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SUDOERS(5)                FreeBSD File Formats Manual               SUDOERS(5)

NAME
     sudoers - list of which users may execute what

DESCRIPTION
     The sudoers file is composed of two types of entries: aliases (basically
     variables) and user specifications (which specify who may run what).

     When multiple entries match for a user, they are applied in order.  Where
     there are multiple matches, the last match is used (which is not
     necessarily the most specific match).

     The sudoers grammar will be described below in Extended Backus-Naur Form
     (EBNF).  Don't despair if you are unfamiliar with EBNF; it is fairly
     simple, and the definitions below are annotated.

   Quick guide to EBNF
     EBNF is a concise and exact way of describing the grammar of a language.
     Each EBNF definition is made up of production rules.  E.g.,

     symbol ::= definition | alternate1 | alternate2 ...

     Each production rule references others and thus makes up a grammar for
     the language.  EBNF also contains the following operators, which many
     readers will recognize from regular expressions.  Do not, however,
     confuse them with ``wildcard'' characters, which have different meanings.

     ?     Means that the preceding symbol (or group of symbols) is optional.
           That is, it may appear once or not at all.

     *     Means that the preceding symbol (or group of symbols) may appear
           zero or more times.

     +     Means that the preceding symbol (or group of symbols) may appear
           one or more times.

     Parentheses may be used to group symbols together.  For clarity, we will
     use single quotes ('') to designate what is a verbatim character string
     (as opposed to a symbol name).

   Aliases
     There are four kinds of aliases: User_Alias, Runas_Alias, Host_Alias and
     Cmnd_Alias.

     Alias ::= 'User_Alias'  User_Alias (':' User_Alias)* |
               'Runas_Alias' Runas_Alias (':' Runas_Alias)* |
               'Host_Alias'  Host_Alias (':' Host_Alias)* |
               'Cmnd_Alias'  Cmnd_Alias (':' Cmnd_Alias)*

     User_Alias ::= NAME '=' User_List

     Runas_Alias ::= NAME '=' Runas_List

     Host_Alias ::= NAME '=' Host_List

     Cmnd_Alias ::= NAME '=' Cmnd_List

     NAME ::= [A-Z]([A-Z][0-9]_)*

     Each alias definition is of the form

     Alias_Type NAME = item1, item2, ...

     where Alias_Type is one of User_Alias, Runas_Alias, Host_Alias, or
     Cmnd_Alias.  A NAME is a string of uppercase letters, numbers, and
     underscore characters (`_').  A NAME must start with an uppercase letter.
     It is possible to put several alias definitions of the same type on a
     single line, joined by a colon (`:').  E.g.,

     Alias_Type NAME = item1, item2, item3 : NAME = item4, item5

     The definitions of what constitutes a valid alias member follow.

     User_List ::= User |
                   User ',' User_List

     User ::= '!'* user name |
              '!'* #uid |
              '!'* %group |
              '!'* %#gid |
              '!'* +netgroup |
              '!'* %:nonunix_group |
              '!'* %:#nonunix_gid |
              '!'* User_Alias

     A User_List is made up of one or more user names, user ids (prefixed with
     `#'), system group names and ids (prefixed with `%' and `%#'
     respectively), netgroups (prefixed with `+'), non-Unix group names and
     IDs (prefixed with `%:' and `%:#' respectively) and User_Aliases. Each
     list item may be prefixed with zero or more `!' operators.  An odd number
     of `!' operators negate the value of the item; an even number just cancel
     each other out.

     A user name, uid, group, gid, netgroup, nonunix_group or nonunix_gid may
     be enclosed in double quotes to avoid the need for escaping special
     characters.  Alternately, special characters may be specified in escaped
     hex mode, e.g. \x20 for space.  When using double quotes, any prefix
     characters must be included inside the quotes.

     The actual nonunix_group and nonunix_gid syntax depends on the underlying
     implementation.  For instance, the QAS AD backend supports the following
     formats:

     +o     Group in the same domain: "%:Group Name"

     +o     Group in any domain: "%:Group Name@FULLY.QUALIFIED.DOMAIN"

     +o     Group SID: "%:S-1-2-34-5678901234-5678901234-5678901234-567"

     Note that quotes around group names are optional.  Unquoted strings must
     use a backslash (`\') to escape spaces and special characters.  See Other
     special characters and reserved words for a list of characters that need
     to be escaped.

     Runas_List ::= Runas_Member |
                    Runas_Member ',' Runas_List

     Runas_Member ::= '!'* user name |
                      '!'* #uid |
                      '!'* %group |
                      '!'* %#gid |
                      '!'* %:nonunix_group |
                      '!'* %:#nonunix_gid |
                      '!'* +netgroup |
                      '!'* Runas_Alias

     A Runas_List is similar to a User_List except that instead of
     User_Aliases it can contain Runas_Aliases.  Note that user names and
     groups are matched as strings.  In other words, two users (groups) with
     the same uid (gid) are considered to be distinct.  If you wish to match
     all user names with the same uid (e.g. root and toor), you can use a uid
     instead (#0 in the example given).

     Host_List ::= Host |
                   Host ',' Host_List

     Host ::= '!'* host name |
              '!'* ip_addr |
              '!'* network(/netmask)? |
              '!'* +netgroup |
              '!'* Host_Alias

     A Host_List is made up of one or more host names, IP addresses, network
     numbers, netgroups (prefixed with `+') and other aliases.  Again, the
     value of an item may be negated with the `!' operator.  If you do not
     specify a netmask along with the network number, sudo will query each of
     the local host's network interfaces and, if the network number
     corresponds to one of the hosts's network interfaces, the corresponding
     netmask will be used.  The netmask may be specified either in standard IP
     address notation (e.g. 255.255.255.0 or ffff:ffff:ffff:ffff::), or CIDR
     notation (number of bits, e.g. 24 or 64).  A host name may include shell-
     style wildcards (see the Wildcards section below), but unless the host
     name command on your machine returns the fully qualified host name,
     you'll need to use the fqdn option for wildcards to be useful.  Note that
     sudo only inspects actual network interfaces; this means that IP address
     127.0.0.1 (localhost) will never match.  Also, the host name
     ``localhost'' will only match if that is the actual host name, which is
     usually only the case for non-networked systems.

     Cmnd_List ::= Cmnd |
                   Cmnd ',' Cmnd_List

     command name ::= file name |
                      file name args |
                      file name '""'

     Cmnd ::= '!'* command name |
              '!'* directory |
              '!'* "sudoedit" |
              '!'* Cmnd_Alias

     A Cmnd_List is a list of one or more command names, directories, and
     other aliases.  A command name is a fully qualified file name which may
     include shell-style wildcards (see the Wildcards section below).  A
     simple file name allows the user to run the command with any arguments
     he/she wishes.  However, you may also specify command line arguments
     (including wildcards).  Alternately, you can specify "" to indicate that
     the command may only be run without command line arguments.  A directory
     is a fully qualified path name ending in a `/'.  When you specify a
     directory in a Cmnd_List, the user will be able to run any file within
     that directory (but not in any sub-directories therein).

