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#26 2022-01-28 21:50:13

Toolybird
Member
Registered: 2017-09-30
Posts: 72

Re: Libvirt, dnsmasq, QUEMU/KVM : default network dhcp not working

> The status looks like this:

Hmm,  looks basically fine. In my case I'm using systemd-networkd and systemd-resolved so my output is slightly different. It would be interesting to see a few other logs for comparison. Here's my "journalctl -b -u libvirtd" output immediately after boot:

Jan 29 06:55:03 ryzen systemd[1]: Starting Virtualization daemon...
Jan 29 06:55:03 ryzen systemd[1]: Started Virtualization daemon.
Jan 29 06:55:04 ryzen dnsmasq[1259]: started, version 2.86 cachesize 150
Jan 29 06:55:04 ryzen dnsmasq[1259]: compile time options: IPv6 GNU-getopt DBus no-UBus i18n IDN2 DHCP DHCPv6 no-Lua TFTP conntrack ipset auth cr>
Jan 29 06:55:04 ryzen dnsmasq-dhcp[1259]: DHCP, IP range 192.168.122.2 -- 192.168.122.254, lease time 1h
Jan 29 06:55:04 ryzen dnsmasq-dhcp[1259]: DHCP, sockets bound exclusively to interface virbr0
Jan 29 06:55:04 ryzen dnsmasq[1259]: reading /etc/resolv.conf
Jan 29 06:55:04 ryzen dnsmasq[1259]: using nameserver 127.0.0.53#53
Jan 29 06:55:04 ryzen dnsmasq[1259]: read /etc/hosts - 3 addresses
Jan 29 06:55:04 ryzen dnsmasq[1259]: read /var/lib/libvirt/dnsmasq/default.addnhosts - 0 addresses
Jan 29 06:55:04 ryzen dnsmasq-dhcp[1259]: read /var/lib/libvirt/dnsmasq/default.hostsfile
Jan 29 06:57:03 ryzen systemd[1]: libvirtd.service: Deactivated successfully.
Jan 29 06:57:03 ryzen systemd[1]: libvirtd.service: Unit process 1259 (dnsmasq) remains running after unit stopped.
Jan 29 06:57:03 ryzen systemd[1]: libvirtd.service: Unit process 1260 (dnsmasq) remains running after unit stopped.

Here's the same but after booting a VM:

Jan 29 07:41:09 ryzen systemd[1]: libvirtd.service: Found left-over process 1259 (dnsmasq) in control group while starting unit. Ignoring.
Jan 29 07:41:09 ryzen systemd[1]: This usually indicates unclean termination of a previous run, or service implementation deficiencies.
Jan 29 07:41:09 ryzen systemd[1]: libvirtd.service: Found left-over process 1260 (dnsmasq) in control group while starting unit. Ignoring.
Jan 29 07:41:09 ryzen systemd[1]: This usually indicates unclean termination of a previous run, or service implementation deficiencies.
Jan 29 07:41:09 ryzen systemd[1]: Starting Virtualization daemon...
Jan 29 07:41:09 ryzen systemd[1]: Started Virtualization daemon.
Jan 29 07:41:09 ryzen dnsmasq[1259]: read /etc/hosts - 3 addresses
Jan 29 07:41:09 ryzen dnsmasq[1259]: read /var/lib/libvirt/dnsmasq/default.addnhosts - 0 addresses
Jan 29 07:41:09 ryzen dnsmasq-dhcp[1259]: read /var/lib/libvirt/dnsmasq/default.hostsfile
Jan 29 07:43:23 ryzen dnsmasq-dhcp[1259]: DHCPDISCOVER(virbr0) 52:54:00:22:e2:25
Jan 29 07:43:23 ryzen dnsmasq-dhcp[1259]: DHCPOFFER(virbr0) 192.168.122.87 52:54:00:22:e2:25
Jan 29 07:43:23 ryzen dnsmasq-dhcp[1259]: DHCPREQUEST(virbr0) 192.168.122.87 52:54:00:22:e2:25
Jan 29 07:43:23 ryzen dnsmasq-dhcp[1259]: DHCPACK(virbr0) 192.168.122.87 52:54:00:22:e2:25 archiso
Jan 29 07:46:27 ryzen systemd[1]: libvirtd.service: Deactivated successfully.
Jan 29 07:46:27 ryzen systemd[1]: libvirtd.service: Unit process 1259 (dnsmasq) remains running after unit stopped.
Jan 29 07:46:27 ryzen systemd[1]: libvirtd.service: Unit process 1260 (dnsmasq) remains running after unit stopped.
Jan 29 07:46:27 ryzen systemd[1]: libvirtd.service: Consumed 1.157s CPU time.

