sudoers

a b c d e f g h i j k l m n o p q r s t u v w x y z _

SUDOERS(5) MAINTENANCE COMMANDS SUDOERS(5)

NAME
sudoers - list of which users may execute what

DESCRIPTION
The sudoers file is composed of two types of entries: aliases (basi-
cally variables) and user specifications (which specify who may run
what). The grammar of sudoers will be described below in Extended
Backus-Naur Form (EBNF). Don’t despair if you don’t know what EBNF
is; it is fairly simple, and the definitions below are annotated.

Quick guide to EBNF

EBNF is a concise and exact way of describing the grammar of a lan-
guage. Each EBNF definition is made up of production rules. E.g.,

symbol ::= definition │ alternate1 │ alternate2 ...

Each production rule references others and thus makes up a grammar for
the language. EBNF also contains the following operators, which many
readers will recognize from regular expressions. Do not, however,
confuse them with "wildcard" characters, which have different mean-
ings.

? Means that the preceding symbol (or group of symbols) is
optional. That is, it may appear once or not at all.

* Means that the preceding symbol (or group of symbols) may
appear zero or more times.

+ Means that the preceding symbol (or group of symbols) may
appear one or more times.

Parentheses may be used to group symbols together. For clarity, we
will use single quotes (’’) to designate what is a verbatim character
string (as opposed to a symbol name).

Aliases

There are four kinds of aliases: User_Alias, Runas_Alias, Host_Alias
and Cmnd_Alias.

Alias ::= ’User_Alias’ User_Alias (’:’ User_Alias)* │
’Runas_Alias’ Runas_Alias (’:’ Runas_Alias)* │
’Host_Alias’ Host_Alias (’:’ Host_Alias)* │
’Cmnd_Alias’ Cmnd_Alias (’:’ Cmnd_Alias)*

User_Alias ::= NAME ’=’ User_List

Runas_Alias ::= NAME ’=’ Runas_List

Host_Alias ::= NAME ’=’ Host_List

Cmnd_Alias ::= NAME ’=’ Cmnd_List

NAME ::= [A-Z]([A-Z][0-9]_)*

Each alias definition is of the form

Alias_Type NAME = item1, item2, ...

where Alias_Type is one of User_Alias, Runas_Alias, Host_Alias, or
Cmnd_Alias. A NAME is a string of uppercase letters, numbers, and
underscore characters (’_’). A NAME must start with an uppercase let-
ter. It is possible to put several alias definitions of the same type
on a single line, joined by a colon (’:’). E.g.,

Alias_Type NAME = item1, item2, item3 : NAME = item4, item5

The definitions of what constitutes a valid alias member follow.

User_List ::= User │
User ’,’ User_List

User ::= ’!’* username │
’!’* ’%’group │
’!’* ’+’netgroup │
’!’* User_Alias

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

Runas_List ::= Runas_User │
Runas_User ’,’ Runas_List

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

A Runas_List is similar to a User_List except that it can also contain
uids (prefixed with ’#’) and instead of User_Aliases it can contain
Runas_Aliases.

Host_List ::= Host │
Host ’,’ Host_List

Host ::= ’!’* hostname │
’!’* ip_addr │
’!’* network(/netmask)? │
’!’* ’+’netgroup │
’!’* Host_Alias

A Host_List is made up of one or more hostnames, IP addresses, network
numbers, netgroups (prefixed with ’+’) and other aliases. Again, the
value of an item may be negated with the ’!’ operator. If you do not
specify a netmask with a network number, the netmask of the host’s
ethernet interface(s) will be used when matching. The netmask may be
specified either in dotted quad notation (e.g. 255.255.255.0) or CIDR
notation (number of bits, e.g. 24). A hostname may include shell-
style wildcards (see ‘Wildcards’ section below), but unless the host-
name command on your machine returns the fully qualified hostname,
you’ll need to use the fqdn option for wildcards to be useful.

