The present invention relates to an optical network terminal (ONT), a method for configuring rate limiting attributes of ports, and a method for processing packets. The ONT includes a passive optical network (PON) protocol processing module, and a user network interface (UNI) module, which are connected through an internal interface. The ONT also includes a port rate limiting module connected to a UNI. The port rate limiting module stores rate limiting attributes, and the ONT uses these attributes to control the traffic of the UNI. The port rate limiting attributes are configured for the ONT through an ONT management and control interface (OMCI) message of an optical line terminal (OLT). In this way, when the ONT receives data from the UNI, it can control the traffic of the UNI according to the port rate limiting attributes. The present invention enables the port rate limiting function for the ONT, prevents overflow of the internal receiving buffer of the ONT, and prevents denial of service (DoS) attacks from illegal users.