Provided by: sudo-ldap_1.9.15p5-3ubuntu5.24.04.1_amd64 
NAME
sudoers.ldap — sudo LDAP configuration
DESCRIPTION
In addition to the standard sudoers file, sudo may be configured via LDAP. This can be especially useful
for synchronizing sudoers in a large, distributed environment.
Using LDAP for sudoers has several benefits:
• sudo no longer needs to read sudoers in its entirety. When LDAP is used, there are only two or three
LDAP queries per invocation. This makes it especially fast and particularly usable in LDAP
environments.
• It is possible to specify per-entry options that override the global default options. /etc/sudoers
only supports default options and limited options associated with user/host/commands/aliases. The
syntax is complicated and can be difficult for users to understand. Placing the options directly in
the entry is more natural.
• The visudo program is no longer needed. visudo provides locking and syntax checking of the
/etc/sudoers file. Since LDAP updates are atomic, locking is no longer necessary. Because syntax is
checked when the data is inserted into LDAP, there is no need for a specialized tool to check syntax.
SUDOers LDAP container
The sudoers configuration is contained in the ‘ou=SUDOers’ LDAP container.
Sudo first looks for the ‘cn=defaults’ entry in the SUDOers container. If found, the multi-valued
sudoOption attribute is parsed in the same manner as a global Defaults line in /etc/sudoers. In the
following example, the SSH_AUTH_SOCK variable will be preserved in the environment for all users.
dn: cn=defaults,ou=SUDOers,dc=my-domain,dc=com
objectClass: top
objectClass: sudoRole
cn: defaults
description: Default sudoOption's go here
sudoOption: env_keep+=SSH_AUTH_SOCK
The equivalent of a sudoer in LDAP is a sudoRole. It consists of the following attributes:
sudoUser
A user name, user-ID (prefixed with ‘#’), Unix group name or ID (prefixed with ‘%’ or ‘%#’
respectively), user netgroup (prefixed with ‘+’), or non-Unix group name or ID (prefixed with ‘%:’
or ‘%:#’ respectively). User netgroups are matched using the user and domain members only; the
host member is not used when matching. Non-Unix group support is only available when an
appropriate group_plugin is defined in the global defaults sudoRole object. If a sudoUser entry is
preceded by an exclamation point, ‘!’, and the entry matches, the sudoRole in which it resides will
be ignored. Negated sudoUser entries are only supported by version 1.9.9 or higher.
sudoHost
A host name, IP address, IP network, or host netgroup (prefixed with a ‘+’). The special value ALL
will match any host. Host netgroups are matched using the host (both qualified and unqualified)
and domain members only; the user member is not used when matching. If a sudoHost entry is
preceded by an exclamation point, ‘!’, and the entry matches, the sudoRole in which it resides will
be ignored. Negated sudoHost entries are only supported by version 1.8.18 or higher.
sudoCommand
A fully-qualified Unix command name with optional command line arguments, potentially including
globbing characters (aka wild cards). If a command name is preceded by an exclamation point, ‘!’,
the user will be prohibited from running that command.
The built-in command “sudoedit” is used to permit a user to run sudo with the -e option (or as
sudoedit). It may take command line arguments just as a normal command does. Unlike other
commands, “sudoedit” is a built into sudo itself and must be specified in without a leading path.
The special value ALL will match any command.
If a command name is prefixed with a SHA-2 digest, it will only be allowed if the digest matches.
This may be useful in situations where the user invoking sudo has write access to the command or
its parent directory. The following digest formats are supported: sha224, sha256, sha384, and
sha512. The digest name must be followed by a colon (‘:’) and then the actual digest, in either
hex or base64 format. For example, given the following value for sudoCommand:
sha224:0GomF8mNN3wlDt1HD9XldjJ3SNgpFdbjO1+NsQ /bin/ls
The user may only run /bin/ls if its sha224 digest matches the specified value. Command digests
are only supported by version 1.8.7 or higher.
sudoOption
Identical in function to the global options described above, but specific to the sudoRole in which
it resides.
sudoRunAsUser
A user name or user-ID (prefixed with ‘#’) that commands may be run as or a Unix group (prefixed
with a ‘%’) or user netgroup (prefixed with a ‘+’) that contains a list of users that commands may
be run as. The special value ALL will match any user. If a sudoRunAsUser entry is preceded by an
exclamation point, ‘!’, and the entry matches, the sudoRole in which it resides will be ignored.
