=cut
Copyright (c) 1994-1996,1998-2000 Todd C. Miller <Todd.Miller@courtesan.com>
All rights reserved.
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modification, are permitted provided that the following conditions
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$Sudo: sudoers.pod,v 1.36 2000/03/27 03:26:24 millert Exp $
=pod
=head1 NAME
sudoers - list of which users may execute what
=head1 DESCRIPTION
The I<sudoers> file is composed two types of entries:
aliases (basically variables) and user specifications
(which specify who may run what). The grammar of I<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.
=head2 Quick guide to EBNF
EBNF is a concise and exact way of describing the grammar of a language.
Each EBNF definition is made up of I<production rules>. Eg.
symbol ::= definition | alternate1 | alternate2 ...
Each I<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.
=over 8
=item C<?>
Means that the preceding symbol (or group of symbols) is optional.
That is, it may appear once or not at all.
=item C<*>
Means that the preceding symbol (or group of symbols) may appear
zero or more times.
=item C<+>
Means that the preceding symbol (or group of symbols) may appear
one or more times.
=back
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).
=head2 Aliases
There are four kinds of aliases: the C<User_Alias>, C<Runas_Alias>,
C<Host_Alias> and C<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_User_List
Host_Alias ::= NAME '=' Host_List
Cmnd_Alias ::= NAME '=' Cmnd_List
NAME ::= [A-Z]([A-Z][0-9]_)*
Each I<alias> definition is of the form
Alias_Type NAME = item1, item2, ...
where I<Alias_Type> is one of C<User_Alias>, C<Runas_Alias>, C<Host_Alias>,
or C<Cmnd_Alias>. A C<NAME> is a string of upper case letters, numbers,
and the underscore characters ('_'). A C<NAME> B<must> start with an
upper case letter. It is possible to put several alias definitions
of the same type on a single line, joined by a semicolon (':'). Eg.
Alias_Type NAME = item1, item2, item3 : NAME = item4, item5
The definitions of what constitutes a valid I<alias> member follow.
User_List ::= User |
User ',' User_List
User ::= '!'* username |
'!'* '#'uid |
'!'* '%'group |
'!'* '+'netgroup |
'!'* User_Alias
A C<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 negates 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
Likewise, a C<Runas_List> has the same possible elements
as a C<User_List>, except that it can include a C<Runas_Alias>,
instead of a C<User_Alias>.
Host_List ::= Host |
Host ',' Host_List
Host ::= '!'* hostname |
'!'* ip_addr |
'!'* network(/netmask)? |
'!'* '+'netgroup |
'!'* Host_Alias
A C<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 (eg.
255.255.255.0) or CIDR notation (number of bits, eg. 24). A hostname
may include shell-style wildcards (see `Wildcards' section below),
but unless the C<hostname> command on your machine returns the fully
qualified hostname, you'll need to use the I<fqdn> option for wildcards
to be useful.
Cmnd_List ::= Cmnd |
Cmnd ',' Cmnd_List
commandname ::= filename |
filename args |
filename '""'
Cmnd ::= '!'* commandname |
'!'* directory |
'!'* Cmnd_Alias
A C<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 command line arguments (including wildcards).
Alternately, you can specify C<""> to indicate that the command
may only be run B<without> command line arguments. A directory is a
fully qualified pathname ending in a '/'. When you specify a directory
in a C<Cmnd_List>, the user will be able to run any file within that directory
(but not in any subdirectories therein).
If a C<Cmnd> has associated command line arguments, then the arguments
in the C<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: ',', ':', '=', '\'.
=head2 Defaults
Certain configuration options may be changed from their default
values at runtime via one or more C<Default_Entry> lines. These
may affect all users on any host, all users on a specific host,
or just 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' ':' User ||
'Defaults' '@' Host
Default_Entry ::= Default_Type Parameter_List
Parameter ::= Parameter '=' Value ||
'!'* Parameter ||
Parameters may be B<flags>, B<integer> values, or B<strings>. Flags
are implicitly boolean and can be turned off via the '!' operator.
Some integer and string parameters may also be used in a boolean
context to disable them. Values may be enclosed in double quotes
(C<">) when they contain multiple words. Special characters may
be escaped with a backslash (C<\>).
