1SUDOERS(5) BSD File Formats Manual SUDOERS(5)
2
4 sudoers — default sudo security policy plugin
5
7 The sudoers policy plugin determines a user's sudo privileges. It is the
8 default sudo policy plugin. The policy is driven by the /etc/sudoers
9 file or, optionally in LDAP. The policy format is described in detail in
10 the SUDOERS FILE FORMAT section. For information on storing sudoers pol‐
11 icy information in LDAP, please see sudoers.ldap(5).
12 Configuring sudo.conf for sudoers
14 sudo consults the sudo.conf(5) file to determine which policy and and I/O
15 logging plugins to load. If no sudo.conf(5) file is present, or if it
16 contains no Plugin lines, sudoers will be used for policy decisions and
17 I/O logging. To explicitly configure sudo.conf(5) to use the sudoers
18 plugin, the following configuration can be used.
19 Plugin sudoers_policy sudoers.so
21 Plugin sudoers_io sudoers.so
22 Starting with sudo 1.8.5, it is possible to specify optional arguments to
24 the sudoers plugin in the sudo.conf(5) file. These arguments, if
25 present, should be listed after the path to the plugin (i.e. after
26 sudoers.so). Multiple arguments may be specified, separated by white
27 space. For example:
28 Plugin sudoers_policy sudoers.so sudoers_mode=0400
30 The following plugin arguments are supported:
32 ldap_conf=pathname
34 The ldap_conf argument can be used to override the default path
35 to the ldap.conf file.
36 ldap_secret=pathname
38 The ldap_secret argument can be used to override the default
39 path to the ldap.secret file.
40 sudoers_file=pathname
42 The sudoers_file argument can be used to override the default
43 path to the sudoers file.
44 sudoers_uid=uid
46 The sudoers_uid argument can be used to override the default
47 owner of the sudoers file. It should be specified as a numeric
48 user ID.
49 sudoers_gid=gid
51 The sudoers_gid argument can be used to override the default
52 group of the sudoers file. It must be specified as a numeric
53 group ID (not a group name).
54 sudoers_mode=mode
56 The sudoers_mode argument can be used to override the default
57 file mode for the sudoers file. It should be specified as an
58 octal value.
59 For more information on configuring sudo.conf(5), please refer to its
61 manual.
62 User Authentication
64 The sudoers security policy requires that most users authenticate them‐
65 selves before they can use sudo. A password is not required if the
66 invoking user is root, if the target user is the same as the invoking
67 user, or if the policy has disabled authentication for the user or com‐
68 mand. Unlike su(1), when sudoers requires authentication, it validates
69 the invoking user's credentials, not the target user's (or root's) cre‐
70 dentials. This can be changed via the rootpw, targetpw and runaspw
71 flags, described later.
72 If a user who is not listed in the policy tries to run a command via
74 sudo, mail is sent to the proper authorities. The address used for such
75 mail is configurable via the mailto Defaults entry (described later) and
76 defaults to root.
77 Note that no mail will be sent if an unauthorized user tries to run sudo
79 with the -l or -v option unless there is an authentication error and
80 either the mail_always or mail_badpass flags are enabled. This allows
81 users to determine for themselves whether or not they are allowed to use
82 sudo. All attempts to run sudo (successful or not) will be logged,
83 regardless of whether or not mail is sent.
84 If sudo is run by root and the SUDO_USER environment variable is set, the
86 sudoers policy will use this value to determine who the actual user is.
87 This can be used by a user to log commands through sudo even when a root
88 shell has been invoked. It also allows the -e option to remain useful
89 even when invoked via a sudo-run script or program. Note, however, that
90 the sudoers file lookup is still done for root, not the user specified by
91 SUDO_USER.
92 sudoers uses per-user time stamp files for credential caching. Once a
94 user has been authenticated, a record is written containing the user ID
95 that was used to authenticate, the terminal session ID, the start time of
96 the session leader (or parent process) and a time stamp (using a mono‐
97 tonic clock if one is available). The user may then use sudo without a
98 password for a short period of time (5 minutes unless overridden by the
99 timestamp_timeout option). By default, sudoers uses a separate record
100 for each terminal, which means that a user's login sessions are authenti‐
101 cated separately. The timestamp_type option can be used to select the
102 type of time stamp record sudoers will use.
103 Logging
105 sudoers can log both successful and unsuccessful attempts (as well as
106 errors) to syslog(3), a log file, or both. By default, sudoers will log
107 via syslog(3) but this is changeable via the syslog and logfile Defaults
108 settings. See LOG FORMAT for a description of the log file format.
109 sudoers is also capable of running a command in a pseudo-tty and logging
111 all input and/or output. The standard input, standard output and stan‐
112 dard error can be logged even when not associated with a terminal. I/O
113 logging is not on by default but can be enabled using the log_input and
114 log_output options as well as the LOG_INPUT and LOG_OUTPUT command tags.
115 See I/O LOG FILES for details on how I/O log files are stored.
116 Command environment
118 Since environment variables can influence program behavior, sudoers pro‐
119 vides a means to restrict which variables from the user's environment are
120 inherited by the command to be run. There are two distinct ways sudoers
121 can deal with environment variables.
122 By default, the env_reset option is enabled. This causes commands to be
124 executed with a new, minimal environment. On AIX (and Linux systems
125 without PAM), the environment is initialized with the contents of the
126 /etc/environment file. The new environment contains the TERM, PATH,
127 HOME, MAIL, SHELL, LOGNAME, USER, USERNAME and SUDO_* variables in addi‐
128 tion to variables from the invoking process permitted by the env_check
129 and env_keep options. This is effectively a whitelist for environment
130 variables. The environment variables LOGNAME, USER and USERNAME are
131 treated specially. If one or more variables are preserved from the
132 invoking process, any of the three remaining variables (that were not
133 explicitly preserved) will be set to the same value as the first one in
134 the list that was preserved. This avoids an inconsistent environment
135 where some of the variables describing the user name are set to the
136 invoking user and some are set to the target user. () are removed unless
137 both the name and value parts are matched by env_keep or env_check, as
138 they may be interpreted as functions by the bash shell. Prior to version
139 1.8.11, such variables were always removed.
140 If, however, the env_reset option is disabled, any variables not explic‐
142 itly denied by the env_check and env_delete options are inherited from
143 the invoking process. In this case, env_check and env_delete behave like
144 a blacklist. Prior to version 1.8.21, environment variables with a value
145 beginning with () were always removed. Beginning with version 1.8.21, a
146 pattern in env_delete is used to match bash shell functions instead.
147 Since it is not possible to blacklist all potentially dangerous environ‐
148 ment variables, use of the default env_reset behavior is encouraged.
149 Environment variables specified by env_check, env_delete, or env_keep may
151 include one or more ‘*’ characters which will match zero or more charac‐
152 ters. No other wildcard characters are supported.
153 By default, environment variables are matched by name. However, if the
155 pattern includes an equal sign (‘=’), both the variables name and value
156 must match. For example, a bash shell function could be matched as fol‐
157 lows:
158 env_keep += "BASH_FUNC_my_func%%=()*"
160 Without the “=()*” suffix, this would not match, as bash shell functions
162 are not preserved by default.
163 The complete list of environment variables that sudo allows or denies is
165 contained in the output of “sudo -V” when run as root. Please note that
166 this list varies based on the operating system sudo is running on.
167 On systems that support PAM where the pam_env module is enabled for sudo,
169 variables in the PAM environment may be merged in to the environment. If
170 a variable in the PAM environment is already present in the user's envi‐
171 ronment, the value will only be overridden if the variable was not pre‐
172 served by sudoers. When env_reset is enabled, variables preserved from
173 the invoking user's environment by the env_keep list take precedence over
174 those in the PAM environment. When env_reset is disabled, variables
175 present the invoking user's environment take precedence over those in the
176 PAM environment unless they match a pattern in the env_delete list.
177 Note that the dynamic linker on most operating systems will remove vari‐
179 ables that can control dynamic linking from the environment of setuid
180 executables, including sudo. Depending on the operating system this may
181 include _RLD*, DYLD_*, LD_*, LDR_*, LIBPATH, SHLIB_PATH, and others.
182 These type of variables are removed from the environment before sudo even
183 begins execution and, as such, it is not possible for sudo to preserve
184 them.
185 As a special case, if sudo's -i option (initial login) is specified,
187 sudoers will initialize the environment regardless of the value of
188 env_reset. The DISPLAY, PATH and TERM variables remain unchanged; HOME,
189 MAIL, SHELL, USER, and LOGNAME are set based on the target user. On AIX
190 (and Linux systems without PAM), the contents of /etc/environment are
191 also included. All other environment variables are removed unless per‐
192 mitted by env_keep or env_check, described above.
193 Finally, the restricted_env_file and env_file files are applied, if
195 present. The variables in restricted_env_file are applied first and are
196 subject to the same restrictions as the invoking user's environment, as
197 detailed above. The variables in env_file are applied last and are not
198 subject to these restrictions. In both cases, variables present in the
199 files will only be set to their specified values if they would not con‐
200 flict with an existing environment variable.
201
203 The sudoers file is composed of two types of entries: aliases (basically
204 variables) and user specifications (which specify who may run what).
205 When multiple entries match for a user, they are applied in order. Where
207 there are multiple matches, the last match is used (which is not neces‐
208 sarily the most specific match).
209 The sudoers file grammar will be described below in Extended Backus-Naur
211 Form (EBNF). Don't despair if you are unfamiliar with EBNF; it is fairly
212 simple, and the definitions below are annotated.
213 Quick guide to EBNF
215 EBNF is a concise and exact way of describing the grammar of a language.
216 Each EBNF definition is made up of production rules. E.g.,
217 symbol ::= definition | alternate1 | alternate2 ...
219 Each production rule references others and thus makes up a grammar for
221 the language. EBNF also contains the following operators, which many
222 readers will recognize from regular expressions. Do not, however, con‐
223 fuse them with “wildcard” characters, which have different meanings.
224 ? Means that the preceding symbol (or group of symbols) is optional.
226 That is, it may appear once or not at all.
227 * Means that the preceding symbol (or group of symbols) may appear
229 zero or more times.
230 + Means that the preceding symbol (or group of symbols) may appear
232 one or more times.
233 Parentheses may be used to group symbols together. For clarity, we will
235 use single quotes ('') to designate what is a verbatim character string
236 (as opposed to a symbol name).
237 Aliases
239 There are four kinds of aliases: User_Alias, Runas_Alias, Host_Alias and
240 Cmnd_Alias.
241 Alias ::= 'User_Alias' User_Alias_Spec (':' User_Alias_Spec)* |
243 'Runas_Alias' Runas_Alias_Spec (':' Runas_Alias_Spec)* |
244 'Host_Alias' Host_Alias_Spec (':' Host_Alias_Spec)* |
245 'Cmnd_Alias' Cmnd_Alias_Spec (':' Cmnd_Alias_Spec)*
246 User_Alias ::= NAME
248 User_Alias_Spec ::= User_Alias '=' User_List
250 Runas_Alias ::= NAME
252 Runas_Alias_Spec ::= Runas_Alias '=' Runas_List
254 Host_Alias ::= NAME
256 Host_Alias_Spec ::= Host_Alias '=' Host_List
258 Cmnd_Alias ::= NAME
260 Cmnd_Alias_Spec ::= Cmnd_Alias '=' Cmnd_List
262 NAME ::= [A-Z]([A-Z][0-9]_)*
264 Each alias definition is of the form
266 Alias_Type NAME = item1, item2, ...
268 where Alias_Type is one of User_Alias, Runas_Alias, Host_Alias, or
270 Cmnd_Alias. A NAME is a string of uppercase letters, numbers, and under‐
271 score characters (‘_’). A NAME must start with an uppercase letter. It
272 is possible to put several alias definitions of the same type on a single
273 line, joined by a colon (‘:’). E.g.,
274 Alias_Type NAME = item1, item2, item3 : NAME = item4, item5
276 It is a syntax error to redefine an existing alias. It is possible to
278 use the same name for aliases of different types, but this is not recom‐
279 mended.
280 The definitions of what constitutes a valid alias member follow.
282 User_List ::= User |
284 User ',' User_List
285 User ::= '!'* user name |
287 '!'* #uid |
288 '!'* %group |
289 '!'* %#gid |
290 '!'* +netgroup |
291 '!'* %:nonunix_group |
292 '!'* %:#nonunix_gid |
293 '!'* User_Alias
294 A User_List is made up of one or more user names, user IDs (prefixed with
296 ‘#’), system group names and IDs (prefixed with ‘%’ and ‘%#’ respec‐
297 tively), netgroups (prefixed with ‘+’), non-Unix group names and IDs
298 (prefixed with ‘%:’ and ‘%:#’ respectively) and User_Aliases. Each list
299 item may be prefixed with zero or more ‘!’ operators. An odd number of
300 ‘!’ operators negate the value of the item; an even number just cancel
301 each other out. User netgroups are matched using the user and domain
302 members only; the host member is not used when matching.
303 A user name, uid, group, gid, netgroup, nonunix_group or nonunix_gid may
305 be enclosed in double quotes to avoid the need for escaping special char‐
306 acters. Alternately, special characters may be specified in escaped hex
307 mode, e.g. \x20 for space. When using double quotes, any prefix charac‐
308 ters must be included inside the quotes.
309 The actual nonunix_group and nonunix_gid syntax depends on the underlying
311 group provider plugin. For instance, the QAS AD plugin supports the fol‐
312 lowing formats:
313 · Group in the same domain: "%:Group Name"
315 · Group in any domain: "%:Group Name@FULLY.QUALIFIED.DOMAIN"
317 · Group SID: "%:S-1-2-34-5678901234-5678901234-5678901234-567"
319 See GROUP PROVIDER PLUGINS for more information.
321 Note that quotes around group names are optional. Unquoted strings must
323 use a backslash (‘\’) to escape spaces and special characters. See Other
324 special characters and reserved words for a list of characters that need
325 to be escaped.
326 Runas_List ::= Runas_Member |
328 Runas_Member ',' Runas_List
329 Runas_Member ::= '!'* user name |
331 '!'* #uid |
332 '!'* %group |
333 '!'* %#gid |
334 '!'* %:nonunix_group |
335 '!'* %:#nonunix_gid |
336 '!'* +netgroup |
337 '!'* Runas_Alias
338 A Runas_List is similar to a User_List except that instead of
340 User_Aliases it can contain Runas_Aliases. Note that user names and
341 groups are matched as strings. In other words, two users (groups) with
342 the same uid (gid) are considered to be distinct. If you wish to match
343 all user names with the same uid (e.g. root and toor), you can use a uid
344 instead (#0 in the example given).
