TCP and UDP solve this problem by using a port number field within the TCP or UDP header, respectively. Each of Hannah's TCP and UDP segments uses a special destination port number so that Jessie knows which application to give the data to. Figure 5-3 shows an example. Multiplexing relies on an idea called a socket. A socket consists of three. The TCP/Ip model is a compact version of the OSI model. It consists of 5 layers as compared to OSI models which have 7 layers.TCP and IP are two independent computer network protocols. IP is the part that obtains the address to which data is sent. TCP manages data delivery once that IP address has been found. Think of it this way. The TCP header is up to 24 bytes long and consists of the following fields: source port - the port number of the application on the host sending the data. ... options - various TCP options, such as Maximum Segment Size (MSS) or Window Scaling. NOTE. The header consists of fields for the source port, destination port, the datagram’s length, and a checksum. ... When hackers inspect a TCP segment, they can get enough information to create fake segments. This spoofing lets them transmit commands to the receiving system to support a breach. Generating random SNs should prevent this attack. .