     If a Cmnd has associated command line arguments, then the arguments in
     the Cmnd must match exactly those given by the user on the command line
     (or match the wildcards if there are any).  Note that the following
     characters must be escaped with a `\' if they are used in command
     arguments: `,', `:', `=', `\'.  The special command ``sudoedit'' is used
     to permit a user to run sudo with the -e option (or as sudoedit).  It may
     take command line arguments just as a normal command does.

   Defaults
     Certain configuration options may be changed from their default values at
     run-time via one or more Default_Entry lines.  These may affect all users
     on any host, all users on a specific host, a specific user, a specific
     command, or commands being run as a specific user.  Note that per-command
     entries may not include command line arguments.  If you need to specify
     arguments, define a Cmnd_Alias and reference that instead.

     Default_Type ::= 'Defaults' |
                      'Defaults' '@' Host_List |
                      'Defaults' ':' User_List |
                      'Defaults' '!' Cmnd_List |
                      'Defaults' '>' Runas_List

     Default_Entry ::= Default_Type Parameter_List

     Parameter_List ::= Parameter |
                        Parameter ',' Parameter_List

     Parameter ::= Parameter '=' Value |
                   Parameter '+=' Value |
                   Parameter '-=' Value |
                   '!'* Parameter

     Parameters may be flags, integer values, strings, or lists.  Flags are
     implicitly boolean and can be turned off via the `!' operator.  Some
     integer, string and list parameters may also be used in a boolean context
     to disable them.  Values may be enclosed in double quotes ("") when they
     contain multiple words.  Special characters may be escaped with a
     backslash (`\').

     Lists have two additional assignment operators, += and -=.  These
     operators are used to add to and delete from a list respectively.  It is
     not an error to use the -= operator to remove an element that does not
     exist in a list.

     Defaults entries are parsed in the following order: generic, host and
     user Defaults first, then runas Defaults and finally command defaults.

     See SUDOERS OPTIONS for a list of supported Defaults parameters.

   User Specification
     User_Spec ::= User_List Host_List '=' Cmnd_Spec_List \
                   (':' Host_List '=' Cmnd_Spec_List)*

     Cmnd_Spec_List ::= Cmnd_Spec |
                        Cmnd_Spec ',' Cmnd_Spec_List

     Cmnd_Spec ::= Runas_Spec? Tag_Spec* Cmnd

     Runas_Spec ::= '(' Runas_List? (':' Runas_List)? ')'

     Tag_Spec ::= ('NOPASSWD:' | 'PASSWD:' | 'NOEXEC:' | 'EXEC:' |
                   'SETENV:' | 'NOSETENV:')

     A user specification determines which commands a user may run (and as
     what user) on specified hosts.  By default, commands are run as root, but
     this can be changed on a per-command basis.

     The basic structure of a user specification is ``who where = (as_whom)
     what''.  Let's break that down into its constituent parts:

   Runas_Spec
     A Runas_Spec determines the user and/or the group that a command may be
     run as.  A fully-specified Runas_Spec consists of two Runas_Lists (as
     defined above) separated by a colon (`:') and enclosed in a set of
     parentheses.  The first Runas_List indicates which users the command may
     be run as via sudo's -u option.  The second defines a list of groups that
     can be specified via sudo's -g option.  If both Runas_Lists are
     specified, the command may be run with any combination of users and
     groups listed in their respective Runas_Lists. If only the first is
     specified, the command may be run as any user in the list but no -g
     option may be specified.  If the first Runas_List is empty but the second
     is specified, the command may be run as the invoking user with the group
     set to any listed in the Runas_List.  If no Runas_Spec is specified the
     command may be run as root and no group may be specified.

     A Runas_Spec sets the default for the commands that follow it.  What this
     means is that for the entry:

     dgb     boulder = (operator) /bin/ls, /bin/kill, /usr/bin/lprm

     The user dgb may run /bin/ls, /bin/kill, and /usr/bin/lprm--but only as
     operator.  E.g.,

     $ sudo -u operator /bin/ls

     It is also possible to override a Runas_Spec later on in an entry.  If we
     modify the entry like so:

     dgb     boulder = (operator) /bin/ls, (root) /bin/kill, /usr/bin/lprm

     Then user dgb is now allowed to run /bin/ls as operator, but /bin/kill
     and /usr/bin/lprm as root.

     We can extend this to allow dgb to run /bin/ls with either the user or
     group set to operator:

     dgb     boulder = (operator : operator) /bin/ls, (root) /bin/kill,\
             /usr/bin/lprm

     Note that while the group portion of the Runas_Spec permits the user to
     run as command with that group, it does not force the user to do so.  If
     no group is specified on the command line, the command will run with the
     group listed in the target user's password database entry.  The following
     would all be permitted by the sudoers entry above:

     $ sudo -u operator /bin/ls
     $ sudo -u operator -g operator /bin/ls
     $ sudo -g operator /bin/ls

     In the following example, user tcm may run commands that access a modem
     device file with the dialer group.

     tcm     boulder = (:dialer) /usr/bin/tip, /usr/bin/cu,\
             /usr/local/bin/minicom

     Note that in this example only the group will be set, the command still
     runs as user tcm.  E.g.

     $ sudo -g dialer /usr/bin/cu

     Multiple users and groups may be present in a Runas_Spec, in which case
     the user may select any combination of users and groups via the -u and -g
     options.  In this example:

     alan    ALL = (root, bin : operator, system) ALL

     user alan may run any command as either user root or bin, optionally
     setting the group to operator or system.

   Tag_Spec
     A command may have zero or more tags associated with it.  There are six
     possible tag values: NOPASSWD, PASSWD, NOEXEC, EXEC, SETENV, and
     NOSETENV.  Once a tag is set on a Cmnd, subsequent Cmnds in the
     Cmnd_Spec_List, inherit the tag unless it is overridden by the opposite
     tag (in other words, PASSWD overrides NOPASSWD and NOEXEC overrides
     EXEC).

     NOPASSWD and PASSWD

     By default, sudo requires that a user authenticate him or herself before
     running a command.  This behavior can be modified via the NOPASSWD tag.
     Like a Runas_Spec, the NOPASSWD tag sets a default for the commands that
     follow it in the Cmnd_Spec_List.  Conversely, the PASSWD tag can be used
     to reverse things.  For example:

     ray     rushmore = NOPASSWD: /bin/kill, /bin/ls, /usr/bin/lprm

     would allow the user ray to run /bin/kill, /bin/ls, and /usr/bin/lprm as
     root on the machine rushmore without authenticating himself.  If we only
     want ray to be able to run /bin/kill without a password the entry would
     be:

     ray     rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls, /usr/bin/lprm

     Note, however, that the PASSWD tag has no effect on users who are in the
     group specified by the exempt_group option.