345 Host_List ::= Host |
347 Host ',' Host_List
348 Host ::= '!'* host name |
350 '!'* ip_addr |
351 '!'* network(/netmask)? |
352 '!'* +netgroup |
353 '!'* Host_Alias
354 A Host_List is made up of one or more host names, IP addresses, network
356 numbers, netgroups (prefixed with ‘+’) and other aliases. Again, the
357 value of an item may be negated with the ‘!’ operator. Host netgroups
358 are matched using the host (both qualified and unqualified) and domain
359 members only; the user member is not used when matching. If you specify
360 a network number without a netmask, sudo will query each of the local
361 host's network interfaces and, if the network number corresponds to one
362 of the hosts's network interfaces, will use the netmask of that inter‐
363 face. The netmask may be specified either in standard IP address nota‐
364 tion (e.g. 255.255.255.0 or ffff:ffff:ffff:ffff::), or CIDR notation
365 (number of bits, e.g. 24 or 64). A host name may include shell-style
366 wildcards (see the Wildcards section below), but unless the host name
367 command on your machine returns the fully qualified host name, you'll
368 need to use the fqdn option for wildcards to be useful. Note that sudo
369 only inspects actual network interfaces; this means that IP address
370 127.0.0.1 (localhost) will never match. Also, the host name “localhost”
371 will only match if that is the actual host name, which is usually only
372 the case for non-networked systems.
373 digest ::= [A-Fa-f0-9]+ |
375 [[A-Za-z0-9+/=]+
376 Digest_Spec ::= "sha224" ':' digest |
378 "sha256" ':' digest |
379 "sha384" ':' digest |
380 "sha512" ':' digest
381 Cmnd_List ::= Cmnd |
383 Cmnd ',' Cmnd_List
384 command name ::= file name |
386 file name args |
387 file name '""'
388 Cmnd ::= Digest_Spec? '!'* command name |
390 '!'* directory |
391 '!'* "sudoedit" |
392 '!'* Cmnd_Alias
393 A Cmnd_List is a list of one or more command names, directories, and
395 other aliases. A command name is a fully qualified file name which may
396 include shell-style wildcards (see the Wildcards section below). A sim‐
397 ple file name allows the user to run the command with any arguments
398 he/she wishes. However, you may also specify command line arguments
399 (including wildcards). Alternately, you can specify "" to indicate that
400 the command may only be run without command line arguments. A directory
401 is a fully qualified path name ending in a ‘/’. When you specify a
402 directory in a Cmnd_List, the user will be able to run any file within
403 that directory (but not in any sub-directories therein).
404 If a Cmnd has associated command line arguments, then the arguments in
406 the Cmnd must match exactly those given by the user on the command line
407 (or match the wildcards if there are any). Note that the following char‐
408 acters must be escaped with a ‘\’ if they are used in command arguments:
409 ‘,’, ‘:’, ‘=’, ‘\’. The built-in command “sudoedit” is used to permit a
410 user to run sudo with the -e option (or as sudoedit). It may take com‐
411 mand line arguments just as a normal command does. Note that “sudoedit”
412 is a command built into sudo itself and must be specified in the sudoers
413 file without a leading path.
414 If a command name is prefixed with a Digest_Spec, the command will only
416 match successfully if it can be verified using the specified SHA-2
417 digest. The following digest formats are supported: sha224, sha256,
418 sha384 and sha512. The string may be specified in either hex or base64
419 format (base64 is more compact). There are several utilities capable of
420 generating SHA-2 digests in hex format such as openssl, shasum,
421 sha224sum, sha256sum, sha384sum, sha512sum.
422 For example, using openssl:
424 $ openssl dgst -sha224 /bin/ls
426 SHA224(/bin/ls)= 118187da8364d490b4a7debbf483004e8f3e053ec954309de2c41a25
427 It is also possible to use openssl to generate base64 output:
429 $ openssl dgst -binary -sha224 /bin/ls | openssl base64
431 EYGH2oNk1JC0p9679IMATo8+BT7JVDCd4sQaJQ==
432 Warning, if the user has write access to the command itself (directly or
434 via a sudo command), it may be possible for the user to replace the com‐
435 mand after the digest check has been performed but before the command is
436 executed. A similar race condition exists on systems that lack the
437 fexecve(2) system call when the directory in which the command is located
438 is writable by the user. See the description of the fdexec setting for
439 more information on how sudo executes commands that have an associated
440 digest.
441 Command digests are only supported by version 1.8.7 or higher.
443 Defaults
445 Certain configuration options may be changed from their default values at
446 run-time via one or more Default_Entry lines. These may affect all users
447 on any host, all users on a specific host, a specific user, a specific
448 command, or commands being run as a specific user. Note that per-command
449 entries may not include command line arguments. If you need to specify
450 arguments, define a Cmnd_Alias and reference that instead.
451 Default_Type ::= 'Defaults' |
453 'Defaults' '@' Host_List |
454 'Defaults' ':' User_List |
455 'Defaults' '!' Cmnd_List |
456 'Defaults' '>' Runas_List
457 Default_Entry ::= Default_Type Parameter_List
459 Parameter_List ::= Parameter |
461 Parameter ',' Parameter_List
462 Parameter ::= Parameter '=' Value |
464 Parameter '+=' Value |
465 Parameter '-=' Value |
466 '!'* Parameter
467 Parameters may be flags, integer values, strings, or lists. Flags are
469 implicitly boolean and can be turned off via the ‘!’ operator. Some
470 integer, string and list parameters may also be used in a boolean context
471 to disable them. Values may be enclosed in double quotes ("") when they
472 contain multiple words. Special characters may be escaped with a back‐
473 slash (‘\’).
474 Lists have two additional assignment operators, += and -=. These opera‐
476 tors are used to add to and delete from a list respectively. It is not
477 an error to use the -= operator to remove an element that does not exist
478 in a list.
479 Defaults entries are parsed in the following order: generic, host, user
481 and runas Defaults first, then command defaults. If there are multiple
482 Defaults settings of the same type, the last matching setting is used.
483 The following Defaults settings are parsed before all others since they
484 may affect subsequent entries: fqdn, group_plugin, runas_default,
485 sudoers_locale.
486 See SUDOERS OPTIONS for a list of supported Defaults parameters.
488 User specification
490 User_Spec ::= User_List Host_List '=' Cmnd_Spec_List \
491 (':' Host_List '=' Cmnd_Spec_List)*
492 Cmnd_Spec_List ::= Cmnd_Spec |
494 Cmnd_Spec ',' Cmnd_Spec_List
495 Cmnd_Spec ::= Runas_Spec? Option_Spec* Tag_Spec* Cmnd
497 Runas_Spec ::= '(' Runas_List? (':' Runas_List)? ')'
499 Option_Spec ::= (SELinux_Spec | Date_Spec | Timeout_Spec)
501 SELinux_Spec ::= ('ROLE=role' | 'TYPE=type')
503 Date_Spec ::= ('NOTBEFORE=timestamp' | 'NOTAFTER=timestamp')
505 Timeout_Spec ::= 'TIMEOUT=timeout'
507 Tag_Spec ::= ('EXEC:' | 'NOEXEC:' | 'FOLLOW:' | 'NOFOLLOW' |
509 'LOG_INPUT:' | 'NOLOG_INPUT:' | 'LOG_OUTPUT:' |
510 'NOLOG_OUTPUT:' | 'MAIL:' | 'NOMAIL:' | 'PASSWD:' |
511 'NOPASSWD:' | 'SETENV:' | 'NOSETENV:')
512 A user specification determines which commands a user may run (and as
514 what user) on specified hosts. By default, commands are run as root, but
515 this can be changed on a per-command basis.
516 The basic structure of a user specification is “who where = (as_whom)
518 what”. Let's break that down into its constituent parts:
519 Runas_Spec
521 A Runas_Spec determines the user and/or the group that a command may be
522 run as. A fully-specified Runas_Spec consists of two Runas_Lists (as
523 defined above) separated by a colon (‘:’) and enclosed in a set of paren‐
524 theses. The first Runas_List indicates which users the command may be
525 run as via sudo's -u option. The second defines a list of groups that
526 can be specified via sudo's -g option. If both Runas_Lists are speci‐
527 fied, the command may be run with any combination of users and groups
528 listed in their respective Runas_Lists. If only the first is specified,
529 the command may be run as any user in the list but no -g option may be
530 specified. If the first Runas_List is empty but the second is specified,
531 the command may be run as the invoking user with the group set to any
532 listed in the Runas_List. If both Runas_Lists are empty, the command may
533 only be run as the invoking user. If no Runas_Spec is specified the com‐
534 mand may be run as root and no group may be specified.
535 A Runas_Spec sets the default for the commands that follow it. What this
537 means is that for the entry:
538 dgb boulder = (operator) /bin/ls, /bin/kill, /usr/bin/lprm
540 The user dgb may run /bin/ls, /bin/kill, and /usr/bin/lprm on the host
542 boulder—but only as operator. E.g.,
543 $ sudo -u operator /bin/ls
545 It is also possible to override a Runas_Spec later on in an entry. If we
547 modify the entry like so:
548 dgb boulder = (operator) /bin/ls, (root) /bin/kill, /usr/bin/lprm
550 Then user dgb is now allowed to run /bin/ls as operator, but /bin/kill
552 and /usr/bin/lprm as root.
553 We can extend this to allow dgb to run /bin/ls with either the user or
555 group set to operator:
556 dgb boulder = (operator : operator) /bin/ls, (root) /bin/kill,\
558 /usr/bin/lprm
559 Note that while the group portion of the Runas_Spec permits the user to
561 run as command with that group, it does not force the user to do so. If
562 no group is specified on the command line, the command will run with the
563 group listed in the target user's password database entry. The following
564 would all be permitted by the sudoers entry above:
565 $ sudo -u operator /bin/ls
567 $ sudo -u operator -g operator /bin/ls
568 $ sudo -g operator /bin/ls
569 In the following example, user tcm may run commands that access a modem
571 device file with the dialer group.
572 tcm boulder = (:dialer) /usr/bin/tip, /usr/bin/cu,\
574 /usr/local/bin/minicom
575 Note that in this example only the group will be set, the command still
577 runs as user tcm. E.g.
578 $ sudo -g dialer /usr/bin/cu
580 Multiple users and groups may be present in a Runas_Spec, in which case
582 the user may select any combination of users and groups via the -u and -g
583 options. In this example:
584 alan ALL = (root, bin : operator, system) ALL
586 user alan may run any command as either user root or bin, optionally set‐
588 ting the group to operator or system.
589 Option_Spec
591 A Cmnd may have zero or more options associated with it. Depending on
592 the system, options may consist of SELinux roles and/or types, Solaris
593 privileges sets, and command timeouts. Once an option is set for a Cmnd,
594 subsequent Cmnds in the Cmnd_Spec_List, inherit that option unless it is
595 overridden by another option.
596 SELinux_Spec
598 On systems with SELinux support, sudoers file entries may optionally have
599 an SELinux role and/or type associated with a command. If a role or type
600 is specified with the command it will override any default values speci‐
601 fied in sudoers. A role or type specified on the command line, however,
602 will supersede the values in sudoers.
603 Date_Spec
605 sudoers rules can be specified with a start and end date via the
606 NOTBEFORE and NOTAFTER settings. The time stamp must be specified in
607 Generalized Time as defined by RFC 4517. The format is effectively
608 yyyymmddHHMMSSZ where the minutes and seconds are optional. The ‘Z’ suf‐
609 fix indicates that the time stamp is in Coordinated Universal Time (UTC).
610 It is also possible to specify a timezone offset from UTC in hours and
611 minutes instead of a ‘Z’. For example, ‘-0500’ would correspond to East‐
612 ern Standard time in the US. As an extension, if no ‘Z’ or timezone off‐
613 set is specified, local time will be used.
614 The following are all valid time stamps:
616 20170214083000Z
618 2017021408Z
619 20160315220000-0500
620 20151201235900
621 Timeout_Spec
623 A command may have a timeout associated with it. If the timeout expires
624 before the command has exited, the command will be terminated. The time‐
625 out may be specified in combinations of days, hours, minutes and seconds
626 with a single-letter case-insensitive suffix that indicates the unit of
627 time. For example, a timeout of 7 days, 8 hours, 30 minutes and 10 sec‐
628 onds would be written as 7d8h30m10s. If a number is specified without a
629 unit, seconds are assumed. Any of the days, minutes, hours or seconds
630 may be omitted. The order must be from largest to smallest unit and a
631 unit may not be specified more than once.
632 The following are all valid timeout values: 7d8h30m10s, 14d, 8h30m, 600s,
634 3600. The following are invalid timeout values: 12m2w1d, 30s10m4h,
635 1d2d3h.
636 This option is only supported by version 1.8.20 or higher.
638 Tag_Spec
640 A command may have zero or more tags associated with it. The following
641 tag values are supported: EXEC, NOEXEC, FOLLOW, NOFOLLOW, LOG_INPUT,
642 NOLOG_INPUT, LOG_OUTPUT, NOLOG_OUTPUT, MAIL, NOMAIL, PASSWD, NOPASSWD,
643 SETENV, and NOSETENV. Once a tag is set on a Cmnd, subsequent Cmnds in
644 the Cmnd_Spec_List, inherit the tag unless it is overridden by the oppo‐
645 site tag (in other words, PASSWD overrides NOPASSWD and NOEXEC overrides
646 EXEC).
647 EXEC and NOEXEC
649 If sudo has been compiled with noexec support and the underlying oper‐
651 ating system supports it, the NOEXEC tag can be used to prevent a
652 dynamically-linked executable from running further commands itself.
653 In the following example, user aaron may run /usr/bin/more and
655 /usr/bin/vi but shell escapes will be disabled.
656 aaron shanty = NOEXEC: /usr/bin/more, /usr/bin/vi
658 See the Preventing shell escapes section below for more details on how
660 NOEXEC works and whether or not it will work on your system.
661 FOLLOW and NOFOLLOW Starting with version 1.8.15, sudoedit will not open
663 a file that is a symbolic link unless the sudoedit_follow option is
664 enabled. The FOLLOW and NOFOLLOW tags override the value of
665 sudoedit_follow and can be used to permit (or deny) the editing of sym‐
666 bolic links on a per-command basis. These tags are only effective for
667 the sudoedit command and are ignored for all other commands.
