ping
https://inc0x0.com/tcp-ip-packets-introduction/tcp-ip-packets-2-analysis-of-a-raw-tcp-ip-packet/ https://inc0x0.com/icmp-ip-packets-ping-manually-create-and-send-icmp-ip-packets/ https://cseweb.ucsd.edu//~braghava/notes/freebsd-sockets.txt https://www.binarytides.com/raw-sockets-c-code-linux/