B<Flags>:
=over 12
=item long_otp_prompt
When validating with a One Time Password scheme (B<S/Key> or B<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.
=item ignore_dot
If set, B<sudo> will ignore '.' or '' (current dir) in C<$PATH>;
the C<$PATH> itself is not modified. This flag is off by default.
=item mail_always
Send mail to the I<mailto> user every time a users runs B<sudo>.
This flag is off by default.
=item mail_no_user
If set, mail will be sent to the I<mailto> user if the invoking
user is not in the I<sudoers> file. This flag is on by default.
=item mail_no_host
If set, mail will be sent to the I<mailto> user if the invoking
user exists in the I<sudoers> file, but is not allowed to run
commands on the current host. This flag is off by default.
=item mail_no_perms
If set, mail will be sent to the I<mailto> user if the invoking
user allowed to use B<sudo> but the command they are trying is not
listed in their I<sudoers> file entry. This flag is off by default.
=item tty_tickets
If set, users must authenticate on a per-tty basis. Normally,
B<sudo> uses a directory in the ticket dir with the same name as
the user running it. With this flag enabled, B<sudo> will use a
file named for the tty the user is logged in on in that directory.
This flag is off by default.
=item lecture
If set, a user will receive a short lecture the first time he/she
runs B<sudo>. This flag is on by default.
=item 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 C<PASSWD> and C<NOPASSWD> tags.
This flag is on by default.
=item root_sudo
If set, root is allowed to run B<sudo> too. Disabling this prevents users
from "chaining" B<sudo> commands to get a root shell by doing something
like C<"sudo sudo /bin/sh">.
This flag is on by default.
=item log_host
If set, the hostname will be logged in the (non-syslog) B<sudo> log file.
This flag is off by default.
=item log_year
If set, the four-digit year will be logged in the (non-syslog) B<sudo> log file.
This flag is off by default.
=item shell_noargs
If set and B<sudo> is invoked with no arguments it acts as if the
C<-s> flag had been given. That is, it runs a shell as root (the
shell is determined by the C<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.
=item set_home
If set and B<sudo> is invoked with the C<-s> flag the C<HOME>
environment variable will be set to the home directory of the target
user (which is root unless the C<-u> option is used). This effectively
makes the C<-s> flag imply C<-H>. This flag is off by default.
=item path_info
Normally, B<sudo> will tell the user when a command could not be
found in their C<$PATH>. Some sites may wish to disable this as
it could be used to gather information on the location of executables
that the normal user does not have access to. The disadvantage is
that if the executable is simply not in the user's C<$PATH>, B<sudo>
will tell the user that they are not allowed to run it, which can
be confusing. This flag is off by default.
=item fqdn
Set this flag if you want to put fully qualified hostnames in the
I<sudoers> file. Ie: 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 I<fqdn> requires B<sudo> to make DNS lookups
which may make B<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 (C<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 C<hostname>
command) is already fully qualified you shouldn't need to set
I<fqfn>. This flag is off by default.
=item insults
If set, B<sudo> will insult users when they enter an incorrect
password. This flag is off by default.
=item requiretty
If set, B<sudo> will only run when the user is logged in to a real
tty. This will disallow things like C<"rsh somehost sudo ls"> since
rsh(1) does not allocate a tty. Because it is not possible to turn
of 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.
=item env_editor
If set, B<visudo> will use the value of the EDITOR or VISUAL environment
falling back on the default editor. Note that this may create a
security hole as most editors allow a user to get a shell (which
would be a root shell and not be logged).
=item rootpw
If set, B<sudo> will prompt for the root password instead of the password
of the invoking user.
=item runaspw
If set, B<sudo> will prompt for the password of the user defined by the
I<runas_default> option (defaults to root) instead of the password
of the invoking user.
=item targetpw
If set, B<sudo> will prompt for the password of the user specified by
the C<-u> flag (defaults to root) instead of the password of the
invoking user.
=item set_logname
Normally, B<sudo> will set the C<LOGNAME> and C<USER> environment variables
to the name of the target user (usually root unless the C<-u> flag is given).
However, since some programs (including the RCS revision control system)
use C<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.
