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 (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
EBNF is a concise and exact way of describing the grammar of a language. Each EBNF defi-
nition 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 differ-
ent 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
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 com-
mandname is a fully qualified filename which may include shell-style wildcards (see 'Wild-
cards' 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 spe-
cific 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 conve-
nient. This flag is off by default.
ignore_dot If set, sudo will ignore '.' or '' (current dir) in the PATH environment vari-
able; 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 cor-
rect 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 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 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 effec-
tively 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 net-
work). 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 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 allo-
cate 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 vari-
ables before falling back on the default editor list. Note that this may cre-
ate 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 invok-
ing 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 dis-
able 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 fail-
ure, 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 vari-
ables: 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 vari-
able if possible, or the first editor in the list that exists and is exe-
cutable. 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 authpriv.
mailerpath Path to mail program used to send warning mail. Defaults to the path to send-
mail 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 vari-
able'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 dou-
ble-quotes. The list can be replaced, added to, deleted from, or disabled by
using the =, +=, -=, and ! operators respectively. The default list of envi-
ronment 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 dou-
ble-quotes. The list can be replaced, added to, deleted from, or disabled by
using the =, +=, -=, and ! operators respectively. The default list of envi-
ronment 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 dou-
ble-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, 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 warning.
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 speci-
fied hosts. By default, commands are run as root, but this can be changed on a per-com-
mand 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 com-
mand. 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. Con-
versely, 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 veri-
fypw and listpw options.
Wildcards (aka meta characters):
sudo allows shell-style wildcards to be used in pathnames as well as command line argu-
ments 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 charac-
ters 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" com-
mands 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): '@', '!', '=', ':', ',', '(', ')', '\'.
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 sys-
log(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 com-
mands related to backups, killing processes, the printing system, shutting down the sys-
tem, 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) with-
out 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 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 reinforced 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 host-
names 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)
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