Abstract: A physical latching mechanism prevents access to or tampering with an I/O port of a computer system. In the preferred embodiment, a display monitor cable of an unattended workstation being operated remotely is disconnected and latched to prevent re-connection and display of remote activity. The latch includes a first latch which locks the cable to the workstation system unit, and a second latch which blocks the open end of the cable. Each latch preferably a pair of L-shaped members which engage each other in a nested fashion, one being attached to a cable coupling while the other is connected to the system unit or is used to block the cable open end. The members are locked by engagement means at one end and a padlock at the other.