Transmission Control
Protocol (TCP) Introduction
Introduction
The Transmission Control Protocol, or TCP as we will
refer to it from now on, is one of the most important
and well-known protocols in the world on networks today.
Used in every type of network world-wide, it enables
millions of data transmissions to reach their
destination and works as a bridge, connecting hosts with
one another and allowing them to use various programs in
order to exchange data.
The Need For Reliable Delivery
TCP is defined by
RFC 793 and was introduced to
the world towards the end of 1981. The motivation behind
creating such a protocol was the fact that back in the
early 80s, computer communication systems were playing a
very important role for the military, education and
normal office environments. As such, there was the need
to create a mechanism that would be robust, reliable and
complete data transmission on various mediums without
great losses.
TCP was designed to be able to deliver all of the above,
and so it was adopted promptly by the rest of the world.
Because TCP is not the type of protocol you can analyse
in one page, it has been separated and analysed over 13
pages in order to cover all its characteristics and help
you gain a better understanding of how it works and what
its capabilities are.
Section 1:
TCP, A Transport Protocol.
This page is a brief introduction
to TCP. It will show you how TCP fits into the OSI
Model, by using simple diagrams. It also helps you
understand the concept of a "Transport Protocol".
Section 2:
Quick TCP Overview.
This page is aimed for readers
requiring a good and quick overview of the protocol's
features without getting into too much technical detail.
Section 3:
The TCP Header/Segment.
Find out what the "TCP Header" and "TCP Segment" refer
to. These two terms are used quite often when talking
about the protocol, thus it is essential we understand
what these two terms are related to.
Section 4:
In-Depth TCP Analysis.
This subsection is a whole topic
in itself and deals with the in-depth analysis of the
TCP Header. We examine each field step-by-step, using
plenty of examples and our well known
cool-3D
diagrams to make sure you
understand all the material. This analysis is covered
over 7 pages of hardcore information, so be prepared!
Section 4.1:
TCP
Analysis - [Section 1]: Source & Destination port
number.
Find out what ports are and
how they are used in a typical data transfer.
Section 4.2:
TCP
Analysis - [Section 2]: Sequence & Acknowledgement
Numbers.
At last, everything you
wanted to know about sequence and acknowledgment
numbers. We will cover them in much detail using
plenty of diagrams to ensure you are not left with
unanswered questions.
Section 4.3:
TCP
Analysis - [Section 3]: Header Length.
We examine the meaning of this
field and how it is calculated.
Section 4.4:
TCP
Analysis - [Section 4]: TCP Flag Options.
This is one of the most important pages in our
in-depth analysis. Here you will learn what these
flags are, how many flags the protocol supports and
lastly, how they are used. We will also examine how
hackers can use specific flags to gain vital
information on remote systems.
Section 4.5:
TCP
Analysis - [Section 5]: Window Size, Checksum &
Urgent Pointer.
These fields play one of the
most important roles in bandwidth utilisation. Find
out how you can increase data throughput and
minimise delays between WAN links by playing around
with these fields! This page is highly recommended
for anyone seeking details about WAN link efficiency
and data throughput.
Section 4.6:
TCP
Analysis - [Section 6]: TCP Options.
This page is considered to be
an extension to the previous one. Here you will
learn about selective acknowledgments, window
scalling and several other options available to TCP
that ensure data is handled the best possible way as
it transits to its destination.
Section 4.7:
TCP
Analysis - [Section 7]: Data.
The reason for all of the
above! Our last section provides an overview of TCP
protocol and concludes with several good notes.
You will surely agree that there is much to cover in
this fantastic protocol. So, let us not loose any more
time and begin our cool analysis! If you need to grab
any brain food, now's your chance cause once we start
.... there is no stopping till we're done!
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