Cmnd_List ::= Cmnd │
Cmnd ’,’ Cmnd_List

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

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

A Cmnd_List is a list of one or more commandnames, directories, and
other aliases. A commandname is a fully qualified filename which may
include shell-style wildcards (see ‘Wildcards’ section below). A sim-
ple filename allows the user to run the command with any arguments
he/she wishes. However, you may also specify command line arguments
(including wildcards). Alternately, you can specify "" to indicate
that the command may only be run without command line arguments. A
directory is a fully qualified pathname ending in a ’/’. When you
specify a directory in a Cmnd_List, the user will be able to run any
file within that directory (but not in any subdirectories therein).

If a Cmnd has associated command line arguments, then the arguments in
the Cmnd must match exactly those given by the user on the command
line (or match the wildcards if there are any). Note that the follow-
ing characters must be escaped with a ’\’ if they are used in command
arguments: ’,’, ’:’, ’=’, ’\’.

Defaults

Certain configuration options may be changed from their default values
at runtime via one or more Default_Entry lines. These may affect all
users on any host, all users on a specific host, a specific user, or
commands being run as a specific user. When multiple entries match,
they are applied in order. Where there are conflicting values, the
last value on a matching line takes effect.

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

Default_Entry ::= Default_Type Parameter_List

Parameter ::= Parameter ’=’ Value ││
Parameter ’+=’ Value ││
Parameter ’-=’ Value ││
’!’* Parameter ││

Parameters may be flags, integer values, strings, or lists. Flags are
implicitly boolean and can be turned off via the ’!’ operator. Some
integer, string and list parameters may also be used in a boolean con-
text to disable them. Values may be enclosed in double quotes (")
when they contain multiple words. Special characters may be escaped
with a backslash (\).

Lists have two additional assignment operators, += and -=. These
operators are used to add to and delete from a list respectively. It
is not an error to use the -= operator to remove an element that does
not exist in a list.

Note that since the sudoers file is parsed in order the best place to
put the Defaults section is after the Host, User, and Cmnd aliases but
before the user specifications.

Flags:

long_otp_prompt
When validating with a One Time Password scheme (S/Key or
OPIE), a two-line prompt is used to make it easier to cut
and paste the challenge to a local window. It’s not as
pretty as the default but some people find it more conve-
nient. This flag is off by default.

ignore_dot If set, sudo will ignore ’.’ or ’’ (current dir) in the
PATH environment variable; the PATH itself is not modi-
fied. This flag is on by default.

mail_always Send mail to the mailto user every time a users runs sudo.
This flag is off by default.

mail_badpass
Send mail to the mailto user if the user running sudo does
not enter the correct password. This flag is off by
default.

mail_no_user
If set, mail will be sent to the mailto user if the invok-
ing user is not in the sudoers file. This flag is on by
default.

mail_no_host
If set, mail will be sent to the mailto user if the invok-
ing 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 invok-
ing user is allowed to use sudo but the command they are
trying is not listed in their sudoers file entry. This
flag is off by default.

tty_tickets If set, users must authenticate on a per-tty basis. Nor-
mally, sudo uses a directory in the ticket dir with the
same name as the user running it. With this flag enabled,
sudo will use a file named for the tty the user is logged
in on in that directory. This flag is on by default.

lecture If set, a user will receive a short lecture the first time
he/she runs sudo. This flag is on by default.

authenticate
If set, users must authenticate themselves via a password
(or other means of authentication) before they may run
commands. This default may be overridden via the PASSWD
and NOPASSWD tags. This flag is on by default.

root_sudo If set, root is allowed to run sudo too. Disabling this
prevents users from "chaining" sudo commands to get a root
shell by doing something like "sudo sudo /bin/sh". This
flag is on by default.

log_host If set, the hostname will be logged in the (non-syslog)
sudo log file. This flag is off by default.

log_year If set, the four-digit year will be logged in the
(non-syslog) sudo log file. This flag is off by default.

