OSI Model Summary

fossjon
OSI Layers – Summary
 
Layer 2 – Data Link – Frame (802.3/Ethernet)
Dst MAC (6 bytes) Src MAC (6 bytes) 802.1q (4 bytes) [opt] Type/Leng (2 bytes)
Layer 3 – Network – Packet (IPv4)
Version/IHL (1 byte) DSCP/ECN (1 byte) Leng (2 bytes)
Identification (2 bytes) Flags/Frag Offset (2 bytes)
TTL (1 byte) Protocol (1 byte) Header Checksum (2 bytes)
Src IP (4 bytes)
Dst IP (4 bytes)
Layer 4 – Transport – Segment (UDP)
Src Port (2 bytes) Dst Port (2 bytes)
Leng (2 bytes) Checksum (2 bytes)
 
Layer 4 – Transport – Segment (TCP)
Src Port (2 bytes) Dst Port (2 bytes)
Leng (2 bytes) Checksum (2 bytes)
Sequence Number (4 bytes)
Acknowledgment Number (4 bytes)
Data Offset (1 byte) Flags (1 byte)
SYN/ACK/RST/FIN		 Window Size (2 bytes)
Layer 5/6/7 – Application – Data (DHCP/DNS/SSH/HTTP)
Payload
OSI Model Summary

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