sudo's behavior can be modified by Default_Entry lines, as
explained earlier. A list of all supported Defaults parameters,
grouped by type, are listed below.
Boolean Flags:
always_query_group_plugin
If a group_plugin is configured, use it to
resolve groups of the form %group as long as
there is not also a system group of the same
name. Normally, only groups of the form %:group
are passed to the group_plugin. This flag is off
by default.
always_set_home If enabled, sudo will set the HOME environment
variable to the home directory of the target user
(which is the root user unless the -u option is
used). This flag is largely obsolete and has no
effect unless the env_reset flag has been
disabled or HOME is present in the env_keep list,
both of which are strongly discouraged. This
flag is off by default.
authenticate If set, users must authenticate themselves via a
password (or other means of authentication)
before they may run commands. This default may
be overridden via the PASSWD and NOPASSWD tags.
This flag is on by default.
case_insensitive_group
If enabled, group names in sudoers will be
matched in a case insensitive manner. This may
be necessary when users are stored in LDAP or AD.
This flag is on by default.
case_insensitive_user
If enabled, user names in sudoers will be matched
in a case insensitive manner. This may be
necessary when groups are stored in LDAP or AD.
This flag is on by default.
closefrom_override
If set, the user may use the -C option which
overrides the default starting point at which
sudo begins closing open file descriptors. This
flag is off by default.
compress_io If set, and sudo is configured to log a command's
input or output, the I/O logs will be compressed
using zlib. This flag is on by default when sudo
is compiled with zlib support.
exec_background By default, sudo runs a command as the foreground
process as long as sudo itself is running in the
foreground. When the exec_background flag is
enabled and the command is being run in a pseudo-
terminal (due to I/O logging or the use_pty
flag), the command will be run as a background
process. Attempts to read from the controlling
terminal (or to change terminal settings) will
result in the command being suspended with the
SIGTTIN signal (or SIGTTOU in the case of
terminal settings). If this happens when sudo is
a foreground process, the command will be granted
the controlling terminal and resumed in the
foreground with no user intervention required.
The advantage of initially running the command in
the background is that sudo need not read from
the terminal unless the command explicitly
requests it. Otherwise, any terminal input must
be passed to the command, whether it has required
it or not (the kernel buffers terminals so it is
not possible to tell whether the command really
wants the input). This is different from
historic sudo behavior or when the command is not
being run in a pseudo-terminal.
For this to work seamlessly, the operating system
must support the automatic restarting of system
calls. Unfortunately, not all operating systems
do this by default, and even those that do may
have bugs. For example, macOS fails to restart
the tcgetattr() and tcsetattr() system calls
(this is a bug in macOS). Furthermore, because
this behavior depends on the command stopping
with the SIGTTIN or SIGTTOU signals, programs
that catch these signals and suspend themselves
with a different signal (usually SIGTOP) will not
be automatically foregrounded. Some versions of
the linux su(1) command behave this way. This
flag is off by default.
This setting is only supported by version 1.8.7
or higher. It has no effect unless I/O logging
is enabled or the use_pty flag is enabled.
env_editor If set, visudo will use the value of the
SUDO_EDITOR, VISUAL or EDITOR environment
variables before falling back on the default
editor list. Note that visudo is typically run
as root so this flag may allow a user with visudo
privileges to run arbitrary commands as root
without logging. An alternative is to place a
colon-separated list of 'safe' editors int the
editor variable. visudo will then only use
SUDO_EDITOR, VISUAL or EDITOR if they match a
value specified in editor. If the env_reset flag
is enabled, the SUDO_EDITOR, VISUAL and/or EDITOR
environment variables must be present in the
env_keep list for the env_editor flag to function
when visudo is invoked via sudo. This flag is on
by default.
env_reset If set, sudo will run the command in a minimal
environment containing the TERM, PATH, HOME,
MAIL, SHELL, LOGNAME, USER and SUDO_* variables.
Any variables in the caller's environment or in
the file specified by the restricted_env_file
setting that match the env_keep and env_check
lists are then added, followed by any variables
present in the file specified by the env_file
setting (if any). The contents of the env_keep
and env_check lists, as modified by global
Defaults parameters in sudoers, are displayed
when sudo is run by root with the -V option. If
the secure_path setting is enabled, its value
will be used for the PATH environment variable.
This flag is on by default.
fast_glob Normally, sudo uses the glob(3) function to do
shell-style globbing when matching path names.
However, since it accesses the file system,
glob(3) can take a long time to complete for some
patterns, especially when the pattern references
a network file system that is mounted on demand
(auto mounted). The fast_glob flag causes sudo
to use the fnmatch(3) function, which does not
access the file system to do its matching. The
disadvantage of fast_glob is that it is unable to
match relative path names such as ./ls or
../bin/ls. This has security implications when
path names that include globbing characters are
used with the negation operator, '!', as such
rules can be trivially bypassed. As such, this
flag should not be used when the sudoers file
contains rules that contain negated path names
which include globbing characters. This flag is
off by default.
fqdn Set this flag if you want to put fully qualified
host names in the sudoers file when the local
host name (as returned by the hostname command)
does not contain the domain name. In other
words, instead of myhost you would use
myhost.mydomain.edu. You may still use the short
form if you wish (and even mix the two). This
flag is only effective when the 'canonical' host
name, as returned by the getaddrinfo() or
gethostbyname() function, is a fully-qualified
domain name. This is usually the case when the
system is configured to use DNS for host name
resolution.
If the system is configured to use the /etc/hosts
file in preference to DNS, the 'canonical' host
name may not be fully-qualified. The order that
sources are queried for host name resolution is
usually specified in the /etc/nsswitch.conf,
/etc/netsvc.conf, /etc/host.conf, or, in some
cases, /etc/resolv.conf file. In the /etc/hosts
file, the first host name of the entry is
considered to be the 'canonical' name; subsequent
names are aliases that are not used by sudoers.
For example, the following hosts file line for
the machine 'xyzzy' has the fully-qualified
domain name as the 'canonical' host name, and the
short version as an alias.
192.168.1.1 xyzzy.sudo.ws xyzzy
If the machine's hosts file entry is not
formatted properly, the fqdn flag will not be
effective if it is queried before DNS.