If sudoRunAsUser is specified but empty, it will match the invoking user. If neither sudoRunAsUser
nor sudoRunAsGroup are present, the value of the runas_default sudoOption is used (defaults to
root).
The sudoRunAsUser attribute is only available in sudo versions 1.7.0 and higher. Older versions of
sudo use the sudoRunAs attribute instead. Negated sudoRunAsUser entries are only supported by
version 1.8.26 or higher.
sudoRunAsGroup
A Unix group or group-ID (prefixed with ‘#’) that commands may be run as. The special value ALL
will match any group. If a sudoRunAsGroup entry is preceded by an exclamation point, ‘!’, and the
entry matches, the sudoRole in which it resides will be ignored.
The sudoRunAsGroup attribute is only available in sudo versions 1.7.0 and higher. Negated
sudoRunAsGroup entries are only supported by version 1.8.26 or higher.
sudoNotBefore
A timestamp in the form ‘yyyymmddHHMMSSZ’ that can be used to provide a start date/time for when
the sudoRole will be valid. If multiple sudoNotBefore entries are present, the earliest is used.
Timestamps must be in Coordinated Universal Time (UTC), not the local timezone. The minute and
seconds portions are optional, but some LDAP servers require that they be present (contrary to the
RFC).
The sudoNotBefore attribute is only available in sudo versions 1.7.5 and higher and must be
explicitly enabled via the SUDOERS_TIMED option in /etc/sudo-ldap.conf.
sudoNotAfter
A timestamp in the form ‘yyyymmddHHMMSSZ’ that indicates an expiration date/time, after which the
sudoRole will no longer be valid. If multiple sudoNotAfter entries are present, the last one is
used. Timestamps must be in Coordinated Universal Time (UTC), not the local timezone. The minute
and seconds portions are optional, but some LDAP servers require that they be present (contrary to
the RFC).
The sudoNotAfter attribute is only available in sudo versions 1.7.5 and higher and must be
explicitly enabled via the SUDOERS_TIMED option in /etc/sudo-ldap.conf.
sudoOrder
The sudoRole entries retrieved from the LDAP directory have no inherent order. The sudoOrder
attribute is an integer (or floating point value for LDAP servers that support it) that is used to
sort the matching entries. This allows LDAP-based sudoers entries to more closely mimic the
behavior of the sudoers file, where the order of the entries influences the result. If multiple
entries match, the entry with the highest sudoOrder attribute is chosen. This corresponds to the
“last match” behavior of the sudoers file. If the sudoOrder attribute is not present, a value of 0
is assumed.
The sudoOrder attribute is only available in sudo versions 1.7.5 and higher.
Each attribute listed above should contain a single value, but there may be multiple instances of each
attribute type. A sudoRole must contain at least one sudoUser, sudoHost, and sudoCommand.
The following example allows users in group wheel to run any command on any host via sudo:
dn: cn=%wheel,ou=SUDOers,dc=my-domain,dc=com
objectClass: top
objectClass: sudoRole
cn: %wheel
sudoUser: %wheel
sudoHost: ALL
sudoCommand: ALL
Anatomy of LDAP sudoers lookup
When looking up a sudoer using LDAP there are only two or three LDAP queries per invocation. The first
query is to parse the global options. The second is to match against the user's name and the groups that
the user belongs to. (The special ALL tag is matched in this query too.) If no match is returned for
the user's name and groups, a third query returns all entries containing user netgroups and other non-
Unix groups and checks to see if the user belongs to any of them.
