Automated Install Xenserver Hetzner for EX4S Guest Networking Enabled

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  • Hetzner’s gateway setup requires special network settings (all XenServer releases)
  • the XenServer 5.6 unattended installation has a bug so the installed system will not boot
  • XenServer 5.6 FP1 has a problem with the RealTek 8169 NIC which are used in Hetzner’s servers

This article explains how to circumvent these problems. Some workarounds are needed even when installing from a physical CD (by using Hetzner’s LARA console).

This How-To also works for XenServer 5.61 SP2

Copy contents of the installation CD to a directory on a webserver

Copy the contents of the Citrix XenServer installation CD to a directory on a web server. This directory must be accessible by ip address (in this example it ishttp://, so you might need to set up a default virtual host.

# mount -o loop XenServer-5.6.1-fp1-install-cd.iso /mnt
# cp -a /mnt xenserver

Create answerfile

In the xenserver directory, create a new file xenserver.xml containing the following XML code. Make sure to enter your own hostname, root password, ip address, subnet mask, gateway and name server ip addresses. The source URL is of course the URL to the installation directory you have just created. It must contain the ip address, not the domain name.

<installation mode="fresh" srtype="lvm">
 <primary-disk gueststorage="yes">sda</primary-disk>
 <source type ="url"></source>
 <!-- No Post install scripts configured -->
 <admin-interface name="eth0" proto="static">

Configure new server for unattended installation

The new XenServer host must be initialized with an arbitrary Linux system. Its only purpose is to boot a special XenServer kernel, which in turn will start the actual installation process by downloading the answerfile and the installation packages from the web server.

When installing the Linux system, do not use a software raid. There seems to be a bug in the XenServer 5.6 installer: if the Linux system used to boot the XenServer installer had software raid turned on, the installed XenServer system was corrupt. Files were missing or had binary data in them.

To install the initial Linux system, do the following for a Hetzner root server:

  1. boot the server in the rescue console 

  2. wipe all disks so that they do not have partitions of type 0xfd (Linux raid autodetect):
    # dd if=/dev/zero of=/dev/sda count=256
    # dd if=/dev/zero of=/dev/sdb count=256

    Note that this will destroy all data on your disks. 

  3. install Linux using the installimage command. I was using CentOS 5.5 32bit with good success. Remember to turn off the software raid option, this is done by editing the configuration to SW RAID = 0

  4. After installing Linux, mount the boot partition:
    # mount /dev/sda3 /mnt
    # mount /dev/sda2 /mnt/boot
  5. Replace the file /mnt/boot/grub/menu.lst with the following content:
    timeout 5
    default 0
    title Install Xenserver
    root (hd0,1)
    kernel /boot/xen.gz dom0_mem=752M acpi=off nosmp noapic noirqbalance
    module /boot/vmlinuz answerfile= install
    module /boot/install.img

    Note that the file references the answerfile created earlier. The URL must contain the ip address, a domain name will not work. 

  6. if there is a file grub.conf, copy menu.lst to it 

  7. some files must be copied from the XenServer installation directory into the /boot directory. On the server containing the XenServer installation files (the web server), do the following:
    scp xenserver/install.img xenserver/boot/vmlinuz xenserver/boot/xen.gz newserver.mydomain:/mnt/boot
    root@newserver.mydomain's password: ********
    install.img     100%   26MB  12.9MB/s   00:02
    vmlinuz         100% 2058KB   2.0MB/s   00:00
    xen.gz          100%  585KB 585.2KB/s   00:00
  8. to see whether the XenServer installer actually retrieves the files from the web server, run the tail command:
    # tail -f access_log.2011-04-16-00_00_00  | grep xenserver - - [16/Apr/2011:11:36:11 +0200] "GET /download/xenserver/xenserver.xml HTTP/1.1" 200 871 "-" "Python-urllib/2.4" - - [16/Apr/2011:11:36:23 +0200] "GET /download/xenserver/XS-REPOSITORY-LIST HTTP/1.1" 200 21 "-" "Python-urllib/2.4" - - [16/Apr/2011:11:36:23 +0200] "GET /download/xenserver/XS-REPOSITORY HTTP/1.1" 404 230 "-" "Python-urllib/2.4" - - [16/Apr/2011:11:36:23 +0200] "GET /download/xenserver/XS-PACKAGES HTTP/1.1" 404 228 "-" "Python-urllib/2.4" - - [16/Apr/2011:11:36:23 +0200] "GET /download/xenserver/packages/XS-REPOSITORY HTTP/1.1" 404 239 "-" "Python-urllib/2.4" - - [16/Apr/2011:11:36:23 +0200] "GET /download/xenserver/packages/XS-PACKAGES HTTP/1.1" 404 237 "-" "Python-urllib/2.4" - - [16/Apr/2011:11:36:23 +0200] "GET /download/xenserver/packages.main/XS-REPOSITORY HTTP/1.1" 200 145 "-" "Python-urllib/2.4" - - [16/Apr/2011:11:36:23 +0200] "GET /download/xenserver/packages.main/XS-PACKAGES HTTP/1.1" 200 3720 "-" "Python-urllib/2.4"
  9. if you want to install XenServer 5.5, you can now restart the server. You should see the XenServer installer accessing the installation files a couple of minutes later. After the automatic reboot you should be able to connect to the new server via XenCenter 

