The situation - I need a virtual machine on one of bigger hards say /hda1. Ideally, it would be a light linux box for experiments, which should communicate with the host with "ssh".
I had this windows virtual machine I set up some time ago,so I decided to use it for a test. So starting qemu, the first thing I see is that I don't have access to my virtual machine - permission denied. Because it resided on /run/media/user/hd1 and of course, the qemu user didn't have permission to mess with /run/media.
To fix this, you need to edit the following file and to change the user to either your user or root. Both work.
$nano /etc/libvirt/qemu.conf
# The user for QEMU processes run by the system instance. It can be
# specified as a user name or as a user id. The qemu driver will try to
# parse this value first as a name and then, if the name doesn't exist,
# as a user id.
#
# Since a sequence of digits is a valid user name, a leading plus sign
# can be used to ensure that a user id will not be interpreted as a user
# name.
#
# Some examples of valid values are:
#
# user = "qemu" # A user named "qemu"
# user = "+0" # Super user (uid=0)
# user = "100" # A user named "100" or a user with uid=100
#
user = "root"
# The group for QEMU processes run by the system instance. It can be
# specified in a similar way to user.
group = "root"
# Whether libvirt should dynamically change file ownership
# to match the configured user/group above. Defaults to 1.
# Set to 0 to disable file ownership changes.
#dynamic_ownership = 1
Then you need to restart libvertd.
On older systems with:
# [root@dev1 ~]# service libvirtd restart
On mine:
$systemctl restart libvirtd.
And that did the trick for the permissions. Now I can access my virt. machine! YAY
New problem - the virt. machine doesn't have internet. And trying to get it connected ruins the host internet connection. It turns out this is a major problem stemming from the fact you cannot bridge wifi connection with virtual network. At least not very easily. Well, luckily, it turned out it's not that impossible as it seemed in the beginning.Note: in all thing below: when I say "guest" I refer to the virtual machine OS, when I say "host" I mean the host OS as in your laptop's OS.
So this is how I did it. For the moment I have tested it only on one virtual machine, it worked, but clearly you'll have to do the arp line after each restart of the computer.
1. Start virt-manager
2. Connection details->Virtual Networks -> New (sub)network
The new network can have any name, but the network ip should be part of your network but not the same as you host network:
so if your host ip is: 192.168.1.240 and your router is at 192.168.1.1 (this is the gateway).
then the new subnetwork can be: 192.168.1.129/25
you need to know your guest ip for the last step so what I did for the DHCP is :
starting: 192.168.1.150
ending: 192.168.1.151
this will give you only 2 ips, but this way, you'll know that your host ip is either 150 or 151. If you plan to use only 1 virtual machine, even better, give it just 1 ip.
Also notice that when changing the ips, the gateway written in the text between the "network" field and the DHCP fields change. So when playing with the numbers, make sure the gateway is still the correct one and not something random (it happened to me like 3 times to get weird gateways).
After setting up that, you click next, and next and in the final window, you choose from the falling menu
"Physical device: Wlan0" and from the second "Route".
Then you just click finish.
If you get an error: "Wlan0 already in use" the change the /25 to something different like /27 etc. IF you get some other random error, you either need to change the use in
qemu.conf to "root" or just google it and be persistent :)
After you click "Finish" and you get the message your subnetwork is ready, you need to test your host network, because if you get things wrong it will screw it. So try loading Google in host's browser or pinging it. If it works, rejoice!
If it doesn't work, stop that network from the virt-manager gui (the button is "-", or directly the "trash").
Then make a new one and try with different ips - the previous ones may be have been taken already.
If you do:
$route
you'll see info on your networks.‘virbr1’ and ‘wlan0’
shouldn’t have the
same Destination. If they do, you'll need to remove virbr1 from the virt-manager gui and create a new subnetwork. Btw , if you like me get it to work from try number N, "vibr1" might be "vibr2" or more, just check the Connection details->Virtual Networks for the actual name.
Final step:
$sudo
arp -i wlan0 -Ds 192.168.1.180 wlan0 pub
where the ip you see is your GUEST ip! So in my case, I had two ips *.150 and *.151 and I did it twice.
$ sudo
arp -i wlan0 -Ds 192.168.1.150 wlan0 pub
$sudo arp -i wlan0 -Ds 192.168.1.151 wlan0 pub
After that, you are ready to give network to your virtual machine. You go to virt-manager, you click on the details of your virt. machine and from the NIC section you choose "VIRBR1" and for the device name - the hypervisor defaul. Click "Ok" (or whatever) and start your machine.With some luck, it will be finally connected!
If it is not, start over. For better description, see the post where I found
the solution +
one similar which also helped.
I got it working after like 7 hours of googling and trying out solutions. But to my defence, I had no idea what all those options like "bridge, vepa, and passtrough" mean. So it could be just me, but if it's not working for you, just keep trying. The solution does work, even if it's messy and ugly.
Some resources which helped me figure out the situation:
qemu networking explained (
source1,
source2, s
ource3 !!!, same as source3 but on
ubuntu)
if you want to start the qemu from konsole, this
link might come handy.
For eth0 bridging, I suspect things will be piece of cake, but I haven't tried them, so
this link seems important.
There is aslo a
script for routing from Wifi to qemu, but I couldn't make it work, probably because at the time I didn't know my guest ip.
P.S. If after restart you don't have internet on your virtual machine you may want to 1) delete all the unnecessary connections in Connection details->Virtual Networks and 2) run
$ sudo
arp -i wlan0 -Ds 192.168.1.150 wlan0 pub before starting virt-machine, then do
$systemctl restart libvirtd.
and then start your machine.
And or disconnect and reconnect it couple of times from inside the guest machine. At some point it starts working.