668 LOG_INPUT and NOLOG_INPUT
670 These tags override the value of the log_input option on a per-command
672 basis. For more information, see the description of log_input in the
673 SUDOERS OPTIONS section below.
674 LOG_OUTPUT and NOLOG_OUTPUT
676 These tags override the value of the log_output option on a per-command
678 basis. For more information, see the description of log_output in the
679 SUDOERS OPTIONS section below.
680 MAIL and NOMAIL
682 These tags provide fine-grained control over whether mail will be sent
684 when a user runs a command by overriding the value of the
685 mail_all_cmnds option on a per-command basis. They have no effect when
686 sudo is run with the -l or -v options. A NOMAIL tag will also override
687 the mail_always and mail_no_perms options. For more information, see
688 the descriptions of mail_all_cmnds, mail_always, and mail_no_perms in
689 the SUDOERS OPTIONS section below.
690 PASSWD and NOPASSWD
692 By default, sudo requires that a user authenticate him or herself
694 before running a command. This behavior can be modified via the
695 NOPASSWD tag. Like a Runas_Spec, the NOPASSWD tag sets a default for
696 the commands that follow it in the Cmnd_Spec_List. Conversely, the
697 PASSWD tag can be used to reverse things. For example:
698 ray rushmore = NOPASSWD: /bin/kill, /bin/ls, /usr/bin/lprm
700 would allow the user ray to run /bin/kill, /bin/ls, and /usr/bin/lprm
702 as root on the machine rushmore without authenticating himself. If we
703 only want ray to be able to run /bin/kill without a password the entry
704 would be:
705 ray rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls, /usr/bin/lprm
707 Note, however, that the PASSWD tag has no effect on users who are in
709 the group specified by the exempt_group option.
710 By default, if the NOPASSWD tag is applied to any of the entries for a
712 user on the current host, he or she will be able to run “sudo -l” with‐
713 out a password. Additionally, a user may only run “sudo -v” without a
714 password if the NOPASSWD tag is present for all a user's entries that
715 pertain to the current host. This behavior may be overridden via the
716 verifypw and listpw options.
717 SETENV and NOSETENV
719 These tags override the value of the setenv option on a per-command
721 basis. Note that if SETENV has been set for a command, the user may
722 disable the env_reset option from the command line via the -E option.
723 Additionally, environment variables set on the command line are not
724 subject to the restrictions imposed by env_check, env_delete, or
725 env_keep. As such, only trusted users should be allowed to set vari‐
726 ables in this manner. If the command matched is ALL, the SETENV tag is
727 implied for that command; this default may be overridden by use of the
728 NOSETENV tag.
729 Wildcards
731 sudo allows shell-style wildcards (aka meta or glob characters) to be
732 used in host names, path names and command line arguments in the sudoers
733 file. Wildcard matching is done via the glob(3) and fnmatch(3) functions
734 as specified by IEEE Std 1003.1 (“POSIX.1”).
735 * Matches any set of zero or more characters (including white
737 space).
738 ? Matches any single character (including white space).
740 [...] Matches any character in the specified range.
742 [!...] Matches any character not in the specified range.
744 \x For any character ‘x’, evaluates to ‘x’. This is used to
746 escape special characters such as: ‘*’, ‘?’, ‘[’, and ‘]’.
747 Note that these are not regular expressions. Unlike a regular expression
749 there is no way to match one or more characters within a range.
750 Character classes may be used if your system's glob(3) and fnmatch(3)
752 functions support them. However, because the ‘:’ character has special
753 meaning in sudoers, it must be escaped. For example:
754 /bin/ls [[\:alpha\:]]*
756 Would match any file name beginning with a letter.
758 Note that a forward slash (‘/’) will not be matched by wildcards used in
760 the file name portion of the command. This is to make a path like:
761 /usr/bin/*
763 match /usr/bin/who but not /usr/bin/X11/xterm.
765 When matching the command line arguments, however, a slash does get
767 matched by wildcards since command line arguments may contain arbitrary
768 strings and not just path names.
769 Wildcards in command line arguments should be used with care.
771 Command line arguments are matched as a single, concatenated string.
772 This mean a wildcard character such as ‘?’ or ‘*’ will match across word
773 boundaries, which may be unexpected. For example, while a sudoers entry
774 like:
775 %operator ALL = /bin/cat /var/log/messages*
777 will allow command like:
779 $ sudo cat /var/log/messages.1
781 It will also allow:
783 $ sudo cat /var/log/messages /etc/shadow
785 which is probably not what was intended. In most cases it is better to
787 do command line processing outside of the sudoers file in a scripting
788 language.
789 Exceptions to wildcard rules
791 The following exceptions apply to the above rules:
792 "" If the empty string "" is the only command line argument in the
794 sudoers file entry it means that command is not allowed to be
795 run with any arguments.
796 sudoedit Command line arguments to the sudoedit built-in command should
798 always be path names, so a forward slash (‘/’) will not be
799 matched by a wildcard.
800 Including other files from within sudoers
802 It is possible to include other sudoers files from within the sudoers
803 file currently being parsed using the #include and #includedir direc‐
804 tives.
805 This can be used, for example, to keep a site-wide sudoers file in addi‐
807 tion to a local, per-machine file. For the sake of this example the
808 site-wide sudoers file will be /etc/sudoers and the per-machine one will
809 be /etc/sudoers.local. To include /etc/sudoers.local from within
810 /etc/sudoers we would use the following line in /etc/sudoers:
811 #include /etc/sudoers.local
813 When sudo reaches this line it will suspend processing of the current
815 file (/etc/sudoers) and switch to /etc/sudoers.local. Upon reaching the
816 end of /etc/sudoers.local, the rest of /etc/sudoers will be processed.
817 Files that are included may themselves include other files. A hard limit
818 of 128 nested include files is enforced to prevent include file loops.
819 If the path to the include file is not fully-qualified (does not begin
821 with a ‘/’), it must be located in the same directory as the sudoers file
822 it was included from. For example, if /etc/sudoers contains the line:
823 #include sudoers.local
825 the file that will be included is /etc/sudoers.local.
827 The file name may also include the %h escape, signifying the short form
829 of the host name. In other words, if the machine's host name is
830 “xerxes”, then
831 #include /etc/sudoers.%h
833 will cause sudo to include the file /etc/sudoers.xerxes.
835 The #includedir directive can be used to create a sudoers.d directory
837 that the system package manager can drop sudoers file rules into as part
838 of package installation. For example, given:
839 #includedir /etc/sudoers.d
841 sudo will suspend processing of the current file and read each file in
843 /etc/sudoers.d, skipping file names that end in ‘~’ or contain a ‘.’
844 character to avoid causing problems with package manager or editor tempo‐
845 rary/backup files. Files are parsed in sorted lexical order. That is,
846 /etc/sudoers.d/01_first will be parsed before /etc/sudoers.d/10_second.
847 Be aware that because the sorting is lexical, not numeric,
848 /etc/sudoers.d/1_whoops would be loaded after /etc/sudoers.d/10_second.
849 Using a consistent number of leading zeroes in the file names can be used
850 to avoid such problems. After parsing the files in the directory, con‐
851 trol returns to the file that contained the #includedir directive.
852 Note that unlike files included via #include, visudo will not edit the
854 files in a #includedir directory unless one of them contains a syntax
855 error. It is still possible to run visudo with the -f flag to edit the
856 files directly, but this will not catch the redefinition of an alias that
857 is also present in a different file.
858 Other special characters and reserved words
860 The pound sign (‘#’) is used to indicate a comment (unless it is part of
861 a #include directive or unless it occurs in the context of a user name
862 and is followed by one or more digits, in which case it is treated as a
863 uid). Both the comment character and any text after it, up to the end of
864 the line, are ignored.
865 The reserved word ALL is a built-in alias that always causes a match to
867 succeed. It can be used wherever one might otherwise use a Cmnd_Alias,
868 User_Alias, Runas_Alias, or Host_Alias. You should not try to define
869 your own alias called ALL as the built-in alias will be used in prefer‐
870 ence to your own. Please note that using ALL can be dangerous since in a
871 command context, it allows the user to run any command on the system.
872 An exclamation point (‘!’) can be used as a logical not operator in a
874 list or alias as well as in front of a Cmnd. This allows one to exclude
875 certain values. For the ‘!’ operator to be effective, there must be
876 something for it to exclude. For example, to match all users except for
877 root one would use:
878 ALL,!root
880 If the ALL, is omitted, as in:
882 !root
884 it would explicitly deny root but not match any other users. This is
886 different from a true “negation” operator.
887 Note, however, that using a ‘!’ in conjunction with the built-in ALL
889 alias to allow a user to run “all but a few” commands rarely works as
890 intended (see SECURITY NOTES below).
891 Long lines can be continued with a backslash (‘\’) as the last character
893 on the line.
894 White space between elements in a list as well as special syntactic char‐
896 acters in a User Specification (‘=’, ‘:’, ‘(’, ‘)’) is optional.
897 The following characters must be escaped with a backslash (‘\’) when used
899 as part of a word (e.g. a user name or host name): ‘!’, ‘=’, ‘:’, ‘,’,
900 ‘(’, ‘)’, ‘\’.
901
903 sudo's behavior can be modified by Default_Entry lines, as explained ear‐
904 lier. A list of all supported Defaults parameters, grouped by type, are
905 listed below.
906 Boolean Flags:
908 always_query_group_plugin
910 If a group_plugin is configured, use it to resolve
911 groups of the form %group as long as there is not also
912 a system group of the same name. Normally, only groups
913 of the form %:group are passed to the group_plugin.
914 This flag is off by default.
915 always_set_home If enabled, sudo will set the HOME environment variable
917 to the home directory of the target user (which is root
918 unless the -u option is used). This effectively means
919 that the -H option is always implied. Note that by
920 default, HOME will be set to the home directory of the
921 target user when the env_reset option is enabled, so
922 always_set_home only has an effect for configurations
923 where either env_reset is disabled or HOME is present
924 in the env_keep list. This flag is off by default.
925 authenticate If set, users must authenticate themselves via a pass‐
927 word (or other means of authentication) before they may
928 run commands. This default may be overridden via the
929 PASSWD and NOPASSWD tags. This flag is on by default.
930 case_insensitive_group
932 If enabled, group names in sudoers will be matched in a
933 case insensitive manner. This may be necessary when
934 users are stored in LDAP or AD. This flag is on by
935 default.
936 case_insensitive_user
938 If enabled, user names in sudoers will be matched in a
939 case insensitive manner. This may be necessary when
940 groups are stored in LDAP or AD. This flag is on by
941 default.
942 closefrom_override
944 If set, the user may use sudo's -C option which over‐
945 rides the default starting point at which sudo begins
946 closing open file descriptors. This flag is off by
947 default.
948 compress_io If set, and sudo is configured to log a command's input
950 or output, the I/O logs will be compressed using zlib.
951 This flag is on by default when sudo is compiled with
952 zlib support.
953 exec_background By default, sudo runs a command as the foreground
955 process as long as sudo itself is running in the fore‐
956 ground. When the exec_background flag is enabled and
957 the command is being run in a pty (due to I/O logging
958 or the use_pty flag), the command will be run as a
959 background process. Attempts to read from the control‐
960 ling terminal (or to change terminal settings) will
961 result in the command being suspended with the SIGTTIN
962 signal (or SIGTTOU in the case of terminal settings).
963 If this happens when sudo is a foreground process, the
964 command will be granted the controlling terminal and
965 resumed in the foreground with no user intervention
966 required. The advantage of initially running the com‐
967 mand in the background is that sudo need not read from
968 the terminal unless the command explicitly requests it.
969 Otherwise, any terminal input must be passed to the
970 command, whether it has required it or not (the kernel
971 buffers terminals so it is not possible to tell whether
972 the command really wants the input). This is different
973 from historic sudo behavior or when the command is not
974 being run in a pty.
975 For this to work seamlessly, the operating system must
977 support the automatic restarting of system calls.
978 Unfortunately, not all operating systems do this by
979 default, and even those that do may have bugs. For
980 example, macOS fails to restart the tcgetattr() and
981 tcsetattr() system calls (this is a bug in macOS).
982 Furthermore, because this behavior depends on the com‐
983 mand stopping with the SIGTTIN or SIGTTOU signals, pro‐
984 grams that catch these signals and suspend themselves
985 with a different signal (usually SIGTOP) will not be
986 automatically foregrounded. Some versions of the linux
987 su(1) command behave this way. This flag is off by
988 default.
989 This setting is only supported by version 1.8.7 or
991 higher. It has no effect unless I/O logging is enabled
992 or the use_pty flag is enabled.
993 env_editor If set, visudo will use the value of the SUDO_EDITOR,
995 VISUAL or EDITOR environment variables before falling
996 back on the default editor list. Note that this may
997 create a security hole as it allows the user to run any
998 arbitrary command as root without logging. A safer
999 alternative is to place a colon-separated list of edi‐
1000 tors in the editor variable. visudo will then only use
1001 SUDO_EDITOR, VISUAL or EDITOR if they match a value
1002 specified in editor. If the env_reset flag is enabled,
1003 the SUDO_EDITOR, VISUAL and/or EDITOR environment vari‐
1004 ables must be present in the env_keep list for the
1005 env_editor flag to function when visudo is invoked via
1006 sudo. This flag is on by default.
1007 env_reset If set, sudo will run the command in a minimal environ‐
1009 ment containing the TERM, PATH, HOME, MAIL, SHELL,
1010 LOGNAME, USER, USERNAME and SUDO_* variables. Any
1011 variables in the caller's environment or in the file
1012 specified by the restricted_env_file option that match
1013 the env_keep and env_check lists are then added, fol‐
1014 lowed by any variables present in the file specified by
1015 the env_file option (if any). The contents of the
1016 env_keep and env_check lists, as modified by global
1017 Defaults parameters in sudoers, are displayed when sudo
1018 is run by root with the -V option. If the secure_path
1019 option is set, its value will be used for the PATH
1020 environment variable. This flag is on by default.
1021 fast_glob Normally, sudo uses the glob(3) function to do shell-
1023 style globbing when matching path names. However,
1024 since it accesses the file system, glob(3) can take a
1025 long time to complete for some patterns, especially
1026 when the pattern references a network file system that
1027 is mounted on demand (auto mounted). The fast_glob
1028 option causes sudo to use the fnmatch(3) function,
1029 which does not access the file system to do its match‐
1030 ing. The disadvantage of fast_glob is that it is
1031 unable to match relative path names such as ./ls or
1032 ../bin/ls. This has security implications when path
1033 names that include globbing characters are used with
1034 the negation operator, ‘!’, as such rules can be triv‐
1035 ially bypassed. As such, this option should not be
1036 used when the sudoers file contains rules that contain
1037 negated path names which include globbing characters.
