A protocol defines common rules for network communication between devices. Some common protocols include HTTP, HTTPS, FTP, SMTP, and Telnet. HTTP is used for web browsing and transferring HTML files. HTTPS provides secure communication over HTTP using encryption. FTP transfers files between servers and clients. SMTP sends and receives email. Telnet allows interactive text-based sessions between devices. Each protocol has a specific purpose and set of rules for data exchange and transmission.

2. WHAT IS A PROTOCOL?
A protocol defines a common set of
rules used by network computers to
share data and communicate.
Two computers must use a common
protocol to be able to communicate
with each other.
In the same way, two or more

3. TYPES OF PROTOCOL.
• HTTP(Hyper Text
Transfer Protocol)
• HTTPS(Hyper Text
Transfer Protocol
Secure)
• FTP(File Transfer
Protocol)
• SMTP(Simple Mail
Transfer Protocol)
• TELNET
THERE ARE
MANY TYPES
OF
PROTOCOL
BUT THE
COMMONLY
USED ONE
ARE:

4. Basic requirements for protocols.
• Data formats for data exchange.
• Address formats for data
exchange.
• Address mapping.
• Routing.
• Detection of transmission errors.
• Direction of information flow .

5. Hyper Text Transfer Protocol.(HTTP)
The Hypertext Transfer Protocol (HTTP) is
an application protocol for distributed,
collaborative, hypermedia information
systems.
HTTP is the foundation of data
communication for the World Wide Web.
Hypertext is structured text that uses
logical links (hyperlinks)
between nodes containing text.

6. HISTORY OF HTTP.
 The term hypertext was coined by Ted
Nelson in 1965 in the Xanadu Project, which
was in turn inspired by Vanneva Bush's
vision (1930s) of the microfilm-based
information retrieval and management
"memex" system described in his essay As
We May Think (1945).
The first documented version of HTTP
was HTTP V0.9 (1991).
RFC 1945 officially introduced and

7. An HTTP session is a sequence of
network request-response
transactions.
An HTTP client initiates a request by
establishing a Transmission Control
Protocol (TCP) connection to a
particular port on a server (typically
port 80, occasionally port 8080).
An HTTP server listening on that port

8. Access to HTTP or HTTP Authentication.
 HTTP provides multiple authentication
schemes such as Basic access
authentication and Digest access
authentication which operate via a challenge-
response mechanism whereby the server
identifies and issues a challenge before
serving the requested content.
 HTTP provides a general framework for
access control and authentication, via an
extensible set of challenge-response
authentication schemes, which can be used

9. Request Methods in HTTP.
Some of the common request
methods in HTTP are:
 GET
 HEAD
 POST
 PUT
 DELETE
 TRACE
 CONNECT
 PATCH, ETC…

10. Hypertext Transfer Protocol Secure. (HTTPS).
 HTTPS is
a protocol for secure communication over a
computer network which is widely used on
the Internet.
 HTTPS consists of communication
over Hypertext Transfer Protocol (HTTP)
within a connection encrypted by Transport
Layer Security or its predecessor, Secure
Sockets Layer.

11. History of HTTPS.
 Netscape Communications created
HTTPS in 1994 for its Netscape
Navigator web browser.
 Originally,HTTPS was used with
the SSL protocol. As SSL evolved
into Transport Layer
Security (TLS), the current version

12. What is the Difference between HTTP & HTTPS.
 HTTP is not encrypted and is vulnerable to
man-in-the-middle and eavesdropping
attacks, which can let attackers gain access
to website accounts and sensitive
information, and modify webpages to
inject malware or advertisements.
 HTTPS is designed to withstand such
attacks and is considered secure against
them (with the exception of older,

13. Limitations of HTTPS.
SSL/TLS comes in two options, simple and
mutual. The mutual version is more secure,
but requires the user to install a
personal client certificate into their web
browser in order to authenticate
themselves.
Whatever strategy is used (simple or
mutual), the level of protection strongly
depends on the correctness of

14. File Transfer Protocol (FTP).
 The File Transfer Protocol (FTP) is a
standard network protocol used to
transfer computer files between a
client and server on a computer
network.
 FTP is built on a client-server model
architecture and uses separate
control and data connections between
the client and the server.

15. History of FTP.
The original specification for the File
Transfer Protocol was written
by Abhay Bhushan and published
as RFC 114 on 16 April 1971. Until
1980, FTP ran on NCP, the predecessor
of TCP/IP.
The protocol was later replaced by a

16. Security in FTP.
FTP was not designed to be a secure protocol, and
has many security weaknesses.
In May 1999, the authors of RFC 2577 listed a
vulnerability to the following problems:
• Brute force attack
• FTP bounce attack
• Packet capture
• Port stealing
• Spoofing attack
• Username protection

17. Commands in FTP(some).
Command RFC Description
ABOR Abort an active file transfer.
ACCT Account information.
ADAT RFC 2228 Authentication/Security Data
ALLO
Allocate sufficient disk space to receive a
file.
APPE Append.
AUTH RFC 2228 Authentication/Security Mechanism
CCC RFC 2228 Clear Command Channel
CDUP Change to Parent Directory.
CONF RFC 2228 Confidentiality Protection Command

18. Simple Mail Transfer Protocol(SMTP).
 Simple Mail Transfer Protocol (SMTP)
is an Internet standard for electronic
mail (email) transmission.
 First defined by RFC 821 in 1982, it
was last updated in 2008 with
the Extended SMTP additions by RFC
5321 —which is the protocol in

19. History of SMTP.
 Various forms of one-to-one electronic
messaging were used in the 1960s. People
communicated with one another using
systems developed for
specific mainframe computers.
 As more computers were interconnected,
especially in the US Government's
ARPANET, standards were developed to
allow users of different systems to email
one another.

20. How is the mail processed in SMTP? (model).
Email is submitted by a mail client
(MUA, mail user agent) to a mail server
(MSA, mail submission agent) using
SMTP on TCP port 587.
Most mailbox providers still allow
submission on traditional port 25.
From there, the MSA delivers the mail
to its mail transfer agent (MTA, mail
transfer agent).

21. Commands in SMTP.
MAIL command, to establish the
return address
RCPT command, to establish a
recipient of this message
DATA to signal the beginning of

22. TELNET
• Telnet is an application layer protocol
used on the Internet or local area
networks to provide a bidirectional
interactive text-oriented
communication facility using a
virtual terminal connection.
• The term telnet is also used to refer to
the software that implements the client
part of the protocol.

23. History of TELNET.
Telnet is a client-server protocol, based on
a reliable connection-oriented transport.
Typically, this protocol is used to establish
a connection to Transmission Control
Protocol(TCP) port number 23, where a
Telnet server application is listening.
Telnet is best understood in the context of a
user with a simple terminal using the local
Telnet program (known as the client
program) to run a logon session on a

24. Security in TELNET.
Telnet, by default, does
not encrypt any data sent over the
connection (including passwords).
 So it is often feasible to eavesdrop on
the communications and use the
password later for malicious
purposes; anybody who has access to
a router, switch, hub or gateway locate
d on the network between the two
hosts.

25. List of various Protocols.
WIFI/WIMAX Protocols
Bluetooth protocol
Fibre Channel network protocols
Yahoo! Messenger, underlying protocol used
by the Yahoo messenger
RTPS protocol, an interoperability protocol
SSH Secure Shell