Exercise Debian DHCP Server

Exercise 3: DHCP Service on srv1

Building on Exercise 1, add a DHCP service to srv1 so that clients on the LAN segment — including client1 — receive their network configuration automatically instead of via static assignment.

1. DHCP Server Installation & Configuration (isc-dhcp-server)

Install isc-dhcp-server on srv1 and configure it as follows:

• The service must only offer DHCP on the LAN interface (the host-only network) — it must not listen on or respond to requests from the WAN/NAT interface.
• Subnet: 172.30.0.0/16, matching the network srv1 and client1 are already on.
  • srv1’s own static address (172.30.0.1) must not be part of the handed-out address pool.
  • Define a reasonable range of addresses to lease to clients.
• DNS option: Clients must be told to use srv1 (172.30.0.1) as their DNS server.
• Domain option: Clients must be told the domain name mydomain.intern.

2. Client Reconfiguration (client1)

Change client1’s LAN interface from static addressing to DHCP, so it obtains its IP address, subnet mask, and DNS server automatically from srv1.

3. Verification & Proof

1. Lease assignment: Confirm client1 received an IPv4 address within 172.30.0.0/16 via DHCP (e.g. ip a on client1), and that srv1 shows a corresponding lease was issued.
2. DNS configuration: Confirm client1’s resolver was automatically set to 172.30.0.1 (e.g. check its resolver configuration).
3. DNS resolution (repeat from Exercise 1): From client1, re-run the forward, reverse, and forwarder resolution tests using dig and nslookup, and confirm they still succeed now that addressing comes via DHCP instead of static configuration.
4. Interface restriction: Confirm the DHCP service on srv1 is not offering or responding to requests on the WAN/NAT interface.