IPv4 headers

Post author: ToRapture
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From: TCP/IP Illustrated, Volume 1: The Protocols.

IHL

The Internet Header Length (IHL) field is the number of 32-bit words in the IPv4 header, including any options. Because this is also a 4-bit field, the IPv4 header is limited to a maximum of fifteen 32-bit words or 60 bytes. ### Total Length The Total Length field is the total length of the IPv4 datagram in bytes. ### Protocol The Protocol field in the IPv4 header contains a number indicating the type of data found in the payload portion of the datagram. The most common values are 17 (for UDP) and 6 (for TCP).