TCP/IP Concepts Review – Chapter 2

This chapter was an overview of networking concepts with a focus on Transmission Control Protocol/Internet Protocol. (TCP/IP) It concluded by reviewing the following number systems binary, octal and hexadecimal. Within this section ‘nibbles’ were discussed with an emphasis on converting binary to decimal.

The section began with discussing protocol and specifically TCP/IP. It noted that TCP/IP was the most widely used protocol. It continued with the four layers application, transport, internet, and network giving a brief description of each one.

                                                   

                                       

 The chapter covers the six TCP segment flags which are:

 ◦SYN flag: The synch flag signifies the beginning of a session.

◦ACK flag: The acknowledgment flag acknowledges a connection and is sent by a host after receiving a

   SYN-ACK packet.

◦PSH flag: The push flag is used to deliver data directly to an application. Data isn’t buffered it’s sent

   immediately.

◦URG flag: This flag is used to signify urgent data.

◦RST flag: The reset flag resets or drops a connection.

◦FIN flag: The finish flag signifies that the connection is finished.

It also talks about the top TCP ports a security professional and penetration tester use and should understand. They are Ports 20&21, 25, 53, 69, 110, 119, 135, 139, and 143.

The chapter goes into IP addressing and explains classes A, B, and C. It also reviews IP address assignments and IPv6 addressing. This chapter was a great help for me.