the router, so long
as the main server is off and failover is complete.</p>
<p>There are no files at all in /var/log/kea. There is
also no fles called kea-dhcp4.log in /var/log, where the
config file indicates it should be. I think my logging
parameters are screwed up, perhaps I need to change the
debug level or severity, perhaps there is a stupid typo.</p>
<p>Regards</p>
<p>Stuart MacGregor</p>
<div class="moz-cite-prefix">On 21/2/26 20:10, Razvan
Becheriu wrote:</div>
<blockquote>
<div
style="font-size: 12pt; font-family: 'arial' , 'helvetica' , sans-serif; color: #000000;">
<div>Hi,</div>
<div
style="font-size: 12pt; font-family: 'arial' , 'helvetica' , sans-serif; color: #000000;"> </div>
<div
style="font-size: 12pt; font-family: 'arial' , 'helvetica' , sans-serif; color: #000000;">How
is it that the vms acquire ip using secondary
server? does the secondary bind on the same
interface at the same time?</div>
<div
style="font-size: 12pt; font-family: 'arial' , 'helvetica' , sans-serif; color: #000000;"> </div>
<div
style="font-size: 12pt; font-family: 'arial' , 'helvetica' , sans-serif; color: #000000;">Logs
should be under /kea/install/path/var/log/kea</div>
<div
style="font-size: 12pt; font-family: 'arial' , 'helvetica' , sans-serif; color: #000000;"> </div>
<div
style="font-size: 12pt; font-family: 'arial' , 'helvetica' , sans-serif; color: #000000;">I
think that only one of your servers successfully
binds to the interface and because the server uses
reuse port/address the secondary if starts second
will receive traffic.</div>
<div
style="font-size: 12pt; font-family: 'arial' , 'helvetica' , sans-serif; color: #000000;"> </div>
<div
style="font-size: 12pt; font-family: 'arial' , 'helvetica' , sans-serif; color: #000000;"> </div>
<div> </div>
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<blockquote
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<hr id="MESSAGE_DATA_MARKER"><strong>From: </strong>Stuart
<a href="mailto:sleepygriogar@gmail.com"
target="_blank" rel="noopener noreferrer"
moz-do-not-send="true"><sleepygriogar@gmail.com></a><br>
<strong>To: </strong>kea-users <a
href="mailto:kea-users@lists.isc.org"
target="_blank" rel="noopener noreferrer"
moz-do-not-send="true"><kea-users@lists.isc.org></a><br>
<strong>Date: </strong>Saturday, 21 February
2026 3:31 AM EET<br>
<strong>Subject: </strong>[Kea-users] Kea
DHCP4 not working on newly configured bridged
network<br>
<br>
<p>Good Morning,</p>
<p>I am running Ubuntu 24.04, Kea 2.4.1. I
have been using Kea without major issues for
a year or two, isc-dhcp for a couple of
years prior. During recent kernel updates I
decided I was sick of Virtualbox
compatibility issues, so I created a bridged
network so that I could move my vms
(Nextcloud, Stork) to KVM. I am somewhat
incompetent, but after about 100 attempts I
have managed to setup a bridged network that
connects my server to the rest of the
network and to the internet. My new KVM VMs
are joining the network as if they were real
devices. My problem is my kea DHCP4 server.
I guess have done something stupid, either
with selecting the interface in
kea-dhcp4.conf or with configuring my
bridged network (br0). At this stage, when
I start kea-dhcp4-server, it communicates to
my HA standby to to take control of DHCP but
then completely fails to provide ip
addresses itself. So, the network currently
looks like this:</p>
<p><i>dad@<a class="moz-txt-link-freetext" href="macserver:~$">macserver:~$</a> ip a<br>
1: lo: <LOOPBACK,UP,LOWER_UP> mtu
65536 qdisc noqueue state UNKNOWN group
default qlen 1000<br>
link/loopback 00:00:00:00:00:00 brd
00:00:00:00:00:00<br>
inet 127.0.0.1/8 scope host lo<br>
valid_lft forever preferred_lft
forever<br>
inet6 ::1/128 scope host
noprefixroute <br>
valid_lft forever preferred_lft
forever<br>
2: enp34s0:
<BROADCAST,MULTICAST,UP,LOWER_UP>
