Debian Network-Configuration for KVM - Provider OVH - networking

Question

I need some help to configure the network for my KVM. My Hostingprovider is OVH, and since they are a bit different, I'm in need of help.
My old Network-Interfaces File:
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 94.23.209.170
netmask 255.255.255.0
network 94.23.209.0
broadcast 94.23.209.255
gateway 94.23.209.254
auto br0
iface br0 inet static
address 91.134.173.185
netmask 255.255.255.0
broadcast 91.134.173.185
bridge_ports eth0
bridge_stp off
bridge_fd 0
bridge_maxwait 0
dns-nameservers 8.8.8.8
iface eth0 inet6 static
address 2001:41d0:0002:54aa::
netmask 64
dns-nameservers 2001:41d0:3:163::1
post-up /sbin/ip -family inet6 route add 2001:41d0:0002:54ff:ff:ff:ff:ff dev eth0
post-up /sbin/ip -family inet6 route add default via 2001:41d0:0002:54ff:ff:ff:ff:ff
pre-down /sbin/ip -family inet6 route del default via 2001:41d0:0002:54ff:ff:ff:ff:ff
pre-down /sbin/ip -family inet6 route del 2001:41d0:0002:54ff:ff:ff:ff:ff dev eth0
I had to go into the resecue mode and remove the bridge, otherwise my machine wouldn't come up again. Can someone help me maybe, and tell me what I did wrong?
Thanks, and have a good day/night! :)

Answer 1

I had a similar problem. I just moved to OVH from Phoenix nap. I like the control panel better but their networking is a little weird. I have an IP on a /24 and I ordered a /29 for whm/cpanel and some other virtual machines.
My config to get the host functional:
auto eth0
iface eth0 inet manual
address 111.222.333.145
netmask 255.255.255.0
network 111.222.333.0
broadcast 111.222.333.255
gateway 111.222.333.254
auto br0
iface br0 inet static
address 111.222.333.145
netmask 255.255.255.0
network 111.222.333.0
broadcast 111.222.333.255
gateway 111.222.333.254
bridge_ports eth0
bridge_stp off
bridge_fd 0
bridge_maxwait 0
dns-nameservers 213.186.33.99
NOTE: 111.222.333 is your first 3 octets. Obviously change them. the .145 was arbitrary to illustrate a host assigned to you.
Then restart the networking service.
service networking restart
Now I had to get a CentOS container for WHM/cPanel going and a few debian containers.
I'm assuming you bought a block of IPs and need to get that IP into a VM. Log into the OVH control panel, Select IP. Expand the IP block. to right you will see a gear you can click on. Create an OVH Virtual MAC. Take note of that MAC!
For CentOS the guide is correct.
In Debian it was a missing little something.
You want to edit the /etc/libvirt/qemu/autostart/YOU_VM_NAME.xml
...
<interface type='bridge'>
<mac address='YO:UR:VI:RT:MA:CA'/>
...
After saving restart the libvirtd service. Restart your debian container to pick up the new MAC and you should be good.
When installing I could not set an IP out side the range of my network. After getting virt-manager up, I logged in blew out the GW and modified the interfaces file according to the guide:

Answer 2

Don't need to change your host network config.
You need a Failover IP (create in OVH Panel). Then, assign a Virtual MAC for it.
In your dedicated server:
virsh net-edit default
Change this way:
<network>
<name>default</name>
<uuid>...</uuid>
<bridge name='virbr0' stp='off' delay='0'/>
<mac address='...'/>
</network>
Now edit the VM:
virsh edit myvmname
and set (change "eno1" to your network card name, like "eth0" or "ens0p0" etc):
<interface type='direct'>
<mac address='--VIRTUAL MAC CREATED IN OVH PANEL--'/>
<source dev='eno1' mode='bridge'/>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>
Now edit your VM network (in my example, a Debian /etc/network/interfaces and change the network name as well):
auto eno1
iface eno1 inet static
address -FAILOVER IP-
netmask 255.255.255.255
gateway -HOST GATEWAY-
broadcast -FAILOVER IP-
So, the VM will have the failover IP and use the same gateway than the host. In OVH the gateway is final .254 (or use ip r in the host).