=item use_loginclass
If set, B<sudo> will apply the defaults specified for the target user's
login class if one exists. Only available if B<sudo> is configured with
the --with-logincap option.
=back
B<Integers>:
=over 12
=item passwd_tries
The number of tries a user gets to enter his/her password before
B<sudo> logs the failure and exits. The default is 3.
=back
B<Integers that can be used in a boolean context>:
=over 12
=item 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 to disable word wrap).
=item timestamp_timeout
Number of minutes that can elapse before B<sudo> will ask for a passwd
again. The default is 5, set this to 0 to always prompt for a password.
=item passwd_timeout
Number of minutes before the B<sudo> password prompt times out.
The default is 5, set this to 0 for no password timeout.
=item umask
Umask to use when running the root command. Set this to 0777 to
not override the user's umask. The default is 0022.
=back
B<Strings>:
=over 12
=item mailsub
Subject of the mail sent to the I<mailto> user. The escape C<%h>
will expand to the hostname of the machine.
Default is "*** SECURITY information for %h ***".
=item badpass_message
Message that is displayed if a user enters an incorrect password.
The default is "Sorry, try again." unless insults are enabled.
=item timestampdir
The directory in which B<sudo> stores its timestamp files.
The default is F<@TIMEDIR@>.
=item passprompt
The default prompt to use when asking for a password; can be overridden
via the C<-p> option or the C<SUDO_PROMPT> environment variable. Supports
two escapes: "%u" expands to the user's login name and "%h" expands
to the local hostname. The default value is "Password:".
=item runas_default
The default user to run commands as if the C<-u> flag is not specified
on the command line. This defaults to "root".
=item syslog_goodpri
Syslog priority to use when user authenticates successfully.
Defaults to "notice".
=item syslog_badpri
Syslog priority to use when user authenticates unsuccessfully.
Defaults to "alert".
=item editor
Path to the editor to be used by B<visudo>. The default is the path
to vi on your system.
=back 12
B<Strings that can be used in a boolean context>:
=over 12
=item logfile
Path to the B<sudo> log file (not the syslog log file). Setting a path
turns on logging to a file, negating this option turns it off.
=item syslog
Syslog facility if syslog is being used for logging (negate to
disable syslog logging). Defaults to "local2".
=item mailerpath
Path to mail program used to send warning mail.
Defaults to the path to sendmail found at configure time.
=item mailerflags
Flags to use when invoking mailer. Defaults to C<-t>.
=item mailto
Address to send warning and erorr mail to. Defaults to "root".
=item exempt_group
Users in this group are exempt from password and PATH requirements.
This is not set by default.
=item secure_path
Path used for every command run from B<sudo>. If you don't trust the
people running B<sudo> to have a sane C<PATH> environment variable you may
want to use this. Another use is if you want to have the "root path"
be separate from the "user path." This is not set by default.
=item verifypw
This option controls when a password will be required when a
user runs B<sudo> with the B<-v>. It has the following possible values:
all All the user's I<sudoers> entries for the
current host must have the C<NOPASSWD>
flag set to avoid entering a password.
any At least one of the user's I<sudoers> entries
for the current host must have the
C<NOPASSWD> flag set to avoid entering a
password.
never The user need never enter a password to use
the B<-v> flag.
always The user must always enter a password to use
the B<-v> flag.
The default value is `all'.
=item listpw
This option controls when a password will be required when a
user runs B<sudo> with the B<-l>. It has the following possible values:
all All the user's I<sudoers> entries for the
current host must have the C<NOPASSWD>
flag set to avoid entering a password.
any At least one of the user's I<sudoers> entries
for the current host must have the
C<NOPASSWD> flag set to avoid entering a
password.
never The user need never enter a password to use
the B<-l> flag.
always The user must always enter a password to use
the B<-l> flag.
The default value is `any'.
=back 12
When logging via syslog(3), B<sudo> accepts the following values for the syslog
facility (the value of the B<syslog> Parameter): B<authpriv> (if your OS
supports it), B<auth>, B<daemon>, B<user>, B<local0>, B<local1>, B<local2>,
B<local3>, B<local4>, B<local5>, B<local6>, and B<local7>. The following
syslog priorities are supported: B<alert>, B<crit>, B<debug>, B<emerg>,
B<err>, B<info>, B<notice>, and B<warning>.
