How to troubleshoot a macvtap network in kvm/virt-manager
I have same problem with Ubuntu 13.10, I also update to 14.04 development branch to try but still does not work.
I do not know a good way debug, for my problem, I found eth0 does not enter promiscuous mode, I can not find message like device eth0 entered promiscuous mode
in dmesg output. So I force eth0 into promiscuous mode, the problem then disappears.
This is what I did:
- Force eth0 into promiscuous mode: sudo ifconfig eth0 promisc
- Use virt-manager to start the VM
ifconfig -a
and ping outside to see whether it works for you.
I do not know why libvirt does not put eth0 into promiscuous mode, maybe a bug of it.
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T_S_
Updated on September 18, 2022Comments
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T_S_ over 1 year
I have a virtual machine running under qemu-kvm, on a 13.10 host. I am using virt-manager to define the machine, and I have added a virtual NIC, using the new macvtap driver. I have the following definition:
<interface type='direct'> <mac address='52:54:00:1f:dd:c4'/> <source dev='eth0' mode='bridge'/> <model type='virtio'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface>
On the host machine, I can see that the tap interface is created:
$ip link 5: macvtap0@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN mode DEFAULT qlen 500 link/ether 52:54:00:1f:dd:c4 brd ff:ff:ff:ff:ff:ff $ls /dev/tap5 /dev/tap5
But in the virtual machine, interface eth0 is unable to access the network. dhcp fails. Static configuration obviously works, but then I cannot ping anything.
I have no iptables rules, neither on the host, nor in the virtual machine.
So, how can I troubleshoot this problem ?
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sdaffa23fdsf about 9 yearsI had the same issue on CentOS 7 as KVM host. The guest OS aren't learning any MAC address. Manually setting the physical interface on the host to promiscuous mode fixed the problem. Does macvtap actually requires promiscuous mode?