DORA Process:
The
DORA process is an acronym for Discovery, Offer, Request, and Acknowledge,
which is the four-step process that a DHCP (Dynamic Host Configuration
Protocol) client and server use to obtain IP addresses and other network
configuration information
Here
is a brief explanation of each step of the DORA process:
Discovery:
The
DHCP client sends a broadcast DHCPDISCOVER message to the network, requesting
an IP address and other configuration information.
The
message is broadcast to all devices on the network using the destination
address of 255.255.255.255.
Here’s an example of a DHCPDISCOVER
packet capture:
This
is an example what packet info packet contain not real packet.
Ethernet
Src: client_mac_address
Dst: ff: ff: ff:ff:ff:ff
IPv4
Src: 0.0.0.0,
Dst: 255.255.255.255
User
Datagram Protocol,
Src Port: 68,
Dst Port: 67
Dynamic
Host Configuration Protocol (Discover)
Offer:
The
DHCP server receives the DHCPDISCOVER message and responds with a DHCPOFFER
message that includes an available IP address and other configuration
information.
The
message is unicast to the DHCP client using the client’s MAC address as the
destination.
Here’s
an example of a DHCPOFFER packet capture:
Ethernet
Src: server_mac_address,
Dst: client_mac_address
IPv4
Src: server_ip_address,
Dst: client_ip_address
User
Datagram Protocol
Src Port: 67
Dst Port: 68
Dynamic
Host Configuration Protocol (Offer)
Request:
The
DHCP client receives the DHCPOFFER message and sends a DHCPREQUEST message to
request to use the offered IP address and configuration information.
The
message is broadcast to all devices on the network using the destination
address of 255.255.255.255.
Here’s an example of a DHCPREQUEST packet
capture:
Ethernet —
Src: client_mac_address, Dst: ff: ff: ff:ff:ff:ff
IPv4 –
Src: 0.0.0.0, Dst: 255.255.255.255
User Datagram Protocol,
Src Port: 68, Dst Port: 67
Dynamic Host Configuration Protocol (Request)
Acknowledge:
The
DHCP server receives the DHCPREQUEST message and responds with a DHCPACK
message that includes the lease duration for the IP address and any other
configuration information.
The
message is unicast to the DHCP client using the client’s MAC address as the
destination.
Here’s an example of a DHCPACK packet
capture:
Ethernet
Src: server_mac_address,
Dst: client_mac_address
IPv4
Src: server_ip_address,
Dst: client_ip_address
User Datagram Protocol
Src Port: 67, Dst Port: 68
Dynamic Host Configuration Protocol (Ack)
After the DHCP client
receives the DHCPACK message, it configures its network settings and can begin
communicating on the network using the assigned IP address and other
configuration information. The DHCP lease duration is the amount of time that
the DHCP client can use the assigned IP address before it must request a