sudoers - list of which users may execute what
The sudoers file is composed of two types of entries:
aliases (basically 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 [Toc] [Back]
EBNF is a concise and exact way of describing the grammar
of a language. Each EBNF definition is made up of produc-
tion rules. E.g.,
symbol ::= definition | alternate1 | alternate2 ...
Each production rule references others and thus makes up a
grammar for the language. EBNF also contains the following
operators, which many readers will recognize from regular
expressions. Do not, however, confuse them with
"wildcard" characters, which have different meanings.
? Means that the preceding symbol (or group of symbols)
is optional. That is, it may appear once or
not at all.
* Means that the preceding symbol (or group of symbols)
may appear zero or more times.
+ Means that the preceding symbol (or group of symbols)
may appear one or more times.
Parentheses may be used to group symbols together. For
clarity, we will use single quotes ('') to designate what
is a verbatim character string (as opposed to a symbol
name).
Aliases [Toc] [Back]
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 letter. It is possible
to put several alias definitions of the same type on a
single line, joined by a colon (':'). E.g.,
Alias_Type NAME = item1, item2, item3 : NAME = item4,
item5
The definitions of what constitutes a valid alias member
follow.
User_List ::= User |
User ',' User_List
User ::= '!'* username |
'!'* '%'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 hostname
command on your machine returns the fully qualified hostname,
you'll need to use the fqdn option for wildcards to
be useful.
Cmnd_List ::= Cmnd |
Cmnd ',' Cmnd_List
commandname ::= filename |
filename args |
filename '""'
Cmnd ::= '!'* commandname |
'!'* directory |
'!'* 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 simple filename allows
the user to run the command with any arguments he/she
wishes. However, you may also specify command line arguments
(including wildcards). Alternately, you can specify
"" to indicate that the command may only be run without
command line arguments. A directory is a fully qualified
pathname ending in a '/'. When you specify a directory in
a Cmnd_List, the user will be able to run any file within
that directory (but not in any subdirectories therein).
If a Cmnd has associated command line arguments, then the
arguments in the Cmnd must match exactly those given by
the user on the command line (or match the wildcards if
there are any). Note that the following characters must
be escaped with a '' if they are used in command arguments:
',', ':', '=', ''.
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 context to disable
them. Values may be enclosed in double quotes (")
when they contain multiple words. Special characters may
be escaped with a backslash (.
Lists have two additional assignment operators, += and -=.
These operators are used to add to and delete from a list
respectively. It is not an error to use the -= operator
to remove an element that does not exist in a list.
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 convenient. This flag is off by default.
ignore_dot If set, sudo will ignore '.' or '' (current
dir) in the PATH environment variable; the
PATH itself is not modified. This flag is 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 invoking 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 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. This flag is off
by default.
tty_tickets If set, users must authenticate on a per-tty
basis. Normally, sudo uses a directory in the
ticket dir with the same name as the user running
it. With this flag enabled, sudo will
use a file named for the tty the user is
logged in on in that directory. This flag is
off by default.
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 environment variable will be set to
the home directory of the target user (which
is root unless the -u option is used). This
effectively makes the -s 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 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.
fqdn Set this flag if you want to put fully qualified
hostnames in the sudoers file. I.e.,
instead of myhost you would use myhost.mydomain.edu.
You may still use the short form if
you wish (and even mix the two). Beware that
turning on fqdn requires sudo to make DNS
lookups which may make sudo unusable if DNS
stops working (for example if the machine is
not plugged into the network). Also note that
you must use the host's official name as DNS
knows it. That is, you may not use a host
alias (CNAME entry) due to performance issues
and the fact that there is no way to get all
aliases from DNS. If your machine's hostname
(as returned by the hostname command) is
already fully qualified you shouldn't need to
set fqdn. This flag is off by default.
insults If set, sudo will insult users when they enter
an incorrect password. This flag is on 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 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.
stay_setuid Normally, when sudo executes a command the
real and effective UIDs are set to the target
user (root by default). This option changes
that behavior such that the real UID is left
as the invoking user's UID. In other words,
this makes sudo act as a setuid wrapper. This
can be useful on systems that disable some
potentially dangerous functionality when a
program is run setuid. 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 processes.