Beware that when using DNS for host name
resolution, turning on fqdn requires sudoers to
make DNS lookups which renders sudo unusable if
DNS stops working (for example if the machine is
disconnected from the network). Also note that
just like with the hosts file, you must use the
'canonical' name as DNS knows it. That is, you
may not use a host alias (CNAME entry) due to
performance issues and the fact that there is no
way to get all aliases from DNS.
This flag is off by default.
ignore_audit_errors
Allow commands to be run even if sudoers cannot
write to the audit log. If enabled, an audit log
write failure is not treated as a fatal error.
If disabled, a command may only be run after the
audit event is successfully written. This flag
is only effective on systems for which sudoers
supports audit logging, including FreeBSD, Linux,
macOS and Solaris. This flag is on by default.
ignore_dot If set, sudo will ignore "." or "" (both denoting
current directory) in the PATH environment
variable; the PATH itself is not modified. This
flag is off by default.
ignore_iolog_errors
Allow commands to be run even if sudoers cannot
write to the I/O log (local or remote). If
enabled, an I/O log write failure is not treated
as a fatal error. If disabled, the command will
be terminated if the I/O log cannot be written
to. This flag is off by default.
ignore_logfile_errors
Allow commands to be run even if sudoers cannot
write to the log file. If enabled, a log file
write failure is not treated as a fatal error.
If disabled, a command may only be run after the
log file entry is successfully written. This
flag only has an effect when sudoers is
configured to use file-based logging via the
logfile setting. This flag is on by default.
ignore_local_sudoers
If set via LDAP, parsing of /etc/sudoers will be
skipped. This is intended for Enterprises that
wish to prevent the usage of local sudoers files
so that only LDAP is used. This thwarts the
efforts of rogue operators who would attempt to
add roles to /etc/sudoers. When this flag is
enabled, /etc/sudoers does not even need to
exist. Since this flag tells sudo how to behave
when no specific LDAP entries have been matched,
this sudoOption is only meaningful for the
cn=defaults section. This flag is off by
default.
ignore_unknown_defaults
If set, sudo will not produce a warning if it
encounters an unknown Defaults entry in the
sudoers file or an unknown sudoOption in LDAP.
This flag is off by default.
insults If set, sudo will insult users when they enter an
incorrect password. This flag is off by default.
log_allowed If set, sudoers will log commands allowed by the
policy to the system audit log (where supported)
as well as to syslog and/or a log file. This
flag is on by default.
This setting is only supported by version 1.8.29
or higher.
log_children If set, sudoers will log when a command spawns a
child process and executes a program using the
execv() or execve() library functions. For
example, if a shell is run by sudo, the
individual commands run via the shell will be
logged. This flag is off by default.
The log_children flag uses the same underlying
mechanism as the intercept and noexec settings.
See Preventing shell escapes for more information
on what systems support this option and its
limitations. This setting is only supported by
version 1.9.8 or higher.
log_denied If set, sudoers will log commands denied by the
policy to the system audit log (where supported)
as well as to syslog and/or a log file. This
flag is on by default.
This setting is only supported by version 1.8.29
or higher.
log_exit_status If set, sudoers will log the exit value of
commands that are run to syslog and/or a log
file. If a command was terminated by a signal,
the signal name is logged as well. This flag is
off by default.
This setting is only supported by version 1.9.8
or higher.
log_host If set, the host name will be included in log
entries written to the file configured by the
logfile setting. This flag is off by default.
log_input If set, sudo will run the command in a pseudo-
terminal and log all user input. If the standard
input is not connected to the user's tty, due to
I/O redirection or because the command is part of
a pipeline, that input is also captured and
stored in a separate log file. Anything sent to
the standard input will be consumed, regardless
of whether or not the command run via sudo is
actually reading the standard input. This may
have unexpected results when using sudo in a
shell script that expects to process the standard
input. For more information about I/O logging,
see the I/O LOG FILES section. This flag is off
by default.
log_output If set, sudo will run the command in a pseudo-
terminal and log all output that is sent to the
screen, similar to the script(1) command. For
more information about I/O logging, see the I/O
LOG FILES section. This flag is off by default.
log_server_keepalive
If set, sudo will enable the TCP keepalive socket
option on the connection to the log server. This
enables the periodic transmission of keepalive
messages to the server. If the server does not
respond to a message, the connection will be
closed and the running command will be terminated
unless the ignore_iolog_errors flag (I/O logging
enabled) or the ignore_log_errors flag (I/O
logging disabled) is set. This flag is on by
default.
This setting is only supported by version 1.9.0
or higher.
log_server_verify
If set, the server certificate received during
the TLS handshake must be valid and it must
contain either the server name (from log_servers)
or its IP address. If either of these conditions
is not met, the TLS handshake will fail. This
flag is on by default.
This setting is only supported by version 1.9.0
or higher.
log_year If set, the four-digit year will be logged in the
(non-syslog) sudo log file. This flag is off by
default.
long_otp_prompt When validating with a One Time Password (OTP)
scheme such as S/Key or OPIE, a two-line prompt
is used to make it easier to cut and paste the
challenge to a local window. It's not as pretty
as the default but some people find it more
convenient. This flag is off by default.
mail_all_cmnds Send mail to the mailto user every time a user
attempts to run a command via sudo (this includes
sudoedit). No mail will be sent if the user runs
sudo with the -l or -v option unless there is an
authentication error and the mail_badpass flag is
also set. This flag is off by default.
mail_always Send mail to the mailto user every time a user
runs sudo. This flag is off by default.
mail_badpass Send mail to the mailto user if the user running
sudo does not enter the correct password. If the
command the user is attempting to run is not
permitted by sudoers and one of the
mail_all_cmnds, mail_always, mail_no_host,
mail_no_perms or mail_no_user flags are set, this
flag will have no effect. This flag is off by
default.
mail_no_host If set, mail will be sent to the mailto user if
the invoking user exists in the sudoers file, but
is not allowed to run commands on the current
host. This flag is off by default.
mail_no_perms If set, mail will be sent to the mailto user if
the invoking user is allowed to use sudo but the
command they are trying is not listed in their
sudoers file entry or is explicitly denied. This
flag is off by default.
mail_no_user If set, mail will be sent to the mailto user if
the invoking user is not in the sudoers file.
