Verifying source addresses associated with a terminal is disclosed, including: receiving a packet from a terminal, wherein the packet comprises a source Internet Protocol (IP) address and a source Media Access Control (MAC) address associated with the terminal; determining whether a matching entry associated with the terminal is found in a local verification table storing valid source IP addresses and valid source MAC addresses; determine that the matching entry associated with the terminal is not found in the local verification table; generating a request based on the source IP address and the source MAC address; transmitting the request to a dynamic host configuration protocol (DHCP) server; and determining whether the source IP address and the source MAC address associated with the terminal are valid based at least in part on a response from the DHCP server.