A system and method for provisionally authenticating a host moving from a source port of a switch device to a destination port of the switch device is disclosed. The host is initially authenticated at the source port and blocked from forwarding network traffic at the destination port. During a provisional authentication session, an authentication agent executing on the switch intercepts one or more authentication packets sourced by the host and headed for the destination port of the switch device and redirects the authentication packets to an authentication server for validating the host at the destination port of the switch device. The switch device removes the block at the destination port in response to receiving an acknowledgment of successful authentication at the destination port from the authentication server.