This section discusses how to:
<!.IN "Access control list"> <!.IN "Authentication"> X does not provide any protection on a per-window basis. If you find out the resource ID of a resource, you can manipulate it. To provide some minimal level of protection, however, connections are permitted only from machines you trust. This is adequate on single-user workstations but obviously breaks down on timesharing machines. Although provisions exist in the X protocol for proper connection authentication, the lack of a standard authentication server leaves host-level access control as the only common mechanism.
<!.IN "Default Protection"> The initial set of hosts allowed to open connections typically consists of:
If a host is not in the access control list when the access control mechanism is enabled and if the host attempts to establish a connection, the server refuses the connection. To change the access list, the client must reside on the same host as the server and/or must have been granted permission in the initial authorization at connection setup.
Servers also can implement other access control policies in addition to or in place of this host access facility. For further information about other access control implementations, see ``X Window System Protocol.''