The present invention relates to a device and method for increasing the security for a computer or server adapted for communication with a communication network, for example the Internet. The method for automatically controlling access between the computer and the communication network arranges the access to be dependent on user activity. The user activity is determined by monitoring signal activity between the computer and at least one input/output device adapted for communication with the computer, and the user activity being defined as detection of signal activity between the computer and the input/output device. Access to the communication network is only allowed if user activity is occurring or has occurred in a predetermined time period.