     By default, if the NOPASSWD tag is applied to any of the entries for a
     user on the current host, he or she will be able to run ``sudo -l''
     without a password.  Additionally, a user may only run ``sudo -v''
     without a password if the NOPASSWD tag is present for all a user's
     entries that pertain to the current host.  This behavior may be
     overridden via the verifypw and listpw options.

     NOEXEC and EXEC

     If sudo has been compiled with noexec support and the underlying
     operating system supports it, the NOEXEC tag can be used to prevent a
     dynamically-linked executable from running further commands itself.

     In the following example, user aaron may run /usr/bin/more and
     /usr/bin/vi but shell escapes will be disabled.

     aaron   shanty = NOEXEC: /usr/bin/more, /usr/bin/vi

     See the Preventing Shell Escapes section below for more details on how
     NOEXEC works and whether or not it will work on your system.

     SETENV and NOSETENV

     These tags override the value of the setenv option on a per-command
     basis.  Note that if SETENV has been set for a command, the user may
     disable the env_reset option from the command line via the -E option.
     Additionally, environment variables set on the command line are not
     subject to the restrictions imposed by env_check, env_delete, or
     env_keep.  As such, only trusted users should be allowed to set variables
     in this manner.  If the command matched is ALL, the SETENV tag is implied
     for that command; this default may be overridden by use of the NOSETENV
     tag.

   Wildcards
     sudo allows shell-style wildcards (aka meta or glob characters) to be
     used in host names, path names and command line arguments in the sudoers
     file.  Wildcard matching is done via the POSIX glob(3) and fnmatch(3)
     routines.  Note that these are not regular expressions.

     *         Matches any set of zero or more characters.

     ?         Matches any single character.

     [...]     Matches any character in the specified range.

     [!...]    Matches any character not in the specified range.

     \x        For any character `x', evaluates to `x'.  This is used to
               escape special characters such as: `*', `?', `[', and `]'.

     POSIX character classes may also be used if your system's glob(3) and
     fnmatch(3) functions support them.  However, because the `:' character
     has special meaning in sudoers, it must be escaped.  For example:

         /bin/ls [[alpha]]*

     Would match any file name beginning with a letter.

     Note that a forward slash (`/') will not be matched by wildcards used in
     the path name.  This is to make a path like:

         /usr/bin/*

     match /usr/bin/who but not /usr/bin/X11/xterm.

     When matching the command line arguments, however, a slash does get
     matched by wildcards since command line arguments may contain arbitrary
     strings and not just path names.

     Wildcards in command line arguments should be used with care.  Because
     command line arguments are matched as a single, concatenated string, a
     wildcard such as `?' or `*' can match multiple words.  For example, while
     a sudoers entry like:

         %operator ALL = /bin/cat /var/log/messages*

     will allow command like:

         $ sudo cat /var/log/messages.1

     It will also allow:

         $ sudo cat /var/log/messages /etc/shadow

     which is probably not what was intended.

   Exceptions to wildcard rules
     The following exceptions apply to the above rules:

     ""        If the empty string "" is the only command line argument in the
               sudoers entry it means that command is not allowed to be run
               with any arguments.

     sudoedit  Command line arguments to the sudoedit built-in command should
               always be path names, so a forward slash (`/') will not be
               matched by a wildcard.

   Including other files from within sudoers
     It is possible to include other sudoers files from within the sudoers
     file currently being parsed using the #include and #includedir
     directives.

     This can be used, for example, to keep a site-wide sudoers file in
     addition to a local, per-machine file.  For the sake of this example the
     site-wide sudoers will be /etc/sudoers and the per-machine one will be
     /etc/sudoers.local.  To include /etc/sudoers.local from within
     /etc/sudoers we would use the following line in /etc/sudoers:

         #include /etc/sudoers.local

     When sudo reaches this line it will suspend processing of the current
     file (/etc/sudoers) and switch to /etc/sudoers.local.  Upon reaching the
     end of /etc/sudoers.local, the rest of /etc/sudoers will be processed.
     Files that are included may themselves include other files.  A hard limit
     of 128 nested include files is enforced to prevent include file loops.

     If the path to the include file is not fully-qualified (does not begin
     with a `/', it must be located in the same directory as the sudoers file
     it was included from.  For example, if /etc/sudoers contains the line:

         #include sudoers.local

     the file that will be included is /etc/sudoers.local.

     The file name may also include the %h escape, signifying the short form
     of the host name.  In other words, if the machine's host name is
     ``xerxes'', then

         #include /etc/sudoers.%h

     will cause sudo to include the file /etc/sudoers.xerxes.

     The #includedir directive can be used to create a sudo.d directory that
     the system package manager can drop sudoers rules into as part of package
     installation.  For example, given:

         #includedir /etc/sudoers.d

     sudo will read each file in /etc/sudoers.d, skipping file names that end
     in `~' or contain a `.' character to avoid causing problems with package
     manager or editor temporary/backup files.  Files are parsed in sorted
     lexical order.  That is, /etc/sudoers.d/01_first will be parsed before
     /etc/sudoers.d/10_second.  Be aware that because the sorting is lexical,
     not numeric, /etc/sudoers.d/1_whoops would be loaded after
     /etc/sudoers.d/10_second.  Using a consistent number of leading zeroes in
     the file names can be used to avoid such problems.

     Note that unlike files included via #include, visudo will not edit the
     files in a #includedir directory unless one of them contains a syntax
     error.  It is still possible to run visudo with the -f flag to edit the
     files directly.

   Other special characters and reserved words
     The pound sign (`#') is used to indicate a comment (unless it is part of
     a #include directive or unless it occurs in the context of a user name
     and is followed by one or more digits, in which case it is treated as a
     uid).  Both the comment character and any text after it, up to the end of
     the line, are ignored.

     The reserved word ALL is a built-in alias that always causes a match to
     succeed.  It can be used wherever one might otherwise use a Cmnd_Alias,
     User_Alias, Runas_Alias, or Host_Alias.  You should not try to define
     your own alias called ALL as the built-in alias will be used in
     preference to your own.  Please note that using ALL can be dangerous
     since in a command context, it allows the user to run any command on the
     system.

     An exclamation point (`!') can be used as a logical not operator both in
     an alias and in front of a Cmnd.  This allows one to exclude certain
     values.  Note, however, that using a `!' in conjunction with the built-in
     ALL alias to allow a user to run ``all but a few'' commands rarely works
     as intended (see SECURITY NOTES below).

     Long lines can be continued with a backslash (`\') as the last character
     on the line.

     White space between elements in a list as well as special syntactic
     characters in a User Specification (`=', `:', `(', `)') is optional.

     The following characters must be escaped with a backslash (`\') when used
     as part of a word (e.g. a user name or host name): `!', `=', `:', `,',
     `(', `)', `\'.

SUDOERS OPTIONS
     sudo's behavior can be modified by Default_Entry lines, as explained
     earlier.  A list of all supported Defaults parameters, grouped by type,
     are listed below.

