A method includes a client device forming a link-layer protocol packet having a field that includes first credentials of the client device and sending the link-layer protocol packet to a directly attached network device while the client device is in a first configuration. The method further includes a management system obtaining the first credentials from the network device and using the first credentials to access the client device and change the client device from the first configuration to a second configuration. Optionally, a computer system may include a plurality of client devices that implement the method to facilitate securely configuring the entire computer system. Preferably, each client device generates system-unique first credentials.