Bridge networking to a VM… just set the network mode to this and your VM will be able to communicate with your host and larger network alike, right? On VMware and VirtualBox, yes, it works easy and nice like that. But, on QEMU, unfortunately things are more complicated. You can’t just click an option to set it up, if you do setup the easy default “bridged” option this will allow communication from the VM to the larger network, but not between the VM and the host. Why is this? Apparently, if you do setup bridged mode to a particular hardware interface, then this means that communications will go directly to that device completely bypassing the host operating system networking stack. If you want the host and guest to communicate one alike as if they were connected on the same network, you’ve got to setup a tup/tap bridge device and connect the guest machine there. And how do you do that?
Well, unfortunately this doesn’t look too easy, but there are ways. Looks like any way you choose will not play well with NetworkManager autoconfiguration and management. Yeah, sure, this works perfectly fine for the common use case where you are configuring a server sitting inside a datacenter, but if you are setting this up on a personal computer, gosh that’s a nuisance.
20200409/DuckDuckGo qemu virt-manager bridge tap access guest from host
20200409/https://tthtlc.wordpress.com/2015/10/21/qemu-how-to-setup-tuntap-bridge-networking/
20200409/https://wiki.qemu.org/Documentation/Networking
20200409/DuckDuckGo qemu bridge networkmanager
20200409/https://wiki.archlinux.org/index.php/Network_bridge
20200409/DuckDuckGo virt-manager virbr0
20200409/DuckDuckGo libvirt virbr0
20200409/https://askubuntu.com/questions/246343/what-is-the-virbr0-interface-used-for
But… here’s the real trick. You don’t need to follow through all of that setup if you only want NAT for your guest VM, but also want the host to communicate with it directly. Why? Because QEMU uses a bridge to setup NAT, and as it turns out, you can use that IP address assigned to that bridge for the guest and host to communicate with each other.
Find the IP address as follows:
ip addr show dev virbr0
Now on your own machine, start up a Python SimpleHTTPServer:
python -m SimpleHTTPServer
Now open up the IP address given by virbr0 and the port number that
SimpleHTTPServer is using on your host machine’s web browser. For
example, 192.168.1.150:8000. You should see the directory listing
where you ran SimpleHTTPServer in your browser.
Now, go to your VM and go and do the same. You should also see the same page. Hooray! Easy guest and host machine communication with NAT for internet.