     Boolean Flags:

     always_set_home   If enabled, sudo will set the HOME environment variable
                       to the home directory of the target user (which is root
                       unless the -u option is used).  This effectively means
                       that the -H option is always implied.  This flag is off
                       by default.

     authenticate      If set, users must authenticate themselves via a
                       password (or other means of authentication) before they
                       may run commands.  This default may be overridden via
                       the PASSWD and NOPASSWD tags.  This flag is on by
                       default.

     closefrom_override
                       If set, the user may use sudo's -C option which
                       overrides the default starting point at which sudo
                       begins closing open file descriptors.  This flag is off
                       by default.

     env_editor        If set, visudo will use the value of the EDITOR or
                       VISUAL environment variables before falling back on the
                       default editor list.  Note that this may create a
                       security hole as it allows the user to run any
                       arbitrary command as root without logging.  A safer
                       alternative is to place a colon-separated list of
                       editors in the editor variable.  visudo will then only
                       use the EDITOR or VISUAL if they match a value
                       specified in editor.  This flag is on by default.

     env_reset         If set, sudo will run the command in a minimal
                       environment containing the TERM, PATH, HOME, MAIL,
                       SHELL, LOGNAME, USER, USERNAME and SUDO_* variables.
                       Any variables in the caller's environment that match
                       the env_keep and env_check lists are then added,
                       followed by any variables present in the file specified
                       by the env_file option (if any).  The default contents
                       of the env_keep and env_check lists are displayed when
                       sudo is run by root with the -V option.  If the
                       secure_path option is set, its value will be used for
                       the PATH environment variable.  This flag is on by
                       default.

     fast_glob         Normally, sudo uses the glob(3) function to do shell-
                       style globbing when matching path names.  However,
                       since it accesses the file system, glob(3) can take a
                       long time to complete for some patterns, especially
                       when the pattern references a network file system that
                       is mounted on demand (auto mounted).  The fast_glob
                       option causes sudo to use the fnmatch(3) function,
                       which does not access the file system to do its
                       matching.  The disadvantage of fast_glob is that it is
                       unable to match relative path names such as ./ls or
                       ../bin/ls.  This has security implications when path
                       names that include globbing characters are used with
                       the negation operator, `!', as such rules can be
                       trivially bypassed.  As such, this option should not be
                       used when sudoers contains rules that contain negated
                       path names which include globbing characters.  This
                       flag is off by default.

     fqdn              Set this flag if you want to put fully qualified host
                       names in the sudoers file when the local host name (as
                       returned by the hostname command) does not contain the
                       domain name.  In other words, instead of myhost you
                       would use myhost.mydomain.edu.  You may still use the
                       short form if you wish (and even mix the two).  This
                       option is only effective when the ``canonical'' host
                       name, as returned by the getaddrinfo() or
                       gethostbyname() function, is a fully-qualified domain
                       name.  This is usually the case when the system is
                       configured to use DNS for host name resolution.

                       If the system is configured to use the /etc/hosts file
                       in preference to DNS, the ``canonical'' host name may
                       not be fully-qualified.  The order that sources are
                       queried for hosts name resolution is specified in the
                       /etc/resolv.conf file.  In the /etc/hosts file, the
                       first host name of the entry is considered to be the
                       ``canonical'' name; subsequent names are aliases that
                       are not used by sudoers.  For example, the following
                       hosts file line for the machine ``xyzzy'' has the
                       fully-qualified domain name as the ``canonical'' host
                       name, and the short version as an alias.

                             192.168.1.1    xyzzy.sudo.ws xyzzy

                       If the machine's hosts file entry is not formatted
                       properly, the fqdn option will not be effective if it
                       is queried before DNS.

                       Beware that when using DNS for host name resolution,
                       turning on fqdn requires sudoers to make DNS lookups
                       which renders sudo unusable if DNS stops working (for
                       example if the machine is disconnected from the
                       network).  Also note that just like with the hosts
                       file, you must use the ``canonical'' name as DNS knows
                       it.  That is, you may not use a host alias (CNAME
                       entry) due to performance issues and the fact that
                       there is no way to get all aliases from DNS.

                       This flag is off by default.

     ignore_dot        If set, sudo will ignore "." or "" (both denoting
                       current directory) in the PATH environment variable;
                       the PATH itself is not modified.  This flag is off by
                       default.

     ignore_local_sudoers
                       If set via LDAP, parsing of /etc/sudoers will be
                       skipped.  This is intended for Enterprises that wish to
                       prevent the usage of local sudoers files so that only
                       LDAP is used.  This thwarts the efforts of rogue
                       operators who would attempt to add roles to
                       /etc/sudoers.  When this option is present,
                       /etc/sudoers does not even need to exist.  Since this
                       option tells sudo how to behave when no specific LDAP
                       entries have been matched, this sudoOption is only
                       meaningful for the cn=defaults section.  This flag is
                       off by default.

     insults           If set, sudo will insult users when they enter an
                       incorrect password.  This flag is on by default.

     log_host          If set, the host name will be logged in the (non-
                       syslog) sudo log file.  This flag is off by default.

     log_year          If set, the four-digit year will be logged in the (non-
                       syslog) sudo log file.  This flag is off by default.

     long_otp_prompt   When validating with a One Time Password (OTP) scheme
                       such as S/Key or OPIE, a two-line prompt is used to
                       make it easier to cut and paste the challenge to a
                       local window.  It's not as pretty as the default but
                       some people find it more convenient.  This flag is off
                       by default.

     mail_always       Send mail to the mailto user every time a users runs
                       sudo.  This flag is off by default.

     mail_badpass      Send mail to the mailto user if the user running sudo
                       does not enter the correct password.  If the command
                       the user is attempting to run is not permitted by
                       sudoers and one of the mail_always, mail_no_host,
                       mail_no_perms or mail_no_user flags are set, this flag
                       will have no effect.  This flag is off by default.

     mail_no_host      If set, mail will be sent to the mailto user if the
                       invoking user exists in the sudoers file, but is not
                       allowed to run commands on the current host.  This flag
                       is off by default.

     mail_no_perms     If set, mail will be sent to the mailto user if the
                       invoking user is allowed to use sudo but the command
                       they are trying is not listed in their sudoers file
                       entry or is explicitly denied.  This flag is off by
                       default.

     mail_no_user      If set, mail will be sent to the mailto user if the
                       invoking user is not in the sudoers file.  This flag is
                       on by default.

     noexec            If set, all commands run via sudo will behave as if the
                       NOEXEC tag has been set, unless overridden by a EXEC
                       tag.  See the description of NOEXEC and EXEC below as
                       well as the Preventing Shell Escapes section at the end
                       of this manual.  This flag is off by default.

     path_info         Normally, sudo will tell the user when a command could
                       not be found in their PATH environment variable.  Some
                       sites may wish to disable this as it could be used to
                       gather information on the location of executables that
                       the normal user does not have access to.  The
                       disadvantage is that if the executable is simply not in
                       the user's PATH, sudo will tell the user that they are
                       not allowed to run it, which can be confusing.  This
                       flag is off by default.

