As a consequence, it provides no identification and authentication mechanisms and neither discretionary nor mandatory access control mechanisms. Any user has access to all resources on the system.
Any access control is provided solely by controlling physical access to the computer itself.
If the computer is electronically connected to any other computer, no access control is possible. UNIX is a multi-user operating system originally designed by Ken Thompson and Dennis Ritchie of Bell Laboratories. User identification is supported by password-based authentication. User IDs are associated with processes. UNIX provides a modified version of access control lists for files.