1038 This flag is off by default.
1039 fqdn Set this flag if you want to put fully qualified host
1041 names in the sudoers file when the local host name (as
1042 returned by the hostname command) does not contain the
1043 domain name. In other words, instead of myhost you
1044 would use myhost.mydomain.edu. You may still use the
1045 short form if you wish (and even mix the two). This
1046 option is only effective when the “canonical” host
1047 name, as returned by the getaddrinfo() or
1048 gethostbyname() function, is a fully-qualified domain
1049 name. This is usually the case when the system is con‐
1050 figured to use DNS for host name resolution.
1051 If the system is configured to use the /etc/hosts file
1053 in preference to DNS, the “canonical” host name may not
1054 be fully-qualified. The order that sources are queried
1055 for host name resolution is usually specified in the
1056 /etc/nsswitch.conf, /etc/netsvc.conf, /etc/host.conf,
1057 or, in some cases, /etc/resolv.conf file. In the
1058 /etc/hosts file, the first host name of the entry is
1059 considered to be the “canonical” name; subsequent names
1060 are aliases that are not used by sudoers. For example,
1061 the following hosts file line for the machine “xyzzy”
1062 has the fully-qualified domain name as the “canonical”
1063 host name, and the short version as an alias.
1064 192.168.1.1 xyzzy.sudo.ws xyzzy
1066 If the machine's hosts file entry is not formatted
1068 properly, the fqdn option will not be effective if it
1069 is queried before DNS.
1070 Beware that when using DNS for host name resolution,
1072 turning on fqdn requires sudoers to make DNS lookups
1073 which renders sudo unusable if DNS stops working (for
1074 example if the machine is disconnected from the net‐
1075 work). Also note that just like with the hosts file,
1076 you must use the “canonical” name as DNS knows it.
1077 That is, you may not use a host alias (CNAME entry) due
1078 to performance issues and the fact that there is no way
1079 to get all aliases from DNS.
1080 This flag is off by default.
1082 ignore_audit_errors
1084 Allow commands to be run even if sudoers cannot write
1085 to the audit log. If enabled, an audit log write fail‐
1086 ure is not treated as a fatal error. If disabled, a
1087 command may only be run after the audit event is suc‐
1088 cessfully written. This flag is only effective on sys‐
1089 tems for which sudoers supports audit logging, includ‐
1090 ing FreeBSD, Linux, macOS and Solaris. This flag is on
1091 by default.
1092 ignore_dot If set, sudo will ignore "." or "" (both denoting cur‐
1094 rent directory) in the PATH environment variable; the
1095 PATH itself is not modified. This flag is on by
1096 default.
1097 ignore_iolog_errors
1099 Allow commands to be run even if sudoers cannot write
1100 to the I/O log. If enabled, an I/O log write failure
1101 is not treated as a fatal error. If disabled, the com‐
1102 mand will be terminated if the I/O log cannot be writ‐
1103 ten to. This flag is off by default.
1104 ignore_logfile_errors
1106 Allow commands to be run even if sudoers cannot write
1107 to the log file. If enabled, a log file write failure
1108 is not treated as a fatal error. If disabled, a com‐
1109 mand may only be run after the log file entry is suc‐
1110 cessfully written. This flag only has an effect when
1111 sudoers is configured to use file-based logging via the
1112 logfile option. This flag is on by default.
1113 ignore_local_sudoers
1115 If set via LDAP, parsing of /etc/sudoers will be
1116 skipped. This is intended for Enterprises that wish to
1117 prevent the usage of local sudoers files so that only
1118 LDAP is used. This thwarts the efforts of rogue opera‐
1119 tors who would attempt to add roles to /etc/sudoers.
1120 When this option is present, /etc/sudoers does not even
1121 need to exist. Since this option tells sudo how to
1122 behave when no specific LDAP entries have been matched,
1123 this sudoOption is only meaningful for the cn=defaults
1124 section. This flag is off by default.
1125 ignore_unknown_defaults
1127 If set, sudo will not produce a warning if it encoun‐
1128 ters an unknown Defaults entry in the sudoers file or
1129 an unknown sudoOption in LDAP. This flag is off by
1130 default.
1131 insults If set, sudo will insult users when they enter an
1133 incorrect password. This flag is off by default.
1134 log_host If set, the host name will be logged in the (non-sys‐
1136 log) sudo log file. This flag is off by default.
1137 log_input If set, sudo will run the command in a pseudo-tty and
1139 log all user input. If the standard input is not con‐
1140 nected to the user's tty, due to I/O redirection or
1141 because the command is part of a pipeline, that input
1142 is also captured and stored in a separate log file.
1143 Anything sent to the standard input will be consumed,
1144 regardless of whether or not the command run via sudo
1145 is actually reading the standard input. This may have
1146 unexpected results when using sudo in a shell script
1147 that expects to process the standard input. For more
1148 information about I/O logging, see the I/O LOG FILES
1149 section. This flag is off by default.
1150 log_output If set, sudo will run the command in a pseudo-tty and
1152 log all output that is sent to the screen, similar to
1153 the script(1) command. For more information about I/O
1154 logging, see the I/O LOG FILES section. This flag is
1155 off by default.
1156 log_year If set, the four-digit year will be logged in the (non-
1158 syslog) sudo log file. This flag is off by default.
1159 long_otp_prompt When validating with a One Time Password (OTP) scheme
1161 such as S/Key or OPIE, a two-line prompt is used to
1162 make it easier to cut and paste the challenge to a
1163 local window. It's not as pretty as the default but
1164 some people find it more convenient. This flag is off
1165 by default.
1166 mail_all_cmnds Send mail to the mailto user every time a user attempts
1168 to run a command via sudo (this includes sudoedit). No
1169 mail will be sent if the user runs sudo with the -l or
1170 -v option unless there is an authentication error and
1171 the mail_badpass flag is also set. This flag is off by
1172 default.
1173 mail_always Send mail to the mailto user every time a user runs
1175 sudo. This flag is off by default.
1176 mail_badpass Send mail to the mailto user if the user running sudo
1178 does not enter the correct password. If the command
1179 the user is attempting to run is not permitted by
1180 sudoers and one of the mail_all_cmnds, mail_always,
1181 mail_no_host, mail_no_perms or mail_no_user flags are
1182 set, this flag will have no effect. This flag is off
1183 by default.
1184 mail_no_host If set, mail will be sent to the mailto user if the
1186 invoking user exists in the sudoers file, but is not
1187 allowed to run commands on the current host. This flag
1188 is off by default.
1189 mail_no_perms If set, mail will be sent to the mailto user if the
1191 invoking user is allowed to use sudo but the command
1192 they are trying is not listed in their sudoers file
1193 entry or is explicitly denied. This flag is off by
1194 default.
1195 mail_no_user If set, mail will be sent to the mailto user if the
1197 invoking user is not in the sudoers file. This flag is
1198 on by default.
1199 match_group_by_gid
1201 By default, sudoers will look up each group the user is
1202 a member of by group ID to determine the group name
1203 (this is only done once). The resulting list of the
1204 user's group names is used when matching groups listed
1205 in the sudoers file. This works well on systems where
1206 the number of groups listed in the sudoers file is
1207 larger than the number of groups a typical user belongs
1208 to. On systems where group lookups are slow, where
1209 users may belong to a large number of groups, and where
1210 the number of groups listed in the sudoers file is rel‐
1211 atively small, it may be prohibitively expensive and
1212 running commands via sudo may take longer than normal.
1213 On such systems it may be faster to use the
1214 match_group_by_gid flag to avoid resolving the user's
1215 group IDs to group names. In this case, sudoers must
1216 look up any group name listed in the sudoers file and
1217 use the group ID instead of the group name when deter‐
1218 mining whether the user is a member of the group.
1219 Note that if match_group_by_gid is enabled, group data‐
1221 base lookups performed by sudoers will be keyed by
1222 group name as opposed to group ID. On systems where
1223 there are multiple sources for the group database, it
1224 is possible to have conflicting group names or group
1225 IDs in the local /etc/group file and the remote group
1226 database. On such systems, enabling or disabling
1227 match_group_by_gid can be used to choose whether group
1228 database queries are performed by name (enabled) or ID
1229 (disabled), which may aid in working around group entry
1230 conflicts.
1231 The match_group_by_gid flag has no effect when sudoers
1233 data is stored in LDAP. This flag is off by default.
1234 This setting is only supported by version 1.8.18 or
1236 higher.
1237 netgroup_tuple If set, netgroup lookups will be performed using the
1239 full netgroup tuple: host name, user name and domain
1240 (if one is set). Historically, sudo only matched the
1241 user name and domain for netgroups used in a User_List
1242 and only matched the host name and domain for netgroups
1243 used in a Host_List. This flag is off by default.
1244 noexec If set, all commands run via sudo will behave as if the
1246 NOEXEC tag has been set, unless overridden by an EXEC
1247 tag. See the description of EXEC and NOEXEC above as
1248 well as the Preventing shell escapes section at the end
1249 of this manual. This flag is off by default.
1250 pam_session On systems that use PAM for authentication, sudo will
1252 create a new PAM session for the command to be run in.
1253 Disabling pam_session may be needed on older PAM imple‐
1254 mentations or on operating systems where opening a PAM
1255 session changes the utmp or wtmp files. If PAM session
1256 support is disabled, resource limits may not be updated
1257 for the command being run. If pam_session,
1258 pam_setcred, and use_pty are disabled and I/O logging
1259 has not been configured, sudo will execute the command
1260 directly instead of running it as a child process.
1261 This flag is on by default.
1262 This setting is only supported by version 1.8.7 or
1264 higher.
1265 pam_setcred On systems that use PAM for authentication, sudo will
1267 attempt to establish credentials for the target user by
1268 default, if supported by the underlying authentication
1269 system. One example of a credential is a Kerberos
1270 ticket. If pam_session, pam_setcred, and use_pty are
1271 disabled and I/O logging has not been configured, sudo
1272 will execute the command directly instead of running it
1273 as a child process. This flag is on by default.
1274 This setting is only supported by version 1.8.8 or
1276 higher.
1277 passprompt_override
1279 If set, the prompt specified by passprompt or the
1280 SUDO_PROMPT environment variable will always be used
1281 and will replace the prompt provided by a PAM module or
1282 other authentication method. This flag is off by
1283 default.
1284 path_info Normally, sudo will tell the user when a command could
1286 not be found in their PATH environment variable. Some
1287 sites may wish to disable this as it could be used to
1288 gather information on the location of executables that
1289 the normal user does not have access to. The disadvan‐
1290 tage is that if the executable is simply not in the
1291 user's PATH, sudo will tell the user that they are not
1292 allowed to run it, which can be confusing. This flag
1293 is on by default.
1294 preserve_groups By default, sudo will initialize the group vector to
1296 the list of groups the target user is in. When
1297 preserve_groups is set, the user's existing group vec‐
1298 tor is left unaltered. The real and effective group
1299 IDs, however, are still set to match the target user.
1300 This flag is off by default.
1301 pwfeedback By default, sudo reads the password like most other
1303 Unix programs, by turning off echo until the user hits
1304 the return (or enter) key. Some users become confused
1305 by this as it appears to them that sudo has hung at
1306 this point. When pwfeedback is set, sudo will provide
1307 visual feedback when the user presses a key. Note that
1308 this does have a security impact as an onlooker may be
1309 able to determine the length of the password being
1310 entered. This flag is off by default.
1311 requiretty If set, sudo will only run when the user is logged in
1313 to a real tty. When this flag is set, sudo can only be
1314 run from a login session and not via other means such
1315 as cron(8) or cgi-bin scripts. This flag is off by
1316 default.
1317 root_sudo If set, root is allowed to run sudo too. Disabling
1319 this prevents users from “chaining” sudo commands to
1320 get a root shell by doing something like “sudo sudo
1321 /bin/sh”. Note, however, that turning off root_sudo
1322 will also prevent root from running sudoedit. Dis‐
1323 abling root_sudo provides no real additional security;
1324 it exists purely for historical reasons. This flag is
1325 on by default.
1326 rootpw If set, sudo will prompt for the root password instead
1328 of the password of the invoking user when running a
1329 command or editing a file. This flag is off by
1330 default.
1331 runaspw If set, sudo will prompt for the password of the user
1333 defined by the runas_default option (defaults to root)
1334 instead of the password of the invoking user when run‐
1335 ning a command or editing a file. This flag is off by
1336 default.
1337 set_home If enabled and sudo is invoked with the -s option the
1339 HOME environment variable will be set to the home
1340 directory of the target user (which is root unless the
1341 -u option is used). This effectively makes the -s
1342 option imply -H. Note that HOME is already set when
1343 the env_reset option is enabled, so set_home is only
1344 effective for configurations where either env_reset is
1345 disabled or HOME is present in the env_keep list. This
1346 flag is off by default.
1347 set_logname Normally, sudo will set the LOGNAME, USER and USERNAME
1349 environment variables to the name of the target user
1350 (usually root unless the -u option is given). However,
1351 since some programs (including the RCS revision control
1352 system) use LOGNAME to determine the real identity of
1353 the user, it may be desirable to change this behavior.
1354 This can be done by negating the set_logname option.
1355 Note that set_logname will have no effect if the
1356 env_reset option has not been disabled and the env_keep
1357 list contains LOGNAME, USER or USERNAME. This flag is
1358 on by default.
1359 set_utmp When enabled, sudo will create an entry in the utmp (or
1361 utmpx) file when a pseudo-tty is allocated. A pseudo-
1362 tty is allocated by sudo when the log_input, log_output
1363 or use_pty flags are enabled. By default, the new
1364 entry will be a copy of the user's existing utmp entry
1365 (if any), with the tty, time, type and pid fields
1366 updated. This flag is on by default.
1367 setenv Allow the user to disable the env_reset option from the
1369 command line via the -E option. Additionally, environ‐
1370 ment variables set via the command line are not subject
1371 to the restrictions imposed by env_check, env_delete,
1372 or env_keep. As such, only trusted users should be
1373 allowed to set variables in this manner. This flag is
1374 off by default.
1375 shell_noargs If set and sudo is invoked with no arguments it acts as
1377 if the -s option had been given. That is, it runs a
1378 shell as root (the shell is determined by the SHELL
1379 environment variable if it is set, falling back on the
1380 shell listed in the invoking user's /etc/passwd entry
1381 if not). This flag is off by default.