     passprompt_override
                       The password prompt specified by passprompt will
                       normally only be used if the password prompt provided
                       by systems such as PAM matches the string
                       ``Password:''.  If passprompt_override is set,
                       passprompt will always be used.  This flag is off by
                       default.

     preserve_groups   By default, sudo will initialize the group vector to
                       the list of groups the target user is in.  When
                       preserve_groups is set, the user's existing group
                       vector is left unaltered.  The real and effective group
                       IDs, however, are still set to match the target user.
                       This flag is off by default.

     pwfeedback        By default, sudo reads the password like most other
                       Unix programs, by turning off echo until the user hits
                       the return (or enter) key.  Some users become confused
                       by this as it appears to them that sudo has hung at
                       this point.  When pwfeedback is set, sudo will provide
                       visual feedback when the user presses a key.  Note that
                       this does have a security impact as an onlooker may be
                       able to determine the length of the password being
                       entered.  This flag is off by default.

     requiretty        If set, sudo will only run when the user is logged in
                       to a real tty.  When this flag is set, sudo can only be
                       run from a login session and not via other means such
                       as cron(8) or cgi-bin scripts.  This flag is off by
                       default.

     root_sudo         If set, root is allowed to run sudo too.  Disabling
                       this prevents users from ``chaining'' sudo commands to
                       get a root shell by doing something like ``sudo sudo
                       /bin/sh''.  Note, however, that turning off root_sudo
                       will also prevent root from running sudoedit.
                       Disabling root_sudo provides no real additional
                       security; it exists purely for historical reasons.
                       This flag is on by default.

     rootpw            If set, sudo will prompt for the root password instead
                       of the password of the invoking user.  This flag is off
                       by default.

     runaspw           If set, sudo will prompt for the password of the user
                       defined by the runas_default option (defaults to root)
                       instead of the password of the invoking user.  This
                       flag is off by default.

     set_home          If enabled and sudo is invoked with the -s option the
                       HOME environment variable will be set to the home
                       directory of the target user (which is root unless the
                       -u option is used).  This effectively makes the -s
                       option imply -H.  This flag is off by default.

     set_logname       Normally, sudo will set the LOGNAME, USER and USERNAME
                       environment variables to the name of the target user
                       (usually root unless the -u option is given).  However,
                       since some programs (including the RCS revision control
                       system) use LOGNAME to determine the real identity of
                       the user, it may be desirable to change this behavior.
                       This can be done by negating the set_logname option.
                       Note that if the env_reset option has not been
                       disabled, entries in the env_keep list will override
                       the value of set_logname.  This flag is on by default.

     setenv            Allow the user to disable the env_reset option from the
                       command line via the -E option.  Additionally,
                       environment variables set via the command line are not
                       subject to the restrictions imposed by env_check,
                       env_delete, or env_keep.  As such, only trusted users
                       should be allowed to set variables in this manner.
                       This flag is off by default.

     shell_noargs      If set and sudo is invoked with no arguments it acts as
                       if the -s option had been given.  That is, it runs a
                       shell as root (the shell is determined by the SHELL
                       environment variable if it is set, falling back on the
                       shell listed in the invoking user's /etc/passwd entry
                       if not).  This flag is off by default.

     stay_setuid       Normally, when sudo executes a command the real and
                       effective UIDs are set to the target user (root by
                       default).  This option changes that behavior such that
                       the real UID is left as the invoking user's UID.  In
                       other words, this makes sudo act as a setuid wrapper.
                       This can be useful on systems that disable some
                       potentially dangerous functionality when a program is
                       run setuid.  This option is only effective on systems
                       that support either the setreuid(2) or setresuid(2)
                       system call.  This flag is off by default.

     targetpw          If set, sudo will prompt for the password of the user
                       specified by the -u option (defaults to root) instead
                       of the password of the invoking user.  In addition, the
                       time stamp file name will include the target user's
                       name.  Note that this flag precludes the use of a uid
                       not listed in the passwd database as an argument to the
                       -u option.  This flag is off by default.

     tty_tickets       If set, users must authenticate on a per-tty basis.
                       With this flag enabled, sudo will use a file named for
                       the tty the user is logged in on in the user's time
                       stamp directory.  If disabled, the time stamp of the
                       directory is used instead.  This flag is off by
                       default.

     umask_override    If set, sudo will set the umask as specified by sudoers
                       without modification.  This makes it possible to
                       specify a more permissive umask in sudoers than the
                       user's own umask and matches historical behavior.  If
                       umask_override is not set, sudo will set the umask to
                       be the union of the user's umask and what is specified
                       in sudoers.  This flag is off by default.

     use_loginclass    If set, sudo will apply the defaults specified for the
                       target user's login class if one exists.  Only
                       available if sudo is configured with the
                       --with-logincap option.  This flag is off by default.

     use_pty           If set, sudo will run the command in a pseudo-pty even
                       if no I/O logging is being gone.  A malicious program
                       run under sudo could conceivably fork a background
                       process that retains to the user's terminal device
                       after the main program has finished executing.  Use of
                       this option will make that impossible.  This flag is
                       off by default.

     visiblepw         By default, sudo will refuse to run if the user must
                       enter a password but it is not possible to disable echo
                       on the terminal.  If the visiblepw flag is set, sudo
                       will prompt for a password even when it would be
                       visible on the screen.  This makes it possible to run
                       things like ``ssh somehost sudo ls'' since by default,
                       ssh(1) does not allocate a tty when running a command.
                       This flag is off by default.

     Integers:

     closefrom         Before it executes a command, sudo will close all open
                       file descriptors other than standard input, standard
                       output and standard error (ie: file descriptors 0-2).
                       The closefrom option can be used to specify a different
                       file descriptor at which to start closing.  The default
                       is 3.

     passwd_tries      The number of tries a user gets to enter his/her
                       password before sudo logs the failure and exits.  The
                       default is 3.

     Integers that can be used in a boolean context:

     loglinelen        Number of characters per line for the file log.  This
                       value is used to decide when to wrap lines for nicer
                       log files.  This has no effect on the syslog log file,
                       only the file log.  The default is 80 (use 0 or negate
                       the option to disable word wrap).

     passwd_timeout    Number of minutes before the sudo password prompt times
                       out, or 0 for no timeout.  The timeout may include a
                       fractional component if minute granularity is
                       insufficient, for example 2.5.  The default is 5.

     timestamp_timeout
                       Number of minutes that can elapse before sudo will ask
                       for a passwd again.  The timeout may include a
                       fractional component if minute granularity is
                       insufficient, for example 2.5.  The default is 5.  Set
                       this to 0 to always prompt for a password.  If set to a
                       value less than 0 the user's time stamp will never
                       expire.  This can be used to allow users to create or
                       delete their own time stamps via ``sudo -v'' and ``sudo
                       -k'' respectively.

     umask             Umask to use when running the command.  Negate this
                       option or set it to 0777 to preserve the user's umask.
                       The actual umask that is used will be the union of the
                       user's umask and the value of the umask option, which
                       defaults to 022.  This guarantees that sudo never
                       lowers the umask when running a command.  Note: on
                       systems that use PAM, the default PAM configuration may
                       specify its own umask which will override the value set
                       in sudoers.

