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The answer above : brctl delbr virbr0 or ifconfig virbr0 down do the job temporarily; cause they act on kernel space. If you want to disable it for each reboot, you must search the exact reason. Mee too I have it, and I have choosen to keep it, as long as my other virtual networks in VirtualBox, do not require the same subnet address than virbr0

In Fedora, once you have installed KVM, or maybe an other open source Virtualization software probably libvirt service is running; this service configure a default bridge virbr0, providing : a bridge, connected to a virtual router providing , a dhcp service, and routing+NAT from this bridge to your main interface. So any virtual machine connected to this bridge has direct access to internet, if its interface is in dhcp mode.

VMware, VirtualBox have their own feature: bridge+DHCP+routing+NAT. +++ Which application could use my virbr0 ? check something like:

# find /etc | xargs fgrep virbr0 2> /dev/null

/etc/libvirt/qemu/networks/default.xml: <bridge name="virbr0"/>

/etc/libvirt/qemu/networks/autostart/default.xml: <bridge name="virbr0"/>

/etc/qemu/bridge.conf:allow virbr0

OK qemu could use virbr0, if KVM is available. But only VirtualBox or exclusive KVM can use accelerated hardware required by 64bits VM guest! I using mainly VirtualBox ==> virbr0 will not be used !

+++ ANYWAY for your own reason, now that your are sure that the current hypervisor you are using do not need virbr0, remove it definitively if you want:

check

# systemctl status libvirtd * libvirtd.service - Virtualization daemon Loaded: loaded (/usr/lib/systemd/system/libvirtd.service; enabled; vendor preset: enabled) Active: active (running) since Sun 2016-11-27 10:56:49 CET; 4h 55min ago ... etc ...

==> stop it and disable it

# systemctl stop libvirtd

# systemctl disable libvirtd

The virbr0 will not be destroyed by this action, nor the dnsmasq process will stop now. But when you reboot the system, you will not see them! If you want to remove it immediately , do it as suggested above with brctl