1382 stay_setuid Normally, when sudo executes a command the real and
1384 effective UIDs are set to the target user (root by
1385 default). This option changes that behavior such that
1386 the real UID is left as the invoking user's UID. In
1387 other words, this makes sudo act as a setuid wrapper.
1388 This can be useful on systems that disable some poten‐
1389 tially dangerous functionality when a program is run
1390 setuid. This option is only effective on systems that
1391 support either the setreuid(2) or setresuid(2) system
1392 call. This flag is off by default.
1393 sudoedit_checkdir
1395 If set, sudoedit will check all directory components of
1396 the path to be edited for writability by the invoking
1397 user. Symbolic links will not be followed in writable
1398 directories and sudoedit will refuse to edit a file
1399 located in a writable directory. These restrictions
1400 are not enforced when sudoedit is run by root. On some
1401 systems, if all directory components of the path to be
1402 edited are not readable by the target user, sudoedit
1403 will be unable to edit the file. This flag is on by
1404 default.
1405 This setting was first introduced in version 1.8.15 but
1407 initially suffered from a race condition. The check
1408 for symbolic links in writable intermediate directories
1409 was added in version 1.8.16.
1410 sudoedit_follow By default, sudoedit will not follow symbolic links
1412 when opening files. The sudoedit_follow option can be
1413 enabled to allow sudoedit to open symbolic links. It
1414 may be overridden on a per-command basis by the FOLLOW
1415 and NOFOLLOW tags. This flag is off by default.
1416 This setting is only supported by version 1.8.15 or
1418 higher.
1419 syslog_pid When logging via syslog(3), include the process ID in
1421 the log entry. This flag is off by default.
1422 This setting is only supported by version 1.8.21 or
1424 higher.
1425 targetpw If set, sudo will prompt for the password of the user
1427 specified by the -u option (defaults to root) instead
1428 of the password of the invoking user when running a
1429 command or editing a file. Note that this flag pre‐
1430 cludes the use of a uid not listed in the passwd data‐
1431 base as an argument to the -u option. This flag is off
1432 by default.
1433 tty_tickets If set, users must authenticate on a per-tty basis.
1435 With this flag enabled, sudo will use a separate record
1436 in the time stamp file for each terminal. If disabled,
1437 a single record is used for all login sessions.
1438 This option has been superseded by the timestamp_type
1440 option.
1441 umask_override If set, sudo will set the umask as specified in the
1443 sudoers file without modification. This makes it pos‐
1444 sible to specify a umask in the sudoers file that is
1445 more permissive than the user's own umask and matches
1446 historical behavior. If umask_override is not set,
1447 sudo will set the umask to be the union of the user's
1448 umask and what is specified in sudoers. This flag is
1449 off by default.
1450 use_netgroups If set, netgroups (prefixed with ‘+’), may be used in
1452 place of a user or host. For LDAP-based sudoers, net‐
1453 group support requires an expensive sub-string match on
1454 the server unless the NETGROUP_BASE directive is
1455 present in the /etc/sudo-ldap.conf file. If netgroups
1456 are not needed, this option can be disabled to reduce
1457 the load on the LDAP server. This flag is on by
1458 default.
1459 use_pty If set, and sudo is running in a terminal, the command
1461 will be run in a pseudo-pty (even if no I/O logging is
1462 being done). If the sudo process is not attached to a
1463 terminal, use_pty has no effect.
1464 A malicious program run under sudo may be capable of
1466 injecting injecting commands into the user's terminal
1467 or running a background process that retains access to
1468 the user's terminal device even after the main program
1469 has finished executing. By running the command in a
1470 separate pseudo-pty, this attack is no longer possible.
1471 This flag is off by default.
1472 user_command_timeouts
1474 If set, the user may specify a timeout on the command
1475 line. If the timeout expires before the command has
1476 exited, the command will be terminated. If a timeout
1477 is specified both in the sudoers file and on the com‐
1478 mand line, the smaller of the two timeouts will be
1479 used. See the Timeout_Spec section for a description
1480 of the timeout syntax. This flag is off by default.
1481 This setting is only supported by version 1.8.20 or
1483 higher.
1484 utmp_runas If set, sudo will store the name of the runas user when
1486 updating the utmp (or utmpx) file. By default, sudo
1487 stores the name of the invoking user. This flag is off
1488 by default.
1489 visiblepw By default, sudo will refuse to run if the user must
1491 enter a password but it is not possible to disable echo
1492 on the terminal. If the visiblepw flag is set, sudo
1493 will prompt for a password even when it would be visi‐
1494 ble on the screen. This makes it possible to run
1495 things like “ssh somehost sudo ls” since by default,
1496 ssh(1) does not allocate a tty when running a command.
1497 This flag is off by default.
1498 Integers:
1500 closefrom Before it executes a command, sudo will close all open
1502 file descriptors other than standard input, standard
1503 output and standard error (ie: file descriptors 0-2).
1504 The closefrom option can be used to specify a different
1505 file descriptor at which to start closing. The default
1506 is 3.
1507 command_timeout The maximum amount of time a command is allowed to run
1509 before it is terminated. See the Timeout_Spec section
1510 for a description of the timeout syntax.
1511 This setting is only supported by version 1.8.20 or
1513 higher.
1514 maxseq The maximum sequence number that will be substituted
1516 for the “%{seq}” escape in the I/O log file (see the
1517 iolog_dir description above for more information).
1518 While the value substituted for “%{seq}” is in base 36,
1519 maxseq itself should be expressed in decimal. Values
1520 larger than 2176782336 (which corresponds to the base
1521 36 sequence number “ZZZZZZ”) will be silently truncated
1522 to 2176782336. The default value is 2176782336.
1523 Once the local sequence number reaches the value of
1525 maxseq, it will “roll over” to zero, after which
1526 sudoers will truncate and re-use any existing I/O log
1527 path names.
1528 This setting is only supported by version 1.8.7 or
1530 higher.
1531 passwd_tries The number of tries a user gets to enter his/her pass‐
1533 word before sudo logs the failure and exits. The
1534 default is 3.
1535 syslog_maxlen On many systems, syslog(3) has a relatively small log
1537 buffer. IETF RFC 5424 states that syslog servers must
1538 support messages of at least 480 bytes and should sup‐
1539 port messages up to 2048 bytes. By default, sudoers
1540 creates log messages up to 980 bytes which corresponds
1541 to the historic BSD syslog implementation which used a
1542 1024 byte buffer to store the message, date, hostname
1543 and program name. To prevent syslog messages from
1544 being truncated, sudoers will split up log messages
1545 that are larger than syslog_maxlen bytes. When a mes‐
1546 sage is split, additional parts will include the string
1547 “(command continued)” after the user name and before
1548 the continued command line arguments.
1549 This setting is only supported by version 1.8.19 or
1551 higher.
1552 Integers that can be used in a boolean context:
1554 loglinelen Number of characters per line for the file log. This
1556 value is used to decide when to wrap lines for nicer
1557 log files. This has no effect on the syslog log file,
1558 only the file log. The default is 80 (use 0 or negate
1559 the option to disable word wrap).
1560 passwd_timeout Number of minutes before the sudo password prompt times
1562 out, or 0 for no timeout. The timeout may include a
1563 fractional component if minute granularity is insuffi‐
1564 cient, for example 2.5. The default is 5.
1565 timestamp_timeout
1567 Number of minutes that can elapse before sudo will ask
1568 for a passwd again. The timeout may include a frac‐
1569 tional component if minute granularity is insufficient,
1570 for example 2.5. The default is 5. Set this to 0 to
1571 always prompt for a password. If set to a value less
1572 than 0 the user's time stamp will not expire until the
1573 system is rebooted. This can be used to allow users to
1574 create or delete their own time stamps via “sudo -v”
1575 and “sudo -k” respectively.
1576 umask Umask to use when running the command. Negate this
1578 option or set it to 0777 to preserve the user's umask.
1579 The actual umask that is used will be the union of the
1580 user's umask and the value of the umask option, which
1581 defaults to 0022. This guarantees that sudo never low‐
1582 ers the umask when running a command. Note: on systems
1583 that use PAM, the default PAM configuration may specify
1584 its own umask which will override the value set in
1585 sudoers.
1586 Strings:
1588 authfail_message Message that is displayed after a user fails to authen‐
1590 ticate. The message may include the ‘%d’ escape which
1591 will expand to the number of failed password attempts.
1592 If set, it overrides the default message, %d incorrect
1593 password attempt(s).
1594 badpass_message Message that is displayed if a user enters an incorrect
1596 password. The default is Sorry, try again. unless
1597 insults are enabled.
1598 editor A colon (‘:’) separated list of editors path names used
1600 by sudoedit and visudo. For sudoedit, this list is
1601 used to find an editor when none of the SUDO_EDITOR,
1602 VISUAL or EDITOR environment variables are set to an
1603 editor that exists and is executable. For visudo, it
1604 is used as a white list of allowed editors; visudo will
1605 choose the editor that matches the user's SUDO_EDITOR,
1606 VISUAL or EDITOR environment variable if possible, or
1607 the first editor in the list that exists and is exe‐
1608 cutable if not. Unless invoked as sudoedit, sudo does
1609 not preserve the SUDO_EDITOR, VISUAL and EDITOR envi‐
1610 ronment variables by default, even when the env_reset
1611 option is enabled. The default is /bin/vi.
1612 iolog_dir The top-level directory to use when constructing the
1614 path name for the input/output log directory. Only
1615 used if the log_input or log_output options are enabled
1616 or when the LOG_INPUT or LOG_OUTPUT tags are present
1617 for a command. The session sequence number, if any, is
1618 stored in the directory. The default is
1619 /var/log/sudo-io.
1620 The following percent (‘%’) escape sequences are sup‐
1622 ported:
1623 %{seq}
1625 expanded to a monotonically increasing base-36
1626 sequence number, such as 0100A5, where every two
1627 digits are used to form a new directory, e.g.
1628 01/00/A5
1629 %{user}
1631 expanded to the invoking user's login name
1632 %{group}
1634 expanded to the name of the invoking user's real
1635 group ID
1636 %{runas_user}
1638 expanded to the login name of the user the com‐
1639 mand will be run as (e.g. root)
1640 %{runas_group}
1642 expanded to the group name of the user the com‐
1643 mand will be run as (e.g. wheel)
1644 %{hostname}
1646 expanded to the local host name without the
1647 domain name
1648 %{command}
1650 expanded to the base name of the command being
1651 run
1652 In addition, any escape sequences supported by the sys‐
1654 tem's strftime(3) function will be expanded.
1655 To include a literal ‘%’ character, the string ‘%%’
1657 should be used.
1658 iolog_file The path name, relative to iolog_dir, in which to store
1660 input/output logs when the log_input or log_output
1661 options are enabled or when the LOG_INPUT or LOG_OUTPUT
1662 tags are present for a command. Note that iolog_file
1663 may contain directory components. The default is
1664 “%{seq}”.
1665 See the iolog_dir option above for a list of supported
1667 percent (‘%’) escape sequences.
1668 In addition to the escape sequences, path names that
1670 end in six or more Xs will have the Xs replaced with a
1671 unique combination of digits and letters, similar to
1672 the mktemp(3) function.
1673 If the path created by concatenating iolog_dir and
1675 iolog_file already exists, the existing I/O log file
1676 will be truncated and overwritten unless iolog_file
1677 ends in six or more Xs.
1678 iolog_flush If set, sudo will flush I/O log data to disk after each
1680 write instead of buffering it. This makes it possible
1681 to view the logs in real-time as the program is execut‐
1682 ing but may significantly reduce the effectiveness of
1683 I/O log compression. This flag is off by default.
1684 This setting is only supported by version 1.8.20 or
1686 higher.
1687 iolog_group The group name to look up when setting the group ID on
1689 new I/O log files and directories. If iolog_group is
1690 not set, the primary group ID of the user specified by
1691 iolog_user is used. If neither iolog_group nor
1692 iolog_user are set, I/O log files and directories are
1693 created with group ID 0.
1694 This setting is only supported by version 1.8.19 or
1696 higher.
1697 iolog_mode The file mode to use when creating I/O log files. Mode
1699 bits for read and write permissions for owner, group or
1700 other are honored, everything else is ignored. The
1701 file permissions will always include the owner read and
1702 write bits, even if they are not present in the speci‐
1703 fied mode. When creating I/O log directories, search
1704 (execute) bits are added to to match the read and write
1705 bits specified by iolog_mode. Defaults to 0600 (read
1706 and write by user only).
1707 This setting is only supported by version 1.8.19 or
1709 higher.
1710 iolog_user The user name to look up when setting the user and
1712 group IDs on new I/O log files and directories. If
1713 iolog_group is set, it will be used instead of the
1714 user's primary group ID. By default, I/O log files and
1715 directories are created with user and group ID 0.
1716 This setting can be useful when the I/O logs are stored
1718 on a Network File System (NFS) share. Having a dedi‐
1719 cated user own the I/O log files means that sudoers
1720 does not write to the log files as user ID 0, which is
1721 usually not permitted by NFS.
1722 This setting is only supported by version 1.8.19 or
1724 higher.
1725 lecture_status_dir
1727 The directory in which sudo stores per-user lecture
1728 status files. Once a user has received the lecture, a
1729 zero-length file is created in this directory so that
1730 sudo will not lecture the user again. This directory
1731 should not be cleared when the system reboots. The
1732 default is /var/db/sudo/lectured.
1733 mailsub Subject of the mail sent to the mailto user. The
1735 escape %h will expand to the host name of the machine.
1736 Default is “*** SECURITY information for %h ***”.
1737 noexec_file As of sudo version 1.8.1 this option is no longer sup‐
1739 ported. The path to the noexec file should now be set
1740 in the sudo.conf(5) file.
1741 pam_login_service
1743 On systems that use PAM for authentication, this is the
1744 service name used when the -i option is specified. The
1745 default value is “sudo-i”. See the description of
1746 pam_service for more information.
1747 This setting is only supported by version 1.8.8 or
1749 higher.
1750 pam_service On systems that use PAM for authentication, the service
1752 name specifies the PAM policy to apply. This usually
1753 corresponds to an entry in the pam.conf file or a file
1754 in the /etc/pam.d directory. The default value is
1755 “sudo”.
1756 This setting is only supported by version 1.8.8 or
1758 higher.
