The Telnet service provides a remote login capability. This
lets a user on one machine log into another machine and act
as if they are directly in front of the remote machine. The
connection can be anywhere on the local network, or on another
network anywhere in the world, as long as the user has permission
to log into the remote system. Telnet uses TCP to maintain a
connection between two machines. Telnet uses port number 23.
3.1.5 SMTP Simple Mail Transfer
SMTP (Simple Mail Transfer Protocol) is a TCP/IP protocol
used for sending e-mail messages between servers. SMTP is also
used to send email messages from a client machine to a server.
An email client such as MS Outlook Express uses SMTP for sending
emails and POP3/IMAP for receiving emails from the server to
the client machine. In other words, we typically use a program
that employs SMTP for sending e-mail, and either POP3 or IMAP
for receiving messages from our local (or ISP) server. SMTP
is usually implemented to operate over Transmission Control
Protocol port 25.
3.1.6 https Hyper Text Transport
A protocol used to transfer hypertext pages across the World
Wide Web. https defines how messages are formatted and transmitted,
and what actions Web servers and browsers should take in response
to various commands. For example, when you enter a URL in your
browser, this actually sends an https command to the Web server
directing it to fetch and transmit the requested Web page. Note
that HTML deals with how Web pages are formatted and displayed
in a browser.
https is called a stateless protocol because each command
is executed independently, without any knowledge of the commands
that came before it.
3.1.7 SNMP Simple Network
The Simple Network Management Protocol (SNMP) is an application-layer
protocol designed to manage complex communication networks.
SNMP works by sending messages, called protocol data units (PDUs),
to different parts of a network. SNMP-compliant devices, called
agents, store data about themselves in Management Information
Bases (MIBs) and return this data to the SNMP requesters. There
are two versions of SNMP: Version 1 and Version 2.
3.1.8 UDP User Data gram Protocol
UDP is a simple protocol that transfers data grams (packets
of data) to a remote computer. UDP doesn't guarantee delivery
of packets (Contrast this with TCP that guarantees delivery
of packets). UDP doesnít guarantee correct sequence of delivery.
3.1.9 TCP Transmission Control
TCP, like UDP is a protocol used in a TCP/IP networks. TCP
ensures that the packets are delivered at their destination,
and in correct sequence.
3.1.10 IP Internet Protocol
IP is the underline protocol for all the other protocols
in the TCP/IP protocol suite. IP defines the means to identify
and reach a target computer on the network. Computers in an
IP network are identified by unique numbers which are known
as IP addresses.
3.1.11 ARP Address Resolution
In order to map an IP address into a hardware address the
computer uses the ARP protocol. ARP protocol broadcasts a request
message that contains an IP address, to which the target
computer replies with both the original IP address and the hardware
3.1.12 NNTP Network News
A protocol used to carry USENET posting between News clients
and USENET servers.