If timed entries are enabled with the SUDOERS_TIMED parameter, the LDAP queries include a sub-filter that
limits retrieval to entries that satisfy the time constraints, if any.
If the NETGROUP_BASE parameter is present and NETGROUP_QUERY has not been disabled (see “Configuring
ldap.conf” below), queries are performed to determine the list of netgroups the user belongs to before
the sudoers query. This makes it possible to include netgroups in the sudoers query string in the same
manner as Unix groups. The third query mentioned above is not performed unless a group provider plugin
is also configured. The actual LDAP queries performed by sudo are as follows:
1. Match all nisNetgroup records with a nisNetgroupTriple containing the user, host, and NIS domain.
The query will match nisNetgroupTriple entries with either the short or long form of the host name
or no host name specified in the tuple. If the NIS domain is set, the query will match only match
entries that include the domain or for which there is no domain present. If the NIS domain is not
set, a wildcard is used to match any domain name but be aware that the NIS schema used by some LDAP
servers may not support wild cards for nisNetgroupTriple.
2. Repeated queries are performed to find any nested nisNetgroup records with a memberNisNetgroup entry
that refers to an already-matched record.
For sites with a large number of netgroups, using NETGROUP_BASE can significantly speed up sudo's
execution time as long as the LDAP server supports querying the nisNetgroup object by its
nisNetgroupTriple attribute.
Differences between LDAP and non-LDAP sudoers
One of the major differences between LDAP and file-based sudoers is that in LDAP, sudo-specific Aliases
are not supported.
For the most part, there is little need for sudo-specific Aliases. Unix groups, non-Unix groups (via the
group_plugin), or user netgroups can be used in place of User_Aliases and Runas_Aliases. Host netgroups
can be used in place of Host_Aliases. Since groups and netgroups can also be stored in LDAP there is no
real need for sudo-specific aliases.
There are also some subtle differences in the way sudoers is handled once in LDAP. Probably the biggest
is that according to the RFC, LDAP ordering is arbitrary and you cannot expect that Attributes and
Entries are returned in any specific order.
The order in which different entries are applied can be controlled using the sudoOrder attribute, but
there is no way to guarantee the order of attributes within a specific entry. If there are conflicting
command rules in an entry, the negative takes precedence. This is called paranoid behavior (not
necessarily the most specific match).
Here is an example:
# /etc/sudoers:
# Allow all commands except shell
johnny ALL=(root) ALL,!/bin/sh
# Always allows all commands because ALL is matched last
puddles ALL=(root) !/bin/sh,ALL
# LDAP equivalent of johnny
# Allows all commands except shell
dn: cn=role1,ou=Sudoers,dc=my-domain,dc=com
objectClass: sudoRole
objectClass: top
cn: role1
sudoUser: johnny
sudoHost: ALL
sudoCommand: ALL
sudoCommand: !/bin/sh
# LDAP equivalent of puddles
# Notice that even though ALL comes last, it still behaves like
# role1 since the LDAP code assumes the more paranoid configuration
dn: cn=role2,ou=Sudoers,dc=my-domain,dc=com
objectClass: sudoRole
objectClass: top
cn: role2
sudoUser: puddles
sudoHost: ALL
sudoCommand: !/bin/sh
sudoCommand: ALL
Converting between file-based and LDAP sudoers
The cvtsudoers(1) utility can be used to convert between file-based and LDAP sudoers. However, there are
features in the file-based sudoers that have no equivalent in LDAP-based sudoers (and vice versa). These
cannot be converted automatically.
For example, a Cmnd_Alias in a sudoers file may be converted to a sudoRole that contains multiple
commands. Multiple users and/or groups may be assigned to the sudoRole.
Also, host, user, runas, and command-based Defaults entries are not supported. However, a sudoRole may
contain one or more sudoOption attributes which can often serve the same purpose.
