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 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_audit sudoers.so
21 Plugin sudoers_policy sudoers.so
22 Plugin sudoers_io sudoers.so
23 Starting with sudo 1.8.5, it is possible to specify optional arguments to
25 the sudoers plugin in the sudo.conf(5) file. Plugin arguments, if any,
26 should be listed after the path to the plugin (i.e., after sudoers.so).
27 The arguments are only effective for the plugin that opens (and parses)
28 the sudoers file.
29 For sudo version 1.9.1 and higher, this is the sudoers_audit plugin. For
31 older versions, it is the sudoers_policy plugin. Multiple arguments may
32 be specified, separated by white space. For example:
33 Plugin sudoers_audit sudoers.so sudoers_mode=0400 error_recovery=false
35 The following plugin arguments are supported:
37 error_recovery=bool
39 The error_recovery argument can be used to control whether
40 sudoers should attempt to recover from syntax errors in the
41 sudoers file. If set to true (the default), sudoers will try
42 to recover from a syntax error by discarding the portion of the
43 line that contains the error until the end of the line. A
44 value of false will disable error recovery. Prior to version
45 1.9.3, no error recovery was performed.
46 ldap_conf=pathname
48 The ldap_conf argument can be used to override the default path
49 to the ldap.conf file.
50 ldap_secret=pathname
52 The ldap_secret argument can be used to override the default
53 path to the ldap.secret file.
54 sudoers_file=pathname
56 The sudoers_file argument can be used to override the default
57 path to the sudoers file.
58 sudoers_uid=uid
60 The sudoers_uid argument can be used to override the default
61 owner of the sudoers file. It should be specified as a numeric
62 user-ID.
63 sudoers_gid=gid
65 The sudoers_gid argument can be used to override the default
66 group of the sudoers file. It must be specified as a numeric
67 group-ID (not a group name).
68 sudoers_mode=mode
70 The sudoers_mode argument can be used to override the default
71 file mode for the sudoers file. It should be specified as an
72 octal value.
73 For more information on configuring sudo.conf(5), please refer to its
75 manual.
76 User Authentication
78 The sudoers security policy requires that most users authenticate them‐
79 selves before they can use sudo. A password is not required if the in‐
80 voking user is root, if the target user is the same as the invoking user,
81 or if the policy has disabled authentication for the user or command.
82 Unlike su(1), when sudoers requires authentication, it validates the in‐
83 voking user's credentials, not the target user's (or root's) credentials.
84 This can be changed via the rootpw, targetpw and runaspw flags, described
85 later.
86 If a user who is not listed in the policy tries to run a command via
88 sudo, mail is sent to the proper authorities. The address used for such
89 mail is configurable via the mailto Defaults entry (described later) and
90 defaults to root.
91 Note that no mail will be sent if an unauthorized user tries to run sudo
93 with the -l or -v option unless there is an authentication error and ei‐
94 ther the mail_always or mail_badpass flags are enabled. This allows
95 users to determine for themselves whether or not they are allowed to use
96 sudo. By default, all attempts to run sudo (successful or not) are
97 logged, regardless of whether or not mail is sent.
98 If sudo is run by root and the SUDO_USER environment variable is set, the
100 sudoers policy will use this value to determine who the actual user is.
101 This can be used by a user to log commands through sudo even when a root
102 shell has been invoked. It also allows the -e option to remain useful
103 even when invoked via a sudo-run script or program. Note, however, that
104 the sudoers file lookup is still done for root, not the user specified by
105 SUDO_USER.
106 sudoers uses per-user time stamp files for credential caching. Once a
108 user has been authenticated, a record is written containing the user-ID
109 that was used to authenticate, the terminal session ID, the start time of
110 the session leader (or parent process) and a time stamp (using a mono‐
111 tonic clock if one is available). The user may then use sudo without a
112 password for a short period of time (5 minutes unless overridden by the
113 timestamp_timeout option). By default, sudoers uses a separate record
114 for each terminal, which means that a user's login sessions are authenti‐
115 cated separately. The timestamp_type option can be used to select the
116 type of time stamp record sudoers will use.
117 Logging
119 By default, sudoers logs both successful and unsuccessful attempts (as
120 well as errors). The log_allowed and log_denied flags can be used to
121 control this behavior. Messages can be logged to syslog(3), a log file,
122 or both. The default is to log to syslog(3) but this is configurable via
123 the syslog and logfile settings. See LOG FORMAT for a description of the
124 log file format.
125 sudoers is also capable of running a command in a pseudo-terminal and
127 logging all input and/or output. The standard input, standard output and
128 standard error can be logged even when not associated with a terminal.
129 I/O logging is not on by default but can be enabled using the log_input
130 and log_output options as well as the LOG_INPUT and LOG_OUTPUT command
131 tags. See I/O LOG FILES for details on how I/O log files are stored.
132 Starting with version 1.9, the log_servers setting may be used to send
134 event and I/O log data to a remote server running sudo_logsrvd or another
135 service that implements the protocol described by sudo_logsrv.proto(5).
136 Command environment
138 Since environment variables can influence program behavior, sudoers pro‐
139 vides a means to restrict which variables from the user's environment are
140 inherited by the command to be run. There are two distinct ways sudoers
141 can deal with environment variables.
142 By default, the env_reset flag is enabled. This causes commands to be
144 executed with a new, minimal environment. On AIX (and Linux systems
145 without PAM), the environment is initialized with the contents of the
146 /etc/environment file. The HOME, MAIL, SHELL, LOGNAME and USER environ‐
147 ment variables are initialized based on the target user and the SUDO_*
148 variables are set based on the invoking user. Additional variables, such
149 as DISPLAY, PATH and TERM, are preserved from the invoking user's envi‐
150 ronment if permitted by the env_check or env_keep options. A few envi‐
151 ronment variables are treated specially. If the PATH and TERM variables
152 are not preserved from the user's environment, they will be set to de‐
153 fault values. The LOGNAME and USER are handled as a single entity. If
154 one of them is preserved (or removed) from the user's environment, the
155 other will be as well. If LOGNAME and USER are to be preserved but only
156 one of them is present in the user's environment, the other will be set
157 to the same value. This avoids an inconsistent environment where one of
158 the variables describing the user name is set to the invoking user and
159 one is set to the target user. Environment variables with a value begin‐
160 ning with () are removed unless both the name and value parts are matched
161 by env_keep or env_check, as they may be interpreted as functions by the
162 bash shell. Prior to version 1.8.11, such variables were always removed.
163 If, however, the env_reset flag is disabled, any variables not explicitly
165 denied by the env_check and env_delete options are allowed and their val‐
166 ues are inherited from the invoking process. Prior to version 1.8.21,
167 environment variables with a value beginning with () were always removed.
168 Beginning with version 1.8.21, a pattern in env_delete is used to match
169 bash shell functions instead. Since it is not possible to block all po‐
170 tentially dangerous environment variables, use of the default env_reset
171 behavior is encouraged.
172 Environment variables specified by env_check, env_delete, or env_keep may
174 include one or more ‘*’ characters which will match zero or more charac‐
175 ters. No other wildcard characters are supported.
176 By default, environment variables are matched by name. However, if the
178 pattern includes an equal sign (‘=’), both the variables name and value
179 must match. For example, a bash shell function could be matched as fol‐
180 lows:
181 env_keep += "BASH_FUNC_my_func%%=()*"
183 Without the “=()*” suffix, this would not match, as bash shell functions
185 are not preserved by default.
186 The complete list of environment variables that are preserved or removed,
188 as modified by global Defaults parameters in sudoers, is displayed when
189 sudo is run by root with the -V option. Please note that the list of en‐
190 vironment variables to remove varies based on the operating system sudo
191 is running on.
192 Other sudoers options may influence the command environment, such as
194 always_set_home, secure_path, set_logname, and set_home.
195 On systems that support PAM where the pam_env module is enabled for sudo,
197 variables in the PAM environment may be merged in to the environment. If
198 a variable in the PAM environment is already present in the user's envi‐
199 ronment, the value will only be overridden if the variable was not pre‐
200 served by sudoers. When env_reset is enabled, variables preserved from
201 the invoking user's environment by the env_keep list take precedence over
202 those in the PAM environment. When env_reset is disabled, variables
203 present the invoking user's environment take precedence over those in the
204 PAM environment unless they match a pattern in the env_delete list.
205 Note that the dynamic linker on most operating systems will remove vari‐
207 ables that can control dynamic linking from the environment of set-user-
208 ID executables, including sudo. Depending on the operating system this
209 may include _RLD*, DYLD_*, LD_*, LDR_*, LIBPATH, SHLIB_PATH, and others.
210 These type of variables are removed from the environment before sudo even
211 begins execution and, as such, it is not possible for sudo to preserve
212 them.
213 As a special case, if the -i option (initial login) is specified, sudoers
215 will initialize the environment regardless of the value of env_reset.
216 The DISPLAY, PATH and TERM variables remain unchanged; HOME, MAIL, SHELL,
217 USER, and LOGNAME are set based on the target user. On AIX (and Linux
218 systems without PAM), the contents of /etc/environment are also included.
219 All other environment variables are removed unless permitted by env_keep
220 or env_check, described above.
221 Finally, the restricted_env_file and env_file files are applied, if
223 present. The variables in restricted_env_file are applied first and are
224 subject to the same restrictions as the invoking user's environment, as
225 detailed above. The variables in env_file are applied last and are not
226 subject to these restrictions. In both cases, variables present in the
227 files will only be set to their specified values if they would not con‐
228 flict with an existing environment variable.
229
231 The sudoers file is composed of two types of entries: aliases (basically
232 variables) and user specifications (which specify who may run what).
233 When multiple entries match for a user, they are applied in order. Where
235 there are multiple matches, the last match is used (which is not neces‐
236 sarily the most specific match).
237 The sudoers file grammar will be described below in Extended Backus-Naur
239 Form (EBNF). Don't despair if you are unfamiliar with EBNF; it is fairly
240 simple, and the definitions below are annotated.
241 Quick guide to EBNF
243 EBNF is a concise and exact way of describing the grammar of a language.
244 Each EBNF definition is made up of production rules. E.g.,
245 symbol ::= definition | alternate1 | alternate2 ...
247 Each production rule references others and thus makes up a grammar for
249 the language. EBNF also contains the following operators, which many
250 readers will recognize from regular expressions. Do not, however, con‐
251 fuse them with “wildcard” characters, which have different meanings.
252 ? Means that the preceding symbol (or group of symbols) is optional.
254 That is, it may appear once or not at all.
255 * Means that the preceding symbol (or group of symbols) may appear
257 zero or more times.
258 + Means that the preceding symbol (or group of symbols) may appear
260 one or more times.
261 Parentheses may be used to group symbols together. For clarity, we will
263 use single quotes ('') to designate what is a verbatim character string
264 (as opposed to a symbol name).
265 Aliases
267 There are four kinds of aliases: User_Alias, Runas_Alias, Host_Alias and
268 Cmnd_Alias. Beginning with sudo 1.9.0, Cmd_Alias may be used in place of
269 Cmnd_Alias if desired.
270 Alias ::= 'User_Alias' User_Alias_Spec (':' User_Alias_Spec)* |
272 'Runas_Alias' Runas_Alias_Spec (':' Runas_Alias_Spec)* |
273 'Host_Alias' Host_Alias_Spec (':' Host_Alias_Spec)* |
274 'Cmnd_Alias' Cmnd_Alias_Spec (':' Cmnd_Alias_Spec)* |
275 'Cmd_Alias' Cmnd_Alias_Spec (':' Cmnd_Alias_Spec)*
276 User_Alias ::= NAME
278 User_Alias_Spec ::= User_Alias '=' User_List
280 Runas_Alias ::= NAME
282 Runas_Alias_Spec ::= Runas_Alias '=' Runas_List
284 Host_Alias ::= NAME
286 Host_Alias_Spec ::= Host_Alias '=' Host_List
288 Cmnd_Alias ::= NAME
290 Cmnd_Alias_Spec ::= Cmnd_Alias '=' Cmnd_List
292 NAME ::= [A-Z]([A-Z][0-9]_)*
294 Each alias definition is of the form
296 Alias_Type NAME = item1, item2, ...
298 where Alias_Type is one of User_Alias, Runas_Alias, Host_Alias, or
300 Cmnd_Alias. A NAME is a string of uppercase letters, numbers, and under‐
301 score characters (‘_’). A NAME must start with an uppercase letter. It
302 is possible to put several alias definitions of the same type on a single
303 line, joined by a colon (‘:’). E.g.,
304 Alias_Type NAME = item1, item2, item3 : NAME = item4, item5
306 It is a syntax error to redefine an existing alias. It is possible to
308 use the same name for aliases of different types, but this is not recom‐
309 mended.
310 The definitions of what constitutes a valid alias member follow.
312 User_List ::= User |
314 User ',' User_List
315 User ::= '!'* user name |
317 '!'* #uid |
318 '!'* %group |
319 '!'* %#gid |
320 '!'* +netgroup |
321 '!'* %:nonunix_group |
322 '!'* %:#nonunix_gid |
323 '!'* User_Alias
324 A User_List is made up of one or more user names, user-IDs (prefixed with
326 ‘#’), system group names and IDs (prefixed with ‘%’ and ‘%#’ respec‐
327 tively), netgroups (prefixed with ‘+’), non-Unix group names and IDs
328 (prefixed with ‘%:’ and ‘%:#’ respectively) and User_Aliases. Each list
329 item may be prefixed with zero or more ‘!’ operators. An odd number of
330 ‘!’ operators negate the value of the item; an even number just cancel
331 each other out. User netgroups are matched using the user and domain
332 members only; the host member is not used when matching.
333 A user name, uid, group, gid, netgroup, nonunix_group or nonunix_gid may
335 be enclosed in double quotes to avoid the need for escaping special char‐
336 acters. Alternately, special characters may be specified in escaped hex
337 mode, e.g., \x20 for space. When using double quotes, any prefix charac‐
338 ters must be included inside the quotes.
339 The actual nonunix_group and nonunix_gid syntax depends on the underlying
341 group provider plugin. For instance, the QAS AD plugin supports the fol‐
342 lowing formats:
343 • Group in the same domain: "%:Group Name"
345 • Group in any domain: "%:Group Name@FULLY.QUALIFIED.DOMAIN"
347 • Group SID: "%:S-1-2-34-5678901234-5678901234-5678901234-567"
349 See GROUP PROVIDER PLUGINS for more information.
351 Note that quotes around group names are optional. Unquoted strings must
353 use a backslash (‘\’) to escape spaces and special characters. See Other
354 special characters and reserved words for a list of characters that need
355 to be escaped.
356 Runas_List ::= Runas_Member |
358 Runas_Member ',' Runas_List
359 Runas_Member ::= '!'* user name |
361 '!'* #uid |
362 '!'* %group |
363 '!'* %#gid |
364 '!'* %:nonunix_group |
365 '!'* %:#nonunix_gid |
366 '!'* +netgroup |
367 '!'* Runas_Alias
368 A Runas_List is similar to a User_List except that instead of
370 User_Aliases it can contain Runas_Aliases. Note that user names and
371 groups are matched as strings. In other words, two users (groups) with
372 the same user (group) ID are considered to be distinct. If you wish to
373 match all user names with the same user-ID (e.g., root and toor), you can
374 use a user-ID instead of a name (#0 in the example given). Note that the
375 user-ID or group-ID specified in a Runas_Member need not be listed in the
376 password or group database.
377 Host_List ::= Host |
379 Host ',' Host_List
380 Host ::= '!'* host name |
382 '!'* ip_addr |
383 '!'* network(/netmask)? |
384 '!'* +netgroup |
385 '!'* Host_Alias
386 A Host_List is made up of one or more host names, IP addresses, network
388 numbers, netgroups (prefixed with ‘+’) and other aliases. Again, the
389 value of an item may be negated with the ‘!’ operator. Host netgroups
390 are matched using the host (both qualified and unqualified) and domain
391 members only; the user member is not used when matching. If you specify
392 a network number without a netmask, sudo will query each of the local
393 host's network interfaces and, if the network number corresponds to one
394 of the hosts's network interfaces, will use the netmask of that inter‐
395 face. The netmask may be specified either in standard IP address nota‐
396 tion (e.g., 255.255.255.0 or ffff:ffff:ffff:ffff::), or CIDR notation
397 (number of bits, e.g., 24 or 64). A host name may include shell-style
398 wildcards (see the Wildcards section below), but unless the host name
399 command on your machine returns the fully qualified host name, you'll
400 need to use the fqdn flag for wildcards to be useful. Note that sudo
401 only inspects actual network interfaces; this means that IP address
402 127.0.0.1 (localhost) will never match. Also, the host name “localhost”
403 will only match if that is the actual host name, which is usually only
404 the case for non-networked systems.
