A storage area network resistant to spoofing attack has several nodes each having a port, and storage area network interconnect interconnecting the ports. Each port is provided with a hash function generator for providing and verifying an authentication code for frames transmitted over the storage area network, and a key table for providing a key to the hash function generator. The authentication code is generated by applying a hash function to the key and to at least an address portion of each frame. In each node, the key is selected from that node's key table according to address information of the frame.