Consider the following sudoers lines:
Cmnd_Alias PAGERS = /usr/bin/more, /usr/bin/pg, /usr/bin/less
Defaults!PAGERS noexec
alice, bob ALL = ALL
In this example, alice and bob are allowed to run all commands, but the commands listed in PAGERS will
have the noexec flag set, preventing shell escapes.
When converting this to LDAP, two sudoRole objects can be used:
dn: cn=PAGERS,ou=SUDOers,dc=my-domain,dc=com
objectClass: top
objectClass: sudoRole
cn: PAGERS
sudoUser: alice
sudoUser: bob
sudoHost: ALL
sudoCommand: /usr/bin/more
sudoCommand: /usr/bin/pg
sudoCommand: /usr/bin/less
sudoOption: noexec
sudoOrder: 900
dn: cn=ADMINS,ou=SUDOers,dc=my-domain,dc=com
objectClass: top
objectClass: sudoRole
cn: ADMINS
sudoUser: alice
sudoUser: bob
sudoHost: ALL
sudoCommand: ALL
sudoOrder: 100
In the LDAP version, the sudoOrder attribute is used to guarantee that the PAGERS sudoRole with noexec
has precedence. Unlike the sudoers version, the LDAP version requires that all users for whom the
restriction should apply be assigned to the PAGERS sudoRole. Using a Unix group or netgroup in PAGERS
rather than listing each user would make this easier to maintain.
Per-user Defaults entries can be emulated by using one or more sudoOption attributes in a sudoRole.
Consider the following sudoers lines:
User_Alias ADMINS = john, sally
Defaults:ADMINS !authenticate
ADMINS ALL = (ALL:ALL) ALL
In this example, john and sally are allowed to run any command as any user or group.
When converting this to LDAP, we can use a Unix group instead of the User_Alias.
dn: cn=admins,ou=SUDOers,dc=my-domain,dc=com
objectClass: top
objectClass: sudoRole
cn: admins
sudoUser: %admin
sudoHost: ALL
sudoRunAsUser: ALL
sudoRunAsGroup: ALL
sudoCommand: ALL
sudoOption: !authenticate
This assumes that users john and sally are members of the “admins” Unix group.
Sudoers schema
In order to use sudo's LDAP support, the sudo schema must be installed on your LDAP server. In addition,
be sure to index the sudoUser attribute.
The sudo distribution includes versions of the sudoers schema for multiple LDAP servers:
schema.OpenLDAP
OpenLDAP slapd and OpenBSD ldapd
schema.olcSudo
OpenLDAP slapd 2.3 and higher when on-line configuration is enabled
schema.iPlanet
Netscape-derived servers such as the iPlanet, Oracle, and 389 Directory Servers
schema.ActiveDirectory
Microsoft Active Directory
The schema in OpenLDAP format is also included in the “EXAMPLES” section.
Configuring ldap.conf
Sudo reads the /etc/sudo-ldap.conf file for LDAP-specific configuration. Typically, this file is shared
between different LDAP-aware clients. As such, most of the settings are not sudo-specific. The
/etc/sudo-ldap.conf file is parsed by sudo itself and may support options that differ from those
described in the system's ldap.conf(5) manual. The path to ldap.conf may be overridden via the ldap_conf
plugin argument in sudo.conf(5).
On systems using the OpenLDAP libraries, default values specified in /etc/openldap/ldap.conf or the
user's .ldaprc files are not used.
sudo supports a variety of LDAP library implementations, including OpenLDAP, Netscape-derived (also used
by Solaris and HP-UX), and IBM LDAP (aka Tivoli). Some options are specific to certain LDAP
implementations or have implementation-specific behavior. These differences are noted below where
applicable.
Only those options explicitly listed in /etc/sudo-ldap.conf as being supported by sudo are honored.
Configuration options are listed below in upper case but are parsed in a case-independent manner.
Lines beginning with a pound sign (‘#’) are ignored. Leading white space is removed from the beginning
of lines.
