(Recently, Arp-related malware has become more and more rampant, and there are many victims. Major domestic anti-virus manufacturers have also launched Arp firewalls. This article is not a popular science, but an idea. In addition, it only takes a little more than a week to learn to contact and understand the Arp protocol to write the testcode of Arp spoofing and anti-spoofing. Limited experience, omissions are inevitable, please forgive me.)