9
As
mentioned before,
Internet
protocols,
developed and
promoted
by
Internet
Engineering
Task
Force,
are
used
as
a
set
of
communication
rules
over
Internet,
thus
nearly
every
type
of
computer
system
can
communicate over
Internet.
This
is
possible
only because of
the agreement to
employ these
rules.
The
most
important protocols are
Transmission Control Protocol (TCP) and Internet Protocol (IP).
TCP and IP are
designed
for
communication over
dedicated,
high-speed
transmission
lines.
Other
protocols,
intended
for
use
over
conventional telephone
lines,
are
the
Point-to-Point
Protocol (PPP)
and
the
older
Serial
Line
Internet
Protocol (SLIP).
May
commercial
Internet
providers
offer
PPP
or
SLIP
connections
to
users
that
are
not
using
a
full
TCP/IP connection [3].
Every
host
in
Internet basically
has
its
unique address
to
distinguish each other.
There
are
two
types
of address that
host
can
use:
IP address
and
MAC (Media Access
Control) address.
IP
address
is a 32-bit binary address,
which consists of
four
groups
of
digits
separated
by
periods
or
dots.
This
is
the
IPv4
version
of
IP
address
that
is
still
regularly
used
until
these
days.
The
latest
version,
IPv6
which
uses
6
numbers
rather
than
4,
is
still
under development progress. When
IP
addresses are
assigned
to
computers, some of the bits on the
left side of the 32-bit IP number are used to represent
a
network
[8].
And
the
rest
of
the
numbers
represent
the
host
in
the
network,
usually
called
network
address.
In
classful
networks,
the
number of
bits designated depends on
the
address
class.
There
are
several
classes
of
address,
used
with
different
purposes:
class A, class B, class C, class D, and class E. Computer’s IP address usually consists of
a
network portion and a
host portion that represents a particular computer on a particular
network [8]. IP address is assigned to a host so that other hosts know how to identify and
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