mario.verbelen.org

When I ran kvm/qemu on intrepid (I did not test on other os/version) there was a nice network issue.

Every-time I switched to another workspace or minimized my running kvm (now it was lenny-b2) I saw that the network traffic reduced to 0.
This while a download was running in the guest system.

After switching many times (cos it first looks unbelievable) it was true!

It uses the user-space as default network and I don't like that.
So I did a small workaround (A routed way like on my xen server).

Edit /etc/network/interfaces (as root or sudo)

auto br0
iface br0 inet static
        bridge_ports dummy0
        bridge_maxwait 0
        address 192.168.99.1
        netmask 255.255.255.0

sudo /etc/init.d/networking restart

(just restart network and your dummy0 and your bridge is available)

brctl show
bridge name	bridge id		STP enabled	interfaces
br0		8000.7630f790bddb	no		dummy0

enable ip forwarding for your kernel

sudo sysctl -w net.ipv4.ip_forward=1

change your firewall script if nessessary
(add all your external interfaces for out natting )

# MASQ voor dummy0 kvm
$IPTABLES -t nat -A POSTROUTING -o eth0 -j MASQUERADE
$IPTABLES -t nat -A POSTROUTING -o wlan0 -j MASQUERADE

$IPTABLES -A FORWARD -s 192.168.99.0/24 -j ACCEPT
$IPTABLES -A FORWARD -d 192.168.99.0/24 -j ACCEPT

Edit /etc/kvm/kvm-ifup

#!/bin/sh
BRIDGE=br0
ifconfig $1 0.0.0.0 up
brctl addif $BRIDGE $1

Edit a startscript for your guest

kvm -m 256 -daemonize -boot c -net nic -net tap,ifname=tap0,script=/etc/kvm/kvm-ifup -drive file=/data/kvm/debian.img,index=0,media=disk -no-acpi -localtime

And run this with sudo /your-script

Afcourse in your guest you need to add a fix ip or setup dhcp on your host system