Virt-Manager network not working

[s4ndm4n]

I can’t get virt-manager to work. I followed the step on the wiki page to install. Also did sudo virsh net-autostart default. But still nothing. When I finish the configuration steps it doesn’t show my network,

and gives the below error.

The error

Unable to complete install: 'Requested operation is not valid: network 'default' is not active'

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 65, in cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/createvm.py", line 2001, in _do_async_install
    installer.start_install(guest, meter=meter)
  File "/usr/share/virt-manager/virtinst/install/installer.py", line 701, in start_install
    domain = self._create_guest(
  File "/usr/share/virt-manager/virtinst/install/installer.py", line 649, in _create_guest
    domain = self.conn.createXML(install_xml or final_xml, 0)
  File "/usr/lib/python3.9/site-packages/libvirt.py", line 4376, in createXML
    raise libvirtError('virDomainCreateXML() failed')
libvirt.libvirtError: Requested operation is not valid: network 'default' is not active

And that’s it, what should I do?

[dalto]

Open up wirt-manager and go to edit->connection details. Then select virtual networks and the select the default network and click the start network button. You will get an error. Let us know what that error is.

[s4ndm4n]

Yep, this.

Error starting network 'default': internal error: Failed to initialize a valid firewall backend

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 65, in cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 101, in tmpcb
    callback(*args, **kwargs)
  File "/usr/share/virt-manager/virtManager/object/libvirtobject.py", line 57, in newfn
    ret = fn(self, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/object/network.py", line 69, in start
    self._backend.create()
  File "/usr/lib/python3.9/site-packages/libvirt.py", line 3446, in create
    raise libvirtError('virNetworkCreate() failed')
libvirt.libvirtError: internal error: Failed to initialize a valid firewall backend

EDIT: I found the below answer in SO.

Installing ebtables and dnsmasq seems to fix the problem. Don’t forget to restart the libvirtd service.

The commands:

sudo pacman -Syu ebtables dnsmasq
sudo systemctl restart libvirtd

Don’t know if it’s correct for this though.

[dalto]

Make sure you have the packages dnsmasq and either iptables-nft or ebtables installed. In most cases, iptables-nft is what you want.

[s4ndm4n]

Working … Isn’t iptables-nft and dnsmasq needed part for the main virt-manager installe? is it situational?

[dalto]

@s4ndm4n

is it situational?

It is needed if you want a network in your VM but since that isn’t a hard requirement they are optional dependencies.

[s4ndm4n]

Ah ok. It would be grate if this would get mentioned in the WiKi. If this error happens install these and do this.