42 Build the Baseline Environment (Eagle Net)

Dante Rocca

This section is for building a baseline environment. e.g. Your target.  We’ll call it Eagle Network, The Eagle, or just Eagle for reference.  It will contain many of the devices of a real network, but it will be abbreviated to save on host machine resources.  You will need to create this enterprise network first before starting any of the attack labs.

Learning Objectives

  • Create a network to serve as a target for offensive cyber operations



  • Four (4) Screenshots are required:
    • GNS3 lab environment
    • Kali box receiving an IP address
    • Metasploitable3-Win box receiving an IP address
    • Metasploitable3-Linux box receiving an IP address


  • N/A

Contributors and Testers

  • Mathew J. Heath Van Horn, PhD
  • Jacob M. Christensen, Cybersecurity Student, ERAU-Prescott

Phase I – Setting up the network

This lab provides students with a guide to creating a network containing vulnerabilities to exploit while conducting a cyber attack. Much of this lab is directly from the DHCP Relay chapter. We highly recommend that once the GNS3 environment is complete; you save a master copy for reuse in future activities.
  1.  The goal is to create a network like this:
    Picture of the final product
    Figure 1 – Expected final result
  2. Create the following virtual machines and add them to the GNS3 environment:

    NOTE: Not every VM is used in every lab. To save resources, substitute a Tiny Core Linux box for any unused machine. This device swap will still show live targets on scans, but it only uses 50 MB of memory instead of 2 GB!

    1. TinyCore Linux in Chapter 5 – Installing Tiny Core Linux
    2. Ubuntu Server VM with all add-ons in Chapter 7 – Create a Linux Server
    3. Ubuntu Desktop in Chapter 11 – Create a Ubuntu Desktop
    4. Kali VM in Chapter 12 – Create a Kali Linux VM
    5. Both Metasploitable 3 (Windows and Linux) VMs in Chapter 13 – Create a Vulnerable Desktop VM
  3. Configure the Ubuntu Server to service DHCP requests
    1. Modify the /etc/netplan/*.yaml on the DHCP machine (Figure 2)
    2. Modify the /etc/dhcp/dhcpd.conf file on the DHCP machine (Figure 3)
    3. Ensure sure the daemon is active and running

      NOTE: As a reminder:

      1. Start the service:

      > sudo systemctl start isc-dhcp-server.service

      2. Restart the service:

      > sudo systemctl restart isc-dhcp-server.service

      3. Start the service on system boot:

      > sudo systemctl enable isc-dhcp-server.service

      4. Check service status:

      > systemctl status isc-dhcp-server.service

      5. Check the configuration for errors

      > dhcpd -f

      6. Check the system log for additional error messages

      > journalctl -xeu isc-dhcp-server.service

  4. Assign each interface on the router an IP address according to the IP addresses in the image
  5. Configure the router as a DHCP relay for the Red and Blue networks
  6. Check to make sure that everything is working properly
    1. The attacker’s machine should receive an address from the pool
    2. The blue machines should receive addresses from the pool
End of Lab


3 Screenshots are needed to earn credit for this exercise:

  • Screenshot of Lab Environment
  • Screenshot of Kali VM receiving an IP address
  • Screenshot of Metasploitable3 VM receiving an IP address
Figures for Printed Version
netplan configuration
Figure 2 – Ubuntu Server netplan configuration


terminal command executin
Figure 3 – Ubuntu Server DHCP daemon configuration


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Mastering Enterprise Networks Copyright © 2024 by Dante Rocca is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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