405 digest ::= [A-Fa-f0-9]+ |
407 [A-Za-z0-9\+/=]+
408 Digest_Spec ::= "sha224" ':' digest |
410 "sha256" ':' digest |
411 "sha384" ':' digest |
412 "sha512" ':' digest
413 Digest_List ::= Digest_Spec |
415 Digest_Spec ',' Digest_List
416 Cmnd_List ::= Cmnd |
418 Cmnd ',' Cmnd_List
419 command name ::= file name |
421 file name args |
422 file name '""'
423 Edit_Spec ::= "sudoedit" file name+
425 Cmnd ::= Digest_List? '!'* command name |
427 '!'* directory |
428 '!'* Edit_Spec |
429 '!'* Cmnd_Alias
430 A Cmnd_List is a list of one or more command names, directories, and
432 other aliases. A command name is a fully qualified file name which may
433 include shell-style wildcards (see the Wildcards section below). A sim‐
434 ple file name allows the user to run the command with any arguments they
435 wish. However, you may also specify command line arguments (including
436 wildcards). Alternately, you can specify "" to indicate that the command
437 may only be run without command line arguments. A directory is a fully
438 qualified path name ending in a ‘/’. When you specify a directory in a
439 Cmnd_List, the user will be able to run any file within that directory
440 (but not in any sub-directories therein).
441 If a Cmnd has associated command line arguments, then the arguments in
443 the Cmnd must match exactly those given by the user on the command line
444 (or match the wildcards if there are any). Note that the following char‐
445 acters must be escaped with a ‘\’ if they are used in command arguments:
446 ‘,’, ‘:’, ‘=’, ‘\’. The built-in command “sudoedit” is used to permit a
447 user to run sudo with the -e option (or as sudoedit). It may take com‐
448 mand line arguments just as a normal command does. Note that “sudoedit”
449 is a command built into sudo itself and must be specified in the sudoers
450 file without a leading path. If a leading path is present, for example
451 /usr/bin/sudoedit, the path name will be silently converted to
452 “sudoedit”. A fully-qualified path for sudoedit is treated as an error
453 by visudo.
454 A command name may be preceded by a Digest_List, a comma-separated list
456 of one or more Digest_Spec entries. If a Digest_List is present, the
457 command will only match successfully if it can be verified using one of
458 the SHA-2 digests in the list. Starting with version 1.9.0, the ALL re‐
459 served word can be used in conjunction with a Digest_List. The following
460 digest formats are supported: sha224, sha256, sha384 and sha512. The
461 string may be specified in either hex or base64 format (base64 is more
462 compact). There are several utilities capable of generating SHA-2 di‐
463 gests in hex format such as openssl, shasum, sha224sum, sha256sum,
464 sha384sum, sha512sum.
465 For example, using openssl:
467 $ openssl dgst -sha224 /bin/ls
469 SHA224(/bin/ls)= 118187da8364d490b4a7debbf483004e8f3e053ec954309de2c41a25
470 It is also possible to use openssl to generate base64 output:
472 $ openssl dgst -binary -sha224 /bin/ls | openssl base64
474 EYGH2oNk1JC0p9679IMATo8+BT7JVDCd4sQaJQ==
475 Warning, if the user has write access to the command itself (directly or
477 via a sudo command), it may be possible for the user to replace the com‐
478 mand after the digest check has been performed but before the command is
479 executed. A similar race condition exists on systems that lack the
480 fexecve(2) system call when the directory in which the command is located
481 is writable by the user. See the description of the fdexec setting for
482 more information on how sudo executes commands that have an associated
483 digest.
484 Command digests are only supported by version 1.8.7 or higher.
486 Defaults
488 Certain configuration options may be changed from their default values at
489 run-time via one or more Default_Entry lines. These may affect all users
490 on any host, all users on a specific host, a specific user, a specific
491 command, or commands being run as a specific user. Note that per-command
492 entries may not include command line arguments. If you need to specify
493 arguments, define a Cmnd_Alias and reference that instead.
494 Default_Type ::= 'Defaults' |
496 'Defaults' '@' Host_List |
497 'Defaults' ':' User_List |
498 'Defaults' '!' Cmnd_List |
499 'Defaults' '>' Runas_List
500 Default_Entry ::= Default_Type Parameter_List
502 Parameter_List ::= Parameter |
504 Parameter ',' Parameter_List
505 Parameter ::= Parameter '=' Value |
507 Parameter '+=' Value |
508 Parameter '-=' Value |
509 '!'* Parameter
510 Parameters may be flags, integer values, strings, or lists. Flags are
512 implicitly boolean and can be turned off via the ‘!’ operator. Some in‐
513 teger, string and list parameters may also be used in a boolean context
514 to disable them. Values may be enclosed in double quotes ("") when they
515 contain multiple words. Special characters may be escaped with a back‐
516 slash (‘\’).
517 To include a literal backslash character in a command line argument you
519 must escape the backslash twice. For example, to match ‘\n’ as part of a
520 command line argument, you must use ‘\\\\n’ in the sudoers file. This is
521 due to there being two levels of escaping, one in the sudoers parser it‐
522 self and another when command line arguments are matched by the
523 fnmatch(3) function.
524 Lists have two additional assignment operators, += and -=. These opera‐
526 tors are used to add to and delete from a list respectively. It is not
527 an error to use the -= operator to remove an element that does not exist
528 in a list.
529 Defaults entries are parsed in the following order: generic, host, user
531 and runas Defaults first, then command defaults. If there are multiple
532 Defaults settings of the same type, the last matching setting is used.
533 The following Defaults settings are parsed before all others since they
534 may affect subsequent entries: fqdn, group_plugin, runas_default,
535 sudoers_locale.
536 See SUDOERS OPTIONS for a list of supported Defaults parameters.
538 User specification
540 User_Spec ::= User_List Host_List '=' Cmnd_Spec_List \
541 (':' Host_List '=' Cmnd_Spec_List)*
542 Cmnd_Spec_List ::= Cmnd_Spec |
544 Cmnd_Spec ',' Cmnd_Spec_List
545 Cmnd_Spec ::= Runas_Spec? Option_Spec* Tag_Spec* Cmnd
547 Runas_Spec ::= '(' Runas_List? (':' Runas_List)? ')'
549 Option_Spec ::= (SELinux_Spec | Date_Spec | Timeout_Spec | Chdir_Spec | Chroot_Spec)
551 SELinux_Spec ::= ('ROLE=role' | 'TYPE=type')
553 Date_Spec ::= ('NOTBEFORE=timestamp' | 'NOTAFTER=timestamp')
555 Timeout_Spec ::= 'TIMEOUT=timeout'
557 Chdir_Spec ::= 'CWD=directory'
559 Chroot_Spec ::= 'CHROOT=directory'
561 Tag_Spec ::= ('EXEC:' | 'NOEXEC:' | 'FOLLOW:' | 'NOFOLLOW' |
563 'LOG_INPUT:' | 'NOLOG_INPUT:' | 'LOG_OUTPUT:' |
564 'NOLOG_OUTPUT:' | 'MAIL:' | 'NOMAIL:' | 'PASSWD:' |
565 'NOPASSWD:' | 'SETENV:' | 'NOSETENV:')
566 A user specification determines which commands a user may run (and as
568 what user) on specified hosts. By default, commands are run as root, but
569 this can be changed on a per-command basis.
570 The basic structure of a user specification is “who where = (as_whom)
572 what”. Let's break that down into its constituent parts:
573 Runas_Spec
575 A Runas_Spec determines the user and/or the group that a command may be
576 run as. A fully-specified Runas_Spec consists of two Runas_Lists (as de‐
577 fined above) separated by a colon (‘:’) and enclosed in a set of paren‐
578 theses. The first Runas_List indicates which users the command may be
579 run as via the -u option. The second defines a list of groups that may
580 be specified via the -g option (in addition to any of the target user's
581 groups). If both Runas_Lists are specified, the command may be run with
582 any combination of users and groups listed in their respective
583 Runas_Lists. If only the first is specified, the command may be run as
584 any user in the list and, optionally, with any group the target user be‐
585 longs to. If the first Runas_List is empty but the second is specified,
586 the command may be run as the invoking user with the group set to any
587 listed in the Runas_List. If both Runas_Lists are empty, the command may
588 only be run as the invoking user and the group, if specified, must be one
589 that the invoking user is a member of. If no Runas_Spec is specified,
590 the command may only be run as root and the group, if specified, must be
591 one that root is a member of.
592 A Runas_Spec sets the default for the commands that follow it. What this
594 means is that for the entry:
595 dgb boulder = (operator) /bin/ls, /bin/kill, /usr/bin/lprm
597 The user dgb may run /bin/ls, /bin/kill, and /usr/bin/lprm on the host
599 boulder—but only as operator. E.g.,
600 $ sudo -u operator /bin/ls
602 It is also possible to override a Runas_Spec later on in an entry. If we
604 modify the entry like so:
605 dgb boulder = (operator) /bin/ls, (root) /bin/kill, /usr/bin/lprm
607 Then user dgb is now allowed to run /bin/ls as operator, but /bin/kill
609 and /usr/bin/lprm as root.
610 We can extend this to allow dgb to run /bin/ls with either the user or
612 group set to operator:
613 dgb boulder = (operator : operator) /bin/ls, (root) /bin/kill,\
615 /usr/bin/lprm
616 Note that while the group portion of the Runas_Spec permits the user to
618 run as command with that group, it does not force the user to do so. If
619 no group is specified on the command line, the command will run with the
620 group listed in the target user's password database entry. The following
621 would all be permitted by the sudoers entry above:
622 $ sudo -u operator /bin/ls
624 $ sudo -u operator -g operator /bin/ls
625 $ sudo -g operator /bin/ls
626 In the following example, user tcm may run commands that access a modem
628 device file with the dialer group.
629 tcm boulder = (:dialer) /usr/bin/tip, /usr/bin/cu,\
631 /usr/local/bin/minicom
632 Note that in this example only the group will be set, the command still
634 runs as user tcm. E.g.
635 $ sudo -g dialer /usr/bin/cu
637 Multiple users and groups may be present in a Runas_Spec, in which case
639 the user may select any combination of users and groups via the -u and -g
640 options. In this example:
641 alan ALL = (root, bin : operator, system) ALL
643 user alan may run any command as either user root or bin, optionally set‐
645 ting the group to operator or system.
646 Option_Spec
648 A Cmnd may have zero or more options associated with it. Options may
649 consist of SELinux roles and/or types, start and/or end dates and command
650 timeouts. Once an option is set for a Cmnd, subsequent Cmnds in the
651 Cmnd_Spec_List, inherit that option unless it is overridden by another
652 option. Note that the option names are reserved words in sudoers. This
653 means that none of the valid option names (see below) can be used when
654 declaring an alias.
655 SELinux_Spec
657 On systems with SELinux support, sudoers file entries may optionally have
658 an SELinux role and/or type associated with a command. If a role or type
659 is specified with the command it will override any default values speci‐
660 fied in sudoers. A role or type specified on the command line, however,
661 will supersede the values in sudoers.
662 Date_Spec
664 sudoers rules can be specified with a start and end date via the
665 NOTBEFORE and NOTAFTER settings. The time stamp must be specified in
666 Generalized Time as defined by RFC 4517. The format is effectively
667 yyyymmddHHMMSSZ where the minutes and seconds are optional. The ‘Z’ suf‐
668 fix indicates that the time stamp is in Coordinated Universal Time (UTC).
669 It is also possible to specify a timezone offset from UTC in hours and
670 minutes instead of a ‘Z’. For example, ‘-0500’ would correspond to East‐
671 ern Standard time in the US. As an extension, if no ‘Z’ or timezone off‐
672 set is specified, local time will be used.
673 The following are all valid time stamps:
675 20170214083000Z
677 2017021408Z
678 20160315220000-0500
679 20151201235900
680 Timeout_Spec
682 A command may have a timeout associated with it. If the timeout expires
683 before the command has exited, the command will be terminated. The time‐
684 out may be specified in combinations of days, hours, minutes and seconds
685 with a single-letter case-insensitive suffix that indicates the unit of
686 time. For example, a timeout of 7 days, 8 hours, 30 minutes and 10 sec‐
687 onds would be written as 7d8h30m10s. If a number is specified without a
688 unit, seconds are assumed. Any of the days, minutes, hours or seconds
689 may be omitted. The order must be from largest to smallest unit and a
690 unit may not be specified more than once.
691 The following are all valid timeout values: 7d8h30m10s, 14d, 8h30m, 600s,
693 3600. The following are invalid timeout values: 12m2w1d, 30s10m4h,
694 1d2d3h.
695 This setting is only supported by version 1.8.20 or higher.
697 Chdir_Spec
699 The working directory that the command will be run in can be specified
700 using the CWD setting. The directory must be a fully-qualified path name
701 beginning with a ‘/’ or ‘~’ character, or the special value “*”. A value
702 of “*” indicates that the user may specify the working directory by run‐
703 ning sudo with the -D option. By default, commands are run from the in‐
704 voking user's current working directory, unless the -i option is given.
705 Path names of the form ~user/path/name are interpreted as being relative
706 to the named user's home directory. If the user name is omitted, the
707 path will be relative to the runas user's home directory.
708 This setting is only supported by version 1.9.3 or higher.
710 Chroot_Spec
712 The root directory that the command will be run in can be specified using
713 the CHROOT setting. The directory must be a fully-qualified path name
714 beginning with a ‘/’ or ‘~’ character, or the special value “*”. A value
715 of “*” indicates that the user may specify the root directory by running
716 sudo with the -R option. This setting can be used to run the command in
717 a chroot(2) “sandbox” similar to the chroot(8) utility. Path names of
718 the form ~user/path/name are interpreted as being relative to the named
719 user's home directory. If the user name is omitted, the path will be
720 relative to the runas user's home directory.
721 This setting is only supported by version 1.9.3 or higher.
723 Tag_Spec
725 A command may have zero or more tags associated with it. The following
726 tag values are supported: EXEC, NOEXEC, FOLLOW, NOFOLLOW, LOG_INPUT,
727 NOLOG_INPUT, LOG_OUTPUT, NOLOG_OUTPUT, MAIL, NOMAIL, PASSWD, NOPASSWD,
728 SETENV, and NOSETENV. Once a tag is set on a Cmnd, subsequent Cmnds in
729 the Cmnd_Spec_List, inherit the tag unless it is overridden by the oppo‐
730 site tag (in other words, PASSWD overrides NOPASSWD and NOEXEC overrides
731 EXEC).
732 EXEC and NOEXEC
734 If sudo has been compiled with noexec support and the underlying oper‐
736 ating system supports it, the NOEXEC tag can be used to prevent a dy‐
737 namically-linked executable from running further commands itself.
738 In the following example, user aaron may run /usr/bin/more and
740 /usr/bin/vi but shell escapes will be disabled.
741 aaron shanty = NOEXEC: /usr/bin/more, /usr/bin/vi
743 See the Preventing shell escapes section below for more details on how
745 NOEXEC works and whether or not it will work on your system.
746 FOLLOW and NOFOLLOW Starting with version 1.8.15, sudoedit will not open
748 a file that is a symbolic link unless the sudoedit_follow flag is en‐
749 abled. The FOLLOW and NOFOLLOW tags override the value of
750 sudoedit_follow and can be used to permit (or deny) the editing of sym‐
751 bolic links on a per-command basis. These tags are only effective for
752 the sudoedit command and are ignored for all other commands.
753 LOG_INPUT and NOLOG_INPUT
755 These tags override the value of the log_input flag on a per-command
757 basis. For more information, see the description of log_input in the
758 SUDOERS OPTIONS section below.
759 LOG_OUTPUT and NOLOG_OUTPUT
761 These tags override the value of the log_output flag on a per-command
763 basis. For more information, see the description of log_output in the
764 SUDOERS OPTIONS section below.
765 MAIL and NOMAIL
767 These tags provide fine-grained control over whether mail will be sent
769 when a user runs a command by overriding the value of the
770 mail_all_cmnds flag on a per-command basis. They have no effect when
771 sudo is run with the -l or -v options. A NOMAIL tag will also override
772 the mail_always and mail_no_perms options. For more information, see
773 the descriptions of mail_all_cmnds, mail_always, and mail_no_perms in
774 the SUDOERS OPTIONS section below.
