F5, Inc.
Methods and system for returning requests with javascript for clients before passing a request to a server

Abstract:

Identifying potential network attacks on servers and protecting the servers from those potential attacks until the associated client requests can be confirmed as either legitimate or an actual attack is disclosed. Client requests for server resources are received by a network traffic management device (NTMD). The NTMD initially responds to the client requests on behalf of the associated servers. The initial responses include client side language scripts for execution by the clients. Executing the scripts causes the clients to resend their initial requests identified as a potential attack by the NTMD along with information indicating the client's legitimacy, such as the result of a computational JavaScript challenge. The NTMD receives the resent initial request, determines it was sent from a legitimate requestor and is therefore not an attack, and forwards it to the associated server.