mtu 1500 qdisc fq_codel master br0 state
UP group default qlen 1000<br>
link/ether 2c:<a class="moz-txt-link-freetext" href="f0:5d:2d:88:35">f0:5d:2d:88:35</a> brd
<a class="moz-txt-link-freetext" href="ff:ff:ff:ff:ff:ff">ff:ff:ff:ff:ff:ff</a><br>
3: br0:
<BROADCAST,MULTICAST,UP,LOWER_UP>
mtu 1500 qdisc noqueue state UP group
default qlen 1000<br>
link/ether 42:4c:23:6c:4d:7f brd
<a class="moz-txt-link-freetext" href="ff:ff:ff:ff:ff:ff">ff:ff:ff:ff:ff:ff</a><br>
inet 192.168.1.104/23 brd
192.168.1.255 scope global noprefixroute
br0<br>
valid_lft forever preferred_lft
forever<br>
inet6 <a class="moz-txt-link-freetext" href="fe80::e54c:73f4:f662:95fb/64">fe80::e54c:73f4:f662:95fb/64</a>
scope link noprefixroute <br>
valid_lft forever preferred_lft
forever<br>
4: virbr0:
<NO-CARRIER,BROADCAST,MULTICAST,UP>
mtu 1500 qdisc noqueue state DOWN group
default qlen 1000<br>
link/ether 52:54:00:5b:<a class="moz-txt-link-freetext" href="e6:4e">e6:4e</a> brd
<a class="moz-txt-link-freetext" href="ff:ff:ff:ff:ff:ff">ff:ff:ff:ff:ff:ff</a><br>
inet 192.168.100.1/24 brd
192.168.100.255 scope global virbr0<br>
valid_lft forever preferred_lft
forever<br>
5: vnet0:
<BROADCAST,MULTICAST,UP,LOWER_UP>
mtu 1500 qdisc noqueue master br0 state
UNKNOWN group default qlen 1000<br>
link/ether <a class="moz-txt-link-freetext" href="fe:00:27:dc:06:7e">fe:00:27:dc:06:7e</a> brd
<a class="moz-txt-link-freetext" href="ff:ff:ff:ff:ff:ff">ff:ff:ff:ff:ff:ff</a><br>
inet6 <a class="moz-txt-link-freetext" href="fe80::fc00:27ff:fedc:67e/64">fe80::fc00:27ff:fedc:67e/64</a>
scope link <br>
valid_lft forever preferred_lft
forever<br>
6: vnet1:
<BROADCAST,MULTICAST,UP,LOWER_UP>
mtu 1500 qdisc noqueue master br0 state
UNKNOWN group default qlen 1000<br>
link/ether <a class="moz-txt-link-freetext" href="fe:54:00:80:eb:73">fe:54:00:80:eb:73</a> brd
<a class="moz-txt-link-freetext" href="ff:ff:ff:ff:ff:ff">ff:ff:ff:ff:ff:ff</a><br>
inet6 <a class="moz-txt-link-freetext" href="fe80::fc54:ff:fe80:eb73/64">fe80::fc54:ff:fe80:eb73/64</a> scope
link <br>
valid_lft forever preferred_lft
forever</i></p>
<p>The key sections (eliminating all my lease
reservations and such) of my dhcp4.conf look
like this:</p>
<p><i>{<br>
"Dhcp4": {<br>
"interfaces-config": {<br>
"interfaces": [ "br0" ]<br>
},<br>
"control-socket": {<br>
"socket-type": "unix",<br>
"socket-name":
"/run/kea/kea4-ctrl-socket"<br>
},<br>
"lease-database": {<br>
"type": "memfile",<br>
"lfc-interval": 3600<br>
},<br>
"multi-threading": {<br>
"enable-multi-threading": true,<br>
"thread-pool-size": 2,<br>
"packet-queue-size": 14<br>
},<br>
"client-classes": [<br>
{<br>
"name": "homeauto"<br>
},<br>
{<br>
"name": "normal",<br>
"test": "not member('homeauto')"<br>
}<br>
],<br>
"option-data": [<br>
{<br>
"space": "dhcp4",<br>
"name": "domain-name",<br>
"code": 15,<br>
"data": "skfaf.servesarcasm.com"<br>
},<br>
{<br>
"space": "dhcp4",<br>
"name": "domain-name-servers",<br>
"code": 6,<br>
"data": "192.168.1.1"<br>
},<br>
{<br>
"space": "dhcp4",<br>
"name": "broadcast-address",<br>
"code": 28,<br>
"data": "192.168.1.255"<br>
},<br>
{<br>
"space": "dhcp4",<br>
"name": "routers",<br>
"code": 3,<br>
"data": "192.168.1.1"<br>
},<br>
{<br>
"space": "dhcp4",<br>
"name": "subnet-mask",<br>
"code": 1,<br>
"data": "255.255.254.0"<br>
}<br>
],<br>
"valid-lifetime": 43200,<br>
"renew-timer": 21600,<br>
"rebind-timer": 32400,<br>
"expired-leases-processing": {<br>
"reclaim-timer-wait-time": 3600,<br>
"hold-reclaimed-time": 172800,<br>
"max-reclaim-leases": 0,<br>
"max-reclaim-time": 0<br>
}, <br>
"dhcp-ddns": {<br>
"enable-updates": false<br>
},<br>
"authoritative": true,<br>
"hooks-libraries": [<br>
{<br>
"library":
"/usr/lib/x86_64-linux-gnu/kea/hooks/libdhcp_lease_cmds.so"<br>
},<br>
{<br>
"library":
"/usr/lib/x86_64-linux-gnu/kea/hooks/libdhcp_stat_cmds.so"<br>
},<br>
