Authentication method, client, server, feedthrough server and authentication system

The invention provides an authentication method, an authentication client, an authentication server, a feedthrough server and an authentication system. The authentication method comprises the following steps that: the authentication client sends user information to the authentication server to perform primary authentication, and acquires primary authentication success information which carries aninternet protocol (IP) address of the feedthrough server and is sent by the authentication server after the primary authentication passes, wherein the feedthrough server is used for realizing information interaction between the authentication client and the authentication server; the authentication client acquires an IP address of the authentication client from a dynamic host configuration protocol (DHCP) server; and the authentication client forwards the IP address of the authentication client and the user information to the authentication server by the feedthrough server according to the IPaddress of the feedthrough