A network mediator corresponding to a computing device uses packet filters to restrict network communications. The network mediator includes a set of one or more filters, each filter having parameters that are compared to corresponding parameters of a data packet to be passed through the network mediator. The network mediator determines whether to allow the data packet through based on whether the data packet parameters match any filter parameters. The set of filters can be modified by a remote device, but cannot be modified by the computing device whose communications are being restricted. When a data packet is sent from the computing device, the data packet will include the virtual address which is changed to the network address by the network mediator prior to forwarding the packet on the network, and vice versa. By virtualizing the addresses, the computing device is restricted in accessing other devices over the network.