{<br>
"library":
"/usr/lib/x86_64-linux-gnu/kea/hooks/libdhcp_ha.so",<br>
"parameters": {<br>
"high-availability": [ {<br>
"this-server-name":
"macserver",<br>
"mode": "hot-standby",<br>
"heatbeat-delay": 10000,<br>
"max-response-delay": 60000,<br>
"max-ack-delay": 5000,<br>
"max-unacked-clients": 5,<br>
"sync-timeout": 60000,<br>
"multi-threading": {<br>
"enable-multi-threading": true,<br>
"http-dedicated-listener": true,<br>
"http-listener-threads":
0,<br>
"http-client-threads": 0<br>
},<br>
"peers": [<br>
{<br>
"name": "macserver",<br>
"url": <a
href="http://192.168.1.104:8003/"
target="_blank"
rel="noopener noreferrer"
moz-do-not-send="true">"http://192.168.1.104:8003/"</a>,<br>
"role": "primary"<br>
},<br>
{ <br>
"name": "oldhp",<br>
"url": <a
href="http://192.168.1.110:8003/"
target="_blank"
rel="noopener noreferrer"
moz-do-not-send="true">"http://192.168.1.110:8003/"</a>,<br>
"role": "standby"<br>
}<br>
]<br>
} ]<br>
}<br>
}</i></p>
<p><i> </i></p>
<p><i>],<br>
"shared-networks": [<br>
{<br>
"name": "macnet",<br>
"subnet4": [<br>
{<br>
"id": 1,<br>
"subnet": "192.168.1.0/24",<br>
"pools": [<br>
{<br>
"pool": "192.168.1.124 -
192.168.1.198",<br>
"client-class": "normal"<br>
}<br>
],<br>
"option-data": [<br>
{<br>
"space": "dhcp4",<br>
"name": "routers",<br>
"code": 3,<br>
"data": "192.168.1.1"<br>
}<br>
]<br>
},<br>
{<br>
"id": 2,<br>
"subnet": "192.168.0.0/23",<br>
"pools": [<br>
{<br>
"pool": "192.168.0.150 -
192.168.0.175",<br>
"client-class": "homeauto"<br>
}<br>
],<br>
"option-data": [<br>
{<br>
"space": "dhcp4",<br>
"name": "routers",<br>
"code": 3,<br>
"data": "192.168.1.1"<br>
},<br>
{<br>
"space": "dhcp4",<br>
"name":
"domain-name-servers",<br>
"code": 6,<br>
"data": "192.168.1.1"<br>
}<br>
]<br>
}<br>
]<br>
}<br>
],<br>
"loggers": [<br>
{<br>
"name": "kea-dhcp4",<br>
"output_options": [<br>
{<br>
"output":
"/var/log/kea-dhcp4.log",<br>
"maxsize": 2048000,<br>
"maxver": 4<br>
}<br>
],<br>
"severity": "INFO",<br>
"debuglevel": 0<br>
}<br>
]<br>
}<br>
}</i></p>
<p> </p>
<p>I changed my "interface" to "br0" because
my previous setup (exerp below) stopped
working when I started the br0 network. </p>
<p> <i>{<br>
"Dhcp4": {<br>
"interfaces-config": {<br>
"interfaces": [ "enp34s0" ]</i></p>
<p>Changing the interface to "br0" has had
exactly no effect.</p>
<p>I realise that I have missed something
fundamental and I am wasting your valuable
time. However I have been trying to sort
this out for days (in whatever spare time is
available) and I have acheived nothing. Each
time I start kea-dhcp-server on my main
server it appears in Stork with no errors,
systemd says its running fine and my HA
standby stops providing dhcp. Unfortunately
if I then turn on a device it simply does
not receive an ip lease. If I turn off DHCP
on the main server then eventually the
standby starts takes over dhcp again and
network functions return to normal (though
this takes a very long time & sometimes
requires a restart of kea-dhcp4-server on
the stanby server, perhaps another error to
fix later). Even my new VMs receive ips
seamlessly from the standby server.</p>
<p>If you need to see some logs, please tell
me where I can retreive them because I
haven't been able to work that out either (I
think I need to change my logging parameters
in kea-dhcp4.conf). I used Wireshark to
capture network coms before and after
turning on the main dhcp server but I then
realised that I was too stupid/ignorant to
work out what was going on from the output.
I can provided the Wireshark output, but it
is a large file (ran it for too long and
filtered it poorly, I think) that I won't
inflict on you unless you wish it.</p>
<p>Please give me some ideas of what I have to
do to troubleshoot/fix this.</p>
<p>Regards</p>
<p>Stuart MacGregor</p>
<p> </p>
<p> </p>
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