1759 passprompt The default prompt to use when asking for a password;
1761 can be overridden via the -p option or the SUDO_PROMPT
1762 environment variable. The following percent (‘%’)
1763 escape sequences are supported:
1764 %H expanded to the local host name including the
1766 domain name (only if the machine's host name is
1767 fully qualified or the fqdn option is set)
1768 %h expanded to the local host name without the
1770 domain name
1771 %p expanded to the user whose password is being
1773 asked for (respects the rootpw, targetpw and
1774 runaspw flags in sudoers)
1775 %U expanded to the login name of the user the com‐
1777 mand will be run as (defaults to root)
1778 %u expanded to the invoking user's login name
1780 %% two consecutive % characters are collapsed into a
1782 single % character
1783 On systems that use PAM for authentication, passprompt
1785 will only be used if the prompt provided by the PAM
1786 module matches the string “Password: ” or “username's
1787 Password: ”. This ensures that the passprompt setting
1788 does not interfere with challenge-response style
1789 authentication. The passprompt_override flag can be
1790 used to change this behavior.
1791 The default value is “[sudo] password for %p: ”.
1793 role The default SELinux role to use when constructing a new
1795 security context to run the command. The default role
1796 may be overridden on a per-command basis in the sudoers
1797 file or via command line options. This option is only
1798 available when sudo is built with SELinux support.
1799 runas_default The default user to run commands as if the -u option is
1801 not specified on the command line. This defaults to
1802 root.
1803 sudoers_locale Locale to use when parsing the sudoers file, logging
1805 commands, and sending email. Note that changing the
1806 locale may affect how sudoers is interpreted. Defaults
1807 to “C”.
1808 timestamp_type sudoers uses per-user time stamp files for credential
1810 caching. The timestamp_type option can be used to
1811 specify the type of time stamp record used. It has the
1812 following possible values:
1813 global A single time stamp record is used for all of a
1815 user's login sessions, regardless of the termi‐
1816 nal or parent process ID. An additional record
1817 is used to serialize password prompts when sudo
1818 is used multiple times in a pipeline, but this
1819 does not affect authentication.
1820 ppid A single time stamp record is used for all pro‐
1822 cesses with the same parent process ID (usually
1823 the shell). Commands run from the same shell
1824 (or other common parent process) will not
1825 require a password for timestamp_timeout min‐
1826 utes (5 by default). Commands run via sudo
1827 with a different parent process ID, for example
1828 from a shell script, will be authenticated sep‐
1829 arately.
1830 tty One time stamp record is used for each termi‐
1832 nal, which means that a user's login sessions
1833 are authenticated separately. If no terminal
1834 is present, the behavior is the same as ppid.
1835 Commands run from the same terminal will not
1836 require a password for timestamp_timeout min‐
1837 utes (5 by default).
1838 kernel The time stamp is stored in the kernel as an
1840 attribute of the terminal device. If no termi‐
1841 nal is present, the behavior is the same as
1842 ppid. Negative timestamp_timeout values are
1843 not supported and positive values are limited
1844 to a maximum of 60 minutes. This is currently
1845 only supported on OpenBSD.
1846 The default value is tty.
1848 This setting is only supported by version 1.8.21 or
1850 higher.
1851 timestampdir The directory in which sudo stores its time stamp
1853 files. This directory should be cleared when the sys‐
1854 tem reboots. The default is /run/sudo/ts.
1855 timestampowner The owner of the lecture status directory, time stamp
1857 directory and all files stored therein. The default is
1858 root.
1859 type The default SELinux type to use when constructing a new
1861 security context to run the command. The default type
1862 may be overridden on a per-command basis in the sudoers
1863 file or via command line options. This option is only
1864 available when sudo is built with SELinux support.
1865 Strings that can be used in a boolean context:
1867 env_file The env_file option specifies the fully qualified path to a
1869 file containing variables to be set in the environment of
1870 the program being run. Entries in this file should either
1871 be of the form “VARIABLE=value” or “export VARIABLE=value”.
1872 The value may optionally be surrounded by single or double
1873 quotes. Variables in this file are only added if the vari‐
1874 able does not already exist in the environment. This file
1875 is considered to be part of the security policy, its con‐
1876 tents are not subject to other sudo environment restric‐
1877 tions such as env_keep and env_check.
1878 exempt_group Users in this group are exempt from password and PATH
1880 requirements. The group name specified should not include
1881 a % prefix. This is not set by default.
1882 fdexec Determines whether sudo will execute a command by its path
1884 or by an open file descriptor. It has the following possi‐
1885 ble values:
1886 always Always execute by file descriptor.
1888 never Never execute by file descriptor.
1890 digest_only
1892 Only execute by file descriptor if the command has
1893 an associated digest in the sudoers file.
1894 The default value is digest_only. This avoids a time of
1896 check versus time of use race condition when the command is
1897 located in a directory writable by the invoking user.
1898 Note that fdexec will change the first element of the argu‐
1900 ment vector for scripts ($0 in the shell) due to the way
1901 the kernel runs script interpreters. Instead of being a
1902 normal path, it will refer to a file descriptor. For exam‐
1903 ple, /dev/fd/4 on Solaris and /proc/self/fd/4 on Linux. A
1904 workaround is to use the SUDO_COMMAND environment variable
1905 instead.
1906 The fdexec setting is only used when the command is matched
1908 by path name. It has no effect if the command is matched
1909 by the built-in ALL alias.
1910 This setting is only supported by version 1.8.20 or higher.
1912 If the operating system does not support the fexecve(2)
1913 system call, this setting has no effect.
1914 group_plugin A string containing a sudoers group plugin with optional
1916 arguments. The string should consist of the plugin path,
1917 either fully-qualified or relative to the /usr/libexec/sudo
1918 directory, followed by any configuration arguments the
1919 plugin requires. These arguments (if any) will be passed
1920 to the plugin's initialization function. If arguments are
1921 present, the string must be enclosed in double quotes ("").
1922 For more information see GROUP PROVIDER PLUGINS.
1924 lecture This option controls when a short lecture will be printed
1926 along with the password prompt. It has the following pos‐
1927 sible values:
1928 always Always lecture the user.
1930 never Never lecture the user.
1932 once Only lecture the user the first time they run sudo.
1934 If no value is specified, a value of once is implied.
1936 Negating the option results in a value of never being used.
1937 The default value is once.
1938 lecture_file Path to a file containing an alternate sudo lecture that
1940 will be used in place of the standard lecture if the named
1941 file exists. By default, sudo uses a built-in lecture.
1942 listpw This option controls when a password will be required when
1944 a user runs sudo with the -l option. It has the following
1945 possible values:
1946 all All the user's sudoers file entries for the cur‐
1948 rent host must have the NOPASSWD flag set to
1949 avoid entering a password.
1950 always The user must always enter a password to use the
1952 -l option.
1953 any At least one of the user's sudoers file entries
1955 for the current host must have the NOPASSWD flag
1956 set to avoid entering a password.
1957 never The user need never enter a password to use the
1959 -l option.
1960 If no value is specified, a value of any is implied.
1962 Negating the option results in a value of never being used.
1963 The default value is any.
1964 logfile Path to the sudo log file (not the syslog log file). Set‐
1966 ting a path turns on logging to a file; negating this
1967 option turns it off. By default, sudo logs via syslog.
1968 mailerflags Flags to use when invoking mailer. Defaults to -t.
1970 mailerpath Path to mail program used to send warning mail. Defaults
1972 to the path to sendmail found at configure time.
1973 mailfrom Address to use for the “from” address when sending warning
1975 and error mail. The address should be enclosed in double
1976 quotes ("") to protect against sudo interpreting the @
1977 sign. Defaults to the name of the user running sudo.
1978 mailto Address to send warning and error mail to. The address
1980 should be enclosed in double quotes ("") to protect against
1981 sudo interpreting the @ sign. Defaults to root.
1982 restricted_env_file
1984 The restricted_env_file option specifies the fully quali‐
1985 fied path to a file containing variables to be set in the
1986 environment of the program being run. Entries in this file
1987 should either be of the form “VARIABLE=value” or “export
1988 VARIABLE=value”. The value may optionally be surrounded by
1989 single or double quotes. Variables in this file are only
1990 added if the variable does not already exist in the envi‐
1991 ronment. Unlike env_file, the file's contents are not
1992 trusted and are processed in a manner similar to that of
1993 the invoking user's environment. If env_reset is enabled,
1994 variables in the file will only be added if they are
1995 matched by either the env_check or env_keep list. If
1996 env_reset is disabled, variables in the file are added as
1997 long as they are not matched by the env_delete list. In
1998 either case, the contents of restricted_env_file are pro‐
1999 cessed before the contents of env_file.
2000 secure_path Path used for every command run from sudo. If you don't
2002 trust the people running sudo to have a sane PATH environ‐
2003 ment variable you may want to use this. Another use is if
2004 you want to have the “root path” be separate from the “user
2005 path”. Users in the group specified by the exempt_group
2006 option are not affected by secure_path. This option is not
2007 set by default.
2008 syslog Syslog facility if syslog is being used for logging (negate
2010 to disable syslog logging). Defaults to authpriv.
2011 The following syslog facilities are supported: authpriv (if
2013 your OS supports it), auth, daemon, user, local0, local1,
2014 local2, local3, local4, local5, local6, and local7.
2015 syslog_badpri
2017 Syslog priority to use when the user is not allowed to run
2018 a command or when authentication is unsuccessful. Defaults
2019 to alert.
2020 The following syslog priorities are supported: alert, crit,
2022 debug, emerg, err, info, notice, warning, and none. Negat‐
2023 ing the option or setting it to a value of none will dis‐
2024 able logging of unsuccessful commands.
2025 syslog_goodpri
2027 Syslog priority to use when the user is allowed to run a
2028 command and authentication is successful. Defaults to
2029 notice.
2030 See syslog_badpri for the list of supported syslog priori‐
2032 ties. Negating the option or setting it to a value of none
2033 will disable logging of successful commands.
2034 verifypw This option controls when a password will be required when
2036 a user runs sudo with the -v option. It has the following
2037 possible values:
2038 all All the user's sudoers file entries for the current
2040 host must have the NOPASSWD flag set to avoid
2041 entering a password.
2042 always The user must always enter a password to use the -v
2044 option.
2045 any At least one of the user's sudoers file entries for
2047 the current host must have the NOPASSWD flag set to
2048 avoid entering a password.
2049 never The user need never enter a password to use the -v
2051 option.
2052 If no value is specified, a value of all is implied.
2054 Negating the option results in a value of never being used.
2055 The default value is all.
2056 Lists that can be used in a boolean context:
2058 env_check Environment variables to be removed from the user's
2060 environment unless they are considered “safe”. For all
2061 variables except TZ, “safe” means that the variable's
2062 value does not contain any ‘%’ or ‘/’ characters. This
2063 can be used to guard against printf-style format vul‐
2064 nerabilities in poorly-written programs. The TZ vari‐
2065 able is considered unsafe if any of the following are
2066 true:
2067 · It consists of a fully-qualified path name, option‐
2069 ally prefixed with a colon (‘:’), that does not
2070 match the location of the zoneinfo directory.
2071 · It contains a .. path element.
2073 · It contains white space or non-printable characters.
2075 · It is longer than the value of PATH_MAX.
2077 The argument may be a double-quoted, space-separated
2079 list or a single value without double-quotes. The list
2080 can be replaced, added to, deleted from, or disabled by
2081 using the =, +=, -=, and ! operators respectively.
2082 Regardless of whether the env_reset option is enabled
2083 or disabled, variables specified by env_check will be
2084 preserved in the environment if they pass the aforemen‐
2085 tioned check. The global list of environment variables
2086 to check is displayed when sudo is run by root with the
2087 -V option.
2088 env_delete Environment variables to be removed from the user's
2090 environment when the env_reset option is not in effect.
2091 The argument may be a double-quoted, space-separated
2092 list or a single value without double-quotes. The list
2093 can be replaced, added to, deleted from, or disabled by
2094 using the =, +=, -=, and ! operators respectively. The
2095 global list of environment variables to remove is dis‐
2096 played when sudo is run by root with the -V option.
2097 Note that many operating systems will remove poten‐
2098 tially dangerous variables from the environment of any
2099 setuid process (such as sudo).
2100 env_keep Environment variables to be preserved in the user's
2102 environment when the env_reset option is in effect.
2103 This allows fine-grained control over the environment
2104 sudo-spawned processes will receive. The argument may
2105 be a double-quoted, space-separated list or a single
2106 value without double-quotes. The list can be replaced,
2107 added to, deleted from, or disabled by using the =, +=,
2108 -=, and ! operators respectively. The global list of
2109 variables to keep is displayed when sudo is run by root
2110 with the -V option.
2111
2113 The sudoers plugin supports its own plugin interface to allow non-Unix
2114 group lookups which can query a group source other than the standard Unix
2115 group database. This can be used to implement support for the
2116 nonunix_group syntax described earlier.
2117 Group provider plugins are specified via the group_plugin Defaults set‐
2119 ting. The argument to group_plugin should consist of the plugin path,
2120 either fully-qualified or relative to the /usr/libexec/sudo directory,
2121 followed by any configuration options the plugin requires. These options
2122 (if specified) will be passed to the plugin's initialization function.
2123 If options are present, the string must be enclosed in double quotes
2124 ("").
2125 The following group provider plugins are installed by default:
2127 group_file
2129 The group_file plugin supports an alternate group file that
2130 uses the same syntax as the /etc/group file. The path to the
2131 group file should be specified as an option to the plugin. For
2132 example, if the group file to be used is /etc/sudo-group:
2133 Defaults group_plugin="group_file.so /etc/sudo-group"
2135 system_group
2137 The system_group plugin supports group lookups via the standard
2138 C library functions getgrnam() and getgrid(). This plugin can
2139 be used in instances where the user belongs to groups not
2140 present in the user's supplemental group vector. This plugin
2141 takes no options:
2142 Defaults group_plugin=system_group.so
2144 The group provider plugin API is described in detail in sudo_plugin(5).
2146
2148 sudoers can log events using either syslog(3) or a simple log file. The
2149 log format is almost identical in both cases.
2150 Accepted command log entries
2152 Commands that sudo runs are logged using the following format (split into
2153 multiple lines for readability):
2154 date hostname progname: username : TTY=ttyname ; PWD=cwd ; \
2156 USER=runasuser ; GROUP=runasgroup ; TSID=logid ; \
2157 ENV=env_vars COMMAND=command
2158 Where the fields are as follows:
2160 date The date the command was run. Typically, this is in the
2162 format “MMM, DD, HH:MM:SS”. If logging via syslog(3), the
2163 actual date format is controlled by the syslog daemon. If
2164 logging to a file and the log_year option is enabled, the
2165 date will also include the year.
