/*
+-------------------+-----------------+------+
|       6 byte      |     6 byte      |2 byte|
+-------------------+-----------------+------+
|destination address|  source address | type |
+-------------------+-----------------+------+
*/

/*
+-------+-----------+---------------+-------------------------+
| 4 bit |   4 bit   |    8 bit      |          16 bit         |
+-------+-----------+---------------+-------------------------+
|version|head length|  TOS/DS_byte  |        total length     |
+-------------------+--+---+---+----+-+-+-+-------------------+
|          identification           | |D|M|    offset         |
+-------------------+---------------+-+-+-+-------------------+
|       ttl         |     protocal  |         checksum        |
+-------------------+---------------+-------------------------+
|                   source ip address                         |
+-------------------------------------------------------------+
|                 destination ip address                      |
+-------------------------------------------------------------+
*/

/*
+----------------------+---------------------+
|         16 bit       |       16 bit        |
+----------------------+---------------------+
|      source port     |  destination port   |
+----------------------+---------------------+
|              sequence number               |
+----------------------+---------------------+
|                 ack number                 |
+----+---------+-------+---------------------+
|head| reserve | flags |     window size     |
+----+---------+-------+---------------------+
|     checksum         |   urgent pointer    |
+----------------------+---------------------+
*/

/*
+---------------------+---------------------+
|        16 bit       |        16 bit       |
+---------------------+---------------------+
|    source port      |   destination port  |
+---------------------+---------------------+
| data package length |       checksum      |
+---------------------+---------------------+
*/

/*
+---------------------+---------------------+
|  1 byte  |  1 byte  |        2 byte       |
+---------------------+---------------------+
|   type   |   code   |       checksum      |
+---------------------+---------------------+
|    identification   |       sequence      |
+---------------------+---------------------+
|                  option                   |
+-------------------------------------------+
*/

/*
|<--------  ARP header  ------------>|
+------+--------+-----+------+-------+----------+---------+---------------+--------------+
|2 byte| 2 byte |1byte| 1byte|2 byte |  6 byte  | 4 byte  |     6 byte    |     4 byte   |
+------+--------+-----+------+-------+----------+---------+---------------+--------------+
| type |protocol|e_len|ip_len|op_type|source mac|source ip|destination mac|destination ip|
+------+--------+-----+------+-------+----------+---------+---------------+--------------+
*/

/*
+--------------------------+---------------------------+
|           16 bit         |1b|4bit|1b|1b|1b|1b|3b|4bit|
+--------------------------+--+----+--+--+--+--+--+----+
|      identification      |QR| OP |AA|TC|RD|RA|..|Resp|
+--------------------------+--+----+--+--+--+--+--+----+
|         Question         |       Answer RRs          |
+--------------------------+---------------------------+
|     Authority RRs        |      Additional RRs       |
+--------------------------+---------------------------+
*/