Here's "journalctl -b -g virbr0"

Jan 29 06:55:04 ryzen systemd-networkd[835]: virbr0: Link UP
Jan 29 06:55:04 ryzen dnsmasq-dhcp[1259]: DHCP, sockets bound exclusively to interface virbr0
Jan 29 07:42:23 ryzen kernel: virbr0: port 1(vnet0) entered blocking state
Jan 29 07:42:23 ryzen kernel: virbr0: port 1(vnet0) entered disabled state
Jan 29 07:42:23 ryzen kernel: virbr0: port 1(vnet0) entered blocking state
Jan 29 07:42:23 ryzen kernel: virbr0: port 1(vnet0) entered listening state
Jan 29 07:42:25 ryzen kernel: virbr0: port 1(vnet0) entered learning state
Jan 29 07:42:27 ryzen kernel: virbr0: port 1(vnet0) entered forwarding state
Jan 29 07:42:27 ryzen kernel: virbr0: topology change detected, propagating
Jan 29 07:42:27 ryzen systemd-networkd[835]: virbr0: Gained carrier
Jan 29 07:43:23 ryzen dnsmasq-dhcp[1259]: DHCPDISCOVER(virbr0) 52:54:00:22:e2:25
Jan 29 07:43:23 ryzen dnsmasq-dhcp[1259]: DHCPOFFER(virbr0) 192.168.122.87 52:54:00:22:e2:25
Jan 29 07:43:23 ryzen dnsmasq-dhcp[1259]: DHCPREQUEST(virbr0) 192.168.122.87 52:54:00:22:e2:25
Jan 29 07:43:23 ryzen dnsmasq-dhcp[1259]: DHCPACK(virbr0) 192.168.122.87 52:54:00:22:e2:25 archiso
Jan 29 07:44:11 ryzen kernel: virbr0: port 1(vnet0) entered disabled state
Jan 29 07:44:11 ryzen kernel: virbr0: port 1(vnet0) entered disabled state
Jan 29 07:44:11 ryzen systemd-networkd[835]: virbr0: Lost carrier

Here's "iptables -nL"

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
LIBVIRT_INP  all  --  0.0.0.0/0            0.0.0.0/0           

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         
LIBVIRT_FWX  all  --  0.0.0.0/0            0.0.0.0/0           
LIBVIRT_FWI  all  --  0.0.0.0/0            0.0.0.0/0           
LIBVIRT_FWO  all  --  0.0.0.0/0            0.0.0.0/0           

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
LIBVIRT_OUT  all  --  0.0.0.0/0            0.0.0.0/0           

Chain LIBVIRT_FWI (1 references)
target     prot opt source               destination         
ACCEPT     all  --  0.0.0.0/0            192.168.122.0/24     ctstate RELATED,ESTABLISHED
REJECT     all  --  0.0.0.0/0            0.0.0.0/0            reject-with icmp-port-unreachable

Chain LIBVIRT_FWO (1 references)
target     prot opt source               destination         
ACCEPT     all  --  192.168.122.0/24     0.0.0.0/0           
REJECT     all  --  0.0.0.0/0            0.0.0.0/0            reject-with icmp-port-unreachable

Chain LIBVIRT_FWX (1 references)
target     prot opt source               destination         
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0

Chain LIBVIRT_INP (1 references)
target     prot opt source               destination         
ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0            udp dpt:53
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            tcp dpt:53
ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0            udp dpt:67
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            tcp dpt:67

Chain LIBVIRT_OUT (1 references)
target     prot opt source               destination         
ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0            udp dpt:53
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            tcp dpt:53
ACCEPT     udp  --  0.0.0.0/0            0.0.0.0/0            udp dpt:68
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0            tcp dpt:68

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#27 2022-01-29 01:32:09

Toolybird
Member
Registered: 2017-09-30
Posts: 72

Re: Libvirt, dnsmasq, QUEMU/KVM : default network dhcp not working

Just found another report on reddit:

https://www.reddit.com/r/archlinux/comm … t_problem/

It seems there is a definite problem somewhere...

