Len(4)

TOS (8 bit)

Total Length

(16 bit)

Identification

(16 bit)

Data

Options+Padding

(N*32 bit)

Destination IP

(32 bit)

Source IP

(32 bit)

Header

Checksum (16 bit)

Protocol (8 bit)

TTL (8 bit)

fragment

offset (13 bit)

Vers(4)

flags(3)

15