Hi Daniel, thx for the fast answer. > QEMU is responsible for passing arguments to the interface scripts, > so its out of libvirt's control. QEMU passes a single paramter to > the script, which is the name of the TAP device interface being > added. If you don't give a <target dev='tap3'> libvirt generates > a TAP device name vnetXXXX. If I do not specify the <target>-element inside of <interface>, your docu told me "The guest will have a tun device created with a name of vnetN, which can also be overridden with the <target> element." (http://www.libvirt.org/formatdomain.html#elementsNICS) I understood this in the following way: I can remove the target-element and I will get automatically a target name "vnet<N>" - if I do this, I will get an interfacename "(null") : 5459 ? Sl 0:01 /usr/bin/kvm -S -M pc -m 500 -smp 1 -name solidcam -uuid 60a8db24-86a5-f9fc-16ee-b60b32411dd8 -monitor pty -boot c -drive file=/srv/winxp127-xxx.dsk,if=ide,index=0,boot=on -net nic,macaddr=52:54:00:46:58:41,vlan=0 -net tap,ifname=(null),script=/etc/kvm/qemu-ifup,vlan=0 -serial pty -parallel none -usb -usbdevice tablet -vnc 0.0.0.0:0 So, this means libvirt is NOT responsible for the naming auf the target. Maybe you have to clarify this in the docu. For my case, I have to write a domain-xml dynamically and specify the interface name (target-element) to the domain-xml like <interface type='ethernet'> <script path='/etc/kvm/qemu-ifup'/> <target dev='my-new-name001122'/> </interface> regards Danny -- Libvir-list mailing list Libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list