1
Dynamic Host Configuration Protocol
Instructions
Set up a DHCP server on R4 (eth2) such that it leases IP addresses from the
10.10.11.X/28
subnet to the Ubuntu VM. Calculate the network, broadcast, and useable range of IP addresses
for your address range. Select the first useable IP address as the static address for the R4
interface (remember that we cannot use the network and broadcast). The remaining addresses
will go into the pool that the DHCP server will lease and manage.
Before starting this lab, please read RFC 2131.
Note:
Please make any necessary changes to the /etc/network/interfaces file of Ubuntu before
you proceed. The file should already have an existing entry for DHCP which includes:
iface eth0 inet dhcp
Part 1: Configuring DHCP
The first step is to configure the
dhcpd.conf
(DHCP daemon configuration) file in router R4.
This file is present in the /etc/dhcp directory. You can make edits to this file using any text
editor.
Consult the example configuration options in the
dhcpd.conf
file to configure your DHCP
server on R4. Make sure to set default-lease-time to 300.
Note that you do not need to provide configurations for the option domain-name or domain-
name-servers.
Part 2: Server Interface
Check the /etc/default/isc-dhcp-server file on R4. This file has to be changed so the DHCP
server knows which interface it should listen on for serving IP addresses.
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Part 3: Verifying DHCP and Wireshark
We will verify that Ubuntu has obtained an IP address.
1. Shutdown R4 and Ubuntu.
2. Power on Ubuntu and run Wireshark via the terminal: sudo wireshark
3. Monitor incoming traffic on the appropriate interface.
4. Now power on R4 and view Wireshark traffic on Ubuntu.
5. Use the following filter to show DHCP messages: udp.port == 67
6. Take a screenshot showing all captured DHCP messages.
Note:
Verify that the DHCP server is running properly on R4 by using the following command:
sudo systemctl status isc-dhcp-server.service
Submissions
[20 points] The leases file on R4 found in /var/lib/dhcp/dhcpd.leases
[20 points] Your configuration for the DHCP server.
[20 points] Screenshot of ifconfig on Ubuntu.
[20 points] Screenshot showing Ubuntu pinging R4.
[20 points] Screenshot showing Wireshark DHCP messages (4 Types).
Please remember to submit your lab results as a single PDF document. While you may work in
groups, you
MUST
submit your own work.