This flag is on by default.
match_group_by_gid
By default, sudoers will look up each group the
user is a member of by group-ID to determine the
group name (this is only done once). The
resulting list of the user's group names is used
when matching groups listed in the sudoers file.
This works well on systems where the number of
groups listed in the sudoers file is larger than
the number of groups a typical user belongs to.
On systems where group lookups are slow, where
users may belong to a large number of groups, and
where the number of groups listed in the sudoers
file is relatively small, it may be prohibitively
expensive and running commands via sudo may take
longer than normal. On such systems it may be
faster to use the match_group_by_gid flag to
avoid resolving the user's group-IDs to group
names. In this case, sudoers must look up any
group name listed in the sudoers file and use the
group-ID instead of the group name when
determining whether the user is a member of the
group.
Note that if match_group_by_gid is enabled, group
database lookups performed by sudoers will be
keyed by group name as opposed to group-ID. On
systems where there are multiple sources for the
group database, it is possible to have
conflicting group names or group-IDs in the local
/etc/group file and the remote group database.
On such systems, enabling or disabling
match_group_by_gid can be used to choose whether
group database queries are performed by name
(enabled) or ID (disabled), which may aid in
working around group entry conflicts.
The match_group_by_gid flag has no effect when
sudoers data is stored in LDAP. This flag is off
by default.
This setting is only supported by version 1.8.18
or higher.
intercept If set, all commands run via sudo will behave as
if the INTERCEPT tag has been set, unless
overridden by an NOINTERCEPT tag. See the
description of INTERCEPT and NOINTERCEPT above as
well as the Preventing shell escapes section at
the end of this manual. This flag is off by
default.
This setting is only supported by version 1.9.8
or higher.
intercept_allow_setid
On most systems, the dynamic loader will ignore
LD_PRELOAD (or the equivalent) when running set-
user-ID and set-group-ID programs, effectively
disabling intercept mode. To prevent this from
happening, sudoers will not permit a set-user-ID
or set-group-ID program to be run in intercept
mode unless intercept_allow_setid is set. This
flag has no effect unless the intercept flag is
enabled or the INTERCEPT tag has been set for the
command. This flag is on by default.
This setting is only supported by version 1.9.8
or higher.
intercept_authenticate
If set, commands run by an intercepted process
must be authenticated when the user's time stamp
is not current. For example, if a shell is run
with intercept enabled, as soon as the invoking
user's time stamp is out of date, subsequent
commands will need to be authenticated. This
flag has no effect unless the intercept flag is
enabled or the INTERCEPT tag has been set for the
command. This flag is off by default.
This setting is only supported by version 1.9.8
or higher.
netgroup_tuple If set, netgroup lookups will be performed using
the full netgroup tuple: host name, user name and
domain (if one is set). Historically, sudo only
matched the user name and domain for netgroups
used in a User_List and only matched the host
name and domain for netgroups used in a
Host_List. This flag is off by default.
noexec If set, all commands run via sudo will behave as
if the NOEXEC tag has been set, unless overridden
by an EXEC tag. See the description of EXEC and
NOEXEC above as well as the Preventing shell
escapes section at the end of this manual. This
flag is off by default.
pam_acct_mgmt On systems that use PAM for authentication, sudo
will perform PAM account validation for the
invoking user by default. The actual checks
performed depend on which PAM modules are
configured. If enabled, account validation will
be performed regardless of whether or not a
password is required. This flag is on by
default.
This setting is only supported by version 1.8.28
or higher.
pam_rhost On systems that use PAM for authentication, sudo
will set the PAM remote host value to the name of
the local host when the pam_rhost flag is
enabled. On Linux systems, enabling pam_rhost
may result in DNS lookups of the local host name
when PAM is initialized. On Solaris versions
prior to Solaris 8, pam_rhost must be enabled if
pam_ruser is also enabled to avoid a crash in the
Solaris PAM implementation.
This flag is off by default on systems other than
Solaris.
This setting is only supported by version 1.9.0
or higher.
pam_ruser On systems that use PAM for authentication, sudo
will set the PAM remote user value to the name of
the user that invoked sudo when the pam_ruser
flag is enabled. This flag is on by default.
This setting is only supported by version 1.9.0
or higher.
pam_session On systems that use PAM for authentication, sudo
will create a new PAM session for the command to
be run in. Unless sudo is given the -i or -s
options, PAM session modules are run with the
'silent' flag enabled. This prevents last login
information from being displayed for every
command on some systems. Disabling pam_session
may be needed on older PAM implementations or on
operating systems where opening a PAM session
changes the utmp or wtmp files. If PAM session
support is disabled, resource limits may not be
updated for the command being run. If
pam_session, pam_setcred, and use_pty are
disabled, log_servers has not been set and I/O
logging has not been configured, sudo will
execute the command directly instead of running
it as a child process. This flag is on by
default.
This setting is only supported by version 1.8.7
or higher.
pam_setcred On systems that use PAM for authentication, sudo
will attempt to establish credentials for the
target user by default, if supported by the
underlying authentication system. One example of
a credential is a Kerberos ticket. If
pam_session, pam_setcred, and use_pty are
disabled, log_servers has not been set and I/O
logging has not been configured, sudo will
execute the command directly instead of running
it as a child process. This flag is on by
default.
This setting is only supported by version 1.8.8
or higher.
passprompt_override
If set, the prompt specified by passprompt or the
SUDO_PROMPT environment variable will always be
used and will replace the prompt provided by a
PAM module or other authentication method. This
flag is off by default.
path_info Normally, sudo will tell the user when a command
could not be found in their PATH environment
variable. Some sites may wish to disable this as
it could be used to gather information on the
location of executables that the normal user does
not have access to. The disadvantage is that if
the executable is simply not in the user's PATH,
sudo will tell the user that they are not allowed
to run it, which can be confusing. This flag is
on by default.
preserve_groups By default, sudo will initialize the group vector
to the list of groups the target user is in.
