The present invention relates to an electronic circuit for securing data interchanges between a computer station and a network, said circuit comprising a first network interface connected to said network, said circuit comprising at least a second network interface connected to a network interface of said computer station, a unit for processing data passing between the first network interface and the second network interface, an interface for connection to an internal bus of the computer station suitable for electrically connecting the power supply, said electronic circuit not comprising any means of transferring processed data with the bus of said station. The invention applies in particular to the protection of personal computers handling confidential data.