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SUDO(5)                              BSD File Formats Manual                              SUDO(5)

NAME
     sudo.conf — configuration for sudo front end

DESCRIPTION
     The sudo.conf file is used to configure the sudo front end.  It specifies the security pol‐
     icy and I/O logging plugins, debug flags as well as plugin-agnostic path names and settings.

     The sudo.conf file supports the following directives, described in detail below.

     Plugin    a security policy or I/O logging plugin

     Path      a plugin-agnostic path

     Set       a front end setting, such as disable_coredump or group_source

     Debug     debug flags to aid in debugging sudo, sudoreplay, visudo, and the sudoers plugin.

     The pound sign (‘#’) is used to indicate a comment.  Both the comment character and any text
     after it, up to the end of the line, are ignored.

     Long lines can be continued with a backslash (‘\’) as the last character on the line.  Note
     that leading white space is removed from the beginning of lines even when the continuation
     character is used.

     Non-comment lines that don't begin with Plugin, Path, Debug, or Set are silently ignored.

     The sudo.conf file is always parsed in the “C” locale.

   Plugin configuration
     sudo supports a plugin architecture for security policies and input/output logging.  Third
     parties can develop and distribute their own policy and I/O logging plugins to work seam‐
     lessly with the sudo front end.  Plugins are dynamically loaded based on the contents of
     sudo.conf.

     A Plugin line consists of the Plugin keyword, followed by the symbol_name and the path to
     the dynamic shared object that contains the plugin.  The symbol_name is the name of the
     struct policy_plugin or struct io_plugin symbol contained in the plugin.  The path may be
     fully qualified or relative.  If not fully qualified, it is relative to the directory speci‐
     fied by the plugin_dir Path setting, which defaults to /usr/lib/sudo.  In other words:

           Plugin sudoers_policy sudoers.so

     is equivalent to:

           Plugin sudoers_policy /usr/lib/sudo/sudoers.so

     If the plugin was compiled statically into the sudo binary instead of being installed as a
     dynamic shared object, the path should be specified without a leading directory, as it does
     not actually exist in the file system.  For example:

           Plugin sudoers_policy sudoers.so

     Starting with sudo 1.8.5, any additional parameters after the path are passed as arguments
     to the plugin's open function.  For example, to override the compile-time default sudoers
     file mode:

           Plugin sudoers_policy sudoers.so sudoers_mode=0440

     The same dynamic shared object may contain multiple plugins, each with a different symbol
     name.  The file must be owned by uid 0 and only writable by its owner.  Because of ambigui‐
     ties that arise from composite policies, only a single policy plugin may be specified.  This
     limitation does not apply to I/O plugins.

     If no sudo.conf file is present, or if it contains no Plugin lines, the sudoers plugin will
     be used as the default security policy and for I/O logging (if enabled by the policy).  This
     is equivalent to the following:

           Plugin sudoers_policy sudoers.so
           Plugin sudoers_io sudoers.so

     For more information on the sudo plugin architecture, see the sudo_plugin(8) manual.

   Path settings
     A Path line consists of the Path keyword, followed by the name of the path to set and its
     value.  For example:

           Path noexec /usr/lib/sudo/sudo_noexec.so
           Path askpass /usr/X11R6/bin/ssh-askpass

     If no path name is specified, features relying on the specified setting will be disabled.
     Disabling Path settings is only supported in sudo version 1.8.16 and higher.

     The following plugin-agnostic paths may be set in the /etc/sudo.conf file:

     askpass   The fully qualified path to a helper program used to read the user's password when
               no terminal is available.  This may be the case when sudo is executed from a
               graphical (as opposed to text-based) application.  The program specified by
               askpass should display the argument passed to it as the prompt and write the
               user's password to the standard output.  The value of askpass may be overridden by
               the SUDO_ASKPASS environment variable.

     noexec    The fully-qualified path to a shared library containing dummy versions of the
               execl(), execle(), execlp(), exect(), execv(), execve(), execvP(), execvp(),
               execvpe(), fexecve(), popen(), posix_spawn(), posix_spawnp(), and system() library
               functions that just return an error.  This is used to implement the noexec func‐
               tionality on systems that support LD_PRELOAD or its equivalent.  The default value
               is: /usr/lib/sudo/sudo_noexec.so.

     plugin_dir
               The default directory to use when searching for plugins that are specified without
               a fully qualified path name.  The default value is /usr/lib/sudo.

     sesh      The fully-qualified path to the sesh binary.  This setting is only used when sudo
               is built with SELinux support.  The default value is /usr/lib/sudo/sesh.