When preserve_groups is set, the user's existing
group vector is left unaltered. The real and
effective group-IDs, however, are still set to
match the target user. This flag is off by
default.
pwfeedback By default, sudo reads the password like most
other Unix programs, by turning off echo until
the user hits the return (or enter) key. Some
users become confused by this as it appears to
them that sudo has hung at this point. When
pwfeedback is set, sudo will provide visual
feedback when the user presses a key. Note that
this does have a security impact as an onlooker
may be able to determine the length of the
password being entered. This flag is off by
default.
requiretty If set, sudo will only run when the user is
logged in to a real tty. When this flag is set,
sudo can only be run from a login session and not
via other means such as cron(8) or cgi-bin
scripts. This flag is off by default.
root_sudo If set, root is allowed to run sudo too.
Disabling this prevents users from 'chaining'
sudo commands to get a root shell by doing
something like 'sudo sudo /bin/sh'. Note,
however, that turning off root_sudo will also
prevent root from running sudoedit. Disabling
root_sudo provides no real additional security;
it exists purely for historical reasons. This
flag is on by default.
rootpw If set, sudo will prompt for the root password
instead of the password of the invoking user when
running a command or editing a file. This flag
is off by default.
runas_allow_unknown_id
If enabled, allow matching of runas user and
group IDs that are not present in the password or
group databases. In addition to explicitly
matching unknown user or group IDs in a
Runas_List, this option also allows the ALL alias
to match unknown IDs. This flag is off by
default.
This setting is only supported by version 1.8.30
or higher. Older versions of sudo always allowed
matching of unknown user and group IDs.
runas_check_shell
If enabled, sudo will only run commands as a user
whose shell appears in the /etc/shells file, even
if the invoking user's Runas_List would otherwise
permit it. If no /etc/shells file is present, a
system-dependent list of built-in default shells
is used. On many operating systems, system users
such as 'bin', do not have a valid shell and this
flag can be used to prevent commands from being
run as those users. This flag is off by default.
This setting is only supported by version 1.8.30
or higher.
runaspw If set, sudo will prompt for the password of the
user defined by the runas_default option
(defaults to root) instead of the password of the
invoking user when running a command or editing a
file. This flag is off by default.
set_home If enabled and sudo is invoked with the -s
option, the HOME environment variable will be set
to the home directory of the target user (which
is the root user unless the -u option is used).
This flag is largely obsolete and has no effect
unless the env_reset flag has been disabled or
HOME is present in the env_keep list, both of
which are strongly discouraged. This flag is off
by default.
set_logname Normally, sudo will set the LOGNAME and USER
environment variables to the name of the target
user (usually root unless the -u option is
given). However, since some programs (including
the RCS revision control system) use LOGNAME to
determine the real identity of the user, it may
be desirable to change this behavior. This can
be done by negating the set_logname option. Note
that set_logname will have no effect if the
env_reset option has not been disabled and the
env_keep list contains LOGNAME or USER. This
flag is on by default.
set_utmp When enabled, sudo will create an entry in the
utmp (or utmpx) file when a pseudo-terminal is
allocated. A pseudo-terminal is allocated by
sudo when it is running in a terminal and one or
more of the log_input, log_output or use_pty
flags is enabled. By default, the new entry will
be a copy of the user's existing utmp entry (if
any), with the tty, time, type and pid fields
updated. This flag is on by default.
setenv Allow the user to disable the env_reset option
from the command line via the -E option.
Additionally, environment variables set via the
command line are not subject to the restrictions
imposed by env_check, env_delete, or env_keep.
As such, only trusted users should be allowed to
set variables in this manner. This flag is off
by default.
shell_noargs If set and sudo is invoked with no arguments it
acts as if the -s option had been given. That
is, it runs a shell as root (the shell is
determined by the SHELL environment variable if
it is set, falling back on the shell listed in
the invoking user's /etc/passwd entry if not).
This flag is off by default.
stay_setuid Normally, when sudo executes a command the real
and effective UIDs are set to the target user
(root by default). This option changes that
behavior such that the real UID is left as the
invoking user's UID. In other words, this makes
sudo act as a set-user-ID wrapper. This can be
useful on systems that disable some potentially
dangerous functionality when a program is run
set-user-ID. This option is only effective on
systems that support either the setreuid(2) or
setresuid(2) system call. This flag is off by
default.
sudoedit_checkdir
If set, sudoedit will check all directory
components of the path to be edited for
writability by the invoking user. Symbolic links
will not be followed in writable directories and
sudoedit will refuse to edit a file located in a
writable directory. These restrictions are not
enforced when sudoedit is run by root. On some
systems, if all directory components of the path
to be edited are not readable by the target user,
sudoedit will be unable to edit the file. This
flag is on by default.
This setting was first introduced in version
1.8.15 but initially suffered from a race
condition. The check for symbolic links in
writable intermediate directories was added in
version 1.8.16.
sudoedit_follow By default, sudoedit will not follow symbolic
links when opening files. The sudoedit_follow
option can be enabled to allow sudoedit to open
symbolic links. It may be overridden on a per-
command basis by the FOLLOW and NOFOLLOW tags.
This flag is off by default.
This setting is only supported by version 1.8.15
or higher.
syslog_pid When logging via syslog(3), include the process
ID in the log entry. This flag is off by
default.
This setting is only supported by version 1.8.21
or higher.
targetpw If set, sudo will prompt for the password of the
user specified by the -u option (defaults to
root) instead of the password of the invoking
user when running a command or editing a file.
Note that this flag precludes the use of a user-
ID not listed in the passwd database as an
argument to the -u option. This flag is off by
default.
tty_tickets If set, users must authenticate on a per-tty
basis. With this flag enabled, sudo will use a
separate record in the time stamp file for each
terminal. If disabled, a single record is used
for all login sessions.
This option has been superseded by the
timestamp_type option.
umask_override If set, sudo will set the umask as specified in
the sudoers file without modification. This
makes it possible to specify a umask in the
sudoers file that is more permissive than the
user's own umask and matches historical behavior.
