The IP bound to the socket is inaddr_ The meaning of any htonl (inaddr_any) (0.0.0.0 all addresses, uncertain addresses, arbitrary addresses)

INADDR_ANY Means monitor 0.0.0.0 Address ,socket Bind port only , It is not bound to a specific ip, Let the routing table decide which one to send ip（0.0.0.0 Address means all addresses 、 Uncertain address 、 Any address ）（ If there are multiple network cards in a host, there are multiple ip Address ）（ The routing table should know which port is being used by which ip monitor ）

Reference article ：socket The binding of ip by INADDR_ANY The meaning of