   Other settings
     The sudo.conf file also supports the following front end settings:

     disable_coredump
               Core dumps of sudo itself are disabled by default to prevent the disclosure of
               potentially sensitive information.  To aid in debugging sudo crashes, you may wish
               to re-enable core dumps by setting “disable_coredump” to false in sudo.conf as
               follows:

                     Set disable_coredump false

               All modern operating systems place restrictions on core dumps from setuid pro‐
               cesses like sudo so this option can be enabled without compromising security.  To
               actually get a sudo core file you will likely need to enable core dumps for setuid
               processes.  On BSD and Linux systems this is accomplished in the sysctl command.
               On Solaris, the coreadm command is used to configure core dump behavior.

               This setting is only available in sudo version 1.8.4 and higher.

     group_source
               sudo passes the invoking user's group list to the policy and I/O plugins.  On most
               systems, there is an upper limit to the number of groups that a user may belong to
               simultaneously (typically 16 for compatibility with NFS).  On systems with the
               getconf(1) utility, running:
                     getconf NGROUPS_MAX
               will return the maximum number of groups.

               However, it is still possible to be a member of a larger number of groups--they
               simply won't be included in the group list returned by the kernel for the user.
               Starting with sudo version 1.8.7, if the user's kernel group list has the maximum
               number of entries, sudo will consult the group database directly to determine the
               group list.  This makes it possible for the security policy to perform matching by
               group name even when the user is a member of more than the maximum number of
               groups.

               The group_source setting allows the administrator to change this default behavior.
               Supported values for group_source are:

               static    Use the static group list that the kernel returns.  Retrieving the group
                         list this way is very fast but it is subject to an upper limit as
                         described above.  It is “static” in that it does not reflect changes to
                         the group database made after the user logs in.  This was the default
                         behavior prior to sudo 1.8.7.

               dynamic   Always query the group database directly.  It is “dynamic” in that
                         changes made to the group database after the user logs in will be
                         reflected in the group list.  On some systems, querying the group data‐
                         base for all of a user's groups can be time consuming when querying a
                         network-based group database.  Most operating systems provide an effi‐
                         cient method of performing such queries.  Currently, sudo supports effi‐
                         cient group queries on AIX, BSD, HP-UX, Linux and Solaris.

               adaptive  Only query the group database if the static group list returned by the
                         kernel has the maximum number of entries.  This is the default behavior
                         in sudo 1.8.7 and higher.

               For example, to cause sudo to only use the kernel's static list of groups for the
               user:

                     Set group_source static

               This setting is only available in sudo version 1.8.7 and higher.

     max_groups
               The maximum number of user groups to retrieve from the group database.  Values
               less than one will be ignored.  This setting is only used when querying the group
               database directly.  It is intended to be used on systems where it is not possible
               to detect when the array to be populated with group entries is not sufficiently
               large.  By default, sudo will allocate four times the system's maximum number of
               groups (see above) and retry with double that number if the group database query
               fails.  However, some systems just return as many entries as will fit and do not
               indicate an error when there is a lack of space.

               This setting is only available in sudo version 1.8.7 and higher.

     probe_interfaces
               By default, sudo will probe the system's network interfaces and pass the IP
               address of each enabled interface to the policy plugin.  This makes it possible
               for the plugin to match rules based on the IP address without having to query DNS.
               On Linux systems with a large number of virtual interfaces, this may take a non-
               negligible amount of time.  If IP-based matching is not required, network inter‐
               face probing can be disabled as follows:

                     Set probe_interfaces false

               This setting is only available in sudo version 1.8.10 and higher.

   Debug flags
     sudo versions 1.8.4 and higher support a flexible debugging framework that can help track
     down what sudo is doing internally if there is a problem.

     A Debug line consists of the Debug keyword, followed by the name of the program (or plugin)
     to debug (sudo, visudo, sudoreplay, sudoers), the debug file name and a comma-separated list
     of debug flags.  The debug flag syntax used by sudo and the sudoers plugin is
     subsystem@priority but a plugin is free to use a different format so long as it does not
     include a comma (‘,’).

     For example:

           Debug sudo /var/log/sudo_debug all@warn,plugin@info

     would log all debugging statements at the warn level and higher in addition to those at the
     info level for the plugin subsystem.

     As of sudo 1.8.12, multiple Debug entries may be specified per program.  Older versions of
     sudo only support a single Debug entry per program.  Plugin-specific Debug entries are also
     supported starting with sudo 1.8.12 and are matched by either the base name of the plugin
     that was loaded (for example sudoers.so) or by the plugin's fully-qualified path name.  Pre‐
     viously, the sudoers plugin shared the same Debug entry as the sudo front end and could not
     be configured separately.

     The following priorities are supported, in order of decreasing severity: crit, err, warn,
     notice, diag, info, trace and debug.  Each priority, when specified, also includes all pri‐
     orities higher than it.  For example, a priority of notice would include debug messages
     logged at notice and higher.