     Strings:

     badpass_message   Message that is displayed if a user enters an incorrect
                       password.  The default is Sorry, try again. unless
                       insults are enabled.

     editor            A colon (`:') separated list of editors allowed to be
                       used with visudo.  visudo will choose the editor that
                       matches the user's EDITOR environment variable if
                       possible, or the first editor in the list that exists
                       and is executable.  The default is /usr/bin/vi.

     mailsub           Subject of the mail sent to the mailto user.  The
                       escape %h will expand to the host name of the machine.
                       Default is ``*** SECURITY information for %h ***''.

     noexec_file       The noexec option specifies the the fully-qualified
                       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
                       LD_PRELOAD or its equivalent.  Defaults to
                       /usr/libexec/sudo_noexec.so..

     passprompt        The default prompt to use when asking for a password;
                       can be overridden via the -p option or the SUDO_PROMPT
                       environment variable.  The following percent (`%')
                       escape sequences are supported:

                       %H    expanded to the local host name including the
                             domain name (only if the machine's host name is
                             fully qualified or the fqdn option is set)

                       %h    expanded to the local host name without the
                             domain name

                       %p    expanded to the user whose password is being
                             asked for (respects the rootpw, targetpw and
                             runaspw flags in sudoers)

                       %U    expanded to the login name of the user the
                             command will be run as (defaults to root)

                       %u    expanded to the invoking user's login name

                       %%    two consecutive % characters are collapsed into a
                             single % character

                       The default value is ``Password:''.

     runas_default     The default user to run commands as if the -u option is
                       not specified on the command line.  This defaults to
                       root.

     syslog_badpri     Syslog priority to use when user authenticates
                       unsuccessfully.  Defaults to alert.

                       The following syslog priorities are supported: alert,
                       crit, debug, emerg, err, info, notice, and warning.

     syslog_goodpri    Syslog priority to use when user authenticates
                       successfully.  Defaults to notice.

                       See syslog_badpri for the list of supported syslog
                       priorities.

     sudoers_locale    Locale to use when parsing the sudoers file, logging
                       commands, and sending email.  Note that changing the
                       locale may affect how sudoers is interpreted.  Defaults
                       to ``C''.

     timestampdir      The directory in which sudo stores its time stamp
                       files.  The default is /var/run/sudo.

     timestampowner    The owner of the time stamp directory and the time
                       stamps stored therein.  The default is root.

     askpass           The askpass option specifies 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.

     env_file          The env_file option specifies the fully qualified path
                       to a file containing variables to be set in the
                       environment of the program being run.  Entries in this
                       file should either be of the form ``VARIABLE=value'' or
                       ``export VARIABLE=value''.  The value may optionally be
                       surrounded by single or double quotes.  Variables in
                       this file are subject to other sudo environment
                       settings such as env_keep and env_check.

     exempt_group      Users in this group are exempt from password and PATH
                       requirements.  The group name specified should not
                       include a % prefix.  This is not set by default.

     lecture           This option controls when a short lecture will be
                       printed along with the password prompt.  It has the
                       following possible values:

                       always  Always lecture the user.

                       never   Never lecture the user.

                       once    Only lecture the user the first time they run
                               sudo.

                       If no value is specified, a value of once is implied.
                       Negating the option results in a value of never being
                       used.  The default value is on.

     lecture_file      Path to a file containing an alternate sudo lecture
                       that will be used in place of the standard lecture if
                       the named file exists.  By default, sudo uses a built-
                       in lecture.

     listpw            This option controls when a password will be required
                       when a user runs sudo with the -l option.  It has the
                       following possible values:

                       all       All the user's sudoers entries for the
                                 current host must have the NOPASSWD flag set
                                 to avoid entering a password.

                       always    The user must always enter a password to use
                                 the -l option.

                       any       At least one of the user's sudoers entries
                                 for the current host must have the NOPASSWD
                                 flag set to avoid entering a password.

                       never     The user need never enter a password to use
                                 the -l option.

                       If no value is specified, a value of any is implied.
                       Negating the option results in a value of never being
                       used.  The default value is any.

     logfile           Path to the sudo log file (not the syslog log file).
                       Setting a path turns on logging to a file; negating
                       this option turns it off.  By default, sudo logs via
                       syslog.

     mailerflags       Flags to use when invoking mailer. Defaults to -t.

     mailerpath        Path to mail program used to send warning mail.
                       Defaults to the path to sendmail found at configure
                       time.

     mailfrom          Address to use for the ``from'' address when sending
                       warning and error mail.  The address should be enclosed
                       in double quotes ("") to protect against sudo
                       interpreting the @ sign.  Defaults to the name of the
                       user running sudo.

     mailto            Address to send warning and error mail to.  The address
                       should be enclosed in double quotes ("") to protect
                       against sudo interpreting the @ sign.  Defaults to
                       root.

     secure_path       Path used for every command run from sudo.  If you
                       don't trust the people running sudo to have a sane PATH
                       environment variable you may want to use this.  Another
                       use is if you want to have the ``root path'' be
                       separate from the ``user path''.  Users in the group
                       specified by the exempt_group option are not affected
                       by secure_path.  This option is not set by default.

     syslog            Syslog facility if syslog is being used for logging
                       (negate to disable syslog logging).  Defaults to
                       authpriv.

                       The following syslog facilities are supported: authpriv
                       (if your OS supports it), auth, daemon, user, local0,
                       local1, local2, local3, local4, local5, local6, and
                       local7.

     verifypw          This option controls when a password will be required
                       when a user runs sudo with the -v option.  It has the
                       following possible values:

                       all     All the user's sudoers entries for the current
                               host must have the NOPASSWD flag set to avoid
                               entering a password.

                       always  The user must always enter a password to use
                               the -v option.

                       any     At least one of the user's sudoers entries for
                               the current host must have the NOPASSWD flag
                               set to avoid entering a password.

                       never   The user need never enter a password to use the
                               -v option.

                       If no value is specified, a value of all is implied.
                       Negating the option results in a value of never being
                       used.  The default value is all.