  10. if you are installing XenServer 5.6, the configuration must be modified before the reboot. Otherwise XenServer will hang during reboot and there is no chance to log in and fix the settings. therefore the Hetzner rescue system must be set up before the XenServer installation finishes. The easiest way to do this is: log into the Hetzner server administration, restart the server, and right after you see the installer accessing the packages from the web server, turn on the rescue system for this server. This way, when the freshly installed XenServer reboots after the installation has finished, it will boot into the rescue mode. 

  11. in the rescue console, mount the disks again. In the file /etc/rc.sysinit, find the following line and comment it out:
    # [ -x /sbin/nash ] && echo "raidautorun /dev/md0" | nash --quiet
  12. After that, edit /etc/modprobe.conf and add the line
    options r8169 use_dac=1
  13. Finally, reboot. The new XenServer 5.6 FP1 system should now be accessible from XenCenter


7. Makse sure your /etc/sysctl.conf has this :

# Kernel sysctl configuration file for Red Hat Linux


# For binary values, 0 is disabled, 1 is enabled. See sysctl(8) and

# sysctl.conf(5) for more details.

# Controls IP packet forwarding

net.ipv4.ip_forward = 1

# Controls proxy arp

net.ipv4.conf.default.proxy_arp = 1

# Turn off redirects

net.ipv4.conf.all.send_redirects = 0

net.ipv4.conf.default.send_redirects = 0

net.ipv4.conf.lo.send_redirects = 0

net.ipv4.conf.xenbr0.send_redirects = 0

and validated with ’systcl -p’

# sysctl -p

net.ipv4.ip_forward = 1

net.ipv4.conf.default.proxy_arp = 1

net.ipv4.conf.all.send_redirects = 0

net.ipv4.conf.default.send_redirects = 0

net.ipv4.conf.lo.send_redirects = 0

net.ipv4.conf.xenbr0.send_redirects = 0

net.ipv4.conf.default.rp_filter = 1

net.ipv4.icmp_echo_ignore_broadcasts = 1

net.ipv4.conf.default.accept_source_route = 0

net.ipv4.conf.all.accept_redirects = 0

net.ipv4.conf.all.send_redirects = 0

kernel.sysrq = 1

kernel.core_uses_pid = 1

net.ipv4.tcp_syncookies = 1

kernel.msgmnb = 65536

kernel.msgmax = 65536

kernel.shmmax = 4294967295

kernel.shmall = 268435456

vm.dirty_ratio = 5

kernel.printk = 4 4 1 4

8. Disable SeLinux with

# system-config-securitylevel-tui

9. add your additional subnetwork to your xenserver

# ip addr add dev xenbr0

10. shutdown the iptables

# service iptables stop

11. Create Dummy interface as we would use this as gateway for all Guest machine (Linux or Windows)

let say you have this Ip subnet from Hetzner until



HostMin: (this one we would use as gatway for our guesthost)


# nano /etc/sysconfig/network-scripts/ifcfg-xenbr0:1







12. bring our xenguest gateway ip up

#ifup xenbr0:1

13. now you can use this range until





3 thoughts on “Automated Install Xenserver Hetzner for EX4S Guest Networking Enabled

  1. Hey, I’m working through this just now and have had success installing on one hard drive. I am struggling however to install with raid0 and to install using the fully 3tb on each hard drive.

    • For creating a raid 0 use mdadm and do a disk copy for sda to sdb. Look for raid tutorial on hetzner or in citrix xen. If you are able to make it work then it all about replication and restarting the mdadm.

      One work of caution once the raid is up there is possibility that the one of the device are not added. Add once and it will be part of the raid config.

      And allow the raid to recover.

  2. Hi,
    you describe how to add a whole ip range to the xenserver … any idea how to add a single ip from a different subnet and make it useable within the vm (Hetzner EX 4S)? I tried different things, but nothing seems to work properly ..

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