775 PASSWD and NOPASSWD
777 By default, sudo requires that a user authenticate him or herself be‐
779 fore running a command. This behavior can be modified via the NOPASSWD
780 tag. Like a Runas_Spec, the NOPASSWD tag sets a default for the com‐
781 mands that follow it in the Cmnd_Spec_List. Conversely, the PASSWD tag
782 can be used to reverse things. For example:
783 ray rushmore = NOPASSWD: /bin/kill, /bin/ls, /usr/bin/lprm
785 would allow the user ray to run /bin/kill, /bin/ls, and /usr/bin/lprm
787 as root on the machine rushmore without authenticating himself. If we
788 only want ray to be able to run /bin/kill without a password the entry
789 would be:
790 ray rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls, /usr/bin/lprm
792 Note, however, that the PASSWD tag has no effect on users who are in
794 the group specified by the exempt_group setting.
795 By default, if the NOPASSWD tag is applied to any of a user's entries
797 for the current host, the user will be able to run “sudo -l” without a
798 password. Additionally, a user may only run “sudo -v” without a pass‐
799 word if all of the user's entries for the current host have the
800 NOPASSWD tag. This behavior may be overridden via the verifypw and
801 listpw options.
802 SETENV and NOSETENV
804 These tags override the value of the setenv flag on a per-command ba‐
806 sis. Note that if SETENV has been set for a command, the user may dis‐
807 able the env_reset flag from the command line via the -E option. Addi‐
808 tionally, environment variables set on the command line are not subject
809 to the restrictions imposed by env_check, env_delete, or env_keep. As
810 such, only trusted users should be allowed to set variables in this
811 manner. If the command matched is ALL, the SETENV tag is implied for
812 that command; this default may be overridden by use of the NOSETENV
813 tag.
814 Wildcards
816 sudo allows shell-style wildcards (aka meta or glob characters) to be
817 used in host names, path names and command line arguments in the sudoers
818 file. Wildcard matching is done via the glob(3) and fnmatch(3) functions
819 as specified by IEEE Std 1003.1 (“POSIX.1”).
820 * Matches any set of zero or more characters (including white
822 space).
823 ? Matches any single character (including white space).
825 [...] Matches any character in the specified range.
827 [!...] Matches any character not in the specified range.
829 \x For any character ‘x’, evaluates to ‘x’. This is used to es‐
831 cape special characters such as: ‘*’, ‘?’, ‘[’, and ‘]’.
832 Note that these are not regular expressions. Unlike a regular expression
834 there is no way to match one or more characters within a range.
835 Character classes may be used if your system's glob(3) and fnmatch(3)
837 functions support them. However, because the ‘:’ character has special
838 meaning in sudoers, it must be escaped. For example:
839 /bin/ls [[\:alpha\:]]*
841 Would match any file name beginning with a letter.
843 Note that a forward slash (‘/’) will not be matched by wildcards used in
845 the file name portion of the command. This is to make a path like:
846 /usr/bin/*
848 match /usr/bin/who but not /usr/bin/X11/xterm.
850 When matching the command line arguments, however, a slash does get
852 matched by wildcards since command line arguments may contain arbitrary
853 strings and not just path names.
854 Wildcards in command line arguments should be used with care.
856 Command line arguments are matched as a single, concatenated string.
857 This mean a wildcard character such as ‘?’ or ‘*’ will match across word
858 boundaries, which may be unexpected. For example, while a sudoers entry
859 like:
860 %operator ALL = /bin/cat /var/log/messages*
862 will allow command like:
864 $ sudo cat /var/log/messages.1
866 It will also allow:
868 $ sudo cat /var/log/messages /etc/shadow
870 which is probably not what was intended. In most cases it is better to
872 do command line processing outside of the sudoers file in a scripting
873 language.
874 Exceptions to wildcard rules
876 The following exceptions apply to the above rules:
877 "" If the empty string "" is the only command line argument in the
879 sudoers file entry it means that command is not allowed to be
880 run with any arguments.
881 sudoedit Command line arguments to the sudoedit built-in command should
883 always be path names, so a forward slash (‘/’) will not be
884 matched by a wildcard.
885 Including other files from within sudoers
887 It is possible to include other sudoers files from within the sudoers
888 file currently being parsed using the @include and @includedir direc‐
889 tives. For compatibility with sudo versions prior to 1.9.1, #include and
890 #includedir are also accepted.
891 An include file can be used, for example, to keep a site-wide sudoers
893 file in addition to a local, per-machine file. For the sake of this ex‐
894 ample the site-wide sudoers file will be /etc/sudoers and the per-machine
895 one will be /etc/sudoers.local. To include /etc/sudoers.local from
896 within /etc/sudoers one would use the following line in /etc/sudoers:
897 @include /etc/sudoers.local
899 When sudo reaches this line it will suspend processing of the current
901 file (/etc/sudoers) and switch to /etc/sudoers.local. Upon reaching the
902 end of /etc/sudoers.local, the rest of /etc/sudoers will be processed.
903 Files that are included may themselves include other files. A hard limit
904 of 128 nested include files is enforced to prevent include file loops.
905 The path to the include file may contain white space if it is escaped
907 with a backslash (‘\’). Alternately, the entire path may be enclosed in
908 double quotes (""), in which case no escaping is necessary. To include a
909 literal backslash in the path, ‘\\’ should be used.
910 If the path to the include file is not fully-qualified (does not begin
912 with a ‘/’), it must be located in the same directory as the sudoers file
913 it was included from. For example, if /etc/sudoers contains the line:
914 @include sudoers.local
916 the file that will be included is /etc/sudoers.local.
918 The file name may also include the %h escape, signifying the short form
920 of the host name. In other words, if the machine's host name is
921 “xerxes”, then
922 @include /etc/sudoers.%h
924 will cause sudo to include the file /etc/sudoers.xerxes.
926 The @includedir directive can be used to create a sudoers.d directory
928 that the system package manager can drop sudoers file rules into as part
929 of package installation. For example, given:
930 @includedir /etc/sudoers.d
932 sudo will suspend processing of the current file and read each file in
934 /etc/sudoers.d, skipping file names that end in ‘~’ or contain a ‘.’
935 character to avoid causing problems with package manager or editor tempo‐
936 rary/backup files. Files are parsed in sorted lexical order. That is,
937 /etc/sudoers.d/01_first will be parsed before /etc/sudoers.d/10_second.
938 Be aware that because the sorting is lexical, not numeric,
939 /etc/sudoers.d/1_whoops would be loaded after /etc/sudoers.d/10_second.
940 Using a consistent number of leading zeroes in the file names can be used
941 to avoid such problems. After parsing the files in the directory, con‐
942 trol returns to the file that contained the @includedir directive.
943 Note that unlike files included via @include, visudo will not edit the
945 files in a @includedir directory unless one of them contains a syntax er‐
946 ror. It is still possible to run visudo with the -f flag to edit the
947 files directly, but this will not catch the redefinition of an alias that
948 is also present in a different file.
949 Other special characters and reserved words
951 The pound sign (‘#’) is used to indicate a comment (unless it is part of
952 a #include directive or unless it occurs in the context of a user name
953 and is followed by one or more digits, in which case it is treated as a
954 user-ID). Both the comment character and any text after it, up to the
955 end of the line, are ignored.
956 The reserved word ALL is a built-in alias that always causes a match to
958 succeed. It can be used wherever one might otherwise use a Cmnd_Alias,
959 User_Alias, Runas_Alias, or Host_Alias. Attempting to define an alias
960 named ALL will result in a syntax error. Please note that using ALL can
961 be dangerous since in a command context, it allows the user to run any
962 command on the system.
963 The following option names permitted in an Option_Spec are also consid‐
965 ered reserved words: CHROOT, ROLE, TYPE, TIMEOUT, CWD, NOTBEFORE and
966 NOTAFTER. Attempting to define an alias with the same name as one of the
967 options will result in a syntax error.
968 An exclamation point (‘!’) can be used as a logical not operator in a
970 list or alias as well as in front of a Cmnd. This allows one to exclude
971 certain values. For the ‘!’ operator to be effective, there must be
972 something for it to exclude. For example, to match all users except for
973 root one would use:
974 ALL,!root
976 If the ALL, is omitted, as in:
978 !root
980 it would explicitly deny root but not match any other users. This is
982 different from a true “negation” operator.
983 Note, however, that using a ‘!’ in conjunction with the built-in ALL
985 alias to allow a user to run “all but a few” commands rarely works as in‐
986 tended (see SECURITY NOTES below).
987 Long lines can be continued with a backslash (‘\’) as the last character
989 on the line.
990 White space between elements in a list as well as special syntactic char‐
992 acters in a User Specification (‘=’, ‘:’, ‘(’, ‘)’) is optional.
993 The following characters must be escaped with a backslash (‘\’) when used
995 as part of a word (e.g., a user name or host name): ‘!’, ‘=’, ‘:’, ‘,’,
996 ‘(’, ‘)’, ‘\’.
997
999 sudo's behavior can be modified by Default_Entry lines, as explained ear‐
1000 lier. A list of all supported Defaults parameters, grouped by type, are
1001 listed below.
1002 Boolean Flags:
1004 always_query_group_plugin
1006 If a group_plugin is configured, use it to resolve
1007 groups of the form %group as long as there is not also
1008 a system group of the same name. Normally, only groups
1009 of the form %:group are passed to the group_plugin.
1010 This flag is off by default.
1011 always_set_home If enabled, sudo will set the HOME environment variable
1013 to the home directory of the target user (which is the
1014 root user unless the -u option is used). This flag is
1015 largely obsolete and has no effect unless the env_reset
1016 flag has been disabled or HOME is present in the
1017 env_keep list, both of which are strongly discouraged.
1018 This flag is off by default.
1019 authenticate If set, users must authenticate themselves via a pass‐
1021 word (or other means of authentication) before they may
1022 run commands. This default may be overridden via the
1023 PASSWD and NOPASSWD tags. This flag is on by default.
1024 case_insensitive_group
1026 If enabled, group names in sudoers will be matched in a
1027 case insensitive manner. This may be necessary when
1028 users are stored in LDAP or AD. This flag is on by de‐
1029 fault.
1030 case_insensitive_user
1032 If enabled, user names in sudoers will be matched in a
1033 case insensitive manner. This may be necessary when
1034 groups are stored in LDAP or AD. This flag is on by
1035 default.
1036 closefrom_override
1038 If set, the user may use the -C option which overrides
1039 the default starting point at which sudo begins closing
1040 open file descriptors. This flag is off by default.
1041 compress_io If set, and sudo is configured to log a command's input
1043 or output, the I/O logs will be compressed using zlib.
1044 This flag is on by default when sudo is compiled with
1045 zlib support.
1046 exec_background By default, sudo runs a command as the foreground
1048 process as long as sudo itself is running in the fore‐
1049 ground. When the exec_background flag is enabled and
1050 the command is being run in a pseudo-terminal (due to
1051 I/O logging or the use_pty flag), the command will be
1052 run as a background process. Attempts to read from the
1053 controlling terminal (or to change terminal settings)
1054 will result in the command being suspended with the
1055 SIGTTIN signal (or SIGTTOU in the case of terminal set‐
1056 tings). If this happens when sudo is a foreground
1057 process, the command will be granted the controlling
1058 terminal and resumed in the foreground with no user in‐
1059 tervention required. The advantage of initially run‐
1060 ning the command in the background is that sudo need
1061 not read from the terminal unless the command explic‐
1062 itly requests it. Otherwise, any terminal input must
1063 be passed to the command, whether it has required it or
1064 not (the kernel buffers terminals so it is not possible
1065 to tell whether the command really wants the input).
1066 This is different from historic sudo behavior or when
1067 the command is not being run in a pseudo-terminal.
1068 For this to work seamlessly, the operating system must
1070 support the automatic restarting of system calls. Un‐
1071 fortunately, not all operating systems do this by de‐
1072 fault, and even those that do may have bugs. For exam‐
1073 ple, macOS fails to restart the tcgetattr() and
1074 tcsetattr() system calls (this is a bug in macOS).
1075 Furthermore, because this behavior depends on the com‐
1076 mand stopping with the SIGTTIN or SIGTTOU signals, pro‐
1077 grams that catch these signals and suspend themselves
1078 with a different signal (usually SIGTOP) will not be
1079 automatically foregrounded. Some versions of the linux
1080 su(1) command behave this way. This flag is off by de‐
1081 fault.
1082 This setting is only supported by version 1.8.7 or
1084 higher. It has no effect unless I/O logging is enabled
1085 or the use_pty flag is enabled.
1086 env_editor If set, visudo will use the value of the SUDO_EDITOR,
1088 VISUAL or EDITOR environment variables before falling
1089 back on the default editor list. Note that visudo is
1090 typically run as root so this flag may allow a user
1091 with visudo privileges to run arbitrary commands as
1092 root without logging. An alternative is to place a
1093 colon-separated list of “safe” editors int the editor
1094 variable. visudo will then only use SUDO_EDITOR,
1095 VISUAL or EDITOR if they match a value specified in
1096 editor. If the env_reset flag is enabled, the
1097 SUDO_EDITOR, VISUAL and/or EDITOR environment variables
1098 must be present in the env_keep list for the env_editor
1099 flag to function when visudo is invoked via sudo. This
1100 flag is on by default.
1101 env_reset If set, sudo will run the command in a minimal environ‐
1103 ment containing the TERM, PATH, HOME, MAIL, SHELL,
1104 LOGNAME, USER and SUDO_* variables. Any variables in
1105 the caller's environment or in the file specified by
1106 the restricted_env_file setting that match the env_keep
1107 and env_check lists are then added, followed by any
1108 variables present in the file specified by the env_file
1109 setting (if any). The contents of the env_keep and
1110 env_check lists, as modified by global Defaults parame‐
1111 ters in sudoers, are displayed when sudo is run by root
1112 with the -V option. If the secure_path setting is en‐
1113 abled, its value will be used for the PATH environment
1114 variable. This flag is on by default.
1115 fast_glob Normally, sudo uses the glob(3) function to do shell-
1117 style globbing when matching path names. However,
1118 since it accesses the file system, glob(3) can take a
1119 long time to complete for some patterns, especially
1120 when the pattern references a network file system that
1121 is mounted on demand (auto mounted). The fast_glob
1122 flag causes sudo to use the fnmatch(3) function, which
1123 does not access the file system to do its matching.
1124 The disadvantage of fast_glob is that it is unable to
1125 match relative path names such as ./ls or ../bin/ls.
1126 This has security implications when path names that in‐
1127 clude globbing characters are used with the negation
1128 operator, ‘!’, as such rules can be trivially bypassed.
1129 As such, this flag should not be used when the sudoers
1130 file contains rules that contain negated path names
1131 which include globbing characters. This flag is off by
1132 default.
1133 fqdn Set this flag if you want to put fully qualified host
1135 names in the sudoers file when the local host name (as
1136 returned by the hostname command) does not contain the
1137 domain name. In other words, instead of myhost you
1138 would use myhost.mydomain.edu. You may still use the
1139 short form if you wish (and even mix the two). This
1140 flag is only effective when the “canonical” host name,
1141 as returned by the getaddrinfo() or gethostbyname()
1142 function, is a fully-qualified domain name. This is
1143 usually the case when the system is configured to use
1144 DNS for host name resolution.
1145 If the system is configured to use the /etc/hosts file
1147 in preference to DNS, the “canonical” host name may not
1148 be fully-qualified. The order that sources are queried
1149 for host name resolution is usually specified in the
1150 /etc/nsswitch.conf, /etc/netsvc.conf, /etc/host.conf,
1151 or, in some cases, /etc/resolv.conf file. In the
1152 /etc/hosts file, the first host name of the entry is
1153 considered to be the “canonical” name; subsequent names
1154 are aliases that are not used by sudoers. For example,
1155 the following hosts file line for the machine “xyzzy”
1156 has the fully-qualified domain name as the “canonical”
1157 host name, and the short version as an alias.
1158 192.168.1.1 xyzzy.sudo.ws xyzzy
1160 If the machine's hosts file entry is not formatted
1162 properly, the fqdn flag will not be effective if it is
1163 queried before DNS.
1164 Beware that when using DNS for host name resolution,
1166 turning on fqdn requires sudoers to make DNS lookups
1167 which renders sudo unusable if DNS stops working (for
1168 example if the machine is disconnected from the net‐
1169 work). Also note that just like with the hosts file,
1170 you must use the “canonical” name as DNS knows it.
1171 That is, you may not use a host alias (CNAME entry) due
1172 to performance issues and the fact that there is no way
1173 to get all aliases from DNS.