=head2 User Specification
User_Spec ::= User_list Host_List '=' User_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 B<user specification> determines which commands a user may run
(and as what user) on specified hosts. By default, commands are
run as B<root> but this can be changed on a per-command basis.
Let's break that down into its constituent parts:
=head2 Runas_Spec
A C<Runas_Spec> is simply a C<Runas_List> (as defined above)
enclosed in a set of parentheses. If you do not specify a
C<Runas_Spec> in the user specification, a default C<Runas_Spec>
of B<root> will be used. A C<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/who
The user B<dgb> may run F</bin/ls>, F</bin/kill>, and
F</usr/bin/lprm> -- but only as B<operator>. Eg.
sudo -u operator /bin/ls.
It is also possible to override a C<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 B<dgb> is now allowed to run F</bin/ls> as B<operator>,
but F</bin/kill> and F</usr/bin/lprm> as B<root>.
=head2 NOPASSWD and PASSWD
By default, B<sudo> requires that a user authenticate him or herself
before running a command. This behavior can be modified via the
C<NOPASSWD> tag. Like a C<Runas_Spec>, the C<NOPASSWD> tag sets
a default for the commands that follow it in the C<Cmnd_Spec_List>.
Conversely, the C<PASSWD> tag can be used to reverse things.
For example:
ray rushmore = NOPASSWD: /bin/kill, /bin/ls, /usr/bin/lprm
would allow the user B<ray> to run F</bin/kill>, F</bin/ls>, and
F</usr/bin/lprm> as root on the machine rushmore as B<root> without
authenticating himself. If we only want B<ray> to be able to
run F</bin/kill> without a password the entry would be:
ray rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls, /usr/bin/lprm
Note however, that the C<PASSWD> tag has no effect on users who are
in the group specified by the exempt_group option.
By default, if the C<NOPASSWD> tag is applied to any of the entries
for a user on the current host, he or she will be able to run
C<sudo -l> without a password. Additionally, a user may only run
C<sudo -v> without a password if the C<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.
=head2 Wildcards (aka meta characters):
B<sudo> allows shell-style I<wildcards> to be used in pathnames
as well as command line arguments in the I<sudoers> file. Wildcard
matching is done via the B<POSIX> C<fnmatch(3)> routine. Note that
these are I<not> regular expressions.
=over 8
=item C<*>
Matches any set of zero or more characters.
=item C<?>
Matches any single character.
=item C<[...]>
Matches any character in the specified range.
=item C<[!...]>
Matches any character B<not> in the specified range.
=item C<\x>
For any character "x", evaluates to "x". This is used to
escape special characters such as: "*", "?", "[", and "}".
=back
Note that a forward slash ('/') will B<not> be matched by
wildcards used in the pathname. When matching the command
line arguments, however, as slash B<does> get matched by
wildcards. This is to make a path like:
/usr/bin/*
match C</usr/bin/who> but not C</usr/bin/X11/xterm>.
=head2 Exceptions to wildcard rules:
The following exceptions apply to the above rules:
=over 8
=item C<"">
If the empty string C<""> is the only command line argument in the
I<sudoers> entry it means that command is not allowed to be run
with B<any> arguments.
=back
=head2 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 B<ALL> is a built in I<alias> that always causes
a match to succeed. It can be used wherever one might otherwise
use a C<Cmnd_Alias>, C<User_Alias>, C<Runas_Alias>, or C<Host_Alias>.
You should not try to define your own I<alias> called B<ALL> as the
built in alias will be used in preference to your own. Please note
that using B<ALL> can be dangerous since in a command context, it
allows the user to run B<any> command on the system.
An exclamation point ('!') can be used as a logical I<not> operator
both in an I<alias> and in front of a C<Cmnd>. This allows one to
exclude certain values. Note, however, that using a C<!> in
conjunction with the built in C<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 specicial syntactic
characters in a I<User Specification> ('=', ':', '(', ')') is optional.
The following characters must be escaped with a backslash ('\') when
used as part of a word (eg. a username or hostname):
'@', '!', '=', ':', ',', '(', ')', '\'.