BIND_TIMELIMIT seconds
The BIND_TIMELIMIT parameter specifies the amount of time, in seconds, to wait while trying to
connect to an LDAP server. If multiple URIs or HOSTs are specified, this is the amount of time to
wait before trying the next one in the list.
BINDDN DN
The BINDDN parameter specifies the identity, in the form of a Distinguished Name (DN), to use when
performing LDAP operations. If not specified, LDAP operations are performed with an anonymous
identity. By default, most LDAP servers will allow anonymous access.
BINDPW secret
The BINDPW parameter specifies the password to use when performing LDAP operations. This is
typically used in conjunction with the BINDDN parameter. The secret may be a plaintext password or
a base64-encoded string with a “base64:” prefix. For example:
BINDPW base64:dGVzdA==
If a plaintext password is used, it should be a simple string without quotes. Plain text passwords
may not include the comment character (‘#’) and the escaping of special characters with a backslash
(‘\’) is not supported.
DEREF never/searching/finding/always
How alias dereferencing is to be performed when searching. See the ldap.conf(5) manual for a full
description of this option.
HOST name[:port] ...
If no URI is specified (see below), the HOST parameter specifies a white space-delimited list of
LDAP servers to connect to. Each host may include an optional port separated by a colon (‘:’).
The HOST parameter is deprecated in favor of the URI specification and is included for backward
compatibility only.
KRB5_CCNAME file name
The path to the Kerberos 5 credential cache to use when authenticating with the remote server.
This option is only relevant when using SASL authentication (see below).
LDAP_VERSION number
The version of the LDAP protocol to use when connecting to the server. The default value is
protocol version 3.
NETGROUP_BASE base
The base DN to use when performing LDAP netgroup queries. Typically this is of the form
‘ou=netgroup,dc=my-domain,dc=com’ for the domain my-domain.com. Multiple NETGROUP_BASE lines may
be specified, in which case they are queried in the order specified.
When this option is enabled, sudo will query the LDAP server directly when matching netgroups
present in a sudoRole instead of relying on the C library's innetgr() function.
Additionally, if the NETGROUP_QUERY parameter (which is enabled by default) has not been disabled,
the user's netgroups will be queried directly via LDAP for use in the main sudoers query. This is
usually faster than fetching every sudoRole object containing a sudoUser that begins with a ‘+’
prefix and checking whether the user is a member of each one. The NIS schema used by some LDAP
servers needs a modification to support querying the nisNetgroup object by its nisNetgroupTriple
attribute. For example, OpenLDAP's slapd requires the following change to the nisNetgroupTriple
attribute:
attributetype ( 1.3.6.1.1.1.1.14 NAME 'nisNetgroupTriple'
DESC 'Netgroup triple'
EQUALITY caseIgnoreIA5Match
SUBSTR caseIgnoreIA5SubstringsMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )
Before enabling NETGROUP_BASE, you should verify that your LDAP server supports matching
nisNetgroupTriple. For example, using ldapsearch:
$ ldapsearch -b $NETGROUP_BASE \
'(&(objectClass=nisNetgroup)(nisNetgroupTriple=\28*,USER,\29))'
where your nisNetgroup data includes an object with the following nisNetgroupTriple:
nisNetgroupTriple: (,USER,)
NETGROUP_QUERY on/true/yes/off/false/no
The NETGROUP_QUERY parameter indicates whether or not the LDAP server supports querying nisNetgroup
objects by matching on nisNetgroupTriple attributes. By default, sudoers expects to be able to
perform queries that match on nisNetgroupTriple attributes when NETGROUP_BASE is set, but not all
LDAP servers support this.
If NETGROUP_QUERY is disabled, sudoers will not attempt to determine the list of netgroups the user
belongs to, but will still use NETGROUP_BASE directly when matching netgroups. This can be used to
support netgroups on systems that lack the innetgr() C library function. See the description of
the NETGROUP_BASE parameter for more information.