1174 This flag is off by default.
1176 ignore_audit_errors
1178 Allow commands to be run even if sudoers cannot write
1179 to the audit log. If enabled, an audit log write fail‐
1180 ure is not treated as a fatal error. If disabled, a
1181 command may only be run after the audit event is suc‐
1182 cessfully written. This flag is only effective on sys‐
1183 tems for which sudoers supports audit logging, includ‐
1184 ing FreeBSD, Linux, macOS and Solaris. This flag is on
1185 by default.
1186 ignore_dot If set, sudo will ignore "." or "" (both denoting cur‐
1188 rent directory) in the PATH environment variable; the
1189 PATH itself is not modified. This flag is on by de‐
1190 fault.
1191 ignore_iolog_errors
1193 Allow commands to be run even if sudoers cannot write
1194 to the I/O log (local or remote). If enabled, an I/O
1195 log write failure is not treated as a fatal error. If
1196 disabled, the command will be terminated if the I/O log
1197 cannot be written to. This flag is off by default.
1198 ignore_logfile_errors
1200 Allow commands to be run even if sudoers cannot write
1201 to the log file. If enabled, a log file write failure
1202 is not treated as a fatal error. If disabled, a com‐
1203 mand may only be run after the log file entry is suc‐
1204 cessfully written. This flag only has an effect when
1205 sudoers is configured to use file-based logging via the
1206 logfile setting. This flag is on by default.
1207 ignore_local_sudoers
1209 If set via LDAP, parsing of /etc/sudoers will be
1210 skipped. This is intended for Enterprises that wish to
1211 prevent the usage of local sudoers files so that only
1212 LDAP is used. This thwarts the efforts of rogue opera‐
1213 tors who would attempt to add roles to /etc/sudoers.
1214 When this flag is enabled, /etc/sudoers does not even
1215 need to exist. Since this flag tells sudo how to be‐
1216 have when no specific LDAP entries have been matched,
1217 this sudoOption is only meaningful for the cn=defaults
1218 section. This flag is off by default.
1219 ignore_unknown_defaults
1221 If set, sudo will not produce a warning if it encoun‐
1222 ters an unknown Defaults entry in the sudoers file or
1223 an unknown sudoOption in LDAP. This flag is off by de‐
1224 fault.
1225 insults If set, sudo will insult users when they enter an in‐
1227 correct password. This flag is off by default.
1228 log_allowed If set, sudoers will log commands allowed by the policy
1230 to the system audit log (where supported) as well as to
1231 syslog and/or a log file. This flag is on by default.
1232 This setting is only supported by version 1.8.29 or
1234 higher.
1235 log_denied If set, sudoers will log commands denied by the policy
1237 to the system audit log (where supported) as well as to
1238 syslog and/or a log file. This flag is on by default.
1239 This setting is only supported by version 1.8.29 or
1241 higher.
1242 log_host If set, the host name will be included in log entries
1244 written to the file configured by the logfile setting.
1245 This flag is off by default.
1246 log_input If set, sudo will run the command in a pseudo-terminal
1248 and log all user input. If the standard input is not
1249 connected to the user's tty, due to I/O redirection or
1250 because the command is part of a pipeline, that input
1251 is also captured and stored in a separate log file.
1252 Anything sent to the standard input will be consumed,
1253 regardless of whether or not the command run via sudo
1254 is actually reading the standard input. This may have
1255 unexpected results when using sudo in a shell script
1256 that expects to process the standard input. For more
1257 information about I/O logging, see the I/O LOG FILES
1258 section. This flag is off by default.
1259 log_output If set, sudo will run the command in a pseudo-terminal
1261 and log all output that is sent to the screen, similar
1262 to the script(1) command. For more information about
1263 I/O logging, see the I/O LOG FILES section. This flag
1264 is off by default.
1265 log_server_keepalive
1267 If set, sudo will enable the TCP keepalive socket op‐
1268 tion on the connection to the log server. This enables
1269 the periodic transmission of keepalive messages to the
1270 server. If the server does not respond to a message,
1271 the connection will be closed and the running command
1272 will be terminated unless the ignore_iolog_errors flag
1273 (I/O logging enabled) or the ignore_log_errors flag
1274 (I/O logging disabled) is set. This flag is on by de‐
1275 fault.
1276 This setting is only supported by version 1.9.0 or
1278 higher.
1279 log_server_verify
1281 If set, the server certificate received during the TLS
1282 handshake must be valid and it must contain either the
1283 server name (from log_servers) or its IP address. If
1284 either of these conditions is not met, the TLS hand‐
1285 shake will fail. This flag is on by default.
1286 This setting is only supported by version 1.9.0 or
1288 higher.
1289 log_year If set, the four-digit year will be logged in the (non-
1291 syslog) sudo log file. This flag is off by default.
1292 long_otp_prompt When validating with a One Time Password (OTP) scheme
1294 such as S/Key or OPIE, a two-line prompt is used to
1295 make it easier to cut and paste the challenge to a lo‐
1296 cal window. It's not as pretty as the default but some
1297 people find it more convenient. This flag is off by
1298 default.
1299 mail_all_cmnds Send mail to the mailto user every time a user attempts
1301 to run a command via sudo (this includes sudoedit). No
1302 mail will be sent if the user runs sudo with the -l or
1303 -v option unless there is an authentication error and
1304 the mail_badpass flag is also set. This flag is off by
1305 default.
1306 mail_always Send mail to the mailto user every time a user runs
1308 sudo. This flag is off by default.
1309 mail_badpass Send mail to the mailto user if the user running sudo
1311 does not enter the correct password. If the command
1312 the user is attempting to run is not permitted by
1313 sudoers and one of the mail_all_cmnds, mail_always,
1314 mail_no_host, mail_no_perms or mail_no_user flags are
1315 set, this flag will have no effect. This flag is off
1316 by default.
1317 mail_no_host If set, mail will be sent to the mailto user if the in‐
1319 voking user exists in the sudoers file, but is not al‐
1320 lowed to run commands on the current host. This flag
1321 is off by default.
1322 mail_no_perms If set, mail will be sent to the mailto user if the in‐
1324 voking user is allowed to use sudo but the command they
1325 are trying is not listed in their sudoers file entry or
1326 is explicitly denied. This flag is off by default.
1327 mail_no_user If set, mail will be sent to the mailto user if the in‐
1329 voking user is not in the sudoers file. This flag is
1330 on by default.
1331 match_group_by_gid
1333 By default, sudoers will look up each group the user is
1334 a member of by group-ID to determine the group name
1335 (this is only done once). The resulting list of the
1336 user's group names is used when matching groups listed
1337 in the sudoers file. This works well on systems where
1338 the number of groups listed in the sudoers file is
1339 larger than the number of groups a typical user belongs
1340 to. On systems where group lookups are slow, where
1341 users may belong to a large number of groups, and where
1342 the number of groups listed in the sudoers file is rel‐
1343 atively small, it may be prohibitively expensive and
1344 running commands via sudo may take longer than normal.
1345 On such systems it may be faster to use the
1346 match_group_by_gid flag to avoid resolving the user's
1347 group-IDs to group names. In this case, sudoers must
1348 look up any group name listed in the sudoers file and
1349 use the group-ID instead of the group name when deter‐
1350 mining whether the user is a member of the group.
1351 Note that if match_group_by_gid is enabled, group data‐
1353 base lookups performed by sudoers will be keyed by
1354 group name as opposed to group-ID. On systems where
1355 there are multiple sources for the group database, it
1356 is possible to have conflicting group names or group-
1357 IDs in the local /etc/group file and the remote group
1358 database. On such systems, enabling or disabling
1359 match_group_by_gid can be used to choose whether group
1360 database queries are performed by name (enabled) or ID
1361 (disabled), which may aid in working around group entry
1362 conflicts.
1363 The match_group_by_gid flag has no effect when sudoers
1365 data is stored in LDAP. This flag is off by default.
1366 This setting is only supported by version 1.8.18 or
1368 higher.
1369 netgroup_tuple If set, netgroup lookups will be performed using the
1371 full netgroup tuple: host name, user name and domain
1372 (if one is set). Historically, sudo only matched the
1373 user name and domain for netgroups used in a User_List
1374 and only matched the host name and domain for netgroups
1375 used in a Host_List. This flag is off by default.
1376 noexec If set, all commands run via sudo will behave as if the
1378 NOEXEC tag has been set, unless overridden by an EXEC
1379 tag. See the description of EXEC and NOEXEC above as
1380 well as the Preventing shell escapes section at the end
1381 of this manual. This flag is off by default.
1382 pam_acct_mgmt On systems that use PAM for authentication, sudo will
1384 perform PAM account validation for the invoking user by
1385 default. The actual checks performed depend on which
1386 PAM modules are configured. If enabled, account vali‐
1387 dation will be performed regardless of whether or not a
1388 password is required. This flag is on by default.
1389 This setting is only supported by version 1.8.28 or
1391 higher.
1392 pam_rhost On systems that use PAM for authentication, sudo will
1394 set the PAM remote host value to the name of the local
1395 host when the pam_rhost flag is enabled. On Linux sys‐
1396 tems, enabling pam_rhost may result in DNS lookups of
1397 the local host name when PAM is initialized. On So‐
1398 laris versions prior to Solaris 8, pam_rhost must be
1399 enabled if pam_ruser is also enabled to avoid a crash
1400 in the Solaris PAM implementation.
1401 This flag is off by default on systems other than So‐
1403 laris.
1404 This setting is only supported by version 1.9.0 or
1406 higher.
1407 pam_ruser On systems that use PAM for authentication, sudo will
1409 set the PAM remote user value to the name of the user
1410 that invoked sudo when the pam_ruser flag is enabled.
1411 This flag is on by default.
1412 This setting is only supported by version 1.9.0 or
1414 higher.
1415 pam_session On systems that use PAM for authentication, sudo will
1417 create a new PAM session for the command to be run in.
1418 Unless sudo is given the -i or -s options, PAM session
1419 modules are run with the “silent” flag enabled. This
1420 prevents last login information from being displayed
1421 for every command on some systems. Disabling
1422 pam_session may be needed on older PAM implementations
1423 or on operating systems where opening a PAM session
1424 changes the utmp or wtmp files. If PAM session support
1425 is disabled, resource limits may not be updated for the
1426 command being run. If pam_session, pam_setcred, and
1427 use_pty are disabled, log_servers has not been set and
1428 I/O logging has not been configured, sudo will execute
1429 the command directly instead of running it as a child
1430 process. This flag is on by default.
1431 This setting is only supported by version 1.8.7 or
1433 higher.
1434 pam_setcred On systems that use PAM for authentication, sudo will
1436 attempt to establish credentials for the target user by
1437 default, if supported by the underlying authentication
1438 system. One example of a credential is a Kerberos
1439 ticket. If pam_session, pam_setcred, and use_pty are
1440 disabled, log_servers has not been set and I/O logging
1441 has not been configured, sudo will execute the command
1442 directly instead of running it as a child process.
1443 This flag is on by default.
1444 This setting is only supported by version 1.8.8 or
1446 higher.
1447 passprompt_override
1449 If set, the prompt specified by passprompt or the
1450 SUDO_PROMPT environment variable will always be used
1451 and will replace the prompt provided by a PAM module or
1452 other authentication method. This flag is off by de‐
1453 fault.
1454 path_info Normally, sudo will tell the user when a command could
1456 not be found in their PATH environment variable. Some
1457 sites may wish to disable this as it could be used to
1458 gather information on the location of executables that
1459 the normal user does not have access to. The disadvan‐
1460 tage is that if the executable is simply not in the
1461 user's PATH, sudo will tell the user that they are not
1462 allowed to run it, which can be confusing. This flag
1463 is on by default.
1464 preserve_groups By default, sudo will initialize the group vector to
1466 the list of groups the target user is in. When
1467 preserve_groups is set, the user's existing group vec‐
1468 tor is left unaltered. The real and effective group-
1469 IDs, however, are still set to match the target user.
1470 This flag is off by default.
1471 pwfeedback By default, sudo reads the password like most other
1473 Unix programs, by turning off echo until the user hits
1474 the return (or enter) key. Some users become confused
1475 by this as it appears to them that sudo has hung at
1476 this point. When pwfeedback is set, sudo will provide
1477 visual feedback when the user presses a key. Note that
1478 this does have a security impact as an onlooker may be
1479 able to determine the length of the password being en‐
1480 tered. This flag is off by default.
1481 requiretty If set, sudo will only run when the user is logged in
1483 to a real tty. When this flag is set, sudo can only be
1484 run from a login session and not via other means such
1485 as cron(8) or cgi-bin scripts. This flag is off by de‐
1486 fault.
1487 root_sudo If set, root is allowed to run sudo too. Disabling
1489 this prevents users from “chaining” sudo commands to
1490 get a root shell by doing something like “sudo sudo
1491 /bin/sh”. Note, however, that turning off root_sudo
1492 will also prevent root from running sudoedit. Dis‐
1493 abling root_sudo provides no real additional security;
1494 it exists purely for historical reasons. This flag is
1495 on by default.
1496 rootpw If set, sudo will prompt for the root password instead
1498 of the password of the invoking user when running a
1499 command or editing a file. This flag is off by de‐
1500 fault.
1501 runas_allow_unknown_id
1503 If enabled, allow matching of runas user and group IDs
1504 that are not present in the password or group data‐
1505 bases. In addition to explicitly matching unknown user
1506 or group IDs in a Runas_List, this option also allows
1507 the ALL alias to match unknown IDs. This flag is off
1508 by default.
1509 This setting is only supported by version 1.8.30 or
1511 higher. Older versions of sudo always allowed matching
1512 of unknown user and group IDs.
1513 runas_check_shell
1515 If enabled, sudo will only run commands as a user whose
1516 shell appears in the /etc/shells file, even if the in‐
1517 voking user's Runas_List would otherwise permit it. If
1518 no /etc/shells file is present, a system-dependent list
1519 of built-in default shells is used. On many operating
1520 systems, system users such as “bin”, do not have a
1521 valid shell and this flag can be used to prevent com‐
1522 mands from being run as those users. This flag is off
1523 by default.
1524 This setting is only supported by version 1.8.30 or
1526 higher.
1527 runaspw If set, sudo will prompt for the password of the user
1529 defined by the runas_default option (defaults to root)
1530 instead of the password of the invoking user when run‐
1531 ning a command or editing a file. This flag is off by
1532 default.
1533 selinux If enabled, the user may specify an SELinux role and/or
1535 type to use when running the command, as permitted by
1536 the SELinux policy. If SELinux is disabled on the sys‐
1537 tem, this flag has no effect. This flag is on by de‐
1538 fault.
1539 set_home If enabled and sudo is invoked with the -s option, the
1541 HOME environment variable will be set to the home di‐
1542 rectory of the target user (which is the root user un‐
1543 less the -u option is used). This flag is largely ob‐
1544 solete and has no effect unless the env_reset flag has
1545 been disabled or HOME is present in the env_keep list,
1546 both of which are strongly discouraged. This flag is
1547 off by default.
1548 set_logname Normally, sudo will set the LOGNAME and USER environ‐
1550 ment variables to the name of the target user (usually
1551 root unless the -u option is given). However, since
1552 some programs (including the RCS revision control sys‐
1553 tem) use LOGNAME to determine the real identity of the
1554 user, it may be desirable to change this behavior.
1555 This can be done by negating the set_logname option.
1556 Note that set_logname will have no effect if the
1557 env_reset option has not been disabled and the env_keep
1558 list contains LOGNAME or USER. This flag is on by de‐
1559 fault.
1560 set_utmp When enabled, sudo will create an entry in the utmp (or
1562 utmpx) file when a pseudo-terminal is allocated. A
1563 pseudo-terminal is allocated by sudo when it is running
1564 in a terminal and one or more of the log_input,
1565 log_output or use_pty flags is enabled. By default,
1566 the new entry will be a copy of the user's existing
1567 utmp entry (if any), with the tty, time, type and pid
1568 fields updated. This flag is on by default.
1569 setenv Allow the user to disable the env_reset option from the
1571 command line via the -E option. Additionally, environ‐
1572 ment variables set via the command line are not subject
1573 to the restrictions imposed by env_check, env_delete,
1574 or env_keep. As such, only trusted users should be al‐
1575 lowed to set variables in this manner. This flag is
1576 off by default.
1577 shell_noargs If set and sudo is invoked with no arguments it acts as
1579 if the -s option had been given. That is, it runs a
1580 shell as root (the shell is determined by the SHELL en‐
1581 vironment variable if it is set, falling back on the
1582 shell listed in the invoking user's /etc/passwd entry
1583 if not). This flag is off by default.
