WIRESHARK DHCP PACKET ANALYSIS

DHCP Stands for Dynamic Host Configuration Protocol.

It is used to dynamically assign TCP / IP configuration parameters to the  devices .

TCP/IP Parameters – IP address , Subnet mask , Default gateway , DNS IP address etc.

DHCP Client receives TCP / IP configuration parameters from DHCP Server.

DHCP PROCESS 

The process by which DHCP Server lease TCP/IP Configuration to DHCP Client is 

                       "  D     O     R     A    "   

D - Discover                   
O - Offer
R - Request
A - Ack

DHCP PACKET FORMAT

DISCOVER

CLIENT -> SERVER
It is a broadcast message.
By using this message client discover the DHCP Server.
Source IP – 0.0.0.0
Destination IP- 255.255.255.255
Source MAC :- MAC address of client interface
Destination MAC :- ff:ff:ff:ff:ff:ff
Source UDP Port 68
Destination UDP Port 67

OFFER

SERVER -> CLIENT
It is includes TCP/IP Configuration Parameters.
By using this message client discover the DHCP Server.
Source IP – DHCP SERVER IP
Destination IP- 255.255.255.255
Source MAC :- MAC address of  DHCP Server.
Destination MAC :- ff:ff:ff:ff:ff:ff
Source UDP Port 67
Destination UDP Port 68

REQUEST

CLIENT -> SERVER
Client accepts the offer and send Request broadcast message to request the TCP /IP Configuration offered  by the Server.
Source IP – 0.0.0.0
Destination IP- 255.255.255.255
Source MAC :- MAC address of  Client.
Destination MAC :- ff:ff:ff:ff:ff:ff
Source UDP Port 68
Destination UDP Port 67

ACK

SERVER -> CLIENT
Server sents ACK to client and lease the TCP/IP Configuration parameters.
Source IP – DHCP Server IP
Destination IP- 255.255.255.255
Source MAC :- MAC address of  Server.
Destination MAC :- ff:ff:ff:ff:ff:ff
Source UDP Port 67
Destination UDP Port 68

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