2166 hostname The name of the host sudo was run on. This field is only
2168 present when logging via syslog(3).
2169 progname The name of the program, usually sudo or sudoedit. This
2171 field is only present when logging via syslog(3).
2172 username The login name of the user who ran sudo.
2174 ttyname The short name of the terminal (e.g. “console”, “tty01”, or
2176 “pts/0”) sudo was run on, or “unknown” if there was no ter‐
2177 minal present.
2178 cwd The current working directory that sudo was run in.
2180 runasuser The user the command was run as.
2182 runasgroup The group the command was run as if one was specified on
2184 the command line.
2185 logid An I/O log identifier that can be used to replay the com‐
2187 mand's output. This is only present when the log_input or
2188 log_output option is enabled.
2189 env_vars A list of environment variables specified on the command
2191 line, if specified.
2192 command The actual command that was executed.
2194 Messages are logged using the locale specified by sudoers_locale, which
2196 defaults to the “C” locale.
2197 Denied command log entries
2199 If the user is not allowed to run the command, the reason for the denial
2200 will follow the user name. Possible reasons include:
2201 user NOT in sudoers
2203 The user is not listed in the sudoers file.
2204 user NOT authorized on host
2206 The user is listed in the sudoers file but is not allowed to run com‐
2207 mands on the host.
2208 command not allowed
2210 The user is listed in the sudoers file for the host but they are not
2211 allowed to run the specified command.
2212 3 incorrect password attempts
2214 The user failed to enter their password after 3 tries. The actual num‐
2215 ber of tries will vary based on the number of failed attempts and the
2216 value of the passwd_tries option.
2217 a password is required
2219 sudo's -n option was specified but a password was required.
2220 sorry, you are not allowed to set the following environment variables
2222 The user specified environment variables on the command line that were
2223 not allowed by sudoers.
2224 Error log entries
2226 If an error occurs, sudoers will log a message and, in most cases, send a
2227 message to the administrator via email. Possible errors include:
2228 parse error in /etc/sudoers near line N
2230 sudoers encountered an error when parsing the specified file. In some
2231 cases, the actual error may be one line above or below the line number
2232 listed, depending on the type of error.
2233 problem with defaults entries
2235 The sudoers file contains one or more unknown Defaults settings. This
2236 does not prevent sudo from running, but the sudoers file should be
2237 checked using visudo.
2238 timestamp owner (username): No such user
2240 The time stamp directory owner, as specified by the timestampowner set‐
2241 ting, could not be found in the password database.
2242 unable to open/read /etc/sudoers
2244 The sudoers file could not be opened for reading. This can happen when
2245 the sudoers file is located on a remote file system that maps user ID 0
2246 to a different value. Normally, sudoers tries to open the sudoers file
2247 using group permissions to avoid this problem. Consider either chang‐
2248 ing the ownership of /etc/sudoers or adding an argument like
2249 “sudoers_uid=N” (where ‘N’ is the user ID that owns the sudoers file)
2250 to the end of the sudoers Plugin line in the sudo.conf(5) file.
2251 unable to stat /etc/sudoers
2253 The /etc/sudoers file is missing.
2254 /etc/sudoers is not a regular file
2256 The /etc/sudoers file exists but is not a regular file or symbolic
2257 link.
2258 /etc/sudoers is owned by uid N, should be 0
2260 The sudoers file has the wrong owner. If you wish to change the
2261 sudoers file owner, please add “sudoers_uid=N” (where ‘N’ is the user
2262 ID that owns the sudoers file) to the sudoers Plugin line in the
2263 sudo.conf(5) file.
2264 /etc/sudoers is world writable
2266 The permissions on the sudoers file allow all users to write to it.
2267 The sudoers file must not be world-writable, the default file mode is
2268 0440 (readable by owner and group, writable by none). The default mode
2269 may be changed via the “sudoers_mode” option to the sudoers Plugin line
2270 in the sudo.conf(5) file.
2271 /etc/sudoers is owned by gid N, should be 1
2273 The sudoers file has the wrong group ownership. If you wish to change
2274 the sudoers file group ownership, please add “sudoers_gid=N” (where ‘N’
2275 is the group ID that owns the sudoers file) to the sudoers Plugin line
2276 in the sudo.conf(5) file.
2277 unable to open /run/sudo/ts/username
2279 sudoers was unable to read or create the user's time stamp file. This
2280 can happen when timestampowner is set to a user other than root and the
2281 mode on /run/sudo is not searchable by group or other. The default
2282 mode for /run/sudo is 0711.
2283 unable to write to /run/sudo/ts/username
2285 sudoers was unable to write to the user's time stamp file.
2286 /run/sudo/ts is owned by uid X, should be Y
2288 The time stamp directory is owned by a user other than timestampowner.
2289 This can occur when the value of timestampowner has been changed.
2290 sudoers will ignore the time stamp directory until the owner is cor‐
2291 rected.
2292 /run/sudo/ts is group writable
2294 The time stamp directory is group-writable; it should be writable only
2295 by timestampowner. The default mode for the time stamp directory is
2296 0700. sudoers will ignore the time stamp directory until the mode is
2297 corrected.
2298 Notes on logging via syslog
2300 By default, sudoers logs messages via syslog(3). The date, hostname, and
2301 progname fields are added by the system's syslog() function, not sudoers
2302 itself. As such, they may vary in format on different systems.
2303 The maximum size of syslog messages varies from system to system. The
2305 syslog_maxlen setting can be used to change the maximum syslog message
2306 size from the default value of 980 bytes. For more information, see the
2307 description of syslog_maxlen.
2308 Notes on logging to a file
2310 If the logfile option is set, sudoers will log to a local file, such as
2311 /var/log/sudo. When logging to a file, sudoers uses a format similar to
2312 syslog(3), with a few important differences:
2313 1. The progname and hostname fields are not present.
2315 2. If the log_year option is enabled, the date will also include the
2317 year.
2318 3. Lines that are longer than loglinelen characters (80 by default) are
2320 word-wrapped and continued on the next line with a four character
2321 indent. This makes entries easier to read for a human being, but
2322 makes it more difficult to use grep(1) on the log files. If the
2323 loglinelen option is set to 0 (or negated with a ‘!’), word wrap
2324 will be disabled.
2325
2327 When I/O logging is enabled, sudo will run the command in a pseudo-tty
2328 and log all user input and/or output, depending on which options are
2329 enabled. I/O is logged to the directory specified by the iolog_dir
2330 option (/var/log/sudo-io by default) using a unique session ID that is
2331 included in the sudo log line, prefixed with “TSID=”. The iolog_file
2332 option may be used to control the format of the session ID.
2333 Each I/O log is stored in a separate directory that contains the follow‐
2335 ing files:
2336 log a text file containing the time the command was run, the name
2338 of the user who ran sudo, the name of the target user, the name
2339 of the target group (optional), the terminal that sudo was run
2340 from, the number of rows and columns of the terminal, the work‐
2341 ing directory the command was run from and the path name of the
2342 command itself (with arguments if present)
2343 timing a log of the amount of time between, and the number of bytes
2345 in, each I/O log entry (used for session playback)
2346 ttyin input from the user's tty (what the user types)
2348 stdin input from a pipe or file
2350 ttyout output from the pseudo-tty (what the command writes to the
2352 screen)
2353 stdout standard output to a pipe or redirected to a file
2355 stderr standard error to a pipe or redirected to a file
2357 All files other than log are compressed in gzip format unless the
2359 compress_io flag has been disabled. Due to buffering, it is not normally
2360 possible to display the I/O logs in real-time as the program is executing
2361 The I/O log data will not be complete until the program run by sudo has
2362 exited or has been terminated by a signal. The iolog_flush flag can be
2363 used to disable buffering, in which case I/O log data is written to disk
2364 as soon as it is available. The output portion of an I/O log file can be
2365 viewed with the sudoreplay(8) utility, which can also be used to list or
2366 search the available logs.
2367 Note that user input may contain sensitive information such as passwords
2369 (even if they are not echoed to the screen), which will be stored in the
2370 log file unencrypted. In most cases, logging the command output via
2371 log_output or LOG_OUTPUT is all that is required.
2372 Since each session's I/O logs are stored in a separate directory, tradi‐
2374 tional log rotation utilities cannot be used to limit the number of I/O
2375 logs. The simplest way to limit the number of I/O is by setting the
2376 maxseq option to the maximum number of logs you wish to store. Once the
2377 I/O log sequence number reaches maxseq, it will be reset to zero and
2378 sudoers will truncate and re-use any existing I/O logs.
2379
2381 /etc/sudo.conf Sudo front end configuration
2382 /etc/sudoers List of who can run what
2384 /etc/group Local groups file
2386 /etc/netgroup List of network groups
2388 /var/log/sudo-io I/O log files
2390 /run/sudo/ts Directory containing time stamps for the
2392 sudoers security policy
2393 /var/db/sudo/lectured Directory containing lecture status files for
2395 the sudoers security policy
2396 /etc/environment Initial environment for -i mode on AIX and
2398 Linux systems
2399
2401 Below are example sudoers file entries. Admittedly, some of these are a
2402 bit contrived. First, we allow a few environment variables to pass and
2403 then define our aliases:
2404 # Run X applications through sudo; HOME is used to find the
2406 # .Xauthority file. Note that other programs use HOME to find
2407 # configuration files and this may lead to privilege escalation!
2408 Defaults env_keep += "DISPLAY HOME"
2409 # User alias specification
2411 User_Alias FULLTIMERS = millert, mikef, dowdy
2412 User_Alias PARTTIMERS = bostley, jwfox, crawl
2413 User_Alias WEBMASTERS = will, wendy, wim
2414 # Runas alias specification
2416 Runas_Alias OP = root, operator
2417 Runas_Alias DB = oracle, sybase
2418 Runas_Alias ADMINGRP = adm, oper
2419 # Host alias specification
2421 Host_Alias SPARC = bigtime, eclipse, moet, anchor :\
2422 SGI = grolsch, dandelion, black :\
2423 ALPHA = widget, thalamus, foobar :\
2424 HPPA = boa, nag, python
2425 Host_Alias CUNETS = 128.138.0.0/255.255.0.0
2426 Host_Alias CSNETS = 128.138.243.0, 128.138.204.0/24, 128.138.242.0
2427 Host_Alias SERVERS = master, mail, www, ns
2428 Host_Alias CDROM = orion, perseus, hercules
2429 # Cmnd alias specification
2431 Cmnd_Alias DUMPS = /usr/bin/mt, /usr/sbin/dump, /usr/sbin/rdump,\
2432 /usr/sbin/restore, /usr/sbin/rrestore,\
2433 sha224:0GomF8mNN3wlDt1HD9XldjJ3SNgpFdbjO1+NsQ== \
2434 /home/operator/bin/start_backups
2435 Cmnd_Alias KILL = /usr/bin/kill
2436 Cmnd_Alias PRINTING = /usr/sbin/lpc, /usr/bin/lprm
2437 Cmnd_Alias SHUTDOWN = /usr/sbin/shutdown
2438 Cmnd_Alias HALT = /usr/sbin/halt
2439 Cmnd_Alias REBOOT = /usr/sbin/reboot
2440 Cmnd_Alias SHELLS = /usr/bin/sh, /usr/bin/csh, /usr/bin/ksh,\
2441 /usr/local/bin/tcsh, /usr/bin/rsh,\
2442 /usr/local/bin/zsh
2443 Cmnd_Alias SU = /usr/bin/su
2444 Cmnd_Alias PAGERS = /usr/bin/more, /usr/bin/pg, /usr/bin/less
2445 Here we override some of the compiled in default values. We want sudo to
2447 log via syslog(3) using the auth facility in all cases. We don't want to
2448 subject the full time staff to the sudo lecture, user millert need not
2449 give a password, and we don't want to reset the LOGNAME, USER or USERNAME
2450 environment variables when running commands as root. Additionally, on
2451 the machines in the SERVERS Host_Alias, we keep an additional local log
2452 file and make sure we log the year in each log line since the log entries
2453 will be kept around for several years. Lastly, we disable shell escapes
2454 for the commands in the PAGERS Cmnd_Alias (/usr/bin/more, /usr/bin/pg and
2455 /usr/bin/less). Note that this will not effectively constrain users with
2456 sudo ALL privileges.
2457 # Override built-in defaults
2459 Defaults syslog=auth
2460 Defaults>root !set_logname
2461 Defaults:FULLTIMERS !lecture
2462 Defaults:millert !authenticate
2463 Defaults@SERVERS log_year, logfile=/var/log/sudo.log
2464 Defaults!PAGERS noexec
2465 The User specification is the part that actually determines who may run
2467 what.
2468 root ALL = (ALL) ALL
2470 %wheel ALL = (ALL) ALL
2471 We let root and any user in group wheel run any command on any host as
2473 any user.
2474 FULLTIMERS ALL = NOPASSWD: ALL
2476 Full time sysadmins (millert, mikef, and dowdy) may run any command on
2478 any host without authenticating themselves.
2479 PARTTIMERS ALL = ALL
2481 Part time sysadmins bostley, jwfox, and crawl) may run any command on any
2483 host but they must authenticate themselves first (since the entry lacks
2484 the NOPASSWD tag).
2485 jack CSNETS = ALL
2487 The user jack may run any command on the machines in the CSNETS alias
2489 (the networks 128.138.243.0, 128.138.204.0, and 128.138.242.0). Of those
2490 networks, only 128.138.204.0 has an explicit netmask (in CIDR notation)
2491 indicating it is a class C network. For the other networks in CSNETS,
2492 the local machine's netmask will be used during matching.
2493 lisa CUNETS = ALL
2495 The user lisa may run any command on any host in the CUNETS alias (the
2497 class B network 128.138.0.0).
2498 operator ALL = DUMPS, KILL, SHUTDOWN, HALT, REBOOT, PRINTING,\
2500 sudoedit /etc/printcap, /usr/oper/bin/
2501 The operator user may run commands limited to simple maintenance. Here,
2503 those are commands related to backups, killing processes, the printing
2504 system, shutting down the system, and any commands in the directory
2505 /usr/oper/bin/. Note that one command in the DUMPS Cmnd_Alias includes a
2506 sha224 digest, /home/operator/bin/start_backups. This is because the
2507 directory containing the script is writable by the operator user. If the
2508 script is modified (resulting in a digest mismatch) it will no longer be
2509 possible to run it via sudo.