shell_noargs
If set and sudo is invoked with no arguments it acts as if
the -s flag had been given. That is, it runs a shell as
root (the shell is determined by the SHELL environment
variable if it is set, falling back on the shell listed in
the invoking user’s /etc/passwd entry if not). This flag
is off by default.

set_home If set and sudo is invoked with the -s flag the HOME envi-
ronment variable will be set to the home directory of the
target user (which is root unless the -u option is used).
This effectively makes the -s flag imply -H. This flag is
off by default.

always_set_home
If set, sudo will set the HOME environment variable to the
home directory of the target user (which is root unless
the -u option is used). This effectively means that the
-H flag is always implied. This flag is off by default.

path_info Normally, sudo will tell the user when a command could not
be found in their PATH environment variable. Some sites
may wish to disable this as it could be used to gather
information on the location of executables that the normal
user does not have access to. The disadvantage is that if
the executable is simply not in the user’s PATH, sudo will
tell the user that they are not allowed to run it, which
can be confusing. This flag is off by default.

preserve_groups
By default sudo will initialize the group vector to the
list of groups the target user is in. When pre-
serve_groups is set, the user’s existing group vector is
left unaltered. The real and effective group IDs, how-
ever, are still set to match the target user. This flag
is off by default.

fqdn Set this flag if you want to put fully qualified hostnames
in the sudoers file. I.e., instead of myhost you would
use myhost.mydomain.edu. You may still use the short form
if you wish (and even mix the two). Beware that turning
on fqdn requires sudo to make DNS lookups which may make
sudo unusable if DNS stops working (for example if the
machine is not plugged into the network). Also note that
you must use the host’s official name as DNS knows it.
That is, you may not use a host alias (CNAME entry) due to
performance issues and the fact that there is no way to
get all aliases from DNS. If your machine’s hostname (as
returned by the hostname command) is already fully quali-
fied you shouldn’t need to set fqdn. This flag is off by
default.

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

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

env_editor If set, visudo will use the value of the EDITOR or VISUAL
environment variables before falling back on the default
editor list. Note that this may create a security hole as
it allows the user to run any arbitrary command as root
without logging. A safer alternative is to place a colon-
separated list of editors in the editor variable. visudo
will then only use the EDITOR or VISUAL if they match a
value specified in editor. This flag is on by default.

rootpw If set, sudo will prompt for the root password instead of
the password of the invoking user. This flag is off by
default.

runaspw If set, sudo will prompt for the password of the user
defined by the runas_default option (defaults to root)
instead of the password of the invoking user. This flag
is off by default.

targetpw If set, sudo will prompt for the password of the user
specified by the -u flag (defaults to root) instead of the
password of the invoking user. This flag is off by
default.

set_logname Normally, sudo will set the LOGNAME and USER environment
variables to the name of the target user (usually root
unless the -u flag is given). However, since some pro-
grams (including the RCS revision control system) use LOG-
NAME to determine the real identity of the user, it may be
desirable to change this behavior. This can be done by
negating the set_logname option.

stay_setuid Normally, when sudo executes a command the real and effec-
tive UIDs are set to the target user (root by default).
This option changes that behavior such that the real UID
is left as the invoking user’s UID. In other words, this
makes sudo act as a setuid wrapper. This can be useful on
systems that disable some potentially dangerous function-
ality when a program is run setuid. Note, however, that
this means that sudo will run with the real uid of the
invoking user which may allow that user to kill sudo
before it can log a failure, depending on how your OS
defines the interaction between signals and setuid pro-
cesses.

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

use_loginclass
If set, sudo will apply the defaults specified for the
target user’s login class if one exists. Only available
if sudo is configured with the --with-logincap option.
This flag is off by default.

Integers:

passwd_tries
The number of tries a user gets to enter his/her password
before sudo logs the failure and exits. The default is 3.