If umask_override is not set, sudo will set the
umask to be the union of the user's umask and
what is specified in sudoers. This flag is off
by default.
use_netgroups If set, netgroups (prefixed with '+'), may be
used in place of a user or host. For LDAP-based
sudoers, netgroup support requires an expensive
sub-string match on the server unless the
NETGROUP_BASE directive is present in the
/etc/ldap.conf file. If netgroups are not
needed, this option can be disabled to reduce the
load on the LDAP server. This flag is on by
default.
use_pty If set, and sudo is running in a terminal, the
command will be run in a pseudo-terminal (even if
no I/O logging is being done). If the sudo
process is not attached to a terminal, use_pty
has no effect.
A malicious program run under sudo may be capable
of injecting commands into the user's terminal or
running a background process that retains access
to the user's terminal device even after the main
program has finished executing. By running the
command in a separate pseudo-terminal, this
attack is no longer possible. This flag is off
by default.
user_command_timeouts
If set, the user may specify a timeout on the
command line. If the timeout expires before the
command has exited, the command will be
terminated. If a timeout is specified both in
the sudoers file and on the command line, the
smaller of the two timeouts will be used. See
the Timeout_Spec section for a description of the
timeout syntax. This flag is off by default.
This setting is only supported by version 1.8.20
or higher.
utmp_runas If set, sudo will store the name of the runas
user when updating the utmp (or utmpx) file. By
default, sudo stores the name of the invoking
user. This flag is off by default.
visiblepw By default, sudo will refuse to run if the user
must enter a password but it is not possible to
disable echo on the terminal. If the visiblepw
flag is set, sudo will prompt for a password even
when it would be visible on the screen. This
makes it possible to run things like 'ssh
somehost sudo ls' since by default, ssh(1) does
not allocate a tty when running a command. This
flag is off by default.
Integers:
closefrom Before it executes a command, sudo will close all
open file descriptors other than standard input,
standard output and standard error (ie: file
descriptors 0-2). The closefrom option can be
used to specify a different file descriptor at
which to start closing. The default is 3.
command_timeout The maximum amount of time a command is allowed
to run before it is terminated. See the
Timeout_Spec section for a description of the
timeout syntax.
This setting is only supported by version 1.8.20
or higher.
log_server_timeout
The maximum amount of time to wait when
connecting to a log server or waiting for a
server response. See the Timeout_Spec section
for a description of the timeout syntax. The
default value is 30 seconds.
This setting is only supported by version 1.9.0
or higher.
maxseq The maximum sequence number that will be
substituted for the '%{seq}' escape in the I/O
log file (see the iolog_dir description below for
more information). While the value substituted
for '%{seq}' is in base 36, maxseq itself should
be expressed in decimal. Values larger than
2176782336 (which corresponds to the base 36
sequence number 'ZZZZZZ') will be silently
truncated to 2176782336. The default value is
2176782336.
Once the local sequence number reaches the value
of maxseq, it will 'roll over' to zero, after
which sudoers will truncate and re-use any
existing I/O log path names.
This setting is only supported by version 1.8.7
or higher.
passwd_tries The number of tries a user gets to enter his/her
password before sudo logs the failure and exits.
The default is 3.
syslog_maxlen On many systems, syslog(3) has a relatively small
log buffer. IETF RFC 5424 states that syslog
servers must support messages of at least 480
bytes and should support messages up to 2048
bytes. By default, sudoers creates log messages
up to 980 bytes which corresponds to the historic
BSD syslog implementation which used a 1024 byte
buffer to store the message, date, hostname and
program name. To prevent syslog messages from
being truncated, sudoers will split up log
messages that are larger than syslog_maxlen
bytes. When a message is split, additional parts
will include the string '(command continued)'
after the user name and before the continued
command line arguments.
This setting is only supported by version 1.8.19
or higher.
Integers that can be used in a boolean context:
loglinelen Number of characters per line for the file log.
This value is used to decide when to wrap lines
for nicer log files. This has no effect on the
syslog log file, only the file log. The default
is 80 (use 0 or negate the option to disable word
wrap).
passwd_timeout Number of minutes before the sudo password prompt
times out, or 0 for no timeout. The timeout may
include a fractional component if minute
granularity is insufficient, for example 2.5.
The default is 5.
timestamp_timeout
Number of minutes that can elapse before sudo
will ask for a passwd again. The timeout may
include a fractional component if minute
granularity is insufficient, for example 2.5.
The default is 5. Set this to 0 to always prompt
for a password. If set to a value less than 0
the user's time stamp will not expire until the
system is rebooted. This can be used to allow
users to create or delete their own time stamps
via 'sudo -v' and 'sudo -k' respectively.
umask File mode creation mask to use when running the
command. Negate this option or set it to 0777 to
prevent sudoers from changing the umask. Unless
the umask_override flag is set, the actual umask
will be the union of the user's umask and the
value of the umask setting, which defaults to
0022. This guarantees that sudo never lowers the
umask when running a command.
If umask is explicitly set in sudoers, it will
override any umask setting in PAM or login.conf.
If umask is not set in sudoers, the umask
specified by PAM or login.conf will take
precedence. The umask setting in PAM is not used
for sudoedit, which does not create a new PAM
session.
Strings:
authfail_message Message that is displayed after a user fails to
authenticate. The message may include the '%d'
escape which will expand to the number of failed
password attempts. If set, it overrides the
default message, %d incorrect password
attempt(s).
badpass_message Message that is displayed if a user enters an
incorrect password. The default is Sorry, try
again. unless insults are enabled.
editor A colon (':') separated list of editors path
names used by sudoedit and visudo. For sudoedit,
this list is used to find an editor when none of
the SUDO_EDITOR, VISUAL or EDITOR environment
variables are set to an editor that exists and is
executable. For visudo, it is used as a white
list of allowed editors; visudo will choose the
editor that matches the user's SUDO_EDITOR,
VISUAL or EDITOR environment variable if
possible, or the first editor in the list that
exists and is executable if not. Unless invoked
as sudoedit, sudo does not preserve the
SUDO_EDITOR, VISUAL or EDITOR environment
variables unless they are present in the env_keep
list or the env_reset option is disabled. The
default is /usr/bin/vi.
iolog_dir The top-level directory to use when constructing
the path name for the input/output log directory.
