tcp uses the sequence number in a segment to determine the sequence number of that segment for the rest of the packet. For the purposes of this tutorial, we will assume that a packet is always going to be in a particular sequence.
If you are not interested in learning how tcp works, then you can simply skip to the next section.
Every TCP segment is either a “payload” or a “payload fragment.” The payload is the data that is sent and the fragment is the data that is received.
The sequence number in a TCP segment is the number that tcp uses to tell how many bytes to write in the payload. The sequence number is usually the same as the number of bytes in the payload, but sometimes the sequence number is adjusted. In this section, however, we will assume that the sequence number is always the same.
TCP segments are used to carry data for a number of reasons, but they are usually considered to be for the transfer of data between two hosts. Since TCP is designed to transfer data between two hosts, the sequence number is very important. TCP segments are usually sent and received in a specific order, but not always. In TCP, however, data is usually sent along the entire length of the segment, starting at the beginning and ending at the end of the segment.
TCP segments can be viewed as being like strings of numbers, but there is one exception. When a segment is sent, the sequence number is part of the length of the segment because it is the same as the number of bytes you send in a TCP segment.
The sequence number is part of the TCP header. It is just like the sequence number in UDP, except that TCP does not use the same syntax. It is not written out in the same way. TCP segment headers are usually written in the same order as the TCP segment itself.
TCP header values are used in packet headers and are written in the same order. If a segment has a sequence number in the TCP header, it can be used in TCP segments as well. TCP has a very special syntax for this. The TCP header is called a Segment Identifier (SID), which is a hexadecimal number. The first byte of the SID that is sent is the sequence number. The next byte is the source IP address of the packet.
The sequence number can be used in TCP segments to determine if the segment is for a new connection or if it represents a sequence of an already established connection. Some examples are: a new TCP connection, a TCP SYN packet, and a TCP FIN packet. The sequence number is used by TCP to identify every packet that follows. You can read more about tcp sequence numbers here.
There are two ways to use the sequence number to identify a packet, depending on how you are using it. The TCP and the IP protocols use the sequence number to identify the packet. In TCP, each packet, whether it’s a SYN, SYN+ACK, or FIN, has a sequence number. The sequence number is used to identify what kind of packet it is.