Integers that can be used in a boolean context:

loglinelen Number of characters per line for the file log. This
value is used to decide when to wrap lines for nicer log
files. This has no effect on the syslog log file, only
the file log. The default is 80 (use 0 or negate the
option to disable word wrap).

timestamp_timeout
Number of minutes that can elapse before sudo will ask for
a passwd again. The default is 5. Set this to 0 to
always prompt for a password. If set to a value less than
0 the user’s timestamp will never expire. This can be
used to allow users to create or delete their own times-
tamps via sudo -v and sudo -k respectively.

passwd_timeout
Number of minutes before the sudo password prompt times
out. The default is 5, set this to 0 for no password
timeout.

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

Strings:

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

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

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

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

passprompt The default prompt to use when asking for a password; can
be overridden via the -p option or the SUDO_PROMPT envi-
ronment variable. The following percent (‘%’) escapes are
supported:

%u expanded to the invoking user’s login name

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

%h expanded to the local hostname without the domain
name

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

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

The default value is Password:.

runas_default
The default user to run commands as if the -u flag is not
specified on the command line. This defaults to root.

syslog_goodpri
Syslog priority to use when user authenticates success-
fully. Defaults to notice.

syslog_badpri
Syslog priority to use when user authenticates unsuccess-
fully. Defaults to alert.

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

Strings that can be used in a boolean context:

logfile Path to the sudo log file (not the syslog log file). Set-
ting a path turns on logging to a file; negating this
option turns it off.

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

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

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

mailto Address to send warning and error mail to. The address
should be enclosed in double quotes (") to protect against
sudo interpreting the @ sign. Defaults to root.

exempt_group
Users in this group are exempt from password and PATH
requirements. This is not set by default.

verifypw This option controls when a password will be required when
a user runs sudo with the -v flag. It has the following
possible values:

all All the user’s sudoers entries for the current
host must have the NOPASSWD flag set to avoid
entering a password.

any At least one of the user’s sudoers entries for the
current host must have the NOPASSWD flag set to
avoid entering a password.

never The user need never enter a password to use the -v
flag.

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

The default value is ‘all’.

listpw This option controls when a password will be required when
a user runs sudo with the -l flag. It has the following
possible values:

all All the user’s sudoers entries for the current
host must have the NOPASSWD flag set to avoid
entering a password.

any At least one of the user’s sudoers entries for the
current host must have the NOPASSWD flag set to
avoid entering a password.

never The user need never enter a password to use the -l
flag.

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

The default value is ‘any’.

Lists that can be used in a boolean context:

env_check Environment variables to be removed from the user’s envi-
ronment if the variable’s value contains % or / charac-
ters. This can be used to guard against printf-style for-
mat vulnerabilities in poorly-written programs. The argu-
ment may be a double-quoted, space-separated list or a
single value without double-quotes. The list can be
replaced, added to, deleted from, or disabled by using the
=, +=, -=, and ! operators respectively. The default list
of environment variables to check is printed when sudo is
run by root with the -V option.

env_delete Environment variables to be removed from the user’s envi-
ronment. The argument may be a double-quoted, space-sepa-
rated list or a single value without double-quotes. The
list can be replaced, added to, deleted from, or disabled
by using the =, +=, -=, and ! operators respectively. The
default list of environment variables to remove is printed
when sudo is run by root with the -V option. Note that
many operating systems will remove potentially dangerous
variables from the environment of any setuid process (such
as sudo).

env_keep Environment variables to be preserved in the user’s envi-
ronment when the env_reset option is in effect. This
allows fine-grained control over the environment
sudo-spawned processes will receive. The argument may be
a double-quoted, space-separated list or a single value
without double-quotes. The list can be replaced, added
to, deleted from, or disabled by using the =, +=, -=, and
! operators respectively. This list has no default mem-
bers.

