Arch Linux

shakin

Member

Registered: 2008-08-07

Posts: 24

qemu-kvm: network access from host to guest

I need ssh and http access from my host (Arch) to the guest (other Linux). I've failed at setting up Tap networking as described in the wiki. I don't need to have the whole LAN access the guest, so is there another way the host can access the guest? Using the guest's IP of 10.0.2.15 doesn't work, but I'm hoping there is a way to do it.

Thanks.

Mr.Elendig

#archlinux@freenode channel op

From: The intertubes

Registered: 2004-11-07

Posts: 4,097

Re: qemu-kvm: network access from host to guest

Bridging is the best way todo it, so you should give us some more info on your atempt at it, so that we can help you fix it.

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shakin

Member

Registered: 2008-08-07

Posts: 24

Re: qemu-kvm: network access from host to guest

Bridging is the best way todo it, so you should give us some more info on your atempt at it, so that we can help you fix it.

Ok, I've followed the instructions from the wiki.

One problem is that I'm on a laptop. eth0 is wireless and eth1 is wired. I chose to use eth1 since I thought it'd be easier to get working on one device before trying to make it work on both.

1. bridge and tun modules are loaded from rc.conf

2. In /etc/conf.d/bridges I have this:

bridge_br0="eth1"
BRIDGE_INTERFACES=(br0)

3. In /etc/rc.conf I changed my networking portion to this:

eth1="eth1 up"
br0="dhcp"
INTERFACES=(eth1 br0)

4. In /etc/udev/rules.d/65-kvm.rules I have this:

KERNEL=="tun", NAME="net/%k", GROUP="kvm", MODE="0660"

5. My user is part of the kvm group, although I have also tried running qemu-kvm as root.

6. In /etc/qemu-ifup I put:

#!/bin/sh
 
echo "Executing /etc/qemu-ifup"
echo "Bringing up $1 for bridged mode..."
sudo /sbin/ifconfig $1 0.0.0.0 promisc up
echo "Adding $1 to br0..."
sudo /usr/sbin/brctl addif br0 $1
sleep 2

7. Using visudo I added this to the bottom:

Cmnd_Alias      QEMU=/sbin/ifconfig,/sbin/modprobe,/usr/sbin/brctl,/usr/bin/tunctl
 %kvm     ALL=NOPASSWD: QEMU

8. I launch qemu-kvm with the following script:

USERID=`whoami`
IFACE=`sudo tunctl -b -u $USERID`
qemu-kvm -net nic -net tap,ifname="$IFACE" -vga std -m 1024 -k en-us -usbdevice tablet -localtime /dev/sda
sudo tunctl -d $IFACE &> /dev/null

My system starts with br0 getting the dhcp IP on boot, so that part is working.

When I run the qemu-kvm start script I get this error (running as user or root):

/etc/qemu-ifup: could not launch network script
Could not initialize device 'tap'

/etc/qemu-ifup is executable

Last edited by shakin (2009-06-05 19:13:14)