A protocol is a standard set of rules that allow electronic devices to communicate with each other.
These rules include what type of data may be transmitted, what commands are used to send and receive data, and how data transfers are confirmed
Some common protocols in use today for computers are TCP/IP, HTTP, HTTPS, FTP, SFTP, Telnet, SSH, SCP, etc.
1.TCP/IP (Transmission Control Protocol/Internet Protocol):-
It is the communication protocol for the Internet, it defines the rules that computers and other network devices must follow to communicate with each other over the Internet. Browsers and servers use TCP/IP to connect to the Internet. A browser uses TCP/IP to access a server.
A server uses TCP/IP to send HTML data back to a browser . Your e-mail program uses TCP/IP to connect to the Internet for sending and receiving e-mails.
HTTP (Hypertext Transfer Protocol):-
HTTP or Hypertext Transfer Protocol is the main protocol of the World Wide Web. When you request a Webpage by typing its address into your web browser, that request is sent using HTTP. The browser is an HTTP client , and the Web page server is (not surprisingly) an HTTP server .
In essence, HTTP defines a set of rules as to how messages and other data should be formatted and exchanged between servers and browsers.
HTTPS (Hypertext Transfer Protocol Secure):-
HTTPS or Hypertext Transfer Protocol Secure is an Padlock icon extension of HTTP for secure communications over the Internet.
This protocol uses TLS (Transport Layer Security) or SSL (Secure Sockets Layer) to encrypt data to ensure the authentication of the accessed websites and protection of the privacy and integrity of the exchanged data while making an online transaction.
REMOTE LOGIN AND FILE TRANSFER PROTOCOLS:-
Remote Login (Rlogin) is the ability of accessing the content of a computer located at a different location from a remote site over a public or private network.
This allows employees of an organization to work offsite or an individual to gain access to his/her home computer and work with it even from a distant location. To secure the log in process some protocols are also used.
Telnet (Telecommunications Network):-
Telnet is a contraction of the words Telecommunications Network, and is one of the major network protocols used on the Internet. It allows you to connect to the remote computers (called hosts) over a TCP/IP network (such as the Internet).
The user’s computer, which initiates the connection, is referred to as the local computer, and the machine being connected to, which accepts the connection, is referred to as the remote or host,
FTP (File Transfer Protocol):-
When you want to copy files between two computers that are on the same local network, often you can simply “share” a drive or folder and copy the files the same way you would copy files from one place to another on your own PC.
Transferring Files Using FTP:-
FTP is an application protocol that uses the Internet’s TCP/IP protocol layer to transfer Web pages from a client computer to a Web Server. Transferring files from a client computer to a server computer is called “uploading” and transferring them from a server to a client is “downloading”.
SSH (Secure Shell) Protocol:-
The Secure Shell or SSH is a network protocol that allows users secure access to a remote computer over an unsecured network such as the Internet. It provides options for strong authentication and encrypts data securely to protect the security and integrity of communications between two computers.
SCP (Secure Copy Protocol):-
Secure Copy Protocol (SCP) is a network protocol designed for secure transferring of files across a network (Internet). This protocol can be used to securely transfer files between a local computer and a remote computer (host) or between two remote computers. It runs over a secure channel (SSH) for data transfer and uses the same mechanisms for authentication.
SFTP (Secure FTP):-
Protocol SFTP or Secure File Transfer Protocol (also known as SSH File Transfer Protocol) is a secure version of File Transfer Protocol (FTP). It facilitates files access and files transfer over a Secure Shell(SSH) data steam. It is part of the SSH protocol.
Capabilities of SFTP over SCP:-
Although both SFTP and SCP run over the same Secure Shell (SSH) to transfer data securely, but SFTP provides more features than SCP.
PROTOCOLS USED IN E-MAILS:-
Protocols are used to send and receive e-mails from one computer to another computer over a network or the Internet. Let us learn about some important protocols used in sending and retrieving e-mails.
SMTP (Simple Mail Transfer Protocol):-
SMTP takes care of sending emails. Often emails are sent to an email server (SMTP server), then to other servers, and finally to its destination. SMTP can only transmit pure text. It cannot transmit binary data like pictures, sounds or movies .
POP (Post Office Protocol):-
The POP protocol is used by email programs to retrieve emails from an email server. If your email program uses POP, all your emails are downloaded to your email program (also called email client),each time it connects to your email server.
MIME (Multi-purpose Internet Mail Extensions):-
The MIME protocol lets SMTP transmit multimedia files including voice, audio and binary data across TCP/IP networks . The MIME protocol converts binary data to pure text, before it is sent
IMAP (Internet Message Access Protocol):-
The IMAP protocol works much like the POP protocol. The main difference is that the IMAP protocol will not automatically download all your emails each time your email program connects to your email server.
It allows you to look through your email messages at the email server before you download them giving you a choice either to download your messages or just delete them.