Often after an fresh OS Install in an Gnome Virtual Box the network stops or is restricted to the local machine for no obvious reason.
virsh -c qemu:///session list --all
lists all the actual installed machines
virsh edit machinename
edits the settings of the virtual gnome boxes machine
Inn the settings we are looking for something like this
<interface type='user'>
<mac address='52:54:00:bf:c5:97'/>
<model type='rtl8139'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>
and replace it with the following
<interface type='bridge'>
<mac address='00:16:3e:1a:b3:4a'/>
<source bridge='virbr0'/>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>
if it doesn't work after a restart.
we have to edit additionally the following file /etc/qemu/bridge.conf
that it contains the following line
allow virbr0