TryHackMe — Networking Essentials | Cyber Security 101 (THM)

DHCP: Give Me My Network Settings

1. You opened your laptop at a coffee shop, connected to the WiFi, and it automatically configured the network without manually entering an IP address.
2. To access a network, devices need:

• IP address and subnet mask
• Router (gateway)
• DNS server

1. Manual configuration is ideal for servers, which remain static on the network. Automated configuration is advantageous for mobile devices, preventing address conflicts where two devices have the same IP.
2. The Dynamic Host Configuration Protocol (DHCP) simplifies this process. It uses UDP, with servers listening on UDP port 67 and clients on UDP port 68.
3. DHCP follows four steps: Discover, Offer, Request, and Acknowledge (DORA):

• Discover: Client broadcasts a DHCPDISCOVER message to find a DHCP server.
• Offer: Server replies with a DHCPOFFER message, offering an IP address.
• Request: Client responds with a DHCPREQUEST message, accepting the offered IP.
• Acknowledge: Server sends a DHCPACK message, confirming the assignment of the IP address.

1. A packet capture example shows the DHCP process, where the client receives the address 192.168.66.133:
2. Key points:

• The client initially has no IP…