IP Header Text Summary

Byte 0 - Bits 0-3 - IP version
Byte 0 - Bits 4-7 - IP header Length
Byte 1 - Differentiated Services or TOS
Byte 2 & 3 - Total IP datagram length
Byte 4 & 5 - IP Identification Field
Byte 6 - Bit 0 - Reserved Bit
Byte 6 - Bit 1 - Don't Fragment bit
Byte 6 - Bit 2 - More Fragments bit
Byte 6 - Bit 3 - First bit of Fragment Offset Field 
Byte 7 - Fragment Offset Field (with one bit from byte 6) 
Byte 8 - Time To Live Field 
Byte 9 - Embedded Protocol (TCP, UDP, ICMP, etc.) 
Byte 10 & 11 - IP Header CheckSum Bytes Bytes 12-15 - Source IP Address Bytes 
Bytes 16-19 - Destination IP Address 
Bytes 20 - 59 (optional) IP options - Loose or strict source routing, etc.
Minimum IP header size, 20 bytes, maximum size 60 bytes