Example-DNS

DNS Example

Authors:
David Fernández (david at dit.upm.es)
version 1.7, November 23rd, 2006

Scenario

This is an interesting example to learn and experiment with with the Internet's Domain Name System (DNS) and the configuration of the widest used DNS server implementation: bind.The example implements the complete dual IPv4/IPv6 DNS hierarchy shown in the figure. All DNS servers are under the fictitious .e6 top level domain (used for testing in Euro6IX project).

You can get the complete specification [dns.xml here]. The bind configuration files used are in this [dns.tar tar file], that must be untared in /usr/share/vnuml/examples.

NOTE: if you are experiencing problems with the conventional xterm, we recommend you to uncomment the <xterm> tag in each virtual machine, in order to use gnome-terminal, that seems to be more stable. Of course, you will need the gnome-terminal installed in your system.Once you have started the scenario (vnuml -t ...) and the simulation (vnuml -s ...), you can make queries to the different name servers from any of the virtual machines or the host (which is included in the scenario with address 10.1.1.10) using dig tool. For example:

• dig @10.1.1.1 h1.dit.upm.e6 queries root server (10.1.1.1) to get the A record corresponding to h1.dit.upm.e6 host.
• dig @10.1.1.3 -x 10.12.1.1 queries dit.upm.e6 server (10.1.1.3) to get the PTR record corresponding to 10.12.1.1.
• dig @10.1.1.3 -t ptr 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.4.1.0.0.8.b.d.0.1.0.0.2.ip6.arpa queries dit.upm.e6 server (10.1.1.3) to get the PTR record corresponding to 2001:db8:14:100::1 IPv6 address.

The following table shows the main data related to the scenario:

e6	upm.e6	dit.upm	umu.e6	dif.umu	cons.e6
Server	ns1.e610.1.1.1 2001:db8::1	ns1.upm.e610.1.1.1 2001:db8::1	ns1.dit.upm.e610.1.1.1 2001:db8::1	ns1.umu.e610.1.1.1 2001:db8::1	ns1.dif.umu.e610.1.1.1 2001:db8::1	ns1.cons.e610.1.1.1 2001:db8::1
Authoritative for direct domains:	e6	upm.e6	dit.upm.e6	umu.e6	dif.umu.e6	cons.e6
Authoritative for inverse domains:	10.0.0.0/8 2001:db8::/32	10.12.0.0/16 2001:db8:12::/48	10.12.10.0/24 2001:db8:12:1000::/56	10.13.0.0/16 2001:db8:13::/48	10.13.10.0/24 2001:db8:13:1000::/56	10.14.0.0/16 2001:db8:14::/48
Prefixes used by local hosts:	10.11.0.0/16 2001:db8:11::/48	10.12.1.0/24 2001:db8:12:100:/56	10.12.10.0/24 2001:db8:12:1000::/56	10.13.1.0/24 2001:db8:13:100:/56	10.13.10.0/24 2001:db8:13:1000::/56	10.14.0.0/16 2001:db8:14::/48
Example host locally registered:	h1.e610.11.1.1 2001:db8:11::1	h1.upm.e610.12.1.1 2001:db8:11::1	h1.dit.upm.e610.12.10.1 2001:db8:11::1	h1.umu.e610.13.1.1 2001:db8:11::1	h1.dif.umu.e610.13.10.1 2001:db8:11::1	h1.cons.e610.11.1.1 2001:db8:11::1

VNUML Description

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE vnuml SYSTEM "/usr/share/xml/vnuml/vnuml.dtd">
<vnuml>

   <global>
      <version>1.7</version>
      <simulation_name>dns</simulation_name>

      <ssh_key>/root/.ssh/identity.pub</ssh_key>
      <automac offset="0"/>
      <vm_mgmt type="private" network="192.168.0.0" mask="24" offset="0">

         <host_mapping/>
      </vm_mgmt>
      <vm_defaults>
         <filesystem type="cow">/usr/share/vnuml/filesystems/root_fs_tutorial</filesystem>
         <kernel>/usr/share/vnuml/kernels/linux</kernel>

         <shell>/bin/sh</shell>
         <console id="0">xterm</console>
      </vm_defaults>

   </global>
    
   <net name="lan1" mode="uml_switch" />
    
   <vm name="e6">

      <if id="1" net="lan1">
         <ipv4 mask="255.255.255.0">10.1.1.1</ipv4>
         <ipv6>2001:db8::1/64</ipv6>