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

User Specification

User_Spec ::= User_list Host_List ’=’ Cmnd_Spec_List \
(’:’ User_Spec)*

Cmnd_Spec_List ::= Cmnd_Spec │
Cmnd_Spec ’,’ Cmnd_Spec_List

Cmnd_Spec ::= Runas_Spec? (’NOPASSWD:’ │ ’PASSWD:’)? Cmnd

Runas_Spec ::= ’(’ Runas_List ’)’

A user specification determines which commands a user may run (and as
what user) on specified hosts. By default, commands are run as root,
but this can be changed on a per-command basis.

Let’s break that down into its constituent parts:

Runas_Spec

A Runas_Spec is simply a Runas_List (as defined above) enclosed in a
set of parentheses. If you do not specify a Runas_Spec in the user
specification, a default Runas_Spec of root will be used. A
Runas_Spec sets the default for commands that follow it. What this
means is that for the entry:

dgb boulder = (operator) /bin/ls, /bin/kill, /usr/bin/lprm

The user dgb may run /bin/ls, /bin/kill, and /usr/bin/lprm -- but only
as operator. E.g.,

sudo -u operator /bin/ls.

It is also possible to override a Runas_Spec later on in an entry. If
we modify the entry like so:

dgb boulder = (operator) /bin/ls, (root) /bin/kill, /usr/bin/lprm

Then user dgb is now allowed to run /bin/ls as operator, but
/bin/kill and /usr/bin/lprm as root.

NOPASSWD and PASSWD

By default, sudo requires that a user authenticate him or herself
before running a command. This behavior can be modified via the
NOPASSWD tag. Like a Runas_Spec, the NOPASSWD tag sets a default for
the commands that follow it in the Cmnd_Spec_List. Conversely, the
PASSWD tag can be used to reverse things. For example:

ray rushmore = NOPASSWD: /bin/kill, /bin/ls, /usr/bin/lprm

would allow the user ray to run /bin/kill, /bin/ls, and /usr/bin/lprm
as root on the machine rushmore as root without authenticating him-
self. If we only want ray to be able to run /bin/kill without a pass-
word the entry would be:

ray rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls, /usr/bin/lprm

Note, however, that the PASSWD tag has no effect on users who are in
the group specified by the exempt_group option.

By default, if the NOPASSWD tag is applied to any of the entries for a
user on the current host, he or she will be able to run sudo -l with-
out a password. Additionally, a user may only run sudo -v without a
password if the NOPASSWD tag is present for all a user’s entries that
pertain to the current host. This behavior may be overridden via the
verifypw and listpw options.

Wildcards (aka meta characters):

sudo allows shell-style wildcards to be used in pathnames as well as
command line arguments in the sudoers file. Wildcard matching is done
via the POSIX fnmatch(3) routine. Note that these are not regular
expressions.

* Matches any set of zero or more characters.

? Matches any single character.

[...] Matches any character in the specified range.

[!...] Matches any character not in the specified range.

\x For any character "x", evaluates to "x". This is used to
escape special characters such as: "*", "?", "[", and "}".

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

/usr/bin/*

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

Exceptions to wildcard rules:

The following exceptions apply to the above rules:

"" If the empty string "" is the only command line argument in
the sudoers entry it means that command is not allowed to be
run with any arguments.

Other special characters and reserved words:

The pound sign (’#’) is used to indicate a comment (unless it occurs
in the context of a user name and is followed by one or more digits,
in which case it is treated as a uid). Both the comment character and
any text after it, up to the end of the line, are ignored.

The reserved word ALL is a built in alias that always causes a match
to succeed. It can be used wherever one might otherwise use a
Cmnd_Alias, User_Alias, Runas_Alias, or Host_Alias. You should not
try to define your own alias called ALL as the built in alias will be
used in preference to your own. Please note that using ALL can be
dangerous since in a command context, it allows the user to run any
command on the system.

An exclamation point (’!’) can be used as a logical not operator both
in an alias and in front of a Cmnd. This allows one to exclude cer-
tain values. Note, however, that using a ! in conjunction with the
built in ALL alias to allow a user to run "all but a few" commands
rarely works as intended (see SECURITY NOTES below).

