Techniques are described for a proxy system to provide a client device with transparent access to multiple network file servers. The proxy system may appear to the client device as a single network file server. The proxy may be configured to forward requests received from the client device to multiple servers as well as provide responses from the server back to the client. Further, the proxy system may authenticate itself, as the client, to each of the multiple network servers using authentication credentials supplied by the client. After prompting a user to submit credentials to establish a session with a first network server, the proxy system may send a session timeout error code, prompting the client to submit a fresh authentication request used by the proxy system to establish a session with a second network server.