Provided by: sudo-ldap_1.6.8p12-1ubuntu6_i386 bug

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 conflicting values, 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 don’t know what EBNF is; 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 ::= ’!’* username │
                 ’!’* ’%’group │
                 ’!’* ’+’netgroup │
                 ’!’* User_Alias

       A User_List is made up of one or more usernames, system groups
       (prefixed with ’%’), netgroups (prefixed with ’+’) and other aliases.
       Each list item may be prefixed with one or more ’!’ operators.  An odd
       number of ’!’ operators negate the value of the item; an even number
       just cancel each other out.

        Runas_List ::= Runas_User │
                       Runas_User ’,’ Runas_List

        Runas_User ::= ’!’* username │
                       ’!’* ’#’uid │
                       ’!’* ’%’group │
                       ’!’* +netgroup │
                       ’!’* Runas_Alias

       A Runas_List is similar to a User_List except that it can also contain
       uids (prefixed with ’#’) and instead of User_Aliases it can contain
       Runas_Aliases.  Note that usernames 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 usernames 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 ::= ’!’* hostname │
                 ’!’* ip_addr │
                 ’!’* network(/netmask)? │
                 ’!’* ’+’netgroup │
                 ’!’* Host_Alias

       A Host_List is made up of one or more hostnames, 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 with a network number, the netmask of the host’s
       ethernet interface(s) will be used when matching.  The netmask may be
       specified either in dotted quad notation (e.g.  255.255.255.0) or CIDR
       notation (number of bits, e.g. 24).  A hostname may include shell-style
       wildcards (see the Wildcards section below), but unless the hostname
       command on your machine returns the fully qualified hostname, you’ll
       need to use the fqdn option for wildcards to be useful.

        Cmnd_List ::= Cmnd │
                      Cmnd ’,’ Cmnd_List

        commandname ::= filename │
                        filename args │
                        filename ’""’

        Cmnd ::= ’!’* commandname │
                 ’!’* directory │
                 ’!’* "sudoedit" │
                 ’!’* Cmnd_Alias

       A Cmnd_List is a list of one or more commandnames, directories, and
       other aliases.  A commandname is a fully qualified filename which may
       include shell-style wildcards (see the Wildcards section below).  A
       simple filename 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 pathname 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 subdirectories 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 flag (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 runtime via one or more Default_Entry lines.  These may affect all
       users on any host, all users on a specific host, a specific user, or
       commands being run as a specific user.

        Default_Type ::= ’Defaults’ │
                         ’Defaults’ ’@’ Host │
                         ’Defaults’ ’:’ User │
                         ’Defaults’ ’>’ RunasUser

        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.

       Flags:

       long_otp_prompt
                   When validating with a One Time Password scheme (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.

       ignore_dot  If set, sudo will ignore ’.’ or ’’ (current dir) in the
                   PATH environment variable; the PATH itself is not modified.
                   This flag is off by default.  Currently, while it is
                   possible to set ignore_dot in sudoers, its value is not
                   used.  This option should be considered read-only (it will
                   be fixed in a future version of sudo).

       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.  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.

       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.

       tty_tickets If set, users must authenticate on a per-tty basis.
                   Normally, sudo uses a directory in the ticket dir with the
                   same name as the user running it.  With this flag enabled,
                   sudo will use a file named for the tty the user is logged
                   in on in that directory.  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.

       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
                   and from running sudoedit.  Disabling root_sudo provides no
                   real additional security; it exists purely for historical
                   reasons.  This flag is on by default.

       log_host    If set, the hostname 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.

       shell_noargs
                   If set and sudo is invoked with no arguments it acts as if
                   the -s flag 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.

       set_home    If set and sudo is invoked with the -s flag 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 flag imply -H.  This
                   flag is off by default.

       always_set_home
                   If set, 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
                   flag is always implied.  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.

       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.

       fqdn        Set this flag if you want to put fully qualified hostnames
                   in the sudoers file.  I.e., instead of myhost you would use
                   myhost.mydomain.edu.  You may still use the short form if
                   you wish (and even mix the two).  Beware that turning on
                   fqdn requires sudo to make DNS lookups which may make sudo
                   unusable if DNS stops working (for example if the machine
                   is not plugged into the network).  Also note that you must
                   use the host’s official 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.  If your machine’s hostname (as returned by the
                   hostname command) is already fully qualified you shouldn’t
                   need to set fqdn.  This flag is on by default.