NETGROUP_SEARCH_FILTER ldap_filter
An LDAP filter which is used to restrict the set of records returned when performing an LDAP
netgroup query. Typically, this is of the form ‘attribute=value’ or
‘(&(attribute=value)(attribute2=value2))’. The default search filter is:
‘objectClass=nisNetgroup’. If ldap_filter is omitted, no search filter will be used.
This option is only used when querying netgroups directly via LDAP.
NETWORK_TIMEOUT seconds
An alias for BIND_TIMELIMIT provided for OpenLDAP compatibility.
PORT port_number
If no URI is specified, the PORT parameter specifies the default port to connect to on the LDAP
server if a HOST parameter does not specify the port itself. If no PORT parameter is used, the
default is port 389 for LDAP and port 636 for LDAP over TLS (SSL). The PORT parameter is
deprecated in favor of the URI specification and is included for backward compatibility only.
ROOTBINDDN DN
The ROOTBINDDN parameter specifies the identity, in the form of a Distinguished Name (DN), to use
when performing privileged LDAP operations, such as sudoers queries. The password corresponding to
the identity should be stored in the or the path specified by the ldap_secret plugin argument in
sudo.conf(5), which defaults to /etc/ldap.secret. If no ROOTBINDDN is specified, the BINDDN
identity is used (if any).
ROOTUSE_SASL on/true/yes/off/false/no
Enable ROOTUSE_SASL to enable SASL authentication when connecting to an LDAP server from a
privileged process, such as sudo.
SASL_AUTH_ID identity
The SASL user name to use when connecting to the LDAP server. By default, sudo will use an
anonymous connection.
This option is only relevant when using SASL authentication.
SASL_MECH mechanisms
A white space-delimited list of SASL authentication mechanisms to use. By default, sudo will use
GSSAPI authentication.
SASL_SECPROPS none/properties
SASL security properties or none for no properties. See the SASL programmer's manual for details.
This option is only relevant when using SASL authentication.
SSL on/true/yes/off/false/no
If the SSL parameter is set to on, true, or yes TLS (SSL) encryption is always used when
communicating with the LDAP server. Typically, this involves connecting to the server on port 636
(ldaps).
SSL start_tls
If the SSL parameter is set to start_tls, the LDAP server connection is initiated normally and TLS
encryption is begun before the bind credentials are sent. This has the advantage of not requiring
a dedicated port for encrypted communications. This parameter is only supported by LDAP servers
that honor the start_tls extension, such as the OpenLDAP and IBM Tivoli Directory servers.
SUDOERS_BASE base
The base DN to use when performing sudo LDAP queries. Typically this is of the form
‘ou=SUDOers,dc=my-domain,dc=com’ for the domain my-domain.com. Multiple SUDOERS_BASE lines may be
specified, in which case they are queried in the order specified.
SUDOERS_DEBUG debug_level
This sets the debug level for sudo LDAP queries. Debugging information is printed to the standard
error. A value of 1 results in a moderate amount of debugging information. A value of 2 shows the
results of the matches themselves. This parameter should not be set in a production environment as
the extra information is likely to confuse users.
The SUDOERS_DEBUG parameter is deprecated and will be removed in a future release. The same
information is now logged via the sudo debugging framework using the “ldap” subsystem at priorities
diag and info for debug_level values 1 and 2 respectively. See the sudo.conf(5) manual for details
on how to configure sudo debugging.
SUDOERS_SEARCH_FILTER ldap_filter
An LDAP filter which is used to restrict the set of records returned when performing a sudo LDAP
query. Typically, this is of the form ‘attribute=value’ or
‘(&(attribute=value)(attribute2=value2))’. The default search filter is: ‘objectClass=sudoRole’.
If ldap_filter is omitted, no search filter will be used.
SUDOERS_TIMED on/true/yes/off/false/no
Whether or not to evaluate the sudoNotBefore and sudoNotAfter attributes that implement time-
dependent sudoers entries.