Only used if the log_input or log_output options
are enabled or when the LOG_INPUT or LOG_OUTPUT
tags are present for a command. The session
sequence number, if any, is stored in the
directory. The default is /var/log/sudo-io.
The following percent ('%') escape sequences are
supported:
%{seq}
expanded to a monotonically increasing
base-36 sequence number, such as 0100A5,
where every two digits are used to form a
new directory, e.g., 01/00/A5
%{user}
expanded to the invoking user's login name
%{group}
expanded to the name of the invoking user's
real group-ID
%{runas_user}
expanded to the login name of the user the
command will be run as (e.g., root)
%{runas_group}
expanded to the group name of the user the
command will be run as (e.g., wheel)
%{hostname}
expanded to the local host name without the
domain name
%{command}
expanded to the base name of the command
being run
In addition, any escape sequences supported by
the system's strftime(3) function will be
expanded.
To include a literal '%' character, the string
'%%' should be used.
iolog_file The path name, relative to iolog_dir, in which to
store input/output logs when the log_input or
log_output options are enabled or when the
LOG_INPUT or LOG_OUTPUT tags are present for a
command. Note that iolog_file may contain
directory components. The default is '%{seq}'.
See the iolog_dir option above for a list of
supported percent ('%') escape sequences.
In addition to the escape sequences, path names
that end in six or more Xs will have the Xs
replaced with a unique combination of digits and
letters, similar to the mktemp(3) function.
If the path created by concatenating iolog_dir
and iolog_file already exists, the existing I/O
log file will be truncated and overwritten unless
iolog_file ends in six or more Xs.
iolog_flush If set, sudo will flush I/O log data to disk
after each write instead of buffering it. This
makes it possible to view the logs in real-time
as the program is executing but may significantly
reduce the effectiveness of I/O log compression.
This flag is off by default.
This setting is only supported by version 1.8.20
or higher.
iolog_group The group name to look up when setting the group-
ID on new I/O log files and directories. If
iolog_group is not set, the primary group-ID of
the user specified by iolog_user is used. If
neither iolog_group nor iolog_user are set, I/O
log files and directories are created with group-
ID 0.
This setting is only supported by version 1.8.19
or higher.
iolog_mode The file mode to use when creating I/O log files.
Mode bits for read and write permissions for
owner, group or other are honored, everything
else is ignored. The file permissions will
always include the owner read and write bits,
even if they are not present in the specified
mode. When creating I/O log directories, search
(execute) bits are added to match the read and
write bits specified by iolog_mode. Defaults to
0600 (read and write by user only).
This setting is only supported by version 1.8.19
or higher.
iolog_user The user name to look up when setting the user
and group-IDs on new I/O log files and
directories. If iolog_group is set, it will be
used instead of the user's primary group-ID. By
default, I/O log files and directories are
created with user and group-ID 0.
This setting can be useful when the I/O logs are
stored on a Network File System (NFS) share.
Having a dedicated user own the I/O log files
means that sudoers does not write to the log
files as user-ID 0, which is usually not
permitted by NFS.
This setting is only supported by version 1.8.19
or higher.
lecture_status_dir
The directory in which sudo stores per-user
lecture status files. Once a user has received
the lecture, a zero-length file is created in
this directory so that sudo will not lecture the
user again. This directory should not be cleared
when the system reboots. The default is
/var/db/sudo/lectured.
log_server_cabundle
The path to a certificate authority bundle file,
in PEM format, to use instead of the system's
default certificate authority database when
authenticating the log server. The default is to
use the system's default certificate authority
database. This setting has no effect unless
log_servers is set and the remote log server is
secured with TLS.
This setting is only supported by version 1.9.0
or higher.
log_server_peer_cert
The path to the sudo client's certificate file,
in PEM format. This setting is required when the
remote log server is secured with TLS and client
certificate validation is enabled. For
sudo_logsrvd, client certificate validation is
controlled by the tls_checkpeer option, which
defaults to false.
This setting is only supported by version 1.9.0
or higher.
log_server_peer_key
The path to the sudo client's private key file,
in PEM format. This setting is required when the
remote log server is secured with TLS and client
certificate validation is enabled. For
sudo_logsrvd, client certificate validation is
controlled by the tls_checkpeer option, which
defaults to false.
This setting is only supported by version 1.9.0
or higher.
mailsub Subject of the mail sent to the mailto user. The
escape %h will expand to the host name of the
machine. Default is '*** SECURITY information
for %h ***'.
noexec_file As of sudo version 1.8.1 this option is no longer
supported. The path to the noexec file should
now be set in the sudo.conf(5) file.
pam_login_service
On systems that use PAM for authentication, this
is the service name used when the -i option is
specified. The default value is 'sudo'. See the
description of pam_service for more information.
This setting is only supported by version 1.8.8
or higher.
pam_service On systems that use PAM for authentication, the
service name specifies the PAM policy to apply.
This usually corresponds to an entry in the
pam.conf file or a file in the /etc/pam.d
directory. The default value is 'sudo'.
This setting is only supported by version 1.8.8
or higher.
passprompt The default prompt to use when asking for a
password; can be overridden via the -p option or
the SUDO_PROMPT environment variable. The
following percent ('%') escape sequences are
supported:
%H expanded to the local host name including
the domain name (only if the machine's host
name is fully qualified or the fqdn option
is set)
%h expanded to the local host name without the
domain name
%p expanded to the user whose password is
being asked for (respects the rootpw,
targetpw and runaspw flags in sudoers)
%U expanded to the login name of the user the
command will be run as (defaults to root)
%u expanded to the invoking user's login name
%% two consecutive % characters are collapsed
into a single % character
On systems that use PAM for authentication,
passprompt will only be used if the prompt
provided by the PAM module matches the string
'Password: ' or 'username's Password: '. This
ensures that the passprompt setting does not
interfere with challenge-response style
authentication. The passprompt_override flag can
be used to change this behavior.
The default value is 'Password: '.
runas_default The default user to run commands as if the -u
option is not specified on the command line.