      </if>
      <filetree root="/etc/bind" when="start">/usr/share/vnuml/examples/dns/ns1</filetree>
      <exec seq="start" type="verbatim">rm -f /etc/bind/*</exec>

      <exec seq="start" type="verbatim">mv /etc/bind/ns1/* /etc/bind</exec>
      <exec seq="start" type="verbatim">killall named</exec>

      <exec seq="start" type="verbatim">/usr/sbin/named -c /etc/bind/named.conf</exec>
      <exec seq="stop" type="verbatim">killall named</exec>

   </vm>
   <vm name="upm.e6">      
      <if id="1" net="lan1">
         <ipv4 mask="255.255.255.0">10.1.1.2</ipv4>

         <ipv6>2001:db8::2/64</ipv6>
      </if>
      <filetree root="/etc/bind" when="start">/usr/share/vnuml/examples/dns/ns2</filetree>

      <exec seq="start" type="verbatim">rm -f /etc/bind/*</exec>
      <exec seq="start" type="verbatim">mv /etc/bind/ns2/* /etc/bind</exec>

      <exec seq="start" type="verbatim">killall named</exec>
      <exec seq="start" type="verbatim">/usr/sbin/named -c /etc/bind/named.conf</exec>

      <exec seq="stop" type="verbatim">killall named</exec>
   </vm>
   <vm name="dit.upm">
      <if id="1" net="lan1">

         <ipv4 mask="255.255.255.0">10.1.1.3</ipv4>
         <ipv6>2001:db8::3/64</ipv6>
      </if>
      <filetree root="/etc/bind" when="start">/usr/share/vnuml/examples/dns/ns3</filetree>

      <exec seq="start" type="verbatim">rm -f /etc/bind/*</exec>
      <exec seq="start" type="verbatim">mv /etc/bind/ns3/* /etc/bind</exec>

      <exec seq="start" type="verbatim">killall named</exec>
      <exec seq="start" type="verbatim">/usr/sbin/named -c /etc/bind/named.conf</exec>

      <exec seq="stop" type="verbatim">killall named</exec>
   </vm>
   <vm name="umu.e6">
      <if id="1" net="lan1">

         <ipv4 mask="255.255.255.0">10.1.1.4</ipv4>
         <ipv6>2001:db8::4/64</ipv6>
      </if>
      <filetree root="/etc/bind" when="start">/usr/share/vnuml/examples/dns/ns4</filetree>

      <exec seq="start" type="verbatim">rm -f /etc/bind/*</exec>
      <exec seq="start" type="verbatim">mv /etc/bind/ns4/* /etc/bind</exec>

      <exec seq="start" type="verbatim">killall named</exec>
      <exec seq="start" type="verbatim">/usr/sbin/named -c /etc/bind/named.conf</exec>

      <exec seq="stop" type="verbatim">killall named</exec>
   </vm>
   <vm name="dif.umu">      
      <if id="1" net="lan1">

         <ipv4 mask="255.255.255.0">10.1.1.5</ipv4>
         <ipv6>2001:db8::5/64</ipv6>
      </if>
      <filetree root="/etc/bind" when="start">/usr/share/vnuml/examples/dns/ns5</filetree>

      <exec seq="start" type="verbatim">rm -f /etc/bind/*</exec>
      <exec seq="start" type="verbatim">mv /etc/bind/ns5/* /etc/bind</exec>

      <exec seq="start" type="verbatim">killall named</exec>
      <exec seq="start" type="verbatim">/usr/sbin/named -c /etc/bind/named.conf</exec>

      <exec seq="stop" type="verbatim">killall named</exec>
   </vm>
   <vm name="cons">
      <if id="1" net="lan1">

         <ipv4 mask="255.255.255.0">10.1.1.6</ipv4>
         <ipv6>2001:db8::6/64</ipv6>
      </if>
      <filetree root="/etc/bind" when="start">/usr/share/vnuml/examples/dns/ns6</filetree>

      <exec seq="start" type="verbatim">rm -f /etc/bind/*</exec>
      <exec seq="start" type="verbatim">mv /etc/bind/ns6/* /etc/bind</exec>

      <exec seq="start" type="verbatim">killall named</exec>
      <exec seq="start" type="verbatim">/usr/sbin/named -c /etc/bind/named.conf</exec>

      <exec seq="stop" type="verbatim">killall named</exec>
   </vm>
   
   <host>
      <hostif net="lan1">

         <ipv4 mask="255.255.255.0">10.1.1.10</ipv4>
      </hostif>
   </host>
   
</vnuml>

Old Releases

• 1.3
• 1.6