What is purpose of virbr0 interface

Issues related to configuring your network
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kriticar
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What is purpose of virbr0 interface

Post by kriticar » 2017/03/06 19:43:41

I have installed centos 7, server with gui option. I don't remember that I turned on any kind of virtualisation.
Latter, I have noticed that virbr0 interface has showed.
What is the purpose of virbr0 interface, do I need it, and if not, how can I disable it?

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avij
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Re: What is purpose of virbr0 interface

Post by avij » 2017/03/06 19:58:24

That is indeed related to virtualization. I'm not sure about this, but my best guess for disabling virbr0 is to run systemctl stop libvirtd.service, which will stop the virtualization service. If this helped, systemctl disable libvirtd.service will disable the service permanently.

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TrevorH
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Re: What is purpose of virbr0 interface

Post by TrevorH » 2017/03/06 20:57:18

The default desktop install includes gnome-boxes (possibly just 'boxes') which is a form of virt that uses libvirt. Uninstalling it should fix it too.
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kriticar
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Re: What is purpose of virbr0 interface

Post by kriticar » 2017/03/06 23:49:26

If I execute

systemctl disable libvirtd.service

will I be able latter to enable the service with

systemctl disable libvirtd.service

in case I need it?

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avij
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Re: What is purpose of virbr0 interface

Post by avij » 2017/03/07 08:10:04

I suppose you meant systemctl enable libvirtd.service, but yeah, that will re-enable the service the next time you reboot. To start the service without rebooting, you can use systemctl start libvirtd.service, but that won't be a permanent change.

kriticar
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Re: What is purpose of virbr0 interface

Post by kriticar » 2017/03/07 08:33:46

Thank you very very much.

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jlehtone
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Re: What is purpose of virbr0 interface

Post by jlehtone » 2017/03/07 09:52:58

TrevorH wrote:The default desktop install includes gnome-boxes (possibly just 'boxes') which is a form of virt that uses libvirt. Uninstalling it should fix it too.
Ahh, gnome-boxes requires libvirt.

Libvirt, if installed, has libvirtd.service enabled by default.
Libvirt has a network definition "default" preconfigured and set to autostart.
The "virbr0" is a bridge interface that represents a network (a bridge is essentially a network switch).

Therefore, by installing libvirt (for any reason) by default dynamically creates the "virbr0" on every boot (and adds some netfilter rules too).

One can disable the autostart of the default network.
One can remove the definition of the default network.
One can stop and disable the libvirtd.service.
One can uninstall the libvirt packages.

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Re: What is purpose of virbr0 interface

Post by MartinR » 2017/03/07 10:25:38

This may be of interest. It is meant to be conceptual rather than a detailed analysis.
Virbr-NAT.gif
Virbr-NAT.gif (12.15 KiB) Viewed 37917 times

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