This defaults to root.
sudoers_locale Locale to use when parsing the sudoers file,
logging commands, and sending email. Note that
changing the locale may affect how sudoers is
interpreted. Defaults to 'C'.
timestamp_type sudoers uses per-user time stamp files for
credential caching. The timestamp_type option
can be used to specify the type of time stamp
record used. It has the following possible
values:
global A single time stamp record is used for
all of a user's login sessions,
regardless of the terminal or parent
process ID. An additional record is used
to serialize password prompts when sudo
is used multiple times in a pipeline, but
this does not affect authentication.
ppid A single time stamp record is used for
all processes with the same parent
process ID (usually the shell). Commands
run from the same shell (or other common
parent process) will not require a
password for timestamp_timeout minutes (5
by default). Commands run via sudo with
a different parent process ID, for
example from a shell script, will be
authenticated separately.
tty One time stamp record is used for each
terminal, which means that a user's login
sessions are authenticated separately.
If no terminal is present, the behavior
is the same as ppid. Commands run from
the same terminal will not require a
password for timestamp_timeout minutes (5
by default).
kernel The time stamp is stored in the kernel as
an attribute of the terminal device. If
no terminal is present, the behavior is
the same as ppid. Negative
timestamp_timeout values are not
supported and positive values are limited
to a maximum of 60 minutes. This is
currently only supported on OpenBSD.
The default value is tty.
This setting is only supported by version 1.8.21
or higher.
timestampdir The directory in which sudo stores its time stamp
files. This directory should be cleared when the
system reboots. The default is /run/sudo/ts.
timestampowner The owner of the lecture status directory, time
stamp directory and all files stored therein.
The default is root.
Strings that can be used in a boolean context:
admin_flag The admin_flag option specifies the path to a file
that is created the first time a user that is a
member of the sudo or admin groups runs sudo. Only
available if sudo is configured with the
--enable-admin-flag option. The default value is
~/.sudo_as_admin_successful.
env_file The env_file option specifies the fully qualified
path to a file containing variables to be set in the
environment of the program being run. Entries in
this file should either be of the form
'VARIABLE=value' or 'export VARIABLE=value'. The
value may optionally be enclosed in single or double
quotes. Variables in this file are only added if the
variable does not already exist in the environment.
This file is considered to be part of the security
policy, its contents are not subject to other sudo
environment restrictions such as env_keep and
env_check.
exempt_group Users in this group are exempt from password and PATH
requirements. The group name specified should not
include a % prefix. This is not set by default.
fdexec Determines whether sudo will execute a command by its
path or by an open file descriptor. It has the
following possible values:
always Always execute by file descriptor.
never Never execute by file descriptor.
digest_only
Only execute by file descriptor if the
command has an associated digest in the
sudoers file.
The default value is digest_only. This avoids a time
of check versus time of use race condition when the
command is located in a directory writable by the
invoking user.
Note that fdexec will change the first element of the
argument vector for scripts ($0 in the shell) due to
the way the kernel runs script interpreters. Instead
of being a normal path, it will refer to a file
descriptor. For example, /dev/fd/4 on Solaris and
/proc/self/fd/4 on Linux. A workaround is to use the
SUDO_COMMAND environment variable instead.
The fdexec setting is only used when the command is
matched by path name. It has no effect if the
command is matched by the built-in ALL alias.
This setting is only supported by version 1.8.20 or
higher. If the operating system does not support the
fexecve() system call, this setting has no effect.
group_plugin A string containing a sudoers group plugin with
optional arguments. The string should consist of the
plugin path, either fully-qualified or relative to
the /usr/local/libexec/sudo directory, followed by
any configuration arguments the plugin requires.
These arguments (if any) will be passed to the
plugin's initialization function. If arguments are
present, the string must be enclosed in double quotes
("").
For more information see GROUP PROVIDER PLUGINS.
lecture This option controls when a short lecture will be
printed along with the password prompt. It has the
following possible values:
always Always lecture the user.
never Never lecture the user.
once Only lecture the user the first time they run
sudo.
If no value is specified, a value of once is implied.
Negating the option results in a value of never being
used. The default value is once.
lecture_file Path to a file containing an alternate sudo lecture
that will be used in place of the standard lecture if
the named file exists. By default, sudo uses a
built-in lecture.
listpw This option controls when a password will be required
when a user runs sudo with the -l option. It has the
following possible values:
all All the user's sudoers file entries for the
current host must have the NOPASSWD flag
set to avoid entering a password.
always The user must always enter a password to
use the -l option.
any At least one of the user's sudoers file
entries for the current host must have the
NOPASSWD flag set to avoid entering a
password.
never The user need never enter a password to use
the -l option.
If no value is specified, a value of any is implied.
Negating the option results in a value of never being
used. The default value is any.
log_format The event log format. Supported log formats are:
json Logs in JSON format. JSON log entries
contain the full user details as well as
the execution environment if the command
was allowed. Due to limitations of the
protocol, JSON events sent via syslog may
be truncated.
sudo Traditional sudo-style logs, see LOG FORMAT
for a description of the log file format.
This setting affects logs sent via syslog(3) as well
as the file specified by the logfile setting, if any.
The default value is sudo.
logfile Path to the sudo log file (not the syslog log file).
Setting a path turns on logging to a file; negating
this option turns it off. By default, sudo logs via
syslog.
mailerflags Flags to use when invoking mailer. Defaults to -t.
mailerpath Path to mail program used to send warning mail.
Defaults to the path to sendmail found at configure
time.
mailfrom Address to use for the 'from' address when sending
warning and error mail. The address should be
enclosed in double quotes ("") to protect against
sudo interpreting the @ sign. Defaults to the name
of the user running sudo.
mailto Address to send warning and error mail to. The
address should be enclosed in double quotes ("") to
protect against sudo interpreting the @ sign.
Defaults to root.
restricted_env_file
The restricted_env_file option specifies the fully
qualified path to a file containing variables to be
set in the environment of the program being run.
Entries in this file should either be of the form
'VARIABLE=value' or 'export VARIABLE=value'. The
value may optionally be enclosed in single or double
quotes. Variables in this file are only added if the
variable does not already exist in the environment.
