This guide shows how to clone and simulate devices using free and
commonly used tools. This could be helpful while conducting network
stress-tests, network audits, etc.

This guide is divided into 4 simple steps:if(typeof __ez_fad_position != ‘undefined’){__ez_fad_position(‘div-gpt-ad-howtoforge_com-medrectangle-3-0’)};

1. Installation of SNMP simulator
2. Extracting SNMP record files from a physical device
3. Adding a device to the list of simulated devices
4. Starting the simulation

Requirements and tools:

• 32 or 64 bit Linux distributions including: SuSE, RedHat
  Enterprise and Debian using i386 and x64 architectures.

• TCP/IP network connection.
• Java 1.6 or higher installed.
• NET-SNMP tools http://sourceforge.net/projects/net-snmp/files/net-snmp%20binaries/5.6.1.1-binaries/net-snmp-5.6.1.1-1.x86.exe/download
• Verax SNMP Agent Simulator http://www.veraxsystems.com/en/products/snmpsimulator
• Network monitoring software.

STEP 1: Installing SNMP agent simulator

First, you have to install the SNMP agent simulator (in this example
it’s
free Verax SNMP Agent Simulator).

1. Download and unzip the simulator package (vxsnmpsimulator-1.3.1.zip).
2. Recommended installation directory for the
   simulator: /usr/local/vxsnmpsimulator

3. Create and move the simulator.conf
   file to the following directory: /etc/verax.d/

4. Open the simulator.conf
   file, find the line with the SIMULATOR_HOME
   variable and change it to point to the installation directory.

   SIMULATOR_HOME=”/usr/local/vxsnmpsimulator”

5. In
   the same simulator.conf file,
   find the line with the JRE_HOME
   variable
   file and and point to the folder where your java is located.

   JRE_HOME=/usr/local/java/jdk1.6.0_14/bin/

6. Pay attention to the name of the interface (e.g. ‘eth1’) which is
   used to create interface aliases (e.g. ‘eth1:0’, ‘eth1:1’, etc.). The
   primary interface must be present before the SNMP simulator starts.

   PRIMARY_INTERFACE='eth1'

7. Copy the simulatord
   file to /etc/init.d directory.

8. Give execute permission to the following files:
   • chmod +x /etc/init.d/simulatord
   • chmod +x /usr/local/vxsnmpsimulator/conf/stop
   • chmod +x /usr/local/vxsnmpsimulator/conf/vlan_up
   • chmod +x /usr/local/vxsnmpsimulator/conf/vlan_down

STEP 2: Extracting SNMP record files from a physical device

1. Extracting
   SNMP record files from a physical device can be done using the snmpwalk
   command. In order to do that, you have to install some tools allowing
   for snmpwalk
   command e.g. NET-SNMP.

2. NET-SNMP can be installed by issuing the following command:

   yum install
   net-snmp-utils

3. In order to prepare SNMP record file reflecting actual SNMP
   agent
   available at given IP address, use SNMP tools and issue the following
   command:
   e.g.

   snmpwalk -On -Oe -OU -v2c -c
   public address > [destination folder]/filename.txt

   e.g.

   snmpwalk -On -Oe -OU -v2c -c public
   192.168.100.8 > /root/cisco-snmprecordfile.txt

In this example 192.168.100.8 is an IP
of a physical cisco switch we want to simulate.

Now,
the generated cisco-snmprecordfile.txt file contains OID values of the real
device and will be stored in the simulator/device directory.

STEP 3:
Adding device to the list of simulated devices in SNMP simulator

Navigate
to the vxsnmpsimulator/conf
directory, open devices.conf,
and add
a new <device> record for a simulated device.if(typeof __ez_fad_position != ‘undefined’){__ez_fad_position(‘div-gpt-ad-howtoforge_com-medrectangle-4-0’)};

In order to add a new device, you have to provide a path to a recently
generated file (cisco-snmprecordfile.txt) and add a new IP address.
Remember that the new IP address must be virtual.

e.g.

<type filepath="../device/cisco-snmprecordfile.txt">
      <devices>
               <device ip="192.168.160.34" netmask="24" port="161"</device>
      </devices>
</type>

STEP 4: Starting the simulation

Before running the Verax SNMP Simulator, make sure that port 161 is
available. If not, stop any process using port 161. 

1. In order to start the SNMP Simulator, issue the following
   command in a terminal window
   (shell):

   service
   simulatord start

2. In order to open the Management Console, issue the
   following command in the terminal window (shell):

   service
   simulatord console

3. The
   Management Console will ask for connection details (it may connect to
   multiple simulators). By default, the simulator service process is
   running on the same server as the Management Console – in such a case
   confirm the default parameters by pressing “y” at the prompt:

   Do
   you want to connect to default simulator server? [y/n]

   Note: The default
   connection parameters
   are 127.0.0.1:43500 (localhost as the host name and 43500 for TCP
   port).

4. Use the SHOW
   command to list simulated devices.

Well done, now we’ve got our cisco switch simulated by the SNMP
simulator at given IP address (192.168.160.34).

Final: Adding simulated device to the monitoring system

Make sure that SNMP simulator is started and simulating (type SHOW to
check a list of simulated devices).

Now,
start your network monitoring tool and add a simulated device just like
any other but remember to provide your simulated device IP.

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Well done! You can now clone and simulate multiple SNMP devices or even
networks.