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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 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



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        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 |
                 '!'* '#'uid |
                 '!'* '%'group |
                 '!'* '+'netgroup |
                 '!'* '%:'nonunix_group |
                 '!'* User_Alias

       A User_List is made up of one or more usernames, uids (prefixed with
       '#'), system groups (prefixed with '%'), netgroups (prefixed with '+')
       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 username, group, netgroup and nonunix_groups 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.

       The nonunix_group 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 the '@' symbol.

        Runas_List ::= Runas_Member |
                       Runas_Member ',' Runas_List



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        Runas_Member ::= '!'* username |
                         '!'* '#'uid |
                         '!'* '%'group |
                         '!'* +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 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 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 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



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       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 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 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, 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.



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   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.




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       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

       In the following example, user tcm may run commands that access a modem
       device file with the dialer group.  Note that in this example only the
       group will be set, the command still runs as user tcm.

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

   Tag_Spec
       A command may have zero or more tags associated with it.  There are
       eight 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 (i.e.: 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



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       /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, any environment
       variables set on the command line way 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 UNSETENV tag.

   Wildcards
       sudo allows shell-style wildcards (aka meta or glob characters) to be
       used in hostnames, pathnames 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 filename beginning with a letter.

       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.

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

       ""      If the empty string "" is the only command line argument in the



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               sudoers entry it means that command is not allowed to be run
               with any arguments.

   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.

       The filename may include the %h escape, signifying the short form of
       the hostname.  I.e., if the machine's hostname 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



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       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): '@', '!', '=',
       ':', ',', '(', ')', '\'.

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.

       Flags:

       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 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



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                       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 reset the environment to only contain
                       the LOGNAME, SHELL, USER, USERNAME and the SUDO_*
                       variables.  Any variables in the caller's environment
                       that match the env_keep and env_check lists are then
                       added.  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.

       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
                       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.

       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.




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       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.

       long_otp_prompt When validating with a One Time Password (OPT) 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.  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 passwod prompt provided by



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                       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 and 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 set 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,



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                       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 off by default.

       setenv          Allow the user to disable the env_reset option from the
                       command line.  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.

       fast_glob       Normally, sudo uses the glob(3) function to do shell-
                       style globbing when matching pathnames.  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 (automounted).  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 pathnames such as ./ls or ../bin/ls.  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
                       with either the setreuid() or setresuid() function.
                       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.  Note that this
                       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.



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                       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.

       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.

       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 "rsh somehost sudo ls" since rsh(1) does
                       not allocate a tty.  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.  The default is 5; set this to 0 for no password
                       timeout.

       timestamp_timeout
                       Number of minutes that can elapse before sudo will ask



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                       for a passwd again.  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 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.

       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 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 the path to vi on
                       your system.

       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 ***.

       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..

       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:

                       %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)

                       %h  expanded to the local hostname without the domain
                           name

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



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                           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:.

       role            The default SELinux role to use when constructing a new
                       security context to run the command.  The default role
                       may be overridden on a per-command basis in sudoers or
                       via command line options.  This option is only
                       available whe sudo is built with SELinux support.

       runas_default   The default user to run commands as if the -u option 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_badpri   Syslog priority to use when user authenticates
                       unsuccessfully.  Defaults to alert.

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

       sudoers_locale  Locale to use when parsing the sudoers file.  Note that
                       changing the locale may affect how sudoers is
                       interpreted.  Defaults to "C".

       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.

       type            The default SELinux type to use when constructing a new
                       security context to run the command.  The default type
                       may be overridden on a per-command basis in sudoers or
                       via command line options.  This option is only
                       available whe sudo is built with SELinux support.

       Strings that can be used in a boolean context:

       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



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                   askpass may be overridden by the SUDO_ASKPASS environment
                   variable.

       env_file    The env_file options 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.  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.



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                   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 @secure_path@ by default.

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

       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:



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       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.

       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.

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



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       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
        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



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       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



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       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 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.



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        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 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 if 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.

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

                     sudo -V | grep "dummy exec"




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                 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 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
       rsh(1), su(1), fnmatch(3), glob(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
       Limited free support is available via the sudo-users mailing list, see



OpenBSD 4.7               March 17, 2010                       24





SUDOERS(5)           OpenBSD Reference Manual          SUDOERS(5)


       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.
















































OpenBSD 4.7               March 17, 2010                       25


