Simple DHCP Relay Hardware Lab

In class, working in groups, we will duplicate the environment from week 1:

Equipment:

• 1841 router will be an 1841 router!
• 2960 switches can be small Netgear switches for simplicity
• Laptop/server can be Foster Workstations booted to Kali Linux Thumbdrives

Lab Setup:

Use ethernet cables to connect gear

• use Ethernet ports on the 1841 (and not the Serial ports)

Console into the 1841 using a USB console cable and Putty:

• Plug serial console cable (light blue) into USB port on Workstation
• Open Device Manager to see what COM port it is using:
• Connect cable to console port (also light blue) on router
• Power on switch (plug it in if not already running)
• Open Putty on Workstation
• Under Connection - Go to Serial and enter the following:

Serial Line to Connect: COM port from Step 2 Bits per sec : 9600 Data bits : 8 Parity : none Stop bits : 1 Flow control : none

• Under Session - Select Serial and change the COM port to the # from Step 2:
• Click Open - Hit Enter and you should have access!

Subnet for Foster is 192.168.3.0/24

• Subnet for Skiff is 192.168.1.0/24

Configure appropriate IP's on the router FastEthernet Interfaces

You will Use Bootable Kali Thumbdrives for Foster Laptop and Skiff Server - but do not connect them to switches yet!

Set-up DHCP on Skiff Server (live Kali)

Leave the Skiff/Kali Live system on the Ireland Network (make sure you have Internet Access)

open a terminal and:

sudo apt update

(NOTE: if it fails with a time discrepancy - use the date command to make sure the time is correct. Mine had the right time but in UTC so it was five hours behind: sudo date --set="2024-09-09 14:23:00"

Install isc dhcp server

• sudo apt install isc-dhcp-server

Disconnect Skiff/Kali NUC from Ireland network and connect to your Skiff Switch

Assign a manual IP address (such as 192.168.1.100) on "Skiff Server/Kali" on the Skiff subnet

• Use the "ip addr" command to make sure that your new IP is in effect on eth0 (may need to disable/enable network connection)

On Skiff Server (Kali) - configure the DHCP server

• edit /etc/default/isc-dhcp-server

• • update line to INTERFACESv4="eth0"

• edit /etc/dhcp/dhcpd.conf

• • add the following subnet definitions to the bottom of the file:

subnet 192.168.1.0 netmask 255.255.255.0 {

range 192.168.1.200 192.168.1.205;

option routers 192.168.1.1;

}

subnet 192.168.3.0 netmask 255.255.255.0 {

range 192.168.3.200 192.168.3.205;

option routers 192.168.3.1;

}

start DHCP server with "sudo systemctl start isc-dhcp-server"

If all goes well "sudo systemctl start isc-dhcp-server" should show "active"

Update Cisco router with "ip helper-address" on the Foster interface using the ip address of the DHCP server (e.g. 192.168.1.100)

Getting DHCP to work for Foster laptop

Set Foster laptop to DHCP and obtain address and IP config

If it works, you should be able to ping the Skiff server

Submit (common file/screenshot

screenshot of "ip addr" command on Foster laptop showing the DHCP assignment

screenshot of the contents of "/var/lib/dhcp/dhcpd.leases" on skiff server showing DHCP lease

Update Tech Journal with any new Cisco or Kali commands

Booting Classroom NUCS to Kali Linux

1. Plug the USB Thumbdrive into the powered off workstation
2. Hit the F10 key during the NUC Splash Screen
3. From the Boot Menu – Select UEFI Vendor Product Code 2
4. Select “Live System (amd64)” (first option) from the menu
5. That will take you into a Live Kali Linux desktop
6. If needed:

Username: kali

Password: kali