Long lines can be continued with a backslash (’\’) as the last charac-
ter on the line.

Whitespace between elements in a list as well as special syntactic
characters in a User Specification (’=’, ’:’, ’(’, ’)’) is optional.

The following characters must be escaped with a backslash (’\’) when
used as part of a word (e.g. a username or hostname): ’@’, ’!’, ’=’,
’:’, ’,’, ’(’, ’)’, ’\’.

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

# User alias specification
User_Alias FULLTIMERS = millert, mikef, dowdy
User_Alias PARTTIMERS = bostley, jwfox, crawl
User_Alias WEBMASTERS = will, wendy, wim

# Runas alias specification
Runas_Alias OP = root, operator
Runas_Alias DB = oracle, sybase

# Host alias specification
Host_Alias SPARC = bigtime, eclipse, moet, anchor :\
SGI = grolsch, dandelion, black :\
ALPHA = widget, thalamus, foobar :\
HPPA = boa, nag, python
Host_Alias CUNETS = 128.138.0.0/255.255.0.0
Host_Alias CSNETS = 128.138.243.0, 128.138.204.0/24, 128.138.242.0
Host_Alias SERVERS = master, mail, www, ns
Host_Alias CDROM = orion, perseus, hercules

# Cmnd alias specification
Cmnd_Alias DUMPS = /usr/bin/mt, /usr/sbin/dump, /usr/sbin/rdump,\
/usr/sbin/restore, /usr/sbin/rrestore
Cmnd_Alias KILL = /usr/bin/kill
Cmnd_Alias PRINTING = /usr/sbin/lpc, /usr/bin/lprm
Cmnd_Alias SHUTDOWN = /usr/sbin/shutdown
Cmnd_Alias HALT = /usr/sbin/halt, /usr/sbin/fasthalt
Cmnd_Alias REBOOT = /usr/sbin/reboot, /usr/sbin/fastboot
Cmnd_Alias SHELLS = /usr/bin/sh, /usr/bin/csh, /usr/bin/ksh, \
/usr/local/bin/tcsh, /usr/bin/rsh, \
/usr/local/bin/zsh
Cmnd_Alias SU = /usr/bin/su

Here we override some of the compiled in default values. We want sudo
to log via syslog(3) using the auth facility in all cases. We don’t
want to subject the full time staff to the sudo lecture, user millert
need not give a password, and we don’t want to set the LOGNAME or USER
environment variables when running commands as root. Additionally, on
the machines in the SERVERS Host_Alias, we keep an additional local
log file and make sure we log the year in each log line since the log
entries will be kept around for several years.

# Override built in defaults
Defaults syslog=auth
Defaults>root !set_logname
Defaults:FULLTIMERS !lecture
Defaults:millert !authenticate
Defaults@SERVERS log_year, logfile=/var/log/sudo.log

The User specification is the part that actually determines who may
run what.

root ALL = (ALL) ALL
%wheel ALL = (ALL) ALL

We let root and any user in group wheel run any command on any host as
any user.

FULLTIMERS ALL = NOPASSWD: ALL

Full time sysadmins (millert, mikef, and dowdy) may run any command on
any host without authenticating themselves.

PARTTIMERS ALL = ALL

Part time sysadmins (bostley, jwfox, and crawl) may run any command on
any host but they must authenticate themselves first (since the entry
lacks the NOPASSWD tag).

jack CSNETS = ALL

The user jack may run any command on the machines in the CSNETS alias
(the networks 128.138.243.0, 128.138.204.0, and 128.138.242.0). Of
those networks, only 128.138.204.0 has an explicit netmask (in CIDR
notation) indicating it is a class C network. For the other networks
in CSNETS, the local machine’s netmask will be used during matching.

lisa CUNETS = ALL

The user lisa may run any command on any host in the CUNETS alias (the
class B network 128.138.0.0).

