This document provides information about three computer networking topics: Telnet, VoIP, and HTTPS. It describes Telnet as a remote login protocol that allows users to access terminals on other systems. It explains the basic working of Telnet and how a connection is established. VoIP is summarized as using Internet Protocol to transfer voice calls by digitizing, compressing, and transmitting voice data in packets. Finally, it states that HTTPS secures communications between browsers and websites using TLS/SSL encryption to protect against eavesdropping and spoofing.

1. Computer Seminar
Made By: Arman

2. Contents
• Telnet
• VoIP
• Https

3. Telnet
Telnet is a remote login that helps a user to log on to another user’s terminal without being its
original user. A user who is logging in to their own system can also get access to log on to another
user system and perform various functions such as accessing files or sharing files to/from the remote
system. With TELNET, a user logs in as a regular user with whatever privileges that may have been
granted to the specific application and data on that computer.

4. Working of Telnet
(i) A user is logged in to the local system and invokes a TELNET program (the TELNET client)
by typing telnet<host address> or telnet <IP address>
(ii) The TELNET client is started on the local machine (if it isn’t already running). The client
then establishes a TCP connection with the TELNET server on the destination system.
(iii) Once the connection has been established, the client program accepts characters from
the keyboard feed by the user and passes one character at a time, to the TELNET server.

5. (iv) The server on the destination machine accepts the characters sent to it by the client and passes
them to a terminal server.
(v) The terminal server gives outputs back to the TELNET server and displays them on the user’s
screen. The user can terminate the telnet session by typing LOGOFF or LOGOUT on the system
prompt.

6. VoIP( Voice over Internet Protocol
• VoIP stands for Voice over Internet Protocol. For transferring of voice, voice over internet protocol
is used. The voice calls are first digitized, compressed and then fragmented into small packets,
which are then relayed by Internet Protocol (IP) cross network. Voice-over-IP (VoIP)
implementation enables users to carry voice traffic (For example, telephone calls and faxes) over
an IP network. So, VoIP can be achieved on any data network that uses IP, like the internet,
Computer Networks intranets and Local Area Networks (LAN). As the data is transmitted in the
form of packets, VoIP uses packet switching technology where each packet follows best route to
reach its destination. VoIP allows both voice and data communications to be run over a single
network, which can significantly reduce infrastructure costs.

7. • There are 3 main causes for the evolution of the voice-over IP market:
• 1. Low-cost phone calls
• 2. Add-on services and unified messaging
• 3. Merging of data/voice infrastructures
• Services provided by VoIP are:
• Phone to phone, PC to phone, phone to PC, fax to email, email to fax, fax to fax, voice to email, IP
Phone, transparent CCS (TCCS), toll free number (1-800), class services, call centre applications,
VPN, Unified Messaging, Wireless Connectivity, IN Applications using SS7, IP PABX and soft switch
implementation.
• The various protocols used for VoIP are:
• 1. H.323
• 2. Session Initiation Protocol (SIP)

8. H.323 is a protocol that provides communication for multimedia services such as audio, video and
data communication over packet-based network. It specifies the standards and protocols for all
these services. As H.323 provides various communication facilities, it can be applied in a wide variety
of areas—consumer, business and entertainment applications. H.323 supports call set-up, teardown
and forwarding/transfer. A key feature of H.323 is Quality of Service (QoS). QoS technology allows
real-time prioritization and traffic management constraints to be placed on “best-effort” packet
delivery systems like TCP/IP over Ethernet. It can be applied in a variety of mechanisms:
• Audio only
• Audio and data
• Audio and video
• Audio, video and data
H.323 protocol for VoIP

9. The expanded form of SIP is Session Initiation Protocol. SIP is a communication protocol (more
specifically, a signalling protocol) originally developed in 1996. It uses IP protocol that establishes,
modifies and terminates VoIP telephone calls. It provides video conferencing service to the users, so
that a user can communicate with more than one person at a time. Other SIP applications include
streaming multimedia distribution, instant messaging and information, file transfer, fax over IP and
online games. SIP transparently supports name mapping and redirection services which support
personal mobility.
SIP protocol for VoIP

10. • . Hypertext Transfer Protocol Secure (HTTPS) is a protocol that secures communication and data
transfer between a user's web browser and a website. HTTPS is the secure version of HTTP.
• The protocol protects users against eavesdroppers and man-in-the-middle (MitM) attacks. It also
protects legitimate domains from domain name system (DNS) spoofing attacks.
Https

11. • . A malicious actor can easily impersonate, modify or monitor an HTTP connection. HTTPS provides
protection against these vulnerabilities by encrypting all exchanges between a web browser
and web server. As a result, HTTPS ensures that no one can tamper with these transactions, thus
securing users' privacy and preventing sensitive information from falling into the wrong hands.
• HTTPS is not a separate protocol from HTTP. Rather, it is a variant that uses Transport Layer
Security (TLS)/Secure Sockets Layer (SSL) encryption over HTTP to secure communications. When
a web server and web browser talk to each other over HTTPS, they engage in what's known as
a handshake -- an exchange of TLS/SSL certificates -- to verify the provider's identity and protect
the user and their data.
• An HTTPS URL begins with https:// instead of http://. Most web browsers show that a website is
secure by displaying a closed padlock symbol to the left of the URL in the browser's address bar. In
some browsers, users can click on the padlock icon to check if an HTTPS-enabled website's digital
certificate includes identifying information about the website owner, such as their name or
company name.
Https vs Http