1584 stay_setuid Normally, when sudo executes a command the real and ef‐
1586 fective UIDs are set to the target user (root by de‐
1587 fault). This option changes that behavior such that
1588 the real UID is left as the invoking user's UID. In
1589 other words, this makes sudo act as a set-user-ID wrap‐
1590 per. This can be useful on systems that disable some
1591 potentially dangerous functionality when a program is
1592 run set-user-ID. This option is only effective on sys‐
1593 tems that support either the setreuid(2) or
1594 setresuid(2) system call. This flag is off by default.
1595 sudoedit_checkdir
1597 If set, sudoedit will check all directory components of
1598 the path to be edited for writability by the invoking
1599 user. Symbolic links will not be followed in writable
1600 directories and sudoedit will refuse to edit a file lo‐
1601 cated in a writable directory. These restrictions are
1602 not enforced when sudoedit is run by root. On some
1603 systems, if all directory components of the path to be
1604 edited are not readable by the target user, sudoedit
1605 will be unable to edit the file. This flag is on by
1606 default.
1607 This setting was first introduced in version 1.8.15 but
1609 initially suffered from a race condition. The check
1610 for symbolic links in writable intermediate directories
1611 was added in version 1.8.16.
1612 sudoedit_follow By default, sudoedit will not follow symbolic links
1614 when opening files. The sudoedit_follow option can be
1615 enabled to allow sudoedit to open symbolic links. It
1616 may be overridden on a per-command basis by the FOLLOW
1617 and NOFOLLOW tags. This flag is off by default.
1618 This setting is only supported by version 1.8.15 or
1620 higher.
1621 syslog_pid When logging via syslog(3), include the process ID in
1623 the log entry. This flag is off by default.
1624 This setting is only supported by version 1.8.21 or
1626 higher.
1627 targetpw If set, sudo will prompt for the password of the user
1629 specified by the -u option (defaults to root) instead
1630 of the password of the invoking user when running a
1631 command or editing a file. Note that this flag pre‐
1632 cludes the use of a user-ID not listed in the passwd
1633 database as an argument to the -u option. This flag is
1634 off by default.
1635 tty_tickets If set, users must authenticate on a per-tty basis.
1637 With this flag enabled, sudo will use a separate record
1638 in the time stamp file for each terminal. If disabled,
1639 a single record is used for all login sessions.
1640 This option has been superseded by the timestamp_type
1642 option.
1643 umask_override If set, sudo will set the umask as specified in the
1645 sudoers file without modification. This makes it pos‐
1646 sible to specify a umask in the sudoers file that is
1647 more permissive than the user's own umask and matches
1648 historical behavior. If umask_override is not set,
1649 sudo will set the umask to be the union of the user's
1650 umask and what is specified in sudoers. This flag is
1651 off by default.
1652 use_netgroups If set, netgroups (prefixed with ‘+’), may be used in
1654 place of a user or host. For LDAP-based sudoers, net‐
1655 group support requires an expensive sub-string match on
1656 the server unless the NETGROUP_BASE directive is
1657 present in the /etc/ldap.conf file. If netgroups are
1658 not needed, this option can be disabled to reduce the
1659 load on the LDAP server. This flag is on by default.
1660 use_pty If set, and sudo is running in a terminal, the command
1662 will be run in a pseudo-terminal (even if no I/O log‐
1663 ging is being done). If the sudo process is not at‐
1664 tached to a terminal, use_pty has no effect.
1665 A malicious program run under sudo may be capable of
1667 injecting commands into the user's terminal or running
1668 a background process that retains access to the user's
1669 terminal device even after the main program has fin‐
1670 ished executing. By running the command in a separate
1671 pseudo-terminal, this attack is no longer possible.
1672 This flag is off by default.
1673 user_command_timeouts
1675 If set, the user may specify a timeout on the command
1676 line. If the timeout expires before the command has
1677 exited, the command will be terminated. If a timeout
1678 is specified both in the sudoers file and on the com‐
1679 mand line, the smaller of the two timeouts will be
1680 used. See the Timeout_Spec section for a description
1681 of the timeout syntax. This flag is off by default.
1682 This setting is only supported by version 1.8.20 or
1684 higher.
1685 utmp_runas If set, sudo will store the name of the runas user when
1687 updating the utmp (or utmpx) file. By default, sudo
1688 stores the name of the invoking user. This flag is off
1689 by default.
1690 visiblepw By default, sudo will refuse to run if the user must
1692 enter a password but it is not possible to disable echo
1693 on the terminal. If the visiblepw flag is set, sudo
1694 will prompt for a password even when it would be visi‐
1695 ble on the screen. This makes it possible to run
1696 things like “ssh somehost sudo ls” since by default,
1697 ssh(1) does not allocate a tty when running a command.
1698 This flag is off by default.
1699 Integers:
1701 closefrom Before it executes a command, sudo will close all open
1703 file descriptors other than standard input, standard
1704 output and standard error (ie: file descriptors 0-2).
1705 The closefrom option can be used to specify a different
1706 file descriptor at which to start closing. The default
1707 is 3.
1708 command_timeout The maximum amount of time a command is allowed to run
1710 before it is terminated. See the Timeout_Spec section
1711 for a description of the timeout syntax.
1712 This setting is only supported by version 1.8.20 or
1714 higher.
1715 log_server_timeout
1717 The maximum amount of time to wait when connecting to a
1718 log server or waiting for a server response. See the
1719 Timeout_Spec section for a description of the timeout
1720 syntax. The default value is 30 seconds.
1721 This setting is only supported by version 1.9.0 or
1723 higher.
1724 maxseq The maximum sequence number that will be substituted
1726 for the “%{seq}” escape in the I/O log file (see the
1727 iolog_dir description below for more information).
1728 While the value substituted for “%{seq}” is in base 36,
1729 maxseq itself should be expressed in decimal. Values
1730 larger than 2176782336 (which corresponds to the base
1731 36 sequence number “ZZZZZZ”) will be silently truncated
1732 to 2176782336. The default value is 2176782336.
1733 Once the local sequence number reaches the value of
1735 maxseq, it will “roll over” to zero, after which
1736 sudoers will truncate and re-use any existing I/O log
1737 path names.
1738 This setting is only supported by version 1.8.7 or
1740 higher.
1741 passwd_tries The number of tries a user gets to enter his/her pass‐
1743 word before sudo logs the failure and exits. The de‐
1744 fault is 3.
1745 syslog_maxlen On many systems, syslog(3) has a relatively small log
1747 buffer. IETF RFC 5424 states that syslog servers must
1748 support messages of at least 480 bytes and should sup‐
1749 port messages up to 2048 bytes. By default, sudoers
1750 creates log messages up to 980 bytes which corresponds
1751 to the historic BSD syslog implementation which used a
1752 1024 byte buffer to store the message, date, hostname
1753 and program name. To prevent syslog messages from be‐
1754 ing truncated, sudoers will split up log messages that
1755 are larger than syslog_maxlen bytes. When a message is
1756 split, additional parts will include the string
1757 “(command continued)” after the user name and before
1758 the continued command line arguments.
1759 This setting is only supported by version 1.8.19 or
1761 higher.
1762 Integers that can be used in a boolean context:
1764 loglinelen Number of characters per line for the file log. This
1766 value is used to decide when to wrap lines for nicer
1767 log files. This has no effect on the syslog log file,
1768 only the file log. The default is 80 (use 0 or negate
1769 the option to disable word wrap).
1770 passwd_timeout Number of minutes before the sudo password prompt times
1772 out, or 0 for no timeout. The timeout may include a
1773 fractional component if minute granularity is insuffi‐
1774 cient, for example 2.5. The default is 5.
1775 timestamp_timeout
1777 Number of minutes that can elapse before sudo will ask
1778 for a passwd again. The timeout may include a frac‐
1779 tional component if minute granularity is insufficient,
1780 for example 2.5. The default is 5. Set this to 0 to
1781 always prompt for a password. If set to a value less
1782 than 0 the user's time stamp will not expire until the
1783 system is rebooted. This can be used to allow users to
1784 create or delete their own time stamps via “sudo -v”
1785 and “sudo -k” respectively.
1786 umask File mode creation mask to use when running the com‐
1788 mand. Negate this option or set it to 0777 to prevent
1789 sudoers from changing the umask. Unless the
1790 umask_override flag is set, the actual umask will be
1791 the union of the user's umask and the value of the
1792 umask setting, which defaults to 0022. This guarantees
1793 that sudo never lowers the umask when running a com‐
1794 mand.
1795 If umask is explicitly set in sudoers, it will override
1797 any umask setting in PAM or login.conf. If umask is
1798 not set in sudoers, the umask specified by PAM or lo‐
1799 gin.conf will take precedence. The umask setting in
1800 PAM is not used for sudoedit, which does not create a
1801 new PAM session.
1802 Strings:
1804 authfail_message Message that is displayed after a user fails to authen‐
1806 ticate. The message may include the ‘%d’ escape which
1807 will expand to the number of failed password attempts.
1808 If set, it overrides the default message, %d incorrect
1809 password attempt(s).
1810 badpass_message Message that is displayed if a user enters an incorrect
1812 password. The default is Sorry, try again. unless in‐
1813 sults are enabled.
1814 editor A colon (‘:’) separated list of editors path names used
1816 by sudoedit and visudo. For sudoedit, this list is
1817 used to find an editor when none of the SUDO_EDITOR,
1818 VISUAL or EDITOR environment variables are set to an
1819 editor that exists and is executable. For visudo, it
1820 is used as a white list of allowed editors; visudo will
1821 choose the editor that matches the user's SUDO_EDITOR,
1822 VISUAL or EDITOR environment variable if possible, or
1823 the first editor in the list that exists and is exe‐
1824 cutable if not. Unless invoked as sudoedit, sudo does
1825 not preserve the SUDO_EDITOR, VISUAL or EDITOR environ‐
1826 ment variables unless they are present in the env_keep
1827 list or the env_reset option is disabled. The default
1828 is /bin/vi.
1829 iolog_dir The top-level directory to use when constructing the
1831 path name for the input/output log directory. Only
1832 used if the log_input or log_output options are enabled
1833 or when the LOG_INPUT or LOG_OUTPUT tags are present
1834 for a command. The session sequence number, if any, is
1835 stored in the directory. The default is
1836 /var/log/sudo-io.
1837 The following percent (‘%’) escape sequences are sup‐
1839 ported:
1840 %{seq}
1842 expanded to a monotonically increasing base-36
1843 sequence number, such as 0100A5, where every two
1844 digits are used to form a new directory, e.g.,
1845 01/00/A5
1846 %{user}
1848 expanded to the invoking user's login name
1849 %{group}
1851 expanded to the name of the invoking user's real
1852 group-ID
1853 %{runas_user}
1855 expanded to the login name of the user the com‐
1856 mand will be run as (e.g., root)
1857 %{runas_group}
1859 expanded to the group name of the user the com‐
1860 mand will be run as (e.g., wheel)
1861 %{hostname}
1863 expanded to the local host name without the do‐
1864 main name
1865 %{command}
1867 expanded to the base name of the command being
1868 run
1869 In addition, any escape sequences supported by the sys‐
1871 tem's strftime(3) function will be expanded.
1872 To include a literal ‘%’ character, the string ‘%%’
1874 should be used.
1875 iolog_file The path name, relative to iolog_dir, in which to store
1877 input/output logs when the log_input or log_output op‐
1878 tions are enabled or when the LOG_INPUT or LOG_OUTPUT
1879 tags are present for a command. Note that iolog_file
1880 may contain directory components. The default is
1881 “%{seq}”.
1882 See the iolog_dir option above for a list of supported
1884 percent (‘%’) escape sequences.
1885 In addition to the escape sequences, path names that
1887 end in six or more Xs will have the Xs replaced with a
1888 unique combination of digits and letters, similar to
1889 the mktemp(3) function.
1890 If the path created by concatenating iolog_dir and
1892 iolog_file already exists, the existing I/O log file
1893 will be truncated and overwritten unless iolog_file
1894 ends in six or more Xs.
1895 iolog_flush If set, sudo will flush I/O log data to disk after each
1897 write instead of buffering it. This makes it possible
1898 to view the logs in real-time as the program is execut‐
1899 ing but may significantly reduce the effectiveness of
1900 I/O log compression. This flag is off by default.
1901 This setting is only supported by version 1.8.20 or
1903 higher.
1904 iolog_group The group name to look up when setting the group-ID on
1906 new I/O log files and directories. If iolog_group is
1907 not set, the primary group-ID of the user specified by
1908 iolog_user is used. If neither iolog_group nor
1909 iolog_user are set, I/O log files and directories are
1910 created with group-ID 0.
1911 This setting is only supported by version 1.8.19 or
1913 higher.
1914 iolog_mode The file mode to use when creating I/O log files. Mode
1916 bits for read and write permissions for owner, group or
1917 other are honored, everything else is ignored. The
1918 file permissions will always include the owner read and
1919 write bits, even if they are not present in the speci‐
1920 fied mode. When creating I/O log directories, search
1921 (execute) bits are added to match the read and write
1922 bits specified by iolog_mode. Defaults to 0600 (read
1923 and write by user only).
1924 This setting is only supported by version 1.8.19 or
1926 higher.
1927 iolog_user The user name to look up when setting the user and
1929 group-IDs on new I/O log files and directories. If
1930 iolog_group is set, it will be used instead of the
1931 user's primary group-ID. By default, I/O log files and
1932 directories are created with user and group-ID 0.
1933 This setting can be useful when the I/O logs are stored
1935 on a Network File System (NFS) share. Having a dedi‐
1936 cated user own the I/O log files means that sudoers
1937 does not write to the log files as user-ID 0, which is
1938 usually not permitted by NFS.
1939 This setting is only supported by version 1.8.19 or
1941 higher.
1942 lecture_status_dir
1944 The directory in which sudo stores per-user lecture
1945 status files. Once a user has received the lecture, a
1946 zero-length file is created in this directory so that
1947 sudo will not lecture the user again. This directory
1948 should not be cleared when the system reboots. The de‐
1949 fault is /var/db/sudo/lectured.
1950 log_server_cabundle
1952 The path to a certificate authority bundle file, in PEM
1953 format, to use instead of the system's default certifi‐
1954 cate authority database when authenticating the log
1955 server. The default is to use the system's default
1956 certificate authority database. This setting has no
1957 effect unless log_servers is set and the remote log
1958 server is secured with TLS.
1959 This setting is only supported by version 1.9.0 or
1961 higher.
1962 log_server_peer_cert
1964 The path to the client's certificate file, in PEM for‐
1965 mat. This setting is required when log_servers is set
1966 and the remote log server is secured with TLS.
1967 This setting is only supported by version 1.9.0 or
1969 higher.
1970 log_server_peer_key
1972 The path to the client's private key file, in PEM for‐
1973 mat. This setting is required when log_servers is set
1974 and the remote log server is secured with TLS.
1975 This setting is only supported by version 1.9.0 or
1977 higher.
1978 mailsub Subject of the mail sent to the mailto user. The es‐
1980 cape %h will expand to the host name of the machine.
1981 Default is “*** SECURITY information for %h ***”.
1982 noexec_file As of sudo version 1.8.1 this option is no longer sup‐
1984 ported. The path to the noexec file should now be set
1985 in the sudo.conf(5) file.
1986 pam_login_service
1988 On systems that use PAM for authentication, this is the
1989 service name used when the -i option is specified. The
1990 default value is “sudo-i”. See the description of
1991 pam_service for more information.
1992 This setting is only supported by version 1.8.8 or
1994 higher.
1995 pam_service On systems that use PAM for authentication, the service
1997 name specifies the PAM policy to apply. This usually
1998 corresponds to an entry in the pam.conf file or a file
1999 in the /etc/pam.d directory. The default value is
2000 “sudo”.
2001 This setting is only supported by version 1.8.8 or
2003 higher.
2004 passprompt The default prompt to use when asking for a password;
2006 can be overridden via the -p option or the SUDO_PROMPT
2007 environment variable. The following percent (‘%’) es‐
2008 cape sequences are supported:
2009 %H expanded to the local host name including the do‐
2011 main name (only if the machine's host name is
2012 fully qualified or the fqdn option is set)
2013 %h expanded to the local host name without the do‐
2015 main name
2016 %p expanded to the user whose password is being
2018 asked for (respects the rootpw, targetpw and
2019 runaspw flags in sudoers)
2020 %U expanded to the login name of the user the com‐
2022 mand will be run as (defaults to root)
2023 %u expanded to the invoking user's login name
2025 %% two consecutive % characters are collapsed into a
2027 single % character
2028 On systems that use PAM for authentication, passprompt
2030 will only be used if the prompt provided by the PAM
2031 module matches the string “Password: ” or “username's
2032 Password: ”. This ensures that the passprompt setting
2033 does not interfere with challenge-response style au‐
2034 thentication. The passprompt_override flag can be used
2035 to change this behavior.
