TCP also known as (Transmission Control Protocol ) is a layer 4 protocol (Transport Layer) of an OSI Model. TCP is a connection-oriented transport layer protocol that provides reliable full-duplex data transmission. TCP is part of the TCP/IP protocol stack. In a connection-oriented environment, a connection is established between both ends before the transfer of information can begin. TCP breaks messages into segments, reassembles them at the destination, and resends anything that is not received. TCP supplies a virtual circuit between end-user applications. Common applications that use TCP connection are : FTP, HTTP, SMTP,TELNET etc.
TCP Ports:
A port number is a unique identifier used with an IP address. A port is a 16-bit unsigned integer, and the total number of ports available in the TCP/IP model is 65,535 ports. Therefore, the range of port numbers is 0 to 65535.
For example if you try to browser an ip address of 10.20.101.11 on TCP port of 8081 using browser we simple use
http://10.20.101.11:8081
[ Here 10.20.101.11 is remote computer IP address and 8081 is the port of remote computer ]
Here the server will listen on port 8081 to provide a web service to the client.
The Internet Assigned Numbers Authority (IANA) assigns port numbers. IANA is a standards body that is responsible for assigning various addressing standards.
1. Well-known Ports (Numbers 0 to 1023).
2. Registered Ports (Numbers 1024 to 49151)
3. Dynamic or Private Ports (Numbers 49152 to 65535)
TCP Three-Way Hand Shake
TCP 3-way handshake or three-way handshake is a process which is used in a TCP/IP network to make a connection between server and client.
´Three-way handshake process is designed in such a way that both ends help you to initiate, negotiate, and separate TCP socket connections at the same time. It allows you to transfer multiple TCP socket connections in both directions at the same time.