     The priorities trace and debug also include function call tracing which logs when a function
     is entered and when it returns.  For example, the following trace is for the
     get_user_groups() function located in src/sudo.c:

           sudo[123] -> get_user_groups @ src/sudo.c:385
           sudo[123] <- get_user_groups @ src/sudo.c:429 := groups=10,0,5

     When the function is entered, indicated by a right arrow ‘->’, the program, process ID,
     function, source file and line number are logged.  When the function returns, indicated by a
     left arrow ‘<-’, the same information is logged along with the return value.  In this case,
     the return value is a string.

     The following subsystems are used by the sudo front-end:

     all         matches every subsystem

     args        command line argument processing

     conv        user conversation

     edit        sudoedit

     event       event subsystem

     exec        command execution

     main        sudo main function

     netif       network interface handling

     pcomm       communication with the plugin

     plugin      plugin configuration

     pty         pseudo-tty related code

     selinux     SELinux-specific handling

     util        utility functions

     utmp        utmp handling

     The sudoers(5) plugin includes support for additional subsystems.

FILES
     /etc/sudo.conf            sudo front end configuration

EXAMPLES
     #
     # Default /etc/sudo.conf file
     #
     # Format:
     #   Plugin plugin_name plugin_path plugin_options ...
     #   Path askpass /path/to/askpass
     #   Path noexec /path/to/sudo_noexec.so
     #   Debug sudo /var/log/sudo_debug all@warn
     #   Set disable_coredump true
     #
     # The plugin_path is relative to /usr/lib/sudo unless
     #   fully qualified.
     # The plugin_name corresponds to a global symbol in the plugin
     #   that contains the plugin interface structure.
     # The plugin_options are optional.
     #
     # The sudoers plugin is used by default if no Plugin lines are
     # present.
     Plugin sudoers_policy sudoers.so
     Plugin sudoers_io sudoers.so

     #
     # Sudo askpass:
     #
     # An askpass helper program may be specified to provide a graphical
     # password prompt for "sudo -A" support.  Sudo does not ship with
     # its own askpass program but can use the OpenSSH askpass.
     #
     # Use the OpenSSH askpass
     #Path askpass /usr/X11R6/bin/ssh-askpass
     #
     # Use the Gnome OpenSSH askpass
     #Path askpass /usr/libexec/openssh/gnome-ssh-askpass

     #
     # Sudo noexec:
     #
     # Path to a shared library containing dummy versions of the execv(),
     # execve() and fexecve() library functions that just return an error.
     # This is used to implement the "noexec" functionality on systems that
     # support C or its equivalent.
     # The compiled-in value is usually sufficient and should only be
     # changed if you rename or move the sudo_noexec.so file.
     #
     #Path noexec /usr/lib/sudo/sudo_noexec.so

     #
     # Core dumps:
     #
     # By default, sudo disables core dumps while it is executing
     # (they are re-enabled for the command that is run).
     # To aid in debugging sudo problems, you may wish to enable core
     # dumps by setting "disable_coredump" to false.
     #
     #Set disable_coredump false

     #
     # User groups:
     #
     # Sudo passes the user's group list to the policy plugin.
     # If the user is a member of the maximum number of groups (usually 16),
     # sudo will query the group database directly to be sure to include
     # the full list of groups.
     #
     # On some systems, this can be expensive so the behavior is configurable.
     # The "group_source" setting has three possible values:
     #   static   - use the user's list of groups returned by the kernel.
     #   dynamic  - query the group database to find the list of groups.
     #   adaptive - if user is in less than the maximum number of groups.
     #              use the kernel list, else query the group database.
     #
     #Set group_source static

SEE ALSO
     sudoers(5), sudo(8), sudo_plugin(8)

HISTORY
     See the HISTORY file in the sudo distribution (https://www.sudo.ws/history.html) for a brief
     history of sudo.

AUTHORS
     Many people have worked on sudo over the years; this version consists of code written pri‐
     marily by:

           Todd C. Miller

     See the CONTRIBUTORS file in the sudo distribution (https://www.sudo.ws/contributors.html)
     for an exhaustive list of people who have contributed to sudo.

BUGS
     If you feel you have found a bug in sudo, please submit a bug report at
     https://bugzilla.sudo.ws/

SUPPORT
     Limited free support is available via the sudo-users mailing list, see
     https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search the archives.

DISCLAIMER
     sudo is provided “AS IS” and any express or implied warranties, including, but not limited
     to, the implied warranties of merchantability and fitness for a particular purpose are dis‐
     claimed.  See the LICENSE file distributed with sudo or https://www.sudo.ws/license.html for
     complete details.

Sudo 1.8.16                             November 20, 2015                             Sudo 1.8.16

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