TIMELIMIT seconds
The TIMELIMIT parameter specifies the amount of time, in seconds, to wait for a response to an LDAP
query.
TIMEOUT seconds
The TIMEOUT parameter specifies the amount of time, in seconds, to wait for a response from the
various LDAP APIs.
TLS_CACERT file name
An alias for TLS_CACERTFILE for OpenLDAP compatibility.
TLS_CACERTFILE file name
The path to a certificate authority bundle which contains the certificates for all the Certificate
Authorities the client knows to be valid, e.g., /etc/ssl/ca-bundle.pem.
This option is only supported by the OpenLDAP libraries. Netscape-derived LDAP libraries use the
same certificate database for CA and client certificates (see TLS_CERT).
TLS_CACERTDIR directory
Similar to TLS_CACERTFILE but instead of a file, it is a directory containing individual
Certificate Authority certificates, e.g., /etc/ssl/certs. The directory specified by TLS_CACERTDIR
is checked after TLS_CACERTFILE.
This option is only supported by the OpenLDAP libraries.
TLS_CERT file name
The path to a file containing the client certificate which can be used to authenticate the client
to the LDAP server. The certificate type depends on the LDAP libraries used.
OpenLDAP:
‘tls_cert /etc/ssl/client_cert.pem’
Netscape-derived:
‘tls_cert /var/ldap/cert7.db’
IBM LDAP:
Unused, the key database specified by TLS_KEY contains both keys and certificates.
When using Netscape-derived libraries, this file may also contain Certificate Authority
certificates.
TLS_CHECKPEER on/true/yes/off/false/no
If enabled, TLS_CHECKPEER will cause the LDAP server's TLS certificated to be verified. If the
server's TLS certificate cannot be verified (usually because it is signed by an unknown certificate
authority), sudo will be unable to connect to it. If TLS_CHECKPEER is disabled, no check is made.
Disabling this check creates an opportunity for man-in-the-middle attacks since the server's
identity will not be authenticated. If possible, the CA's certificate should be installed locally
so it can be verified.
This option is not supported by the IBM LDAP libraries.
TLS_KEY file name
The path to a file containing the private key which matches the certificate specified by TLS_CERT.
The private key must not be password-protected. The key type depends on the LDAP libraries used.
OpenLDAP:
‘tls_key /etc/ssl/client_key.pem’
Netscape-derived:
‘tls_key /var/ldap/key3.db’
IBM LDAP:
‘tls_key /usr/ldap/ldapkey.kdb’
When using IBM LDAP libraries, this file may also contain Certificate Authority and client
certificates and may be encrypted.
TLS_CIPHERS cipher list
The TLS_CIPHERS parameter allows the administer to restrict which encryption algorithms may be used
for TLS (SSL) connections. See the OpenLDAP or IBM Tivoli Directory Server manual for a list of
valid ciphers.
This option is not supported by Netscape-derived libraries.
TLS_KEYPW secret
The TLS_KEYPW contains the password used to decrypt the key database on clients using the IBM LDAP
library. The secret may be a plaintext password or a base64-encoded string with a “base64:”
prefix. For example:
TLS_KEYPW base64:dGVzdA==
If a plaintext password is used, it should be a simple string without quotes. Plain text passwords
may not include the comment character (‘#’) and the escaping of special characters with a backslash
(‘\’) is not supported. If this option is used, /etc/sudo-ldap.conf must not be world-readable to
avoid exposing the password. Alternately, a stash file can be used to store the password in
encrypted form (see below).
If no TLS_KEYPW is specified, a stash file will be used if it exists. The stash file must have the
same path as the file specified by TLS_KEY, but use a ‘.sth’ file extension instead of ‘.kdb’, for
example ‘ldapkey.sth’. The default ‘ldapkey.kdb’ that ships with the IBM Tivoli Directory Server
is encrypted with the password ‘ssl_password’. The gsk8capicmd utility can be used to manage the
key database and create a stash file.
This option is only supported by the IBM LDAP libraries.
