Methods and apparatuses for authenticating data communications are disclosed. In a method an intermediate node between a sender device and a receiver device obtains an authenticator associated with the sender device. The intermediate node authenticates the sender device such that the intermediate node acts as the receiver device towards the sender device. The intermediate node is then authenticated to the receiver device such that the intermediate node uses the authenticator associated with the sender device for the authentication to transparently intervene data communications from the sender device to the receiver device.