Hiding Text in Sequence Number Field of TCP / IP

The exchanging process inside Local Area Network (LAN) or through Internet may be exposed to be stolen, altered or damaged by baleful person who was represented as real threats to transport process. Wherefore this data must be secured against such threats. Many ideas was suggested under security concept for protecting data from this threats such as hiding content of the message sent which was named cryptography or concealment the existence of such message which was named steganography. Two ways were suggested to hide this data. One of them used the source port and destination port fields of the Transmission Control Protocol (TCP) header as the Stego key. And the other use the combination of source and destination port fields of the Transmission Control Protocol (TCP) header with the protocol and version fields of the Internet Protocol (IP) header. The process is summarized by the implementation of the exclusive OR (XOR) between those data required to be hidden with the STEGO key.A sequence number field was selected from the Transmission Control Protocol (TCP) to be the carrier for hidden data. Four characters are included in this field and sent in one connection.