     Lists that can be used in a boolean context:

     env_check         Environment variables to be removed from the user's
                       environment if the variable's value contains `%' or `/'
                       characters.  This can be used to guard against printf-
                       style format vulnerabilities in poorly-written
                       programs.  The argument may be a double-quoted, space-
                       separated list or a single value without double-quotes.
                       The list can be replaced, added to, deleted from, or
                       disabled by using the =, +=, -=, and ! operators
                       respectively.  Regardless of whether the env_reset
                       option is enabled or disabled, variables specified by
                       env_check will be preserved in the environment if they
                       pass the aforementioned check.  The default list of
                       environment variables to check is displayed when sudo
                       is run by root with the -V option.

     env_delete        Environment variables to be removed from the user's
                       environment when the env_reset option is not in effect.
                       The argument may be a double-quoted, space-separated
                       list or a single value without double-quotes.  The list
                       can be replaced, added to, deleted from, or disabled by
                       using the =, +=, -=, and ! operators respectively.  The
                       default list of environment variables to remove is
                       displayed when sudo is run by root with the -V option.
                       Note that many operating systems will remove
                       potentially dangerous variables from the environment of
                       any setuid process (such as sudo).

     env_keep          Environment variables to be preserved in the user's
                       environment when the env_reset option is in effect.
                       This allows fine-grained control over the environment
                       sudo-spawned processes will receive.  The argument may
                       be a double-quoted, space-separated list or a single
                       value without double-quotes.  The list can be replaced,
                       added to, deleted from, or disabled by using the =, +=,
                       -=, and ! operators respectively.  The default list of
                       variables to keep is displayed when sudo is run by root
                       with the -V option.

FILES
     /etc/sudoers              List of who can run what

     /etc/group                Local groups file

     /etc/netgroup             List of network groups

EXAMPLES
     Below are example sudoers entries.  Admittedly, some of these are a bit
     contrived.  First, we allow a few environment variables to pass and then
     define our aliases:

     # Run X applications through sudo; HOME is used to find the
     # .Xauthority file.  Note that other programs use HOME to find
     # configuration files and this may lead to privilege escalation!
     Defaults env_keep += "DISPLAY HOME"

     # User alias specification
     User_Alias      FULLTIMERS = millert, mikef, dowdy
     User_Alias      PARTTIMERS = bostley, jwfox, crawl
     User_Alias      WEBMASTERS = will, wendy, wim

     # Runas alias specification
     Runas_Alias     OP = root, operator
     Runas_Alias     DB = oracle, sybase
     Runas_Alias     ADMINGRP = adm, oper

     # Host alias specification
     Host_Alias      SPARC = bigtime, eclipse, moet, anchor :\
                     SGI = grolsch, dandelion, black :\
                     ALPHA = widget, thalamus, foobar :\
                     HPPA = boa, nag, python
     Host_Alias      CUNETS = 128.138.0.0/255.255.0.0
     Host_Alias      CSNETS = 128.138.243.0, 128.138.204.0/24, 128.138.242.0
     Host_Alias      SERVERS = master, mail, www, ns
     Host_Alias      CDROM = orion, perseus, hercules

     # Cmnd alias specification
     Cmnd_Alias      DUMPS = /usr/bin/mt, /usr/sbin/dump, /usr/sbin/rdump,\
                             /usr/sbin/restore, /usr/sbin/rrestore
     Cmnd_Alias      KILL = /usr/bin/kill
     Cmnd_Alias      PRINTING = /usr/sbin/lpc, /usr/bin/lprm
     Cmnd_Alias      SHUTDOWN = /usr/sbin/shutdown
     Cmnd_Alias      HALT = /usr/sbin/halt
     Cmnd_Alias      REBOOT = /usr/sbin/reboot
     Cmnd_Alias      SHELLS = /usr/bin/sh, /usr/bin/csh, /usr/bin/ksh,\
                              /usr/local/bin/tcsh, /usr/bin/rsh,\
                              /usr/local/bin/zsh
     Cmnd_Alias      SU = /usr/bin/su
     Cmnd_Alias      PAGERS = /usr/bin/more, /usr/bin/pg, /usr/bin/less

     Here we override some of the compiled in default values.  We want sudo to
     log via syslog(3) using the auth facility in all cases.  We don't want to
     subject the full time staff to the sudo lecture, user millert need not
     give a password, and we don't want to reset the LOGNAME, USER or USERNAME
     environment variables when running commands as root.  Additionally, on
     the machines in the SERVERS Host_Alias, we keep an additional local log
     file and make sure we log the year in each log line since the log entries
     will be kept around for several years.  Lastly, we disable shell escapes
     for the commands in the PAGERS Cmnd_Alias (/usr/bin/more, /usr/bin/pg and
     /usr/bin/less).

     # Override built-in defaults
     Defaults                syslog=auth
     Defaults>root           !set_logname
     Defaults:FULLTIMERS     !lecture
     Defaults:millert        !authenticate
     Defaults@SERVERS        log_year, logfile=/var/log/sudo.log
     Defaults!PAGERS         noexec

     The User specification is the part that actually determines who may run
     what.

     root            ALL = (ALL) ALL
     %wheel          ALL = (ALL) ALL

     We let root and any user in group wheel run any command on any host as
     any user.

     FULLTIMERS      ALL = NOPASSWD: ALL

     Full time sysadmins (millert, mikef, and dowdy) may run any command on
     any host without authenticating themselves.

     PARTTIMERS      ALL = ALL

     Part time sysadmins bostley, jwfox, and crawl) may run any command on any
     host but they must authenticate themselves first (since the entry lacks
     the NOPASSWD tag).

     jack            CSNETS = ALL

     The user jack may run any command on the machines in the CSNETS alias
     (the networks 128.138.243.0, 128.138.204.0, and 128.138.242.0).  Of those
     networks, only 128.138.204.0 has an explicit netmask (in CIDR notation)
     indicating it is a class C network.  For the other networks in CSNETS,
     the local machine's netmask will be used during matching.

     lisa            CUNETS = ALL

     The user lisa may run any command on any host in the CUNETS alias (the
     class B network 128.138.0.0).

     operator        ALL = DUMPS, KILL, SHUTDOWN, HALT, REBOOT, PRINTING,\
                     sudoedit /etc/printcap, /usr/oper/bin/

     The operator user may run commands limited to simple maintenance.  Here,
     those are commands related to backups, killing processes, the printing
     system, shutting down the system, and any commands in the directory
     /usr/oper/bin/.

     joe             ALL = /usr/bin/su operator

     The user joe may only su(1) to operator.

     pete            HPPA = /usr/bin/passwd [A-Za-z]*, !/usr/bin/passwd root

     %opers          ALL = (: ADMINGRP) /usr/sbin/

     Users in the opers group may run commands in /usr/sbin/ as themselves
     with any group in the ADMINGRP Runas_Alias (the adm and oper groups).

     The user pete is allowed to change anyone's password except for root on
     the HPPA machines.  Note that this assumes passwd(1) does not take
     multiple user names on the command line.

     bob             SPARC = (OP) ALL : SGI = (OP) ALL

     The user bob may run anything on the SPARC and SGI machines as any user
     listed in the OP Runas_Alias (root and operator.)

     jim             +biglab = ALL

     The user jim may run any command on machines in the biglab netgroup.
     sudo knows that ``biglab'' is a netgroup due to the `+' prefix.

