Application-specific network-layer virtual private network connections

Techniques are described for providing secure communication of network traffic from specific applications operating on a client device to a server device using a network-layer virtual private network (VPN). For example, a module on a client device may intercept network traffic from an application executing on the client device. The module may then determine whether to send the application-layer data through a network-layer VPN tunnel from the client device to a gateway device. This network-layer VPN tunnel may be defined by a network address of a physical adapter of the client device and a network address of the VPN gateway. In other words, there may be no need for the interposition of a VPN proxy on the client device. The module makes this determination on an application-by-application basis. The client device then forwards the application-layer data through the VPN tunnel based on the determination.