2036 The default value is “[sudo] password for %p: ”.
2038 role The default SELinux role to use when constructing a new
2040 security context to run the command. The default role
2041 may be overridden on a per-command basis in the sudoers
2042 file or via command line options. This option is only
2043 available when sudo is built with SELinux support.
2044 runas_default The default user to run commands as if the -u option is
2046 not specified on the command line. This defaults to
2047 root.
2048 sudoers_locale Locale to use when parsing the sudoers file, logging
2050 commands, and sending email. Note that changing the
2051 locale may affect how sudoers is interpreted. Defaults
2052 to “C”.
2053 timestamp_type sudoers uses per-user time stamp files for credential
2055 caching. The timestamp_type option can be used to
2056 specify the type of time stamp record used. It has the
2057 following possible values:
2058 global A single time stamp record is used for all of a
2060 user's login sessions, regardless of the termi‐
2061 nal or parent process ID. An additional record
2062 is used to serialize password prompts when sudo
2063 is used multiple times in a pipeline, but this
2064 does not affect authentication.
2065 ppid A single time stamp record is used for all pro‐
2067 cesses with the same parent process ID (usually
2068 the shell). Commands run from the same shell
2069 (or other common parent process) will not re‐
2070 quire a password for timestamp_timeout minutes
2071 (5 by default). Commands run via sudo with a
2072 different parent process ID, for example from a
2073 shell script, will be authenticated separately.
2074 tty One time stamp record is used for each termi‐
2076 nal, which means that a user's login sessions
2077 are authenticated separately. If no terminal
2078 is present, the behavior is the same as ppid.
2079 Commands run from the same terminal will not
2080 require a password for timestamp_timeout min‐
2081 utes (5 by default).
2082 kernel The time stamp is stored in the kernel as an
2084 attribute of the terminal device. If no termi‐
2085 nal is present, the behavior is the same as
2086 ppid. Negative timestamp_timeout values are
2087 not supported and positive values are limited
2088 to a maximum of 60 minutes. This is currently
2089 only supported on OpenBSD.
2090 The default value is tty.
2092 This setting is only supported by version 1.8.21 or
2094 higher.
2095 timestampdir The directory in which sudo stores its time stamp
2097 files. This directory should be cleared when the sys‐
2098 tem reboots. The default is /run/sudo/ts.
2099 timestampowner The owner of the lecture status directory, time stamp
2101 directory and all files stored therein. The default is
2102 root.
2103 type The default SELinux type to use when constructing a new
2105 security context to run the command. The default type
2106 may be overridden on a per-command basis in the sudoers
2107 file or via command line options. This option is only
2108 available when sudo is built with SELinux support.
2109 Strings that can be used in a boolean context:
2111 admin_flag The admin_flag option specifies the path to a file that is
2113 created the first time a user that is a member of the sudo
2114 or admin groups runs sudo. Only available if sudo is con‐
2115 figured with the --enable-admin-flag option. The default
2116 value is ~/.sudo_as_admin_successful.
2117 env_file The env_file option specifies the fully qualified path to a
2119 file containing variables to be set in the environment of
2120 the program being run. Entries in this file should either
2121 be of the form “VARIABLE=value” or “export VARIABLE=value”.
2122 The value may optionally be enclosed in single or double
2123 quotes. Variables in this file are only added if the vari‐
2124 able does not already exist in the environment. This file
2125 is considered to be part of the security policy, its con‐
2126 tents are not subject to other sudo environment restric‐
2127 tions such as env_keep and env_check.
2128 exempt_group Users in this group are exempt from password and PATH re‐
2130 quirements. The group name specified should not include a
2131 % prefix. This is not set by default.
2132 fdexec Determines whether sudo will execute a command by its path
2134 or by an open file descriptor. It has the following possi‐
2135 ble values:
2136 always Always execute by file descriptor.
2138 never Never execute by file descriptor.
2140 digest_only
2142 Only execute by file descriptor if the command has
2143 an associated digest in the sudoers file.
2144 The default value is digest_only. This avoids a time of
2146 check versus time of use race condition when the command is
2147 located in a directory writable by the invoking user.
2148 Note that fdexec will change the first element of the argu‐
2150 ment vector for scripts ($0 in the shell) due to the way
2151 the kernel runs script interpreters. Instead of being a
2152 normal path, it will refer to a file descriptor. For exam‐
2153 ple, /dev/fd/4 on Solaris and /proc/self/fd/4 on Linux. A
2154 workaround is to use the SUDO_COMMAND environment variable
2155 instead.
2156 The fdexec setting is only used when the command is matched
2158 by path name. It has no effect if the command is matched
2159 by the built-in ALL alias.
2160 This setting is only supported by version 1.8.20 or higher.
2162 If the operating system does not support the fexecve(2)
2163 system call, this setting has no effect.
2164 group_plugin A string containing a sudoers group plugin with optional
2166 arguments. The string should consist of the plugin path,
2167 either fully-qualified or relative to the /usr/libexec/sudo
2168 directory, followed by any configuration arguments the
2169 plugin requires. These arguments (if any) will be passed
2170 to the plugin's initialization function. If arguments are
2171 present, the string must be enclosed in double quotes ("").
2172 For more information see GROUP PROVIDER PLUGINS.
2174 lecture This option controls when a short lecture will be printed
2176 along with the password prompt. It has the following pos‐
2177 sible values:
2178 always Always lecture the user.
2180 never Never lecture the user.
2182 once Only lecture the user the first time they run sudo.
2184 If no value is specified, a value of once is implied.
2186 Negating the option results in a value of never being used.
2187 The default value is once.
2188 lecture_file Path to a file containing an alternate sudo lecture that
2190 will be used in place of the standard lecture if the named
2191 file exists. By default, sudo uses a built-in lecture.
2192 listpw This option controls when a password will be required when
2194 a user runs sudo with the -l option. It has the following
2195 possible values:
2196 all All the user's sudoers file entries for the cur‐
2198 rent host must have the NOPASSWD flag set to
2199 avoid entering a password.
2200 always The user must always enter a password to use the
2202 -l option.
2203 any At least one of the user's sudoers file entries
2205 for the current host must have the NOPASSWD flag
2206 set to avoid entering a password.
2207 never The user need never enter a password to use the
2209 -l option.
2210 If no value is specified, a value of any is implied.
2212 Negating the option results in a value of never being used.
2213 The default value is any.
2214 log_format The event log format. Supported log formats are:
2216 json Logs in JSON format. JSON log entries contain
2218 the full user details as well as the execution
2219 environment if the command was allowed. Due to
2220 limitations of the protocol, JSON events sent via
2221 syslog may be truncated.
2222 sudo Traditional sudo-style logs, see LOG FORMAT for a
2224 description of the log file format.
2225 This setting affects logs sent via syslog(3) as well as the
2227 file specified by the logfile setting, if any. The default
2228 value is sudo.
2229 logfile Path to the sudo log file (not the syslog log file). Set‐
2231 ting a path turns on logging to a file; negating this op‐
2232 tion turns it off. By default, sudo logs via syslog.
2233 mailerflags Flags to use when invoking mailer. Defaults to -t.
2235 mailerpath Path to mail program used to send warning mail. Defaults
2237 to the path to sendmail found at configure time.
2238 mailfrom Address to use for the “from” address when sending warning
2240 and error mail. The address should be enclosed in double
2241 quotes ("") to protect against sudo interpreting the @
2242 sign. Defaults to the name of the user running sudo.
2243 mailto Address to send warning and error mail to. The address
2245 should be enclosed in double quotes ("") to protect against
2246 sudo interpreting the @ sign. Defaults to root.
2247 restricted_env_file
2249 The restricted_env_file option specifies the fully quali‐
2250 fied path to a file containing variables to be set in the
2251 environment of the program being run. Entries in this file
2252 should either be of the form “VARIABLE=value” or “export
2253 VARIABLE=value”. The value may optionally be enclosed in
2254 single or double quotes. Variables in this file are only
2255 added if the variable does not already exist in the envi‐
2256 ronment. Unlike env_file, the file's contents are not
2257 trusted and are processed in a manner similar to that of
2258 the invoking user's environment. If env_reset is enabled,
2259 variables in the file will only be added if they are
2260 matched by either the env_check or env_keep list. If
2261 env_reset is disabled, variables in the file are added as
2262 long as they are not matched by the env_delete list. In
2263 either case, the contents of restricted_env_file are pro‐
2264 cessed before the contents of env_file.
2265 runchroot If set, sudo will use this value for the root directory
2267 when running a command. The special value “*” will allow
2268 the user to specify the root directory via sudo's -R op‐
2269 tion. See the Chroot_Spec section for more details.
2270 It is only possible to use runchroot as a command-specific
2272 Defaults setting if the command exists with the same path
2273 both inside and outside the chroot jail. This restriction
2274 does not apply to generic, host or user-based Defaults set‐
2275 tings or to a Cmnd_Spec that includes a Chroot_Spec.
2276 This setting is only supported by version 1.9.3 or higher.
2278 runcwd If set, sudo will use this value for the working directory
2280 when running a command. The special value “*” will allow
2281 the user to specify the working directory via sudo's -D op‐
2282 tion. See the Chdir_Spec section for more details.
2283 This setting is only supported by version 1.9.3 or higher.
2285 secure_path If set, sudo will use this value in place of the user's
2287 PATH environment variable. This option can be used to re‐
2288 set the PATH to a known good value that contains directo‐
2289 ries for system administrator commands such as /usr/sbin.
2290 Users in the group specified by the exempt_group option are
2292 not affected by secure_path. This option is not set by de‐
2293 fault.
2294 syslog Syslog facility if syslog is being used for logging (negate
2296 to disable syslog logging). Defaults to authpriv.
2297 The following syslog facilities are supported: authpriv (if
2299 your OS supports it), auth, daemon, user, local0, local1,
2300 local2, local3, local4, local5, local6, and local7.
2301 syslog_badpri
2303 Syslog priority to use when the user is not allowed to run
2304 a command or when authentication is unsuccessful. Defaults
2305 to alert.
2306 The following syslog priorities are supported: alert, crit,
2308 debug, emerg, err, info, notice, warning, and none. Negat‐
2309 ing the option or setting it to a value of none will dis‐
2310 able logging of unsuccessful commands.
2311 syslog_goodpri
2313 Syslog priority to use when the user is allowed to run a
2314 command and authentication is successful. Defaults to
2315 notice.
2316 See syslog_badpri for the list of supported syslog priori‐
2318 ties. Negating the option or setting it to a value of none
2319 will disable logging of successful commands.
2320 verifypw This option controls when a password will be required when
2322 a user runs sudo with the -v option. It has the following
2323 possible values:
2324 all All the user's sudoers file entries for the current
2326 host must have the NOPASSWD flag set to avoid en‐
2327 tering a password.
2328 always The user must always enter a password to use the -v
2330 option.
2331 any At least one of the user's sudoers file entries for
2333 the current host must have the NOPASSWD flag set to
2334 avoid entering a password.
2335 never The user need never enter a password to use the -v
2337 option.
2338 If no value is specified, a value of all is implied.
2340 Negating the option results in a value of never being used.
2341 The default value is all.
2342 Lists that can be used in a boolean context:
2344 env_check Environment variables to be removed from the user's en‐
2346 vironment unless they are considered “safe”. For all
2347 variables except TZ, “safe” means that the variable's
2348 value does not contain any ‘%’ or ‘/’ characters. This
2349 can be used to guard against printf-style format vul‐
2350 nerabilities in poorly-written programs. The TZ vari‐
2351 able is considered unsafe if any of the following are
2352 true:
2353 • It consists of a fully-qualified path name, option‐
2355 ally prefixed with a colon (‘:’), that does not
2356 match the location of the zoneinfo directory.
2357 • It contains a .. path element.
2359 • It contains white space or non-printable characters.
2361 • It is longer than the value of PATH_MAX.
2363 The argument may be a double-quoted, space-separated
2365 list or a single value without double-quotes. The list
2366 can be replaced, added to, deleted from, or disabled by
2367 using the =, +=, -=, and ! operators respectively. Re‐
2368 gardless of whether the env_reset option is enabled or
2369 disabled, variables specified by env_check will be pre‐
2370 served in the environment if they pass the aforemen‐
2371 tioned check. The global list of environment variables
2372 to check is displayed when sudo is run by root with the
2373 -V option.
2374 env_delete Environment variables to be removed from the user's en‐
2376 vironment when the env_reset option is not in effect.
2377 The argument may be a double-quoted, space-separated
2378 list or a single value without double-quotes. The list
2379 can be replaced, added to, deleted from, or disabled by
2380 using the =, +=, -=, and ! operators respectively. The
2381 global list of environment variables to remove is dis‐
2382 played when sudo is run by root with the -V option.
2383 Note that many operating systems will remove poten‐
2384 tially dangerous variables from the environment of any
2385 set-user-ID process (such as sudo).
2386 env_keep Environment variables to be preserved in the user's en‐
2388 vironment when the env_reset option is in effect. This
2389 allows fine-grained control over the environment
2390 sudo-spawned processes will receive. The argument may
2391 be a double-quoted, space-separated list or a single
2392 value without double-quotes. The list can be replaced,
2393 added to, deleted from, or disabled by using the =, +=,
2394 -=, and ! operators respectively. The global list of
2395 variables to keep is displayed when sudo is run by root
2396 with the -V option.
2397 Preserving the HOME environment variable has security
2399 implications since many programs use it when searching
2400 for configuration or data files. Adding HOME to
2401 env_keep may enable a user to run unrestricted commands
2402 via sudo and is strongly discouraged. Users wishing to
2403 edit files with sudo should run sudoedit (or sudo -e)
2404 to get their accustomed editor configuration instead of
2405 invoking the editor directly.
2406 log_servers A list of one or more servers to use for remote event
2408 and I/O log storage, separated by white space. Log
2409 servers must be running sudo_logsrvd or another service
2410 that implements the protocol described by
2411 sudo_logsrv.proto(5).
2412 Server addresses should be of the form
2414 “host[:port][(tls)]”. The host portion may be a host
2415 name, an IPv4 address, or an IPv6 address in square
2416 brackets.
2417 If the optional tls flag is present, the connection
2419 will be secured with Transport Layer Security (TLS)
2420 version 1.2 or 1.3. Versions of TLS prior to 1.2 are
2421 not supported.
2422 If a port is specified, it may either be a port number
2424 or a well-known service name as defined by the system
2425 service name database. If no port is specified, port
2426 30343 will be used for plaintext connections and port
2427 30344 will be used for TLS connections.
2428 When log_servers is set, event log data will be logged
2430 both locally (see the syslog and log_file settings) as
2431 well as remotely, but I/O log data will only be logged
2432 remotely. If multiple hosts are specified, they will
2433 be attempted in reverse order. If no log servers are
2434 available, the user will not be able to run a command
2435 unless either the ignore_iolog_errors flag (I/O logging
2436 enabled) or the ignore_log_errors flag (I/O logging
2437 disabled) is set. Likewise, if the connection to the
2438 log server is interrupted while sudo is running, the
2439 command will be terminated unless the
2440 ignore_iolog_errors flag (I/O logging enabled) or the
2441 ignore_log_errors flag (I/O logging disabled) is set.
2442 This setting is only supported by version 1.9.0 or
2444 higher.
2445
2447 The sudoers plugin supports its own plugin interface to allow non-Unix
2448 group lookups which can query a group source other than the standard Unix
2449 group database. This can be used to implement support for the
2450 nonunix_group syntax described earlier.
2451 Group provider plugins are specified via the group_plugin setting. The
2453 argument to group_plugin should consist of the plugin path, either fully-
2454 qualified or relative to the /usr/libexec/sudo directory, followed by any
2455 configuration options the plugin requires. These options (if specified)
2456 will be passed to the plugin's initialization function. If options are
2457 present, the string must be enclosed in double quotes ("").
2458 The following group provider plugins are installed by default:
2460 group_file
2462 The group_file plugin supports an alternate group file that
2463 uses the same syntax as the /etc/group file. The path to the
2464 group file should be specified as an option to the plugin. For
2465 example, if the group file to be used is /etc/sudo-group:
2466 Defaults group_plugin="group_file.so /etc/sudo-group"
2468 system_group
2470 The system_group plugin supports group lookups via the standard
2471 C library functions getgrnam() and getgrid(). This plugin can
2472 be used in instances where the user belongs to groups not
2473 present in the user's supplemental group vector. This plugin
2474 takes no options:
2475 Defaults group_plugin=system_group.so
2477 The group provider plugin API is described in detail in sudo_plugin(5).
2479
2481 sudoers can log events in either JSON or sudo format, this section de‐
2482 scribes the sudo log format. Depending on sudoers configuration, sudoers
2483 can log events via syslog(3), to a local log file, or both. The log for‐
2484 mat is almost identical in both cases.
