Kvm on nagg.eu

Debian QEMU/KVM bridged networking and VLAN

Sun, 25 Jul 2021 00:00:00 +0000

By default on every Linux distro after installing QEMU and libvirt two kinds of networking are available:

NAT: VM sits behind a NAT.
MACVTAP: without going into much details it acts more or less like a bridged network, except not really. One of the most annoying limitations is that host to guest communication and vice versa are not really working well. Other important things might be broken as well, like for example VRRP. This mode is good for quick and dirty testing but not really for a stable environment.

BRIDGED networking is also supported by libvirt but requires some manual work.
A possible networking schema could be the following:

FreeBSD network performance on KVM/Qemu

Tue, 13 Nov 2018 00:00:00 +0000

Today I red an article that was comparing Fedora 29 and FreeBSD 11.2 network performance in a KVM/Qemu environment.
Since I use KVM/Qemu and also Fedora and Freebsd I powered on a couple of vm and did my own tests.
Results are quite interesting, I expected FreeBSD to be faster but it turns out Fedora 29 actually is.
Host system configuration:


CPU: Ryzen 7 1700x @4 GHz
Motherboard: Gigabyte X370 K7 - BIOS F23d
RAM: 2x16 GB DDR4 @3133 MHz CAS 16
HDD: Some Samsung SSD

Operating systems
Host: Fedora 29 x86_64
Fedora VM0: Fedora 29 X86_64
Fedora VM1: Fedora 29 X86_64
FreeBSD VM0: FreeBSD 11.2 x86_64
FreeBSD VM1: FreeBSD 11.2 x86_64

Virtualization techonology: Qemu+KVM
Linux kernel version: 4.18.17-300.fc29.x86_64

What I did was setup 2 hidentical Fedora 29 virtual machines and 2 hidentical FreeBSD 11.2 virtual machines, every one of them had iperf3 installed on it.

CentOS 6.4, QEMU+KVM

Mon, 19 Aug 2013 22:54:50 +0000

It’s summer, it’s hot as hell, I am back home from mountains and I’ve plenty of free time.
Between a barbecue and the next one I spend my time playing with and learning new stuff: this week new stuff is called QEMU-KVM.
Yesterday I also tried XenServer but to be honest I wasn’t impressed, it just look like to be an old version of CentOS minimal install with some custom repos and a fancy GUI.
I played with it for just a bunch of hours, but the thing that just performing an installation on a software RAID-1 turned out to be a PITA to say the least is a clear sign that it’s not the best tool for my needs.
I swapped a couple of HDDs and in 2 minutes I went back to the already installed CentOS 6.4 with QEMU+KVM.
The client machine, for what it matters, is my Fedora 19 x86_64 workstation, virsh and virt-manager the tools I use for remote administration tasks.
Installing QEMU-KVM is just a matter of typing yum install libvirtd qemu-kvm bla bla bla, chkconfig libvirtd on and doing a system reboot (better safe than sorry).
The tricky part at least for me was setting up a damn bridged network interface, luckily I found this great writeup.
I am going to report here what I did to setup a couple of bridged network interfaces on my setup.