The present invention relates to a communication system and method, an information processing terminal and method, and an information processing device and method which enable simple and secure restricted access. When a PDA 11 is brought close, a reader 2 of a personal computer 1 reads a device ID form an IC tag 12. The personal computer 1 registers device IDs on a connection permission list, and permits only devices registered on the list to connect. When being instructed to perform accessing, the PDA 11 controls a communication unit to access the personal computer 1 and to transmits its device ID. The personal computer 1 determines whether or not the transmitted ID is registered on the connection permission list, and permits the connection when determining that the ID is registered. The present invention can be applied to various information processing devices such as a personal computer and a PDA.