=head1 EXAMPLES
Below are example I<sudoers> entries. Admittedly, some of
these are a bit contrived. First, we define our I<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
B<sudo> to log via syslog(3) using the I<auth> facility in all cases.
We don't want to subject the full time staff to the B<sudo> lecture,
and user B<millert> need not give a password. In addition, on the
machines in the I<SERVERS> C<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 builtin defaults
Defaults syslog=auth
Defaults:FULLTIMERS !lecture
Defaults:millert !authenticate
Defaults@SERVERS log_year, logfile=/var/log/sudo.log
The I<User specification> is the part that actually determines who may
run what.
root ALL = (ALL) ALL
%wheel ALL = (ALL) ALL
We let B<root> and any user in group B<wheel> run any command on any
host as any user.
FULLTIMERS ALL = NOPASSWD: ALL
Full time sysadmins (B<millert>, B<mikef>, and B<dowdy>) may run any
command on any host without authenticating themselves.
PARTTIMERS ALL = ALL
Part time sysadmins (B<bostley>, B<jwfox>, and B<crawl>) may run any
command on any host but they must authenticate themselves first
(since the entry lacks the C<NOPASSWD> tag).
jack CSNETS = ALL
The user B<jack> may run any command on the machines in the I<CSNETS> alias
(the networks C<128.138.243.0>, C<128.138.204.0>, and C<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 I<CSNETS>, the local machine's netmask will be used
during matching.
lisa CUNETS = ALL
The user B<lisa> may run any command on any host in the I<CUNETS> alias
(the class B network C<128.138.0.0>).
operator ALL = DUMPS, KILL, PRINTING, SHUTDOWN, HALT, REBOOT,\
/usr/oper/bin/
The B<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 F</usr/oper/bin/>.
joe ALL = /usr/bin/su operator
The user B<joe> may only su(1) to operator.
pete HPPA = /usr/bin/passwd [A-z]*, !/usr/bin/passwd root
The user B<pete> is allowed to change anyone's password except for
root on the I<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 B<bob> may run anything on the I<SPARC> and I<SGI> machines
as any user listed in the I<OP> C<Runas_Alias> (B<root> and B<operator>).
jim +biglab = ALL
The user B<jim> may run any command on machines in the I<biglab> netgroup.
B<Sudo> knows that "biglab" is a netgroup due to the '+' prefix.
+secretaries ALL = PRINTING, /usr/bin/adduser, /usr/bin/rmuser
Users in the B<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 B<fred> can run commands as any user in the I<DB> C<Runas_Alias>
(B<oracle> or B<sybase>) without giving a password.
john ALPHA = /usr/bin/su [!-]*, !/usr/bin/su *root*
On the I<ALPHA> machines, user B<john> may su to anyone except root
but he is not allowed to give su(1) any flags.
jen ALL, !SERVERS = ALL
The user B<jen> may run any command on any machine except for those
in the I<SERVERS> C<Host_Alias> (master, mail, www and ns).
jill SERVERS = /usr/bin/, !SU, !SHELLS
For any machine in the I<SERVERS> C<Host_Alias>, B<jill> may run
any commands in the directory /usr/bin/ except for those commands
belonging to the I<SU> and I<SHELLS> C<Cmnd_Aliases>.
steve CSNETS = (operator) /usr/local/op_commands/
The user B<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, B<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 I<WEBMASTERS> C<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
C<Host_Alias> (orion, perseus, hercules) without entering a password.
This is a bit tedious for users to type, so it is a prime candiate
for encapsulating in a shell script.
=head1 SECURITY NOTES
It is generally not effective to "subtract" commands from C<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 B<bill> from running the commands listed in
I<SU> or I<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).
=head1 CAVEATS
The I<sudoers> file should B<always> be edited by the B<visudo>
command which locks the file and does grammatical checking. It is
imperative that I<sudoers> be free of syntax errors since B<sudo>
will not run with a syntactically incorrect I<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 C<hostname> command or use the I<fqdn> option in
I<sudoers>.
=head1 FILES
@sysconfdir@/sudoers List of who can run what
/etc/group Local groups file
/etc/netgroup List of network groups
=head1 SEE ALSO
sudo(@mansectsu@), visudo(@mansectsu@), su(1), fnmatch(3).