I can only assume some recent pkg updates in combination with certain conditions (new setups?) have introduced the problem.

Total speculation, but my top suspects would be systemd and/or networkmanager.

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#28 2022-01-29 04:15:17

Arrowhead
Member
Registered: 2021-11-27
Posts: 7

Re: Libvirt, dnsmasq, QUEMU/KVM : default network dhcp not working

That's interesting!

I have similar logs, but the DHCP part is completely missing:

Jan 29 06:56:04 astoria systemd[1]: Started Virtualization daemon.
Jan 29 06:56:04 astoria libvirtd[5193]: 2022-01-29 03:56:04.812+0000: 5193: info : libvirt version: 8.0.0
Jan 29 06:56:04 astoria libvirtd[5193]: 2022-01-29 03:56:04.812+0000: 5193: info : hostname: astoria
Jan 29 06:56:04 astoria libvirtd[5193]: 2022-01-29 03:56:04.812+0000: 5193: debug : virLogParseOutputs:1635 : outputs=3:file:/var/log/libvirt/libvirtd.log
Jan 29 06:56:04 astoria libvirtd[5193]: 2022-01-29 03:56:04.812+0000: 5193: debug : virLogParseOutput:1482 : output=3:file:/var/log/libvirt/libvirtd.log
Jan 29 06:56:04 astoria dnsmasq[1344]: read /etc/hosts - 9 addresses
Jan 29 06:56:04 astoria dnsmasq[1344]: read /var/lib/libvirt/dnsmasq/default.addnhosts - 0 addresses
Jan 29 06:56:04 astoria dnsmasq-dhcp[1344]: read /var/lib/libvirt/dnsmasq/default.hostsfile

It never gets to `DHCPDISCOVER`, `DHCPOFFER` etc, so I don't see these records. The output from `iptables -nL` is identical.

I'll try replacing my version of NetworkManager with something else.

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#29 2022-01-29 06:06:45

Arrowhead
Member
Registered: 2021-11-27
Posts: 7

Re: Libvirt, dnsmasq, QUEMU/KVM : default network dhcp not working

OK, it's working now!

Toolybird wrote:

Total speculation, but my top suspects would be systemd and/or networkmanager.

You were exactly right.

My problem was that I had both `NetworkManager` and `systemd-networkd` enabled and running at the same time. How this happened I have no idea, but I blame the GUI installer. Once I disabled `systemd-networkd`, the problem disappeared.

Thanks!

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#30 2022-02-09 14:23:08

wildbb
Member
Registered: 2022-01-27
Posts: 5

Re: Libvirt, dnsmasq, QUEMU/KVM : default network dhcp not working

For those who choose systemd-networkd (I have several setup files in /etc/systemd/network/ to rename interfaces and all so I had a kind of incentive on my side).

First thanks @Lone_Wolf, you lead me to the solution on my side (about primarily looking at the bridge setup). I also found this link which helped me understand some other points: Custom routed network

I didn't strictly applied the setup given in the link but from it I understand that starting the virtual network with virsh trigger systemd to start another instance of dnsmasq which is incompatible by default to the dnsmasq setup for my host as a router. So the solution on my side is:

  • manually setup a bridge

  • abandoned the idea of starting a virtual network with virsh

  • adapt the iptable/nftable to add bridge to interfaces on which you forward to internet

  • make bridge interface another interface listen by dnsmasq for dhcp and dns services

  • choose the newly created bridge with network bridge option in virt-manager for each image instead of virtual network 'default' option

From this moment everything worked fine be it a Windows or Linux image.

Hope it can help, if not sorry for the spam.

PS: part of the solution I found is based on my lack of understanding on how to setup correctly two dnsmasq instances (among other things I must admit). There might certainly be a simpler solution with systemd-networkd.

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