     +secretaries    ALL = PRINTING, /usr/bin/adduser, /usr/bin/rmuser

     Users in the secretaries netgroup need to help manage the printers as
     well as add and remove users, so they are allowed to run those commands
     on all machines.

     fred            ALL = (DB) NOPASSWD: ALL

     The user fred can run commands as any user in the DB Runas_Alias (oracle
     or sybase) without giving a password.

     john            ALPHA = /usr/bin/su [!-]*, !/usr/bin/su *root*

     On the ALPHA machines, user john may su to anyone except root but he is
     not allowed to specify any options to the su(1) command.

     jen             ALL, !SERVERS = ALL

     The user jen may run any command on any machine except for those in the
     SERVERS Host_Alias (master, mail, www and ns).

     jill            SERVERS = /usr/bin/, !SU, !SHELLS

     For any machine in the SERVERS Host_Alias, jill may run any commands in
     the directory /usr/bin/ except for those commands belonging to the SU and
     SHELLS Cmnd_Aliases.

     steve           CSNETS = (operator) /usr/local/op_commands/

     The user steve may run any command in the directory
     /usr/local/op_commands/ but only as user operator.

     matt            valkyrie = KILL

     On his personal workstation, valkyrie, matt needs to be able to kill hung
     processes.

     WEBMASTERS      www = (www) ALL, (root) /usr/bin/su www

     On the host www, any user in the WEBMASTERS User_Alias (will, wendy, and
     wim), may run any command as user www (which owns the web pages) or
     simply su(1) to www.

     ALL             CDROM = NOPASSWD: /sbin/umount /CDROM,\
                     /sbin/mount -o nosuidnodev /dev/cd0a /CDROM

     Any user may mount or unmount a CD-ROM on the machines in the CDROM
     Host_Alias (orion, perseus, hercules) without entering a password.  This
     is a bit tedious for users to type, so it is a prime candidate for
     encapsulating in a shell script.

SECURITY NOTES
   Limitations of the `!' operator
     It is generally not effective to ``subtract'' commands from ALL using the
     `!' operator.  A user can trivially circumvent this by copying the
     desired command to a different name and then executing that.  For
     example:

     bill    ALL = ALL, !SU, !SHELLS

     Doesn't really prevent bill from running the commands listed in SU or
     SHELLS since he can simply copy those commands to a different name, or
     use a shell escape from an editor or other program.  Therefore, these
     kind of restrictions should be considered advisory at best (and
     reinforced by policy).

     In general, if a user has sudo ALL there is nothing to prevent them from
     creating their own program that gives them a root shell (or making their
     own copy of a shell) regardless of any `!' elements in the user
     specification.

   Security implications of fast_glob
     If the fast_glob option is in use, it is not possible to reliably negate
     commands where the path name includes globbing (aka wildcard) characters.
     This is because the C library's fnmatch(3) function cannot resolve
     relative paths.  While this is typically only an inconvenience for rules
     that grant privileges, it can result in a security issue for rules that
     subtract or revoke privileges.

     For example, given the following sudoers entry:

     john    ALL = /usr/bin/passwd [a-zA-Z0-9]*, /usr/bin/chsh [a-zA-Z0-9]*,\
                   /usr/bin/chfn [a-zA-Z0-9]*, !/usr/bin/* root

     User john can still run /usr/bin/passwd root if fast_glob is enabled by
     changing to /usr/bin and running ./passwd root instead.

   Preventing Shell Escapes
     Once sudo executes a program, that program is free to do whatever it
     pleases, including run other programs.  This can be a security issue
     since it is not uncommon for a program to allow shell escapes, which lets
     a user bypass sudo's access control and logging.  Common programs that
     permit shell escapes include shells (obviously), editors, paginators,
     mail and terminal programs.

     There are two basic approaches to this problem:

     restrict  Avoid giving users access to commands that allow the user to
               run arbitrary commands.  Many editors have a restricted mode
               where shell escapes are disabled, though sudoedit is a better
               solution to running editors via sudo.  Due to the large number
               of programs that offer shell escapes, restricting users to the
               set of programs that do not is often unworkable.

     noexec    Many systems that support shared libraries have the ability to
               override default library functions by pointing an environment
               variable (usually LD_PRELOAD) to an alternate shared library.
               On such systems, sudo's noexec functionality can be used to
               prevent a program run by sudo from executing any other
               programs.  Note, however, that this applies only to native
               dynamically-linked executables.  Statically-linked executables
               and foreign executables running under binary emulation are not
               affected.

               The noexec feature is known to work on SunOS, Solaris, *BSD,
               Linux, IRIX, Tru64 UNIX, MacOS X, HP-UX 11.x and AIX 5.3 and
               above.  It should be supported on most operating systems that
               support the LD_PRELOAD environment variable.  Check your
               operating system's manual pages for the dynamic linker (usually
               ld.so, ld.so.1, dyld, dld.sl, rld, or loader) to see if
               LD_PRELOAD is supported.

               To enable noexec for a command, use the NOEXEC tag as
               documented in the User Specification section above.  Here is
               that example again:

               aaron   shanty = NOEXEC: /usr/bin/more, /usr/bin/vi

               This allows user aaron to run /usr/bin/more and /usr/bin/vi
               with noexec enabled.  This will prevent those two commands from
               executing other commands (such as a shell).  If you are unsure
               whether or not your system is capable of supporting noexec you
               can always just try it out and check whether shell escapes work
               when noexec is enabled.

     Note that restricting shell escapes is not a panacea.  Programs running
     as root are still capable of many potentially hazardous operations (such
     as changing or overwriting files) that could lead to unintended privilege
     escalation.  In the specific case of an editor, a safer approach is to
     give the user permission to run sudoedit.

SEE ALSO
     ssh(1), su(1), fnmatch(3), glob(3), mktemp(3), strftime(3),
     sudoers.ldap(5), sudo(8), visudo(8)

CAVEATS
     The sudoers file should always be edited by the visudo command which
     locks the file and does grammatical checking.  It is imperative that
     sudoers be free of syntax errors since sudo will not run with a
     syntactically incorrect sudoers file.

     When using netgroups of machines (as opposed to users), if you store
     fully qualified host name in the netgroup (as is usually the case), you
     either need to have the machine's host name be fully qualified as
     returned by the hostname command or use the fqdn option in sudoers.

BUGS
     If you feel you have found a bug in sudo, please submit a bug report at
     http://www.sudo.ws/sudo/bugs/

SUPPORT
     Limited free support is available via the sudo-users mailing list, see
     http://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 disclaimed.  See the LICENSE
     file distributed with sudo or http://www.sudo.ws/sudo/license.html for
     complete details.

FreeBSD 11.0-PRERELEASE         August 17, 2012        FreeBSD 11.0-PRERELEASE

NAME | DESCRIPTION | SUDOERS OPTIONS | FILES | EXAMPLES | SECURITY NOTES | SEE ALSO | CAVEATS | BUGS | SUPPORT | DISCLAIMER

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