The fundamental goal in future mobile multiservice networks is to provide an efficient mobile computing environment which enables a user with a portable computer equipped with multiple wireless access interfaces to move seamlessly between different providers' networks. In particular, if these networks are Wi-Fi WLANs (wireless fidelity wireless local area networks), security features should be defined precisely taking into account seamless roaming. The paper considers one of the most critical security issues in Wi-Fi networks -key management. We propose a centralized approach to deal with key management in the case of an interconnection of remoted Wi-Fi networks based on using a key management server. Security goals and system architecture guidelines are outlined. In respect to the IEEE 802.11i standard, the changing of keys requires only 3 messages and the roaming situation allows the establishment of a new secure 802.11 wireless channel by exchanging only 5 messages against at least 20 messages.