Now we can try to parse the data that we sniffed, and unpack the headers. To parse a packet, we need to have an idea of the Ethernet frame and the packet headers of the IP.
The Ethernet frame structure is as follows:
The first six bytes are for the Destination MAC address and the next six bytes are for the Source MAC. The last two bytes are for the Ether Type. The rest includes DATA and CRC Checksum. According to RFC 791, an IP header looks like the following:
The IP header includes the following sections:
- Protocol Version (four bits): The first four bits. This represents the current IP protocol.
- Header Length (four bits): The length of the IP header is represented in 32-bit words. Since this field is four bits, the maximum header length allowed is 60 bytes. Usually the value is 5, which means five 32-bit words: 5 * 4 = 20 bytes.
- Type of Service (eight...
