TCP connection establishment and clearing
In this section we will learn how the TCP opens and closes its connections. In order to establish a connection, the three-way handshake procedure is used as described in the following section.
TCP three-way handshake
The three-way handshake is a connection establishment procedure from the client socket to the server socket, as shown in the following image:
The TCP state machine
Before the start of the TCP three-way handshake, the client will be in the CLOSED state and the server will be in the LISTEN state as shown:
|
SN |
TCP-A (122.167.84.137) STATE |
FLOW CTL |
TCP-B(10.0.0.221) STATE | ||
|---|---|---|---|---|---|
|
FROM |
TO |
FROM |
TO | ||
|
1 |
CLOSED |
CLOSED |
LISTEN | ||
To examine a three-way handshake in Wireshark, open the normal-connection.pcap file provided in the book.
Handshake message – first step [SYN]
The first step of the handshake process is that the socket client will construct a SYN packet and send it to the server. During this process the socket client will perform the...