Packet Headers
This workshop is about crafting packets so it makes sense to spend some time in understanding what packets are and how they are structured.
Illustrations on this page are reproduced work created and shared by Matt Baxter as seen at https://nmap.org/book/tcpip-ref.html
IP header
TCP header
| TCP flag | Binary | Decimal | TCP Dump syntax |
|---|---|---|---|
| URG | 00100000 | 32 | 'tcp[13] == 32' |
| ACK | 00010000 | 16 | 'tcp[13] == 16' |
| PSH | 00001000 | 8 | 'tcp[13] == 8' |
| RST | 00000100 | 4 | 'tcp[13] == 4' |
| SYN | 00000010 | 2 | 'tcp[13] == 2' |
| FIN | 00000001 | 1 | 'tcp[13] == 1' |
SYN-ACK = 00010010 = 18 RST-ACK = 00010100 = 20
TCP flags mnemonic - Unskilled Attackers Pester Real Security Folks
UDP header
ICMP header
ARP header
