The LOG_IO privilege lets the user's process execute the Queue
I/O Request ($QIO) system service to perform logical-level I/O operations.
LOG_IO privilege is also required for certain device control functions,
such as setting permanent terminal characteristics. A process with
the typical privileges of NETMBX and TMPMBX that also holds LOG_IO
and SYSNAM can reconfigure the Ethernet using the Phase IV network configuration
procedure, NICONFIG.COM.
Usually, process I/O requests are handled indirectly by use
of an I/O package such as OpenVMS Record Management Services (RMS).
However, to increase their control over I/O operations and to improve
the efficiency of I/O operations, skilled users sometimes prefer
to handle the interface between their process and a system I/O driver
program directly. They can do this by executing $QIO; in many instances,
the operation called for is a logical-level I/O operation. Note
that logical level functions are permitted without LOG_IO privilege
on a device mounted with the /FOREIGN qualifier and on non-file-structured
devices.
Grant this privilege only to users who need it because it
allows a process to access data anywhere on the selected volume
without the benefit of any file structuring. If this privilege is
given to unqualified users who have no need for it, the operating
system and service to other processes can be easily disrupted. Such disruptions
can include the destruction of information on the system device,
the destruction of user data, and the exposure of confidential information.
The LOG_IO privilege also lets a process perform the following
tasks:
Task
Interface
Issue physical
I/O calls to a private, non-file-structured device
$QIO
Modify the following terminal
attributes: HANGUP SET_SPEED SECURE_SERVER
SET TERMINAL (or TTDRIVER) /[NO]HANGUP /[NO]SET_SPEED /[NO]SECURE_SERVER
HP OpenVMS Guide to System Security
Security for the System Administrator
