Setup Xen within 20 minutes on Debian/grml
==========================================

Install relevant software und update grub's menu.lst:

apt-get install linux-image-2.6.18-1-xen-686 xen-hypervisor-3.0.3-1-i386 xen-utils-3.0.3-1 xen-tools
update-grub

Example for installation of Debian etch as DomU:

mkdir /mnt/md1/xen
xen-create-image --debootstrap --dir=/mnt/md1/xen --size=2Gb --memory=512Mb --fs=ext3 \
  --cache=yes --dist=etch --hostname=xengrml1 --ip 192.168.1.2 --netmask 255.255.255.0 \
  --gateway 192.168.1.1 --initrd=/boot/initrd.img-2.6.18-1-xen-686 \
  --kernel=/boot/vmlinuz-2.6.18-1-xen-686 --mirror=http://ftp.at.debian.org/debian/

Start services:

/etc/init.d/xend start
/etc/init.d/xendomains start

Setup a bridge for network, either manually:

brctl addbr xenintbr
brctl stp xenintbr off
brctl sethello xenintbr 0
brctl setfd xenintbr 0
ifconfig xenintbr 192.168.1.1 netmask 255.255.255.0 up

or via /etc/network/interfaces (run 'ifup xenintbr' to bring up the device without rebooting):

auto xenintbr
iface xenintbr inet static
  pre-up brctl addbr xenintbr
  post-down brctl delbr xenintbr
  address 192.168.1.1
  netmask 255.255.255.0
  bridge_fd 0
  bridge_hello 0
  bridge_stp off

Setup forwarding (adjust $PUBLIC_IP):

echo "1" > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -o eth0 -s 192.168.0.0/24 -j SNAT --to $PUBLIC_IP
iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to $PUBLIC_IP

Adjust network configuration of Xend:

cat >> /etc/xen/xend-config.sxp << EOF
(network-script    network-route)
(vif-bridge        xenintbr)
(vif-script        vif-bridge)
EOF

List domains, start up a DomU, shutdown later again:

xm create -c /etc/xen/xengrml1.cfg
xm list
xm shutdown 1

Useful Ressources:

* http://www.cl.cam.ac.uk/research/srg/netos/xen/readmes/user/user.html [Users' Manual Xen v3.0]
* http://www.pug.org/index.php/Xen-Installation (german)
* http://www.debian-administration.org/articles/304 [Installing Xen 3.0 upon Debian Sarge]