2485 Accepted command log entries
2487 Commands that sudo runs are logged using the following format (split into
2488 multiple lines for readability):
2489 date hostname progname: username : TTY=ttyname ; PWD=cwd ; \
2491 USER=runasuser ; GROUP=runasgroup ; TSID=logid ; \
2492 ENV=env_vars COMMAND=command
2493 Where the fields are as follows:
2495 date The date the command was run. Typically, this is in the
2497 format “MMM, DD, HH:MM:SS”. If logging via syslog(3), the
2498 actual date format is controlled by the syslog daemon. If
2499 logging to a file and the log_year option is enabled, the
2500 date will also include the year.
2501 hostname The name of the host sudo was run on. This field is only
2503 present when logging via syslog(3).
2504 progname The name of the program, usually sudo or sudoedit. This
2506 field is only present when logging via syslog(3).
2507 username The login name of the user who ran sudo.
2509 ttyname The short name of the terminal (e.g., “console”, “tty01”,
2511 or “pts/0”) sudo was run on, or “unknown” if there was no
2512 terminal present.
2513 cwd The current working directory that sudo was run in.
2515 runasuser The user the command was run as.
2517 runasgroup The group the command was run as if one was specified on
2519 the command line.
2520 logid An I/O log identifier that can be used to replay the com‐
2522 mand's output. This is only present when the log_input or
2523 log_output option is enabled.
2524 env_vars A list of environment variables specified on the command
2526 line, if specified.
2527 command The actual command that was executed.
2529 Messages are logged using the locale specified by sudoers_locale, which
2531 defaults to the “C” locale.
2532 Denied command log entries
2534 If the user is not allowed to run the command, the reason for the denial
2535 will follow the user name. Possible reasons include:
2536 user NOT in sudoers
2538 The user is not listed in the sudoers file.
2539 user NOT authorized on host
2541 The user is listed in the sudoers file but is not allowed to run com‐
2542 mands on the host.
2543 command not allowed
2545 The user is listed in the sudoers file for the host but they are not
2546 allowed to run the specified command.
2547 3 incorrect password attempts
2549 The user failed to enter their password after 3 tries. The actual num‐
2550 ber of tries will vary based on the number of failed attempts and the
2551 value of the passwd_tries option.
2552 a password is required
2554 The -n option was specified but a password was required.
2555 sorry, you are not allowed to set the following environment variables
2557 The user specified environment variables on the command line that were
2558 not allowed by sudoers.
2559 Error log entries
2561 If an error occurs, sudoers will log a message and, in most cases, send a
2562 message to the administrator via email. Possible errors include:
2563 parse error in /etc/sudoers near line N
2565 sudoers encountered an error when parsing the specified file. In some
2566 cases, the actual error may be one line above or below the line number
2567 listed, depending on the type of error.
2568 problem with defaults entries
2570 The sudoers file contains one or more unknown Defaults settings. This
2571 does not prevent sudo from running, but the sudoers file should be
2572 checked using visudo.
2573 timestamp owner (username): No such user
2575 The time stamp directory owner, as specified by the timestampowner set‐
2576 ting, could not be found in the password database.
2577 unable to open/read /etc/sudoers
2579 The sudoers file could not be opened for reading. This can happen when
2580 the sudoers file is located on a remote file system that maps user-ID 0
2581 to a different value. Normally, sudoers tries to open the sudoers file
2582 using group permissions to avoid this problem. Consider either chang‐
2583 ing the ownership of /etc/sudoers or adding an argument like
2584 “sudoers_uid=N” (where ‘N’ is the user-ID that owns the sudoers file)
2585 to the end of the sudoers Plugin line in the sudo.conf(5) file.
2586 unable to stat /etc/sudoers
2588 The /etc/sudoers file is missing.
2589 /etc/sudoers is not a regular file
2591 The /etc/sudoers file exists but is not a regular file or symbolic
2592 link.
2593 /etc/sudoers is owned by uid N, should be 0
2595 The sudoers file has the wrong owner. If you wish to change the
2596 sudoers file owner, please add “sudoers_uid=N” (where ‘N’ is the user-
2597 ID that owns the sudoers file) to the sudoers Plugin line in the
2598 sudo.conf(5) file.
2599 /etc/sudoers is world writable
2601 The permissions on the sudoers file allow all users to write to it.
2602 The sudoers file must not be world-writable, the default file mode is
2603 0440 (readable by owner and group, writable by none). The default mode
2604 may be changed via the “sudoers_mode” option to the sudoers Plugin line
2605 in the sudo.conf(5) file.
2606 /etc/sudoers is owned by gid N, should be 1
2608 The sudoers file has the wrong group ownership. If you wish to change
2609 the sudoers file group ownership, please add “sudoers_gid=N” (where ‘N’
2610 is the group-ID that owns the sudoers file) to the sudoers Plugin line
2611 in the sudo.conf(5) file.
2612 unable to open /run/sudo/ts/username
2614 sudoers was unable to read or create the user's time stamp file. This
2615 can happen when timestampowner is set to a user other than root and the
2616 mode on /run/sudo is not searchable by group or other. The default
2617 mode for /run/sudo is 0711.
2618 unable to write to /run/sudo/ts/username
2620 sudoers was unable to write to the user's time stamp file.
2621 /run/sudo/ts is owned by uid X, should be Y
2623 The time stamp directory is owned by a user other than timestampowner.
2624 This can occur when the value of timestampowner has been changed.
2625 sudoers will ignore the time stamp directory until the owner is cor‐
2626 rected.
2627 /run/sudo/ts is group writable
2629 The time stamp directory is group-writable; it should be writable only
2630 by timestampowner. The default mode for the time stamp directory is
2631 0700. sudoers will ignore the time stamp directory until the mode is
2632 corrected.
2633 Notes on logging via syslog
2635 By default, sudoers logs messages via syslog(3). The date, hostname, and
2636 progname fields are added by the system's syslog() function, not sudoers
2637 itself. As such, they may vary in format on different systems.
2638 The maximum size of syslog messages varies from system to system. The
2640 syslog_maxlen setting can be used to change the maximum syslog message
2641 size from the default value of 980 bytes. For more information, see the
2642 description of syslog_maxlen.
2643 Notes on logging to a file
2645 If the logfile option is set, sudoers will log to a local file, such as
2646 /var/log/sudo. When logging to a file, sudoers uses a format similar to
2647 syslog(3), with a few important differences:
2648 1. The progname and hostname fields are not present.
2650 2. If the log_year option is enabled, the date will also include the
2652 year.
2653 3. Lines that are longer than loglinelen characters (80 by default) are
2655 word-wrapped and continued on the next line with a four character
2656 indent. This makes entries easier to read for a human being, but
2657 makes it more difficult to use grep(1) on the log files. If the
2658 loglinelen option is set to 0 (or negated with a ‘!’), word wrap
2659 will be disabled.
2660
2662 When I/O logging is enabled, sudo will run the command in a pseudo-termi‐
2663 nal and log all user input and/or output, depending on which options are
2664 enabled. I/O can be logged either to the local machine or to a remote
2665 log server. For local logs, I/O is logged to the directory specified by
2666 the iolog_dir option (/var/log/sudo-io by default) using a unique session
2667 ID that is included in the sudo log line, prefixed with “TSID=”. The
2668 iolog_file option may be used to control the format of the session ID.
2669 For remote logs, the log_servers setting is used to specify one or more
2670 log servers running sudo_logsrvd or another server that implements the
2671 protocol described by sudo_logsrv.proto(5).
2672 For both local and remote I/O logs, each log is stored in a separate di‐
2674 rectory that contains the following files:
2675 log A text file containing information about the command. The
2677 first line consists of the following colon-delimited fields:
2678 the time the command was run, the name of the user who ran
2679 sudo, the name of the target user, the name of the target group
2680 (optional), the terminal that sudo was run from, and the number
2681 of lines and columns of the terminal. The second and third
2682 lines contain the working directory the command was run from
2683 and the path name of the command itself (with arguments if
2684 present).
2685 log.json A JSON-formatted file containing information about the command.
2687 This is similar to the log file but contains additional infor‐
2688 mation and is easily extensible. The log.json file will be
2689 used by sudoreplay(8) in preference to the log file if it ex‐
2690 ists. The file may contain the following elements:
2691 timestamp
2693 A JSON object containing time the command was run.
2694 It consists of two values, seconds and nanoseconds.
2695 columns The number of columns of the terminal the command ran
2697 on, or zero if no terminal was present.
2698 command The fully-qualified path of the command that was run.
2700 lines The number of lines of the terminal the command ran
2702 on, or zero if no terminal was present.
2703 runargv A JSON array representing the command's argument vec‐
2705 tor as passed to the execve(2) system call.
2706 runenv A JSON array representing the command's environment
2708 as passed to the execve(2) system call.
2709 rungid The group ID the command ran as. This element is
2711 only present when the user specifies a group on the
2712 command line.
2713 rungroup The name of the group the command ran as. This ele‐
2715 ment is only present when the user specifies a group
2716 on the command line.
2717 runuid The user ID the command ran as.
2719 runuser The name of the user the command ran as.
2721 submitcwd
2723 The current working directory at the time sudo was
2724 run.
2725 submithost
2727 The name of the host the command was run on.
2728 submituser
2730 The name of the user who ran the command via sudo.
2731 ttyname The path name of the terminal the user invoked sudo
2733 from. If the command was run in a pseudo-terminal,
2734 ttyname will be different from the terminal the com‐
2735 mand actually ran in.
2736 timing Timing information used to replay the session. Each line con‐
2738 sists of the I/O log entry type and amount of time since the
2739 last entry, followed by type-specific data. The I/O log entry
2740 types and their corresponding type-specific data are:
2741 0 standard input, number of bytes in the entry
2743 1 standard output, number of bytes in the entry
2744 2 standard error, number of bytes in the entry
2745 3 terminal input, number of bytes in the entry
2746 4 terminal output, number of bytes in the entry
2747 5 window change, new number lines and columns
2748 6 bug compatibility for sudo 1.8.7 terminal output
2749 7 command suspend or resume, signal received
2750 ttyin Raw input from the user's terminal, exactly as it was received.
2752 No post-processing is performed. For manual viewing, you may
2753 wish to convert carriage return characters in the log to line
2754 feeds. For example: ‘gunzip -c ttyin | tr "\r" "\n"’
2755 stdin The standard input when no terminal is present, or input redi‐
2757 rected from a pipe or file.
2758 ttyout Output from the pseudo-terminal (what the command writes to the
2760 screen). Note that terminal-specific post-processing is per‐
2761 formed before the data is logged. This means that, for exam‐
2762 ple, line feeds are usually converted to line feed/carriage re‐
2763 turn pairs and tabs may be expanded to spaces.
2764 stdout The standard output when no terminal is present, or output
2766 redirected to a pipe or file.
2767 stderr The standard error redirected to a pipe or file.
2769 All files other than log are compressed in gzip format unless the
2771 compress_io flag has been disabled. Due to buffering, it is not normally
2772 possible to display the I/O logs in real-time as the program is execut‐
2773 ing. The I/O log data will not be complete until the program run by sudo
2774 has exited or has been terminated by a signal. The iolog_flush flag can
2775 be used to disable buffering, in which case I/O log data is written to
2776 disk as soon as it is available. The output portion of an I/O log file
2777 can be viewed with the sudoreplay(8) utility, which can also be used to
2778 list or search the available logs.
2779 Note that user input may contain sensitive information such as passwords
2781 (even if they are not echoed to the screen), which will be stored in the
2782 log file unencrypted. In most cases, logging the command output via
2783 log_output or LOG_OUTPUT is all that is required.
2784 Since each session's I/O logs are stored in a separate directory, tradi‐
2786 tional log rotation utilities cannot be used to limit the number of I/O
2787 logs. The simplest way to limit the number of I/O is by setting the
2788 maxseq option to the maximum number of logs you wish to store. Once the
2789 I/O log sequence number reaches maxseq, it will be reset to zero and
2790 sudoers will truncate and re-use any existing I/O logs.
2791
2793 /etc/sudo.conf Sudo front end configuration
2794 /etc/sudoers List of who can run what
2796 /etc/group Local groups file
2798 /etc/netgroup List of network groups
2800 /var/log/sudo-io I/O log files
2802 /run/sudo/ts Directory containing time stamps for the
2804 sudoers security policy
2805 /var/db/sudo/lectured Directory containing lecture status files for
2807 the sudoers security policy
2808 /etc/environment Initial environment for -i mode on AIX and
2810 Linux systems
2811
2813 Below are example sudoers file entries. Admittedly, some of these are a
2814 bit contrived. First, we allow a few environment variables to pass and
2815 then define our aliases:
2816 # Run X applications through sudo; HOME is used to find the
2818 # .Xauthority file. Note that other programs use HOME to find
2819 # configuration files and this may lead to privilege escalation!
2820 Defaults env_keep += "DISPLAY HOME"
2821 # User alias specification
2823 User_Alias FULLTIMERS = millert, mikef, dowdy
2824 User_Alias PARTTIMERS = bostley, jwfox, crawl
2825 User_Alias WEBADMIN = will, wendy, wim
2826 # Runas alias specification
2828 Runas_Alias OP = root, operator
2829 Runas_Alias DB = oracle, sybase
2830 Runas_Alias ADMINGRP = adm, oper
2831 # Host alias specification
2833 Host_Alias SPARC = bigtime, eclipse, moet, anchor :\
2834 SGI = grolsch, dandelion, black :\
2835 ALPHA = widget, thalamus, foobar :\
2836 HPPA = boa, nag, python
2837 Host_Alias CUNETS = 128.138.0.0/255.255.0.0
2838 Host_Alias CSNETS = 128.138.243.0, 128.138.204.0/24, 128.138.242.0
2839 Host_Alias SERVERS = primary, mail, www, ns
2840 Host_Alias CDROM = orion, perseus, hercules
2841 # Cmnd alias specification
2843 Cmnd_Alias DUMPS = /usr/bin/mt, /usr/sbin/dump, /usr/sbin/rdump,\
2844 /usr/sbin/restore, /usr/sbin/rrestore,\
2845 sha224:0GomF8mNN3wlDt1HD9XldjJ3SNgpFdbjO1+NsQ== \
2846 /home/operator/bin/start_backups
2847 Cmnd_Alias KILL = /usr/bin/kill
2848 Cmnd_Alias PRINTING = /usr/sbin/lpc, /usr/bin/lprm
2849 Cmnd_Alias SHUTDOWN = /usr/sbin/shutdown
2850 Cmnd_Alias HALT = /usr/sbin/halt
2851 Cmnd_Alias REBOOT = /usr/sbin/reboot
2852 Cmnd_Alias SHELLS = /usr/bin/sh, /usr/bin/csh, /usr/bin/ksh,\
2853 /usr/local/bin/tcsh, /usr/bin/rsh,\
2854 /usr/local/bin/zsh
2855 Cmnd_Alias SU = /usr/bin/su
2856 Cmnd_Alias PAGERS = /usr/bin/more, /usr/bin/pg, /usr/bin/less
2857 Here we override some of the compiled in default values. We want sudo to
2859 log via syslog(3) using the auth facility in all cases and for commands
2860 to be run with the target user's home directory as the working directory.
2861 We don't want to subject the full time staff to the sudo lecture and we
2862 want to allow them to run commands in a chroot(2) “sandbox” via the -R
2863 option. User millert need not provide a password and we don't want to
2864 reset the LOGNAME or USER environment variables when running commands as
2865 root. Additionally, on the machines in the SERVERS Host_Alias, we keep
2866 an additional local log file and make sure we log the year in each log
2867 line since the log entries will be kept around for several years.
2868 Lastly, we disable shell escapes for the commands in the PAGERS
2869 Cmnd_Alias (/usr/bin/more, /usr/bin/pg and /usr/bin/less). Note that
2870 this will not effectively constrain users with sudo ALL privileges.
2871 # Override built-in defaults
2873 Defaults syslog=auth,runcwd=~
2874 Defaults>root !set_logname
2875 Defaults:FULLTIMERS !lecture,runchroot=*
2876 Defaults:millert !authenticate
2877 Defaults@SERVERS log_year, logfile=/var/log/sudo.log
2878 Defaults!PAGERS noexec
2879 The User specification is the part that actually determines who may run
2881 what.
