# TCP basics¶

TCP is one of the key protocols in today’s Internet. A TCP connection always starts with a three-way handshake. The exercises below should help you to improve your understandings of this first phase of a TCP connection.

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Once the connection is established, the client and the server can exchange data and acknowledgments.

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A connection ends with the transmission of segments that include the FIN flag that marks the end of the data transfer.

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TCP can be extended by using options that are negotiated during the three-way handshake.

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With your knowledge of TCP, you should now be able to reorder all the segments exchanged over a TCP connection.

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Footnotes