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

       requiretty  If set, sudo will only run when the user is logged in to a
                   real tty.  This will disallow things like "rsh somehost
                   sudo ls" since rsh(1) does not allocate a tty.  Because it
                   is not possible to turn off echo when there is no tty
                   present, some sites may with to set this flag to prevent a
                   user from entering a visible password.  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.

       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.

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

       set_logname Normally, sudo will set the LOGNAME and USER environment
                   variables to the name of the target user (usually root
                   unless the -u flag 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.

       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.
                   Note, however, that this means that sudo will run with the
                   real uid of the invoking user which may allow that user to
                   kill sudo before it can log a failure, depending on how
                   your OS defines the interaction between signals and setuid
                   processes.

       env_reset   If set, sudo will reset the environment to only contain the
                   following variables: HOME, LOGNAME, PATH, SHELL, TERM, and
                   USER (in addition to the SUDO_* variables).  Of these, only
                   TERM is copied unaltered from the old environment.  The
                   other variables are set to default values (possibly
                   modified by the value of the set_logname option).  If sudo
                   was compiled with the SECURE_PATH option, its value will be
                   used for the PATH environment variable.  Other variables
                   may be preserved with the env_keep option.

       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.

       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.

       ignore_local_sudoers
                   If set via LDAP, parsing of @sysconfdir@/sudoers will be
                   skipped.  This is intended for an 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 @sysconfdir@/sudoers.  When
                   this option is present, @sysconfdir@/sudoers does not even
                   need to exist.  Since this options 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.

       Integers:

       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).

       timestamp_timeout
                   Number of minutes that can elapse before sudo will ask for
                   a passwd again.  The default is 15.  Set this to 0 to
                   always prompt for a password.  If set to a value less than
                   0 the user’s timestamp will never expire.  This can be used
                   to allow users to create or delete their own timestamps via
                   sudo -v and sudo -k respectively.

       passwd_timeout
                   Number of minutes before the sudo password prompt times
                   out.  The default is 0, set this to 0 for no password
                   timeout.

       umask       Umask to use when running the command.  Negate this option
                   or set it to 0777 to preserve the user’s umask.  The
                   default is 0022.

       Strings:

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

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

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

       timestampowner
                   The owner of the timestamp directory and the timestamps
                   stored therein.  The default is root.

       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 (‘%’) escapes
                   are supported:

                   %u      expanded to the invoking user’s login name

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

                   %h      expanded to the local hostname without the domain
                           name

                   %H      expanded to the local hostname including the domain
                           name (on if the machine’s hostname is fully
                           qualified or the fqdn option is set)

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

                   The default value is Password:.

       runas_default
                   The default user to run commands as if the -u flag is not
                   specified on the command line.  This defaults to root.
                   Note that if runas_default is set it must occur before any
                   Runas_Alias specifications.

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

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

       editor      A colon (’:’) separated list of editors allowed to be used
                   with visudo.  visudo will choose the editor that matches
                   the user’s USER environment variable if possible, or the
                   first editor in the list that exists and is executable.
                   The default is the path to vi on your system.

       noexec_file 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.

       Strings that can be used in a boolean context:

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

                   never   Never lecture the user.

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

                   always  Always lecture the user.

                   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 once.

       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.

       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.

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

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

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

       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.

       exempt_group
                   Users in this group are exempt from password and PATH
                   requirements.  On Debian systems, this is set to the group
                   ’sudo’ by default.

       verifypw    This option controls when a password will be required when
                   a user runs sudo with the -v flag.  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.

                   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
                           flag.

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

                   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.

       listpw      This option controls when a password will be required when
                   a user runs sudo with the -l flag.  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.

                   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
                           flag.

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

                   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.

       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.  The default list
                   of environment variables to check is printed when sudo is
                   run by root with the -V option.

       env_delete  Environment variables to be removed from the user’s
                   environment.  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 printed 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.  This list has no default members.

