Methods, devices and apparatus for verifying a terminal device are provided. In one aspect, a method includes: recording a correspondence between a source IP address of an authentication message and an MAC address of the terminal device in a first whitelist after successful authentication is performed for the terminal device based on the authentication message, where the authentication message carries an MAC address of the terminal device; querying the first whitelist based on a source IP address of a data packet when the data packet from the terminal device is monitored; confirming the terminal device is successfully authenticated if the source IP address hits the first whitelist.