operator ALL = DUMPS, KILL, PRINTING, SHUTDOWN, HALT, REBOOT,\
/usr/oper/bin/

The operator user may run commands limited to simple maintenance.
Here, those are commands related to backups, killing processes, the
printing system, shutting down the system, and any commands in the
directory /usr/oper/bin/.

joe ALL = /usr/bin/su operator

The user joe may only su(1) to operator.

pete HPPA = /usr/bin/passwd [A-z]*, !/usr/bin/passwd root

The user pete is allowed to change anyone’s password except for root
on the HPPA machines. Note that this assumes passwd(1) does not take
multiple usernames on the command line.

bob SPARC = (OP) ALL : SGI = (OP) ALL

The user bob may run anything on the SPARC and SGI machines as any
user listed in the OP Runas_Alias (root and operator).

jim +biglab = ALL

The user jim may run any command on machines in the biglab netgroup.
Sudo knows that "biglab" is a netgroup due to the ’+’ prefix.

+secretaries ALL = PRINTING, /usr/bin/adduser, /usr/bin/rmuser

Users in the secretaries netgroup need to help manage the printers as
well as add and remove users, so they are allowed to run those com-
mands on all machines.

fred ALL = (DB) NOPASSWD: ALL

The user fred can run commands as any user in the DB Runas_Alias (ora-
cle or sybase) without giving a password.

john ALPHA = /usr/bin/su [!-]*, !/usr/bin/su *root*

On the ALPHA machines, user john may su to anyone except root but he
is not allowed to give su(1) any flags.

jen ALL, !SERVERS = ALL

The user jen may run any command on any machine except for those in
the SERVERS Host_Alias (master, mail, www and ns).

jill SERVERS = /usr/bin/, !SU, !SHELLS

For any machine in the SERVERS Host_Alias, jill may run any commands
in the directory /usr/bin/ except for those commands belonging to the
SU and SHELLS Cmnd_Aliases.

steve CSNETS = (operator) /usr/local/op_commands/

The user steve may run any command in the directory /usr/local/op_com-
mands/ but only as user operator.

matt valkyrie = KILL

On his personal workstation, valkyrie, matt needs to be able to kill
hung processes.

WEBMASTERS www = (www) ALL, (root) /usr/bin/su www

On the host www, any user in the WEBMASTERS User_Alias (will, wendy,
and wim), may run any command as user www (which owns the web pages)
or simply su(1) to www.

ALL CDROM = NOPASSWD: /sbin/umount /CDROM,\
/sbin/mount -o nosuid\,nodev /dev/cd0a /CDROM

Any user may mount or unmount a CD-ROM on the machines in the CDROM
Host_Alias (orion, perseus, hercules) without entering a password.
This is a bit tedious for users to type, so it is a prime candidate
for encapsulating in a shell script.

SECURITY NOTES
It is generally not effective to "subtract" commands from ALL using
the ’!’ operator. A user can trivially circumvent this by copying the
desired command to a different name and then executing that. For
example:

bill ALL = ALL, !SU, !SHELLS

Doesn’t really prevent bill from running the commands listed in SU or
SHELLS since he can simply copy those commands to a different name, or
use a shell escape from an editor or other program. Therefore, these
kind of restrictions should be considered advisory at best (and rein-
forced by policy).

CAVEATS
The sudoers file should always be edited by the visudo command which
locks the file and does grammatical checking. It is imperative that
sudoers be free of syntax errors since sudo will not run with a
syntactically incorrect sudoers file.

When using netgroups of machines (as opposed to users), if you store
fully qualified hostnames in the netgroup (as is usually the case),
you either need to have the machine’s hostname be fully qualified as
returned by the hostname command or use the fqdn option in sudoers.

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

SEE ALSO
rsh(1), su(1), fnmatch(3), sudo(8), visudo(8)

1.6.7 March 13, 2003 SUDOERS(5)