       When logging via syslog(3), sudo accepts the following values for the
       syslog facility (the value of the syslog Parameter): authpriv (if your
       OS supports it), auth, daemon, user, local0, local1, local2, local3,
       local4, local5, local6, and local7.  The following syslog priorities
       are supported: alert, crit, debug, emerg, err, info, notice, and
       warning.

       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 ’)’

        Tag_Spec ::= (’NOPASSWD:’ │ ’PASSWD:’ │ ’NOEXEC:’ │ ’EXEC:’)

       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.

       Let’s break that down into its constituent parts:

       Runas_Spec

       A Runas_Spec is simply a Runas_List (as defined above) enclosed in a
       set of parentheses.  If you do not specify a Runas_Spec in the user
       specification, a default Runas_Spec of root will be used.  A Runas_Spec
       sets the default for 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.

       Tag_Spec

       A command may have zero or more tags associated with it.  There are
       four possible tag values, NOPASSWD, PASSWD, NOEXEC, EXEC.  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 (ie: PASSWD overrides
       NOPASSWD and EXEC overrides NOEXEC).

       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 as root 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 support 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.

       Wildcards

       sudo allows shell-style wildcards (aka meta or glob characters) to be
       used in pathnames as well as command line arguments in the sudoers
       file.  Wildcard matching is done via the POSIX fnmatch(3) routine.
       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 "}".

       Note that a forward slash (’/’) will not be matched by wildcards used
       in the pathname.  When matching the command line arguments, however, a
       slash does get matched by wildcards.  This is to make a path like:

           /usr/bin/*

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

       WARNING: a pathname with wildcards will not match a user command that
       consists of a relative path.  In other words, given the following
       sudoers entry:

           billy  workstation = /usr/bin/*

       user billy will be able to run any command in /usr/bin as root, such as
       /usr/bin/w.  The following two command will be allowed (the first
       assumes that /usr/bin is in the user’s path):

           $ sudo w
           $ sudo /usr/bin/w

       However, this will not:

           $ cd /usr/bin
           $ sudo ./w

       For this reason you should only grant access to commands using
       wildcards and never restrict access using them.  This limitation will
       be removed in a future version of sudo.

       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.

       Other special characters and reserved words

       The pound sign (’#’) is used to indicate a comment (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.

       Whitespace 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 username or hostname): ’@’, ’!’, ’=’,
       ’:’, ’,’, ’(’, ’)’, ’\’.

FILES

        /etc/sudoers           List of who can run what
        /etc/group             Local groups file
        /etc/netgroup          List of network groups

EXAMPLES

       Since the sudoers file is parsed in a single pass, order is important.
       In general, you should structure sudoers such that the Host_Alias,
       User_Alias, and Cmnd_Alias specifications come first, followed by any
       Default_Entry lines, and finally the Runas_Alias and user
       specifications.  The basic rule of thumb is you cannot reference an
       Alias that has not already been defined.

       Below are example sudoers entries.  Admittedly, some of these are a bit
       contrived.  First, we define our aliases:

        # 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

        # 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

       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 or
       USER 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.

        # 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

       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-z]*, !/usr/bin/passwd root

       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 usernames 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 give su(1) any flags.

        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 nosuid\,nodev /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

       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).

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 restrictions.  Common programs that permit
       shell escapes include shells (obviously), editors, paginators, mail and
       terminal programs.

       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.

       To tell whether or not sudo supports noexec, you can run the following
       as root:

           sudo -V │ grep "dummy exec"

       If the resulting output contains a line that begins with:

           File containing dummy exec functions:

       then sudo may be able to replace the exec family of functions in the
       standard library with its own that simply return an error.
       Unfortunately, there is no foolproof way to know whether or not noexec
       will work at compile-time.  Noexec should work on SunOS, Solaris, *BSD,
       Linux, IRIX, Tru64 UNIX, MacOS X, and HP-UX 11.x.  It is known not to
       work on AIX and UnixWare.  Noexec is expected to work 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 see if it works.

       Note that disabling 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

       rsh(1), su(1), fnmatch(3), 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 hostnames in the netgroup (as is usually the case), you
       either need to have the machine’s hostname 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

       Commercial support is available for sudo, see
       http://www.sudo.ws/sudo/support.html for details.

       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.