A message processing method, apparatus, and system, where the method includes sending, by a Dynamic Host Configuration Protocol for Internet Protocol version 6 (DHCPv6) client apparatus, a first message requesting assignment of an Internet Protocol version 6 (IPv6) address to a DHCPv6 server, where the first message includes a first random identifier identifying the DHCPv6 client apparatus, receiving a first reply message from the DHCPv6 server, sending a second message to the DHCPv6 server, where the second message includes a second random identifier generated using a preset algorithm and the first random identifier and identifies the DHCPv6 client apparatus, and receiving a second reply message from the DHCPv6 server. Therefore, a problem that privacy is easy to monitor or steal in an interaction process between the DHCPv6 client apparatus and the DHCPv6 server is resolved.