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
variables 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 timestamps 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 environment 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
successfully. Defaults to notice.
syslog_badpri
Syslog priority to use when user authenticates
unsuccessfully. 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). Setting 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 local2.
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 environment if the variable's value
contains % or / characters. This can be used
to guard against printf-style format vulnerabilities
in poorly-written programs. The
argument may be a double-quoted, space-separated
list or a single value without double-quotes.
The list can be replaced, added
to, deleted from, or disabled by using the =,
+=, -=, and ! operators respectively. 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 environment. The argument may be a
double-quoted, space-separated list or a single
value without double-quotes. The list can
be replaced, added to, deleted from, or disabled
by using the =, +=, -=, and ! operators
respectively. The default list of environment
variables to remove is 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 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. This list has no default members.
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, dae-
mon, user, local0, local1, local2, local3, local4, local5,
local6, and local7. The following syslog priorities are
supported: alert, crit, debug, emerg, err, info, notice,
and warning.
User Specification [Toc] [Back]
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 [Toc] [Back]
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 [Toc] [Back]
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 himself. If we only want ray to be
able to run /bin/kill without a password the entry would
be:
ray rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls,
/usr/bin/lprm
Note, however, that the PASSWD tag has no effect on users
who are in the group specified by the exempt_group option.
By default, if the NOPASSWD tag is applied to any of the
entries for a user on the current host, he or she will be
able to run sudo -l without a password. Additionally, a
user may only run sudo -v without a password if the
NOPASSWD tag is present for all a user's entries that pertain
to the current host. This behavior may be overridden
via the verifypw and listpw options.
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.
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 certain values. Note, however, that
using a ! in conjunction with the built-in ALL alias to
allow a user to run "all but a few" commands rarely works
as intended (see SECURITY NOTES below).
Long lines can be continued with a backslash ('') as the
last character on the line.
Whitespace between elements in a list as well as special
syntactic characters in a User Specification ('=', ':',
'(', ')') is optional.
The following characters must be escaped with a backslash
('') when used as part of a word (e.g. a username or
hostname): '@', '!', '=', ':', ',', '(', ')', ''.
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 commands on all machines.
fred ALL = (DB) NOPASSWD: ALL
The user fred can run commands as any user in the DB
Runas_Alias (oracle or sybase) without giving a password.
john ALPHA = /usr/bin/su [!-]*, !/usr/bin/su
*root*
On the ALPHA machines, user john may su to anyone except
root but he is not allowed to 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_commands/ but only as user operator.
matt valkyrie = KILL
On his personal workstation, valkyrie, matt needs to be
able to kill hung processes.
WEBMASTERS www = (www) ALL, (root) /usr/bin/su www
On the host www, any user in the WEBMASTERS User_Alias
(will, wendy, and wim), may run any command as user www
(which owns the web pages) or simply su(1) to www.
ALL CDROM = NOPASSWD: /sbin/umount /CDROM,
/sbin/mount -o nosuidnodev /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.
It is generally not effective to "subtract" commands from
ALL using the '!' operator. A user can trivially circumvent
this by copying the desired command to a different
name and then executing that. For example:
bill ALL = ALL, !SU, !SHELLS
Doesn't really prevent bill from running the commands
listed in SU or SHELLS since he can simply copy those commands
to a different name, or use a shell escape from an
editor or other program. Therefore, these kind of
restrictions should be considered advisory at best (and
reinforced by policy). 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.
/etc/sudoers List of who can run what
/etc/group Local groups file
/etc/netgroup List of network groups
rsh(1), su(1), fnmatch(3), sudo(8), visudo(8)
1.6.7 March 13, 2003 19 [ Back ] |
