Initial Sequence Number Abuse

The ISN is a four byte integer
Used for TCP packet ordering.
Four bytes long.
ISN predictability is IP stack specific

Example encoding:

      Set the initial SYN packet to ((ASCII character) * KEY)
      Letter    ASCII   Key        ISN
      'D'   ==   68   * 9876  =>  671568
      'o'   ==  111   * 9876  =>  1096236
      'S    ==   83   * 9876  =>  819708
      ' '   ==   32   * 9876  =>  316032
      'n'   ==  110   * 9876  =>  1086360
      'o'   ==  111   * 9876  =>  1096236
      'w'   ==  119   * 9876  =>  1175244