TLS_REQCERT level
The TLS_REQCERT parameter controls how the LDAP server's TLS certificated will be verified (if at
all). If the server's TLS certificate cannot be verified (usually because it is signed by an
unknown certificate authority), sudo will be unable to connect to it. The following level values
are supported:
never
The server certificate will not be requested or checked.
allow
The server certificate will be requested. A missing or invalid certificate is ignored
and not considered an error.
try The server certificate will be requested. A missing certificate is ignored but an
invalid certificate will result in a connection error.
demand | hard
The server certificate will be requested. A missing or invalid certificate will result
in a connection error. This is the default behavior.
This option is only supported by the OpenLDAP libraries. Other LDAP libraries only support the
TLS_CHECKPEER parameter.
TLS_RANDFILE file name
The TLS_RANDFILE parameter specifies the path to an entropy source for systems that lack a random
device. It is generally used in conjunction with prngd or egd.
This option is only supported by the OpenLDAP libraries.
URI ldap[s]://[hostname[:port]] ...
Specifies a white space-delimited list of one or more URIs describing the LDAP server(s) to connect
to. The protocol may be either ldap ldaps, the latter being for servers that support TLS (SSL)
encryption. If no port is specified, the default is port 389 for ‘ldap://’ or port 636 for
‘ldaps://’. If no hostname is specified, sudo will connect to localhost. Multiple URI lines are
treated identically to a URI line containing multiple entries. Only systems using the OpenSSL
libraries support the mixing of ‘ldap://’ and ‘ldaps://’ URIs. Both the Netscape-derived and IBM
LDAP libraries used on most commercial versions of Unix are only capable of supporting one or the
other.
USE_SASL on/true/yes/off/false/no
Enable USE_SASL for LDAP servers that support SASL authentication.
ROOTSASL_AUTH_ID identity
The SASL user name to use when ROOTUSE_SASL is enabled.
See the ldap.conf entry in the “EXAMPLES” section.
Configuring nsswitch.conf
Unless it is disabled at build time, sudo consults the Name Service Switch file, /etc/nsswitch.conf, to
specify the sudoers search order. Sudo looks for a line beginning with sudoers: and uses this to
determine the search order. By default, sudo does not stop searching after the first match and later
matches take precedence over earlier ones (unless ‘[SUCCESS=return]’ is used, see below). The following
sources are recognized:
files read sudoers from /etc/sudoers
ldap read sudoers from LDAP
In addition, a subset of nsswitch.conf-style action statements is supported, specifically
‘[SUCCESS=return]’ and ‘[NOTFOUND=return]’. These will unconditionally terminate the search if the user
was either found ‘[SUCCESS=return]’ or not found ‘[NOTFOUND=return]’ in the immediately preceding source.
Other action statements tokens are not supported, nor is test negation with ‘!’.
To consult LDAP first followed by the local sudoers file (if it exists), use:
sudoers: ldap files
To consult LDAP only when no match is found in the local sudoers file (if it exists), use:
sudoers: files [SUCCESS=return] ldap
The local sudoers file can be ignored completely by using:
sudoers: ldap
If the /etc/nsswitch.conf file is not present or there is no sudoers line, the following default is
assumed:
sudoers: files
The /etc/nsswitch.conf file is supported even when the underlying operating system does not support it,
except on AIX (see below).
Configuring netsvc.conf
On AIX systems, the /etc/netsvc.conf file is consulted instead of /etc/nsswitch.conf. sudo simply treats
netsvc.conf as a variant of nsswitch.conf; information in the previous section unrelated to the file
format itself still applies.
To consult LDAP first followed by the local sudoers file (if it exists), use:
sudoers = ldap, files
The local sudoers file can be ignored completely by using:
sudoers = ldap
To treat LDAP as authoritative and only use the local sudoers file if the user is not present in LDAP,
use:
sudoers = ldap = auth, files
In the above example, the auth qualifier only affects user lookups; both LDAP