Discussion
qemu-kvm problem: I want my VM to be just another host on the local LAN. I have read extensive Red Hat KVM documentation and it's uh not helping me. Is there a guide to doing this specific thing? I'll even type XML, not just use the VIrtual Machine Manager.
Host is my Debian 13 laptop.
EDIT "Error: Device does not allow enslaving to a bridge" cos it's wifi dammit
@davidgerard The answer on this question seems relevant: https://unix.stackexchange.com/questions/554331/theoretical-tap-interface-w-wifi-parent-interface
In short: bridging might be possible with "4addr" mode, but it will need to be supported by both your AP and the device driver on your laptop. While you can pretend wifi is just ethernet without wires in many cases, this isn't one of them.
@davidgerard what distribution is the host machine running?
@davidgerard I'm trying this all out, so far I get an "operation not supported" adding my wireless to my bridge so I guess I'm more in the camp of "the company your misery loves" instead of being being able to offer anything useful
@davidgerard I'm going to try interface tricks later but having to forward traffic from a wireless interface to a dummy ethernet device seems negate most of the reason to bridge in the first place, it just means that the NAT is happening at the host level instead of via hypervisor configuration. Maybe that's advantageous?
@davidgerard I'll check my config in the morning to confirm, but I'm pretty sure I used vde2 to create an interface for the VM and then bridged it to the host server's interface.
@davidgerard
A gist I found that is close to my setup is here: https://gist.github.com/frjaraur/7bad30cedc484486efd3ba5d12362bec
The Steps in general include:
1. Create bridge device
2. Connect physical device to bridge
3. Tell libvirt about bridge device
4. Configure VM to use bridge device
@davidgerard
I set up a bridge on the host machine's LAN interface and bind the guest's network interface to the host's br0.
On debian with ifupdown this means installing bridge-utils on the host and adding a stanza in /etc/network/interfaces, I don't know what the Red Hat procedure would be.
Guest XML:
<interface type='bridge'>
<source bridge='br0'/>
<model type='virtio'/>
</interface>
This kind of thing is why I still mainly use VirtualBox.
As is often the case with code that RH sponsored, my use cases seem to be things they consider bizarre that nobody would ever want. 🤷♂️
@lproven virtualbox isn't in debian stable because Oracle refuse to separate out backportable patches, one guy told them he'd love to but he specifically wasn't allowed to
Here's how to add the repo and install the native packages:
https://www.virtualbox.org/wiki/Linux_Downloads
I think that Debian's `extrepo` command will add this for you:
https://manpages.debian.org/unstable/extrepo/extrepo.1p.en.html
I also find `deb-get` extremely helpful for this stuff:
@lproven installed, started, VirtualBox just asked me to recompile my fucking kernel
@davidgerard you want a bridge mode adapter. Caveat is that you can’t send packets between the host and VM using bridge mode because NICs don’t do loopback, so you need a second bridge adapter that’s just between host and VM.
This tutorial should be what you’re after - but the key part is forward-mode=bridge instead of NAT
https://www.thelinuxvault.net/blog/how-to-use-bridged-networking-with-libvirt-and-kvm/
@s0 BUP-pow it's wifi so "Error: Device does not allow enslaving to a bridge."
@davidgerard in general you have to set up a bridge and connect the CN to it.
@bthylafh excellent is there a step by step? cos i tried setting up a bridge and it told me i'd set it up wrong and wouldn't start the VM
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