DHCP

Download Lab

Download the lab from here.

tar -xvf lab-dhcp.tar.xz
cd dhcp

Look at the contents of lab.yml and the .startup files. You can see we have the following machines:

  • dh - DHCP server. This is also a gateway to the Internet.

  • pc - our client for testing DHCP.

Start Lab

koble lab start

First we will set up tcpdump to listen for traffic on machine dh.

dh
tcpdump -s0 -i eth1 -w /hostlab/dhcp_lab-1.pcap

First on pc we can check our network settings:

pc
ip addr show eth0
ip route show

You should be able to see that we have no IP address and there is no default route.

pc
dhclient -v eth0

Now we can stop tcpdump on dh and view the capture from wireshark on the host.

If we check the network settings again we should have an IP address from the pool 10.72.16.50-10.72.16.150. and a default route to the gateway 10.72.16.254.

pc
ip addr show eth0
ip route show

As we have an IP address and gateway we can reach the internet:

pc
ping -c1 google.com

Task

Modify the DHCP server configuration so we get the set IP address 10.72.16.28

Solution
/etc/dnsmasq.conf (dh)
...

dhcp-host=4e:a5:c4:29:3d:7c,10.72.16.28
dh
systemctl restart dnsmasq

Now you should be able to get this IP address from the DHCP server:

pc
dhclient -r # release current IP
dhclient -v eth0

Check that the IP address has been set correctly:

pc
ip addr show eth0

You can now shutdown and remove the machines with:

koble lab destroy