What is ARP (address resolution protocol)?

Address resolution protocol , namely ARP（Address Resolution Protocol）, It's based on IP Address obtain Physical address One of the TCP/IP agreement .

host The destination... Will be included when sending the message IP Address of the ARP Request broadcast to all hosts on the LAN , And receive the return message , To determine the physical address of the target ; After receiving the return message, it will be IP The address and physical address are stored in the machine ARP Cache and keep it for a certain time , The next time you ask for it, look it up directly ARP Cache to save resources .

The address resolution protocol is based on the mutual trust of each host in the network , The host on the local area network can send ARP Reply message , Other hosts will not detect the authenticity of the response message when they receive it, and will record it in the local machine ARP cache ; Thus, the attacker can send a fake ARP Reply message , So that the information it sends cannot reach the expected host or the wrong host , This constitutes a ARP cheating .

ARP command Can be used to query the local ARP In cache IP Address and MAC Address Correspondence of 、 Add or delete static correspondence, etc . Relevant agreements include RARP、 agent ARP.NDP Used in IPv6 Instead of address resolution protocol .