Network configuration for KVM using public bridge


#1

Hello!
I have installed KVM/QEMU on my LMDE (Linux Mint Debian Edition) system. The CPU is supporting hardware virtualisation:

s@pc1-lmde ~ $ grep -E '^flags.*\b(vmx|svm)\b' /proc/cpuinfo flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm lahf_lm dts tpr_shadow flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm lahf_lm dts tpr_shadow

The kernel modules have been loaded:

s@pc1-lmde ~ $ lsmod | grep kvm kvm_intel 44826 0 kvm 224567 1 kvm_intel

The guest should use a public bridge that I have set up with /etc/network/interfaces:

[code]s@pc1-lmde ~ $ cat /etc/network/interfaces

This file describes the network interfaces available on your system

and how to activate them. For more information, see interfaces(5).

The loopback network interface

auto lo
iface lo inet loopback

auto eth1
iface eth1 inet manual

auto br1
iface br1 inet static
address 192.168.178.11
netmask 255.255.255.0
gateway 192.168.178.1
bridge_ports eth1
bridge_stp off
bridge_fd 0
bridge_maxwait 0[/code]

Starting a VM with kvm command returns this error:

s@pc1-lmde ~ $ kvm -hda ~/.virtualmachines/aqemu/virtualdisk_converted/vm2-windowsxp-HD01-15G.qcow -boot c -cdrom /dev/cdrom -m 1024 -smp 1 -net nic,macaddr=00:88:4e:ad:2d:61 -net tap kvm: -net tap: could not configure /dev/net/tun (tap%d): Operation not permitted kvm: -net tap: Device 'tap' could not be initialized

Checking the permissions of file /dev/net/tun:

s@pc1-lmde ~ $ ls -l /dev/net/tun crw-rw-rw- 1 root root 10, 200 21. Mai 09:52 /dev/net/tun

If I execute

the VM starts without error.

Checking the permissions of file /dev/net/tun:

s@pc1-lmde ~ $ ls -l /dev/net/tun crw-rw-rw- 1 root root 10, 200 21. Mai 09:52 /dev/net/tun

Can you advice how to troubleshoot this problem? Why do I have to be root for staring KVM?
I thought the group assignment is correct:

s@pc1-lmde ~ $ groups sudo kvm libvirt

I’m running out of ideas.

THX