Unlike env_file, the file's contents are not trusted
and are processed in a manner similar to that of the
invoking user's environment. If env_reset is
enabled, variables in the file will only be added if
they are matched by either the env_check or env_keep
list. If env_reset is disabled, variables in the
file are added as long as they are not matched by the
env_delete list. In either case, the contents of
restricted_env_file are processed before the contents
of env_file.
runchroot If set, sudo will use this value for the root
directory when running a command. The special value
'*' will allow the user to specify the root directory
via sudo's -R option. See the Chroot_Spec section
for more details.
It is only possible to use runchroot as a command-
specific Defaults setting if the command exists with
the same path both inside and outside the chroot
jail. This restriction does not apply to generic,
host or user-based Defaults settings or to a
Cmnd_Spec that includes a Chroot_Spec.
This setting is only supported by version 1.9.3 or
higher.
runcwd If set, sudo will use this value for the working
directory when running a command. The special value
'*' will allow the user to specify the working
directory via sudo's -D option. See the Chdir_Spec
section for more details.
This setting is only supported by version 1.9.3 or
higher.
secure_path If set, sudo will use this value in place of the
user's PATH environment variable. This option can be
used to reset the PATH to a known good value that
contains directories for system administrator
commands such as /usr/sbin.
Users in the group specified by the exempt_group
option are not affected by secure_path. This option
is not set by default.
syslog Syslog facility if syslog is being used for logging
(negate to disable syslog logging). Defaults to
authpriv.
The following syslog facilities are supported:
authpriv (if your OS supports it), auth, daemon,
user, local0, local1, local2, local3, local4, local5,
local6, and local7.
syslog_badpri
Syslog priority to use when the user is not allowed
to run a command or when authentication is
unsuccessful. Defaults to alert.
The following syslog priorities are supported: alert,
crit, debug, emerg, err, info, notice, warning, and
none. Negating the option or setting it to a value
of none will disable logging of unsuccessful
commands.
syslog_goodpri
Syslog priority to use when the user is allowed to
run a command and authentication is successful.
Defaults to notice.
See syslog_badpri for the list of supported syslog
priorities. Negating the option or setting it to a
value of none will disable logging of successful
commands.
verifypw This option controls when a password will be required
when a user runs sudo with the -v option. It has the
following possible values:
all All the user's sudoers file entries for the
current host must have the NOPASSWD flag set
to avoid entering a password.
always The user must always enter a password to use
the -v option.
any At least one of the user's sudoers file
entries for the current host must have the
NOPASSWD flag set to avoid entering a
password.
never The user need never enter a password to use
the -v option.
If no value is specified, a value of all is implied.
Negating the option results in a value of never being
used. The default value is all.
Lists that can be used in a boolean context:
env_check Environment variables to be removed from the
user's environment unless they are considered
'safe'. For all variables except TZ, 'safe'
means that the variable's value does not contain
any '%' or '/' characters. This can be used to
guard against printf-style format vulnerabilities
in poorly-written programs. The TZ variable is
considered unsafe if any of the following are
true:
• It consists of a fully-qualified path name,
optionally prefixed with a colon (':'), that
does not match the location of the zoneinfo
directory.
• It contains a .. path element.
• It contains white space or non-printable
characters.
• It is longer than the value of PATH_MAX.
The argument may be a double-quoted, space-
separated list or a single value without double-
quotes. The list can be replaced, added to,
deleted from, or disabled by using the =, +=, -=,
and ! operators respectively. Regardless of
whether the env_reset option is enabled or
disabled, variables specified by env_check will
be preserved in the environment if they pass the
aforementioned check. The global list of
environment variables to check is displayed when
sudo is run by root with the -V option.
env_delete Environment variables to be removed from the
user's environment when the env_reset option is
not in effect. The argument may be a double-
quoted, space-separated list or a single value
without double-quotes. The list can be replaced,
added to, deleted from, or disabled by using the
=, +=, -=, and ! operators respectively. The
global list of environment variables to remove is
displayed when sudo is run by root with the -V
option. Note that many operating systems will
remove potentially dangerous variables from the
environment of any set-user-ID process (such as
sudo).
env_keep Environment variables to be preserved in the
user's environment when the env_reset option is
in effect. This allows fine-grained control over
the environment sudo-spawned processes will
receive. The argument may be a double-quoted,
space-separated list or a single value without
double-quotes. The list can be replaced, added
to, deleted from, or disabled by using the =, +=,
-=, and ! operators respectively. The global
list of variables to keep is displayed when sudo
is run by root with the -V option.
Preserving the HOME environment variable has
security implications since many programs use it
when searching for configuration or data files.
Adding HOME to env_keep may enable a user to run
unrestricted commands via sudo and is strongly
discouraged. Users wishing to edit files with
sudo should run sudoedit (or sudo -e) to get
their accustomed editor configuration instead of
invoking the editor directly.
log_servers A list of one or more servers to use for remote
event and I/O log storage, separated by white
space. Log servers must be running sudo_logsrvd
or another service that implements the protocol
described by sudo_logsrv.proto(5).
Server addresses should be of the form
'host[:port][(tls)]'. The host portion may be a
host name, an IPv4 address, or an IPv6 address in
square brackets.
If the optional tls flag is present, the
connection will be secured with Transport Layer
Security (TLS) version 1.2 or 1.3. Versions of
TLS prior to 1.2 are not supported.
If a port is specified, it may either be a port
number or a well-known service name as defined by
the system service name database. If no port is
specified, port 30343 will be used for plaintext
connections and port 30344 will be used for TLS
connections.
When log_servers is set, event log data will be
logged both locally (see the syslog and log_file
settings) as well as remotely, but I/O log data
will only be logged remotely. If multiple hosts
are specified, they will be attempted in reverse
order. If no log servers are available, the user
will not be able to run a command unless either
the ignore_iolog_errors flag (I/O logging
enabled) or the ignore_log_errors flag (I/O
logging disabled) is set. Likewise, if the
connection to the log server is interrupted while
sudo is running, the command will be terminated
unless the ignore_iolog_errors flag (I/O logging
enabled) or the ignore_log_errors flag (I/O
logging disabled) is set.
This setting is only supported by version 1.9.0
or higher.
