DHCP - DORA Process

DORA

    DORA is the process that DHCP employs (Dynamic Host Configuration Protocol). It's used to provide clients/host machines with their IP addresses. It is divided into four phases and acquires the IP address from a centralized server.

D-Discover

O-Offer

R-Request

A-Acknowledgment

[BROADCAST] DHCP Discover

• The first communication in the DORA Process is the Discover message, which is used to locate the DHCP Server in the network.

• The host will broadcast a Discover message over the network to locate a DHCP Server.

• 255.255.255.255 is the packet address.

• Because the host does not have an IP address, the IP is currently 0.0.0.0.

• PORTS [at the client - 68] / [at the server - 67].

• The server will use the host's MAC Address to reach out to it.

• Transaction ID: which maintains the specific DHCP session between client-server, which remains the same during [discover + offer] ] the processes.

[UNICAST] DHCP Offer

• When the server receives the Discover Request, it sends the client a DHCP Offer request.

• This offers information about an IP address and the length of time a host can utilize i

• It's a message that's only sent to one person.

[BROADCAST] DHCP Request

• After receiving the Offer packet, the host responds with a Request message

• This message informs the server that it is prepared to accept the IP address offered by the serve

• The broadcast IP is still 255.255.255.255, and this IP is still 0.0.0.0.

[UNICAST] DHCP Acknowledgement

• The host sends the request to the server.

• This message is a response to the host's request message.

• It will also send a DHCP Acknowledgement request to the host. Which will contain the host's IP address and subnet mask as allowed by the server.