2510 joe ALL = /usr/bin/su operator
2512 The user joe may only su(1) to operator.
2514 pete HPPA = /usr/bin/passwd [A-Za-z]*, !/usr/bin/passwd *root*
2516 %opers ALL = (: ADMINGRP) /usr/sbin/
2518 Users in the opers group may run commands in /usr/sbin/ as themselves
2520 with any group in the ADMINGRP Runas_Alias (the adm and oper groups).
2521 The user pete is allowed to change anyone's password except for root on
2523 the HPPA machines. Because command line arguments are matched as a sin‐
2524 gle, concatenated string, the ‘*’ wildcard will match multiple words.
2525 This example assumes that passwd(1) does not take multiple user names on
2526 the command line. Note that on GNU systems, options to passwd(1) may be
2527 specified after the user argument. As a result, this rule will also
2528 allow:
2529 passwd username --expire
2531 which may not be desirable.
2533 bob SPARC = (OP) ALL : SGI = (OP) ALL
2535 The user bob may run anything on the SPARC and SGI machines as any user
2537 listed in the OP Runas_Alias (root and operator.)
2538 jim +biglab = ALL
2540 The user jim may run any command on machines in the biglab netgroup.
2542 sudo knows that “biglab” is a netgroup due to the ‘+’ prefix.
2543 +secretaries ALL = PRINTING, /usr/bin/adduser, /usr/bin/rmuser
2545 Users in the secretaries netgroup need to help manage the printers as
2547 well as add and remove users, so they are allowed to run those commands
2548 on all machines.
2549 fred ALL = (DB) NOPASSWD: ALL
2551 The user fred can run commands as any user in the DB Runas_Alias (oracle
2553 or sybase) without giving a password.
2554 john ALPHA = /usr/bin/su [!-]*, !/usr/bin/su *root*
2556 On the ALPHA machines, user john may su to anyone except root but he is
2558 not allowed to specify any options to the su(1) command.
2559 jen ALL, !SERVERS = ALL
2561 The user jen may run any command on any machine except for those in the
2563 SERVERS Host_Alias (master, mail, www and ns).
2564 jill SERVERS = /usr/bin/, !SU, !SHELLS
2566 For any machine in the SERVERS Host_Alias, jill may run any commands in
2568 the directory /usr/bin/ except for those commands belonging to the SU and
2569 SHELLS Cmnd_Aliases. While not specifically mentioned in the rule, the
2570 commands in the PAGERS Cmnd_Alias all reside in /usr/bin and have the
2571 noexec option set.
2572 steve CSNETS = (operator) /usr/local/op_commands/
2574 The user steve may run any command in the directory /usr/local/op_com‐
2576 mands/ but only as user operator.
2577 matt valkyrie = KILL
2579 On his personal workstation, valkyrie, matt needs to be able to kill hung
2581 processes.
2582 WEBMASTERS www = (www) ALL, (root) /usr/bin/su www
2584 On the host www, any user in the WEBMASTERS User_Alias (will, wendy, and
2586 wim), may run any command as user www (which owns the web pages) or sim‐
2587 ply su(1) to www.
2588 ALL CDROM = NOPASSWD: /sbin/umount /CDROM,\
2590 /sbin/mount -o nosuid\,nodev /dev/cd0a /CDROM
2591 Any user may mount or unmount a CD-ROM on the machines in the CDROM
2593 Host_Alias (orion, perseus, hercules) without entering a password. This
2594 is a bit tedious for users to type, so it is a prime candidate for encap‐
2595 sulating in a shell script.
2596
2598 Limitations of the ‘!’ operator
2599 It is generally not effective to “subtract” commands from ALL using the
2600 ‘!’ operator. A user can trivially circumvent this by copying the
2601 desired command to a different name and then executing that. For exam‐
2602 ple:
2603 bill ALL = ALL, !SU, !SHELLS
2605 Doesn't really prevent bill from running the commands listed in SU or
2607 SHELLS since he can simply copy those commands to a different name, or
2608 use a shell escape from an editor or other program. Therefore, these
2609 kind of restrictions should be considered advisory at best (and rein‐
2610 forced by policy).
2611 In general, if a user has sudo ALL there is nothing to prevent them from
2613 creating their own program that gives them a root shell (or making their
2614 own copy of a shell) regardless of any ‘!’ elements in the user specifi‐
2615 cation.
2616 Security implications of fast_glob
2618 If the fast_glob option is in use, it is not possible to reliably negate
2619 commands where the path name includes globbing (aka wildcard) characters.
2620 This is because the C library's fnmatch(3) function cannot resolve rela‐
2621 tive paths. While this is typically only an inconvenience for rules that
2622 grant privileges, it can result in a security issue for rules that sub‐
2623 tract or revoke privileges.
2624 For example, given the following sudoers file entry:
2626 john ALL = /usr/bin/passwd [a-zA-Z0-9]*, /usr/bin/chsh [a-zA-Z0-9]*,\
2628 /usr/bin/chfn [a-zA-Z0-9]*, !/usr/bin/* root
2629 User john can still run /usr/bin/passwd root if fast_glob is enabled by
2631 changing to /usr/bin and running ./passwd root instead.
2632 Preventing shell escapes
2634 Once sudo executes a program, that program is free to do whatever it
2635 pleases, including run other programs. This can be a security issue
2636 since it is not uncommon for a program to allow shell escapes, which lets
2637 a user bypass sudo's access control and logging. Common programs that
2638 permit shell escapes include shells (obviously), editors, paginators,
2639 mail and terminal programs.
2640 There are two basic approaches to this problem:
2642 restrict Avoid giving users access to commands that allow the user to
2644 run arbitrary commands. Many editors have a restricted mode
2645 where shell escapes are disabled, though sudoedit is a better
2646 solution to running editors via sudo. Due to the large number
2647 of programs that offer shell escapes, restricting users to the
2648 set of programs that do not is often unworkable.
2649 noexec Many systems that support shared libraries have the ability to
2651 override default library functions by pointing an environment
2652 variable (usually LD_PRELOAD) to an alternate shared library.
2653 On such systems, sudo's noexec functionality can be used to
2654 prevent a program run by sudo from executing any other pro‐
2655 grams. Note, however, that this applies only to native dynami‐
2656 cally-linked executables. Statically-linked executables and
2657 foreign executables running under binary emulation are not
2658 affected.
2659 The noexec feature is known to work on SunOS, Solaris, *BSD,
2661 Linux, IRIX, Tru64 UNIX, macOS, HP-UX 11.x and AIX 5.3 and
2662 above. It should be supported on most operating systems that
2663 support the LD_PRELOAD environment variable. Check your oper‐
2664 ating system's manual pages for the dynamic linker (usually
2665 ld.so, ld.so.1, dyld, dld.sl, rld, or loader) to see if
2666 LD_PRELOAD is supported.
2667 To enable noexec for a command, use the NOEXEC tag as docu‐
2669 mented in the User Specification section above. Here is that
2670 example again:
2671 aaron shanty = NOEXEC: /usr/bin/more, /usr/bin/vi
2673 This allows user aaron to run /usr/bin/more and /usr/bin/vi
2675 with noexec enabled. This will prevent those two commands from
2676 executing other commands (such as a shell). If you are unsure
2677 whether or not your system is capable of supporting noexec you
2678 can always just try it out and check whether shell escapes work
2679 when noexec is enabled.
2680 Note that restricting shell escapes is not a panacea. Programs running
2682 as root are still capable of many potentially hazardous operations (such
2683 as changing or overwriting files) that could lead to unintended privilege
2684 escalation. In the specific case of an editor, a safer approach is to
2685 give the user permission to run sudoedit (see below).
2686 Secure editing
2688 The sudoers plugin includes sudoedit support which allows users to
2689 securely edit files with the editor of their choice. As sudoedit is a
2690 built-in command, it must be specified in the sudoers file without a
2691 leading path. However, it may take command line arguments just as a nor‐
2692 mal command does. Wildcards used in sudoedit command line arguments are
2693 expected to be path names, so a forward slash (‘/’) will not be matched
2694 by a wildcard.
2695 Unlike other sudo commands, the editor is run with the permissions of the
2697 invoking user and with the environment unmodified. More information may
2698 be found in the description of the -e option in sudo(8).
2699 For example, to allow user operator to edit the “message of the day”
2701 file:
2702 operator sudoedit /etc/motd
2704 The operator user then runs sudoedit as follows:
2706 $ sudoedit /etc/motd
2708 The editor will run as the operator user, not root, on a temporary copy
2710 of /etc/motd. After the file has been edited, /etc/motd will be updated
2711 with the contents of the temporary copy.
2712 Users should never be granted sudoedit permission to edit a file that
2714 resides in a directory the user has write access to, either directly or
2715 via a wildcard. If the user has write access to the directory it is pos‐
2716 sible to replace the legitimate file with a link to another file, allow‐
2717 ing the editing of arbitrary files. To prevent this, starting with ver‐
2718 sion 1.8.16, symbolic links will not be followed in writable directories
2719 and sudoedit will refuse to edit a file located in a writable directory
2720 unless the sudoedit_checkdir option has been disabled or the invoking
2721 user is root. Additionally, in version 1.8.15 and higher, sudoedit will
2722 refuse to open a symbolic link unless either the sudoedit_follow option
2723 is enabled or the sudoedit command is prefixed with the FOLLOW tag in the
2724 sudoers file.
2725 Time stamp file checks
2727 sudoers will check the ownership of its time stamp directory
2728 (/run/sudo/ts by default) and ignore the directory's contents if it is
2729 not owned by root or if it is writable by a user other than root. Older
2730 versions of sudo stored time stamp files in /tmp; this is no longer rec‐
2731 ommended as it may be possible for a user to create the time stamp them‐
2732 selves on systems that allow unprivileged users to change the ownership
2733 of files they create.
2734 While the time stamp directory should be cleared at reboot time, not all
2736 systems contain a /run or /var/run directory. To avoid potential prob‐
2737 lems, sudoers will ignore time stamp files that date from before the
2738 machine booted on systems where the boot time is available.
2739 Some systems with graphical desktop environments allow unprivileged users
2741 to change the system clock. Since sudoers relies on the system clock for
2742 time stamp validation, it may be possible on such systems for a user to
2743 run sudo for longer than timestamp_timeout by setting the clock back. To
2744 combat this, sudoers uses a monotonic clock (which never moves backwards)
2745 for its time stamps if the system supports it.
2746 sudoers will not honor time stamps set far in the future. Time stamps
2748 with a date greater than current_time + 2 * TIMEOUT will be ignored and
2749 sudoers will log and complain.
2750 If the timestamp_type option is set to “tty”, the time stamp record
2752 includes the device number of the terminal the user authenticated with.
2753 This provides per-terminal granularity but time stamp records may still
2754 outlive the user's session.
2755 Unless the timestamp_type option is set to “global”, the time stamp
2757 record also includes the session ID of the process that last authenti‐
2758 cated. This prevents processes in different terminal sessions from using
2759 the same time stamp record. On systems where a process's start time can
2760 be queried, the start time of the session leader is recorded in the time
2761 stamp record. If no terminal is present or the timestamp_type option is
2762 set to “ppid”, the start time of the parent process is used instead. In
2763 most cases this will prevent a time stamp record from being re-used with‐
2764 out the user entering a password when logging out and back in again.
2765
2767 Versions 1.8.4 and higher of the sudoers plugin support a flexible debug‐
2768 ging framework that can help track down what the plugin is doing inter‐
2769 nally if there is a problem. This can be configured in the sudo.conf(5)
2770 file.
2771 The sudoers plugin uses the same debug flag format as the sudo front-end:
2773 subsystem@priority.
2774 The priorities used by sudoers, in order of decreasing severity, are:
2776 crit, err, warn, notice, diag, info, trace and debug. Each priority,
2777 when specified, also includes all priorities higher than it. For exam‐
2778 ple, a priority of notice would include debug messages logged at notice
2779 and higher.
2780 The following subsystems are used by the sudoers plugin:
2782 alias User_Alias, Runas_Alias, Host_Alias and Cmnd_Alias processing
2784 all matches every subsystem
2786 audit BSM and Linux audit code
2788 auth user authentication
2790 defaults sudoers file Defaults settings
2792 env environment handling
2794 ldap LDAP-based sudoers
2796 logging logging support
2798 match matching of users, groups, hosts and netgroups in the sudoers
2800 file
2801 netif network interface handling
2803 nss network service switch handling in sudoers
2805 parser sudoers file parsing
2807 perms permission setting
2809 plugin The equivalent of main for the plugin.
2811 pty pseudo-tty related code
2813 rbtree redblack tree internals
2815 sssd SSSD-based sudoers
2817 util utility functions
2819 For example:
2820 Debug sudo /var/log/sudo_debug match@info,nss@info
2822 For more information, see the sudo.conf(5) manual.
2824
2826 ssh(1), su(1), fnmatch(3), glob(3), mktemp(3), strftime(3), sudo.conf(5),
2827 sudo_plugin(5), sudoers.ldap(5), sudoers_timestamp(5), sudo(8), visudo(8)
2828
2830 Many people have worked on sudo over the years; this version consists of
2831 code written primarily by:
2832 Todd C. Miller
2834 See the CONTRIBUTORS file in the sudo distribution
2836 (https://www.sudo.ws/contributors.html) for an exhaustive list of people
2837 who have contributed to sudo.
2838
2840 The sudoers file should always be edited by the visudo command which
2841 locks the file and does grammatical checking. It is imperative that the
2842 sudoers file be free of syntax errors since sudo will not run with a syn‐
2843 tactically incorrect sudoers file.
2844 When using netgroups of machines (as opposed to users), if you store
2846 fully qualified host name in the netgroup (as is usually the case), you
2847 either need to have the machine's host name be fully qualified as
2848 returned by the hostname command or use the fqdn option in sudoers.
2849
2851 If you feel you have found a bug in sudo, please submit a bug report at
2852 https://bugzilla.sudo.ws/
2853
2855 Limited free support is available via the sudo-users mailing list, see
2856 https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search
2857 the archives.
2858
2860 sudo is provided “AS IS” and any express or implied warranties, includ‐
2861 ing, but not limited to, the implied warranties of merchantability and
2862 fitness for a particular purpose are disclaimed. See the LICENSE file
2863 distributed with sudo or https://www.sudo.ws/license.html for complete
2864 details.
2865Sudo 1.8.25p1 August 7, 2018 Sudo 1.8.25p1