2882 root ALL = (ALL) ALL
2884 %wheel ALL = (ALL) ALL
2885 We let root and any user in group wheel run any command on any host as
2887 any user.
2888 FULLTIMERS ALL = NOPASSWD: ALL
2890 Full time sysadmins (millert, mikef, and dowdy) may run any command on
2892 any host without authenticating themselves.
2893 PARTTIMERS ALL = ALL
2895 Part time sysadmins bostley, jwfox, and crawl) may run any command on any
2897 host but they must authenticate themselves first (since the entry lacks
2898 the NOPASSWD tag).
2899 jack CSNETS = ALL
2901 The user jack may run any command on the machines in the CSNETS alias
2903 (the networks 128.138.243.0, 128.138.204.0, and 128.138.242.0). Of those
2904 networks, only 128.138.204.0 has an explicit netmask (in CIDR notation)
2905 indicating it is a class C network. For the other networks in CSNETS,
2906 the local machine's netmask will be used during matching.
2907 lisa CUNETS = ALL
2909 The user lisa may run any command on any host in the CUNETS alias (the
2911 class B network 128.138.0.0).
2912 operator ALL = DUMPS, KILL, SHUTDOWN, HALT, REBOOT, PRINTING,\
2914 sudoedit /etc/printcap, /usr/oper/bin/
2915 The operator user may run commands limited to simple maintenance. Here,
2917 those are commands related to backups, killing processes, the printing
2918 system, shutting down the system, and any commands in the directory
2919 /usr/oper/bin/. Note that one command in the DUMPS Cmnd_Alias includes a
2920 sha224 digest, /home/operator/bin/start_backups. This is because the di‐
2921 rectory containing the script is writable by the operator user. If the
2922 script is modified (resulting in a digest mismatch) it will no longer be
2923 possible to run it via sudo.
2924 joe ALL = /usr/bin/su operator
2926 The user joe may only su(1) to operator.
2928 pete HPPA = /usr/bin/passwd [A-Za-z]*, !/usr/bin/passwd *root*
2930 %opers ALL = (: ADMINGRP) /usr/sbin/
2932 Users in the opers group may run commands in /usr/sbin/ as themselves
2934 with any group in the ADMINGRP Runas_Alias (the adm and oper groups).
2935 The user pete is allowed to change anyone's password except for root on
2937 the HPPA machines. Because command line arguments are matched as a sin‐
2938 gle, concatenated string, the ‘*’ wildcard will match multiple words.
2939 This example assumes that passwd(1) does not take multiple user names on
2940 the command line. Note that on GNU systems, options to passwd(1) may be
2941 specified after the user argument. As a result, this rule will also al‐
2942 low:
2943 passwd username --expire
2945 which may not be desirable.
2947 bob SPARC = (OP) ALL : SGI = (OP) ALL
2949 The user bob may run anything on the SPARC and SGI machines as any user
2951 listed in the OP Runas_Alias (root and operator.)
2952 jim +biglab = ALL
2954 The user jim may run any command on machines in the biglab netgroup.
2956 sudo knows that “biglab” is a netgroup due to the ‘+’ prefix.
2957 +secretaries ALL = PRINTING, /usr/bin/adduser, /usr/bin/rmuser
2959 Users in the secretaries netgroup need to help manage the printers as
2961 well as add and remove users, so they are allowed to run those commands
2962 on all machines.
2963 fred ALL = (DB) NOPASSWD: ALL
2965 The user fred can run commands as any user in the DB Runas_Alias (oracle
2967 or sybase) without giving a password.
2968 john ALPHA = /usr/bin/su [!-]*, !/usr/bin/su *root*
2970 On the ALPHA machines, user john may su to anyone except root but he is
2972 not allowed to specify any options to the su(1) command.
2973 jen ALL, !SERVERS = ALL
2975 The user jen may run any command on any machine except for those in the
2977 SERVERS Host_Alias (primary, mail, www and ns).
2978 jill SERVERS = /usr/bin/, !SU, !SHELLS
2980 For any machine in the SERVERS Host_Alias, jill may run any commands in
2982 the directory /usr/bin/ except for those commands belonging to the SU and
2983 SHELLS Cmnd_Aliases. While not specifically mentioned in the rule, the
2984 commands in the PAGERS Cmnd_Alias all reside in /usr/bin and have the
2985 noexec option set.
2986 steve CSNETS = (operator) /usr/local/op_commands/
2988 The user steve may run any command in the directory /usr/local/op_com‐
2990 mands/ but only as user operator.
2991 matt valkyrie = KILL
2993 On his personal workstation, valkyrie, matt needs to be able to kill hung
2995 processes.
2996 WEBADMIN www = (www) ALL, (root) /usr/bin/su www
2998 On the host www, any user in the WEBADMIN User_Alias (will, wendy, and
3000 wim), may run any command as user www (which owns the web pages) or sim‐
3001 ply su(1) to www.
3002 ALL CDROM = NOPASSWD: /sbin/umount /CDROM,\
3004 /sbin/mount -o nosuid\,nodev /dev/cd0a /CDROM
3005 Any user may mount or unmount a CD-ROM on the machines in the CDROM
3007 Host_Alias (orion, perseus, hercules) without entering a password. This
3008 is a bit tedious for users to type, so it is a prime candidate for encap‐
3009 sulating in a shell script.
3010
3012 Limitations of the ‘!’ operator
3013 It is generally not effective to “subtract” commands from ALL using the
3014 ‘!’ operator. A user can trivially circumvent this by copying the de‐
3015 sired command to a different name and then executing that. For example:
3016 bill ALL = ALL, !SU, !SHELLS
3018 Doesn't really prevent bill from running the commands listed in SU or
3020 SHELLS since he can simply copy those commands to a different name, or
3021 use a shell escape from an editor or other program. Therefore, these
3022 kind of restrictions should be considered advisory at best (and rein‐
3023 forced by policy).
3024 In general, if a user has sudo ALL there is nothing to prevent them from
3026 creating their own program that gives them a root shell (or making their
3027 own copy of a shell) regardless of any ‘!’ elements in the user specifi‐
3028 cation.
3029 Security implications of fast_glob
3031 If the fast_glob option is in use, it is not possible to reliably negate
3032 commands where the path name includes globbing (aka wildcard) characters.
3033 This is because the C library's fnmatch(3) function cannot resolve rela‐
3034 tive paths. While this is typically only an inconvenience for rules that
3035 grant privileges, it can result in a security issue for rules that sub‐
3036 tract or revoke privileges.
3037 For example, given the following sudoers file entry:
3039 john ALL = /usr/bin/passwd [a-zA-Z0-9]*, /usr/bin/chsh [a-zA-Z0-9]*,\
3041 /usr/bin/chfn [a-zA-Z0-9]*, !/usr/bin/* root
3042 User john can still run /usr/bin/passwd root if fast_glob is enabled by
3044 changing to /usr/bin and running ./passwd root instead.
3045 Preventing shell escapes
3047 Once sudo executes a program, that program is free to do whatever it
3048 pleases, including run other programs. This can be a security issue
3049 since it is not uncommon for a program to allow shell escapes, which lets
3050 a user bypass sudo's access control and logging. Common programs that
3051 permit shell escapes include shells (obviously), editors, paginators,
3052 mail and terminal programs.
3053 There are two basic approaches to this problem:
3055 restrict Avoid giving users access to commands that allow the user to
3057 run arbitrary commands. Many editors have a restricted mode
3058 where shell escapes are disabled, though sudoedit is a better
3059 solution to running editors via sudo. Due to the large number
3060 of programs that offer shell escapes, restricting users to the
3061 set of programs that do not is often unworkable.
3062 noexec Many systems that support shared libraries have the ability to
3064 override default library functions by pointing an environment
3065 variable (usually LD_PRELOAD) to an alternate shared library.
3066 On such systems, sudo's noexec functionality can be used to
3067 prevent a program run by sudo from executing any other pro‐
3068 grams. Note, however, that this applies only to dynamically-
3069 linked executables. Statically-linked executables and executa‐
3070 bles running under binary emulation are not affected.
3071 The noexec feature is known to work on SunOS, Solaris, *BSD,
3073 Linux, IRIX, Tru64 UNIX, macOS, HP-UX 11.x and AIX 5.3 and
3074 above. It should be supported on most operating systems that
3075 support the LD_PRELOAD environment variable. Check your oper‐
3076 ating system's manual pages for the dynamic linker (usually
3077 ld.so, ld.so.1, dyld, dld.sl, rld, or loader) to see if
3078 LD_PRELOAD is supported.
3079 On Solaris 10 and higher, noexec uses Solaris privileges in‐
3081 stead of the LD_PRELOAD environment variable.
3082 To enable noexec for a command, use the NOEXEC tag as docu‐
3084 mented in the User Specification section above. Here is that
3085 example again:
3086 aaron shanty = NOEXEC: /usr/bin/more, /usr/bin/vi
3088 This allows user aaron to run /usr/bin/more and /usr/bin/vi
3090 with noexec enabled. This will prevent those two commands from
3091 executing other commands (such as a shell). If you are unsure
3092 whether or not your system is capable of supporting noexec you
3093 can always just try it out and check whether shell escapes work
3094 when noexec is enabled.
3095 Note that restricting shell escapes is not a panacea. Programs running
3097 as root are still capable of many potentially hazardous operations (such
3098 as changing or overwriting files) that could lead to unintended privilege
3099 escalation. In the specific case of an editor, a safer approach is to
3100 give the user permission to run sudoedit (see below).
3101 Secure editing
3103 The sudoers plugin includes sudoedit support which allows users to se‐
3104 curely edit files with the editor of their choice. As sudoedit is a
3105 built-in command, it must be specified in the sudoers file without a
3106 leading path. However, it may take command line arguments just as a nor‐
3107 mal command does. Wildcards used in sudoedit command line arguments are
3108 expected to be path names, so a forward slash (‘/’) will not be matched
3109 by a wildcard.
3110 Unlike other sudo commands, the editor is run with the permissions of the
3112 invoking user and with the environment unmodified. More information may
3113 be found in the description of the -e option in sudo(8).
3114 For example, to allow user operator to edit the “message of the day”
3116 file:
3117 operator sudoedit /etc/motd
3119 The operator user then runs sudoedit as follows:
3121 $ sudoedit /etc/motd
3123 The editor will run as the operator user, not root, on a temporary copy
3125 of /etc/motd. After the file has been edited, /etc/motd will be updated
3126 with the contents of the temporary copy.
3127 Users should never be granted sudoedit permission to edit a file that re‐
3129 sides in a directory the user has write access to, either directly or via
3130 a wildcard. If the user has write access to the directory it is possible
3131 to replace the legitimate file with a link to another file, allowing the
3132 editing of arbitrary files. To prevent this, starting with version
3133 1.8.16, symbolic links will not be followed in writable directories and
3134 sudoedit will refuse to edit a file located in a writable directory un‐
3135 less the sudoedit_checkdir option has been disabled or the invoking user
3136 is root. Additionally, in version 1.8.15 and higher, sudoedit will
3137 refuse to open a symbolic link unless either the sudoedit_follow option
3138 is enabled or the sudoedit command is prefixed with the FOLLOW tag in the
3139 sudoers file.
3140 Time stamp file checks
3142 sudoers will check the ownership of its time stamp directory
3143 (/run/sudo/ts by default) and ignore the directory's contents if it is
3144 not owned by root or if it is writable by a user other than root. Older
3145 versions of sudo stored time stamp files in /tmp; this is no longer rec‐
3146 ommended as it may be possible for a user to create the time stamp them‐
3147 selves on systems that allow unprivileged users to change the ownership
3148 of files they create.
3149 While the time stamp directory should be cleared at reboot time, not all
3151 systems contain a /run or /var/run directory. To avoid potential prob‐
3152 lems, sudoers will ignore time stamp files that date from before the ma‐
3153 chine booted on systems where the boot time is available.
3154 Some systems with graphical desktop environments allow unprivileged users
3156 to change the system clock. Since sudoers relies on the system clock for
3157 time stamp validation, it may be possible on such systems for a user to
3158 run sudo for longer than timestamp_timeout by setting the clock back. To
3159 combat this, sudoers uses a monotonic clock (which never moves backwards)
3160 for its time stamps if the system supports it.
3161 sudoers will not honor time stamps set far in the future. Time stamps
3163 with a date greater than current_time + 2 * TIMEOUT will be ignored and
3164 sudoers will log and complain.
3165 If the timestamp_type option is set to “tty”, the time stamp record in‐
3167 cludes the device number of the terminal the user authenticated with.
3168 This provides per-terminal granularity but time stamp records may still
3169 outlive the user's session.
3170 Unless the timestamp_type option is set to “global”, the time stamp
3172 record also includes the session ID of the process that last authenti‐
3173 cated. This prevents processes in different terminal sessions from using
3174 the same time stamp record. On systems where a process's start time can
3175 be queried, the start time of the session leader is recorded in the time
3176 stamp record. If no terminal is present or the timestamp_type option is
3177 set to “ppid”, the start time of the parent process is used instead. In
3178 most cases this will prevent a time stamp record from being re-used with‐
3179 out the user entering a password when logging out and back in again.
3180
3182 Versions 1.8.4 and higher of the sudoers plugin support a flexible debug‐
3183 ging framework that can help track down what the plugin is doing inter‐
3184 nally if there is a problem. This can be configured in the sudo.conf(5)
3185 file.
3186 The sudoers plugin uses the same debug flag format as the sudo front-end:
3188 subsystem@priority.
3189 The priorities used by sudoers, in order of decreasing severity, are:
3191 crit, err, warn, notice, diag, info, trace and debug. Each priority,
3192 when specified, also includes all priorities higher than it. For exam‐
3193 ple, a priority of notice would include debug messages logged at notice
3194 and higher.
3195 The following subsystems are used by the sudoers plugin:
3197 alias User_Alias, Runas_Alias, Host_Alias and Cmnd_Alias processing
3199 all matches every subsystem
3201 audit BSM and Linux audit code
3203 auth user authentication
3205 defaults sudoers file Defaults settings
3207 env environment handling
3209 ldap LDAP-based sudoers
3211 logging logging support
3213 match matching of users, groups, hosts and netgroups in the sudoers
3215 file
3216 netif network interface handling
3218 nss network service switch handling in sudoers
3220 parser sudoers file parsing
3222 perms permission setting
3224 plugin The equivalent of main for the plugin.
3226 pty pseudo-terminal related code
3228 rbtree redblack tree internals
3230 sssd SSSD-based sudoers
3232 util utility functions
3234 For example:
3235 Debug sudo /var/log/sudo_debug match@info,nss@info
3237 For more information, see the sudo.conf(5) manual.
3239
3241 ssh(1), su(1), fnmatch(3), glob(3), mktemp(3), strftime(3), sudo.conf(5),
3242 sudo_plugin(5), sudoers.ldap(5), sudoers_timestamp(5), sudo(8), visudo(8)
3243
3245 Many people have worked on sudo over the years; this version consists of
3246 code written primarily by:
3247 Todd C. Miller
3249 See the CONTRIBUTORS file in the sudo distribution
3251 (https://www.sudo.ws/contributors.html) for an exhaustive list of people
3252 who have contributed to sudo.
3253
3255 The sudoers file should always be edited by the visudo utility which
3256 locks the file and checks for syntax errors. If sudoers contains syntax
3257 errors, sudo may refuse to run, which is a serious problem if sudo is
3258 your only method of obtaining superuser privileges. Recent versions of
3259 sudoers will attempt to recover after a syntax error by ignoring the rest
3260 of the line after encountering an error. Older versions of sudo will not
3261 run if sudoers contains a syntax error.
3262 When using netgroups of machines (as opposed to users), if you store
3264 fully qualified host name in the netgroup (as is usually the case), you
3265 either need to have the machine's host name be fully qualified as re‐
3266 turned by the hostname command or use the fqdn option in sudoers.
3267
3269 If you feel you have found a bug in sudo, please submit a bug report at
3270 https://bugzilla.sudo.ws/
3271
3273 Limited free support is available via the sudo-users mailing list, see
3274 https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search
3275 the archives.
3276
3278 sudo is provided “AS IS” and any express or implied warranties, includ‐
3279 ing, but not limited to, the implied warranties of merchantability and
3280 fitness for a particular purpose are disclaimed. See the LICENSE file
3281 distributed with sudo or https://www.sudo.ws/license.html for complete
3282 details.
3283Sudo 1.9.7p2 May 7, 2021 Sudo 1.9.7p2