my most popular post...

after three months and not exactly sure why, but this is the one on the top of my charts... it was one of my earliest ones... maybe because it is a word description that doesn't rely on a diagram... you tell me...

here it is again...


this shit gets old...

The TCP segment includes 12 fields:

1. Source port  2. Destination port.  These first two fields identify the upper layer source and destination ports processed by TCP services. 3.  Sequence number usually specifies the number assigned to the first byte of data in the current message. It can also be used to identify an initial sequence number for a future transmission. 4.  Acknowledgement number, contains the sequence number of  the next byte of data the sender expects to receive.  5.  Data offset indicates the number of 32 bit words in the TCP header.  6.  Reserved-for future use. 7.  Flags- carries control information, including syn-ack bits for connection establishment, and FIN for connection termination.  8.  Window-specifies the size of the sender’s receive window (buffer space available for incoming data) 9.  Checksum-indicating header transmission damage if applicable.  10.  Urgent pointer- points to the first urgent byte in the packet 11.  Options-various tcp options, and 12. Data, contains upper layer information.