In our Everyday Life, we use many technical terminologies related to internet but we are not aware too much about them, here have a look upon some of them
BROADBAND
"Broadband" is the general term used to refer to high-speed network
connections. In this context, Internet connections via cable modem and
Digital Subscriber Line (DSL) are frequently referred to as broadband Internet
connections.
"Bandwidth" is the term used to describe the relative
speed of a network connection -- for example, most current dial-up modems can
support a bandwidth of 56 kbps (thousand bits per second).
There is no set
bandwidth threshold required for a connection to be referred to as
"broadband", but it is typical for connections in excess of 1 Megabit
per second (Mbps) to be so named.
CABLE MODEM ACCESS
A cable modem allows a single computer (or network of computers) to connect to
the Internet via the cable TV network. The cable modem usually has an Ethernet
LAN (Local Area Network) connection to the computer, and is capable of speeds
in excess of 5 Mbps.
Typical speeds tend to be lower than the maximum, however, since cable
providers turn entire neighborhoods into LANs which share the same
bandwidth.
Because of this "shared-medium" topology, cable
modem users may experience somewhat slower network access during periods of
peak demand, and may be more susceptible to risks such as packet sniffing and
unprotected windows shares than users with other types of connectivity.
DSL ACCESS
Digital Subscriber Line (DSL) Internet connectivity, unlike cable
modem-based service, provides the user with dedicated bandwidth. However, the
maximum bandwidth available to DSL users is usually lower than the maximum
cable modem rate because of differences in their respective network
technologies.
Also, the "dedicated bandwidth" is only dedicated between your home and the DSL provider's central office -- the providers offer little or no guarantee of bandwidth all the way across the Internet.
DSL access is not as susceptible to packet sniffing as cable modem access, but
many of the other security risks we'll cover apply to both DSL and cable modem
access.
BROADBAND SERVICE AND DIAL UP SERVICE
Traditional dial-up Internet services are sometimes referred to as
"dial-on-demand" services. That is, your computer only connects to
the Internet when it has something to send, such as email or a request to load
a web page. Once there is no more data to be sent, or after a certain amount of
idle time, the computer disconnects the call. Also, in most cases each call
connects to a pool of modems at the ISP, and since the modem IP addresses are
dynamically assigned, your computer is usually assigned a different IP address
on each call. As a result, it is more difficult (not impossible, just
difficult) for an attacker to take advantage of vulnerable network services to
take control of your computer.
Broadband services are referred to as "always-on" services because
there is no call setup when your computer has something to send. The computer
is always on the network, ready to send or receive data through its network
interface card (NIC). Since the connection is always up, your computer’s IP
address will change less frequently (if at all), thus making it more of a fixed
target for attack.
What’s more, many broadband service providers use well-known IP addresses for
home users. So while an attacker may not be able to single out your specific
computer as belonging to you, they may at least be able to know that your
service providers’ broadband customers are within a certain address range,
thereby making your computer a more likely target than it might have been
otherwise.
Corporate and government networks are typically protected by many layers of
security, ranging from network firewalls to encryption. In addition, they usually
have support staff who maintain the security and availability of these network
connections.
Although your ISP is responsible for maintaining the services they provide to
you, you probably won’t have dedicated staff on hand to manage and operate your
home network. You are ultimately responsible for your own computers. As a
result, it is up to you to take reasonable precautions to secure your computers
from accidental or intentional misuse.
PROTOCOL
A protocol is a well-defined specification that allows computers to communicate
across a network. In a way, protocols define the "grammar" that
computers can use to "talk" to each other.
IP
IP stands for "Internet Protocol". It can be thought of as the common
language of computers on the Internet. There are a number of detailed
descriptions of IP given elsewhere, so we won't cover it in detail in this
document. However, it is important to know a few things about IP in order to
understand how to secure your computer. Here we’ll cover IP addresses, static vs.
dynamic addressing, NAT, and TCP and UDP Ports.
IP ADRESS
IP addresses are analogous to telephone numbers – when you want to call someone
on the telephone, you must first know their telephone number. Similarly, when a
computer on the Internet needs to send data to another computer, it must first
know its IP address. IP addresses are typically shown as four numbers separated
by decimal points, or “dots”. For example, 10.24.254.3 and 192.168.62.231 are
IP addresses.
If you need to make a telephone call but you only know the person’s name, you
can look them up in the telephone directory (or call directory services) to get
their telephone number. On the Internet, that directory is called the Domain
Name System, or DNS for short. If you know the name of a server, say
www.cert.org, and you type this into your web browser, your computer will then
go ask its DNS server what the numeric IP address is that is associated with
that name.
Every computer on the Internet has an IP address associated with it that uniquely
identifies it. However, that address may change over time, especially if the
computer is
· dialing into an
Internet Service Provider (ISP)
· connected behind a
network firewall
· connected to a broadband service using
dynamic IP addressing.
STATIC AND DYNAMING ADDRESSING
Static IP addressing occurs when an ISP permanently assigns one or more IP
addresses for each user. These addresses do not change over time. However, if a
static address is assigned but not in use, it is effectively wasted. Since ISPs
have a limited number of addresses allocated to them, they sometimes need to
make more efficient use of their addresses.
Dynamic IP addressing allows the ISP to efficiently utilize their address
space. Using dynamic IP addressing, the IP addresses of individual user
computers may change over time. If a dynamic address is not in use, it can be
automatically reassigned to another computer as needed.
NAT
Network Address Translation (NAT) provides a way to hide the IP addresses of a
private network from the Internet while still allowing computers on that
network to access the Internet. NAT can be used in many different ways, but one
method frequently used by home users is called "masquerading".
Using NAT masquerading, one or more devices on a LAN can be made to appear as a
single IP address to the outside Internet. This allows for multiple computers
in a home network to use a single cable modem or DSL connection without
requiring the ISP to provide more than one IP address to the user. Using this
method, the ISP-assigned IP address can be either static or dynamic. Most
network firewalls support NAT masquerading.
TCP/ UDP PORT
TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are both
protocols that use IP. Whereas IP allows two computers to talk to each other
across the Internet, TCP and UDP allow individual applications (also known as
"services") on those computers to talk to each other.
In the same way that a telephone number or physical mail box might be
associated with more than one person, a computer might have multiple
applications(e.g. email, file services, web services) running on the same IP
address. Ports allow a computer to differentiate services such as email data
from web data. A port is simply a number associated with each application that
uniquely identifies that service on that computer. Both TCP and UDP use ports
to identify services. Some common port numbers are 80 for web (HTTP), 25 for
email (SMTP), and 53 for Domain Name System (DNS).
FIREWALL
A firewall is "a system or group of systems that enforces an access
control policy between two networks." In the context of home networks, a
firewall typically takes one of two forms:
Software firewall - specialized software running on an individual computer, or
Network firewall - a dedicated device designed to protect one or more
computers.
Both types of firewall allow the user to define access policies for inbound
connections to the computers they are protecting. Many also provide the ability
to control what services (ports) the protected computers are able to access on
the Internet (outbound access). Most firewalls intended for home use come with
pre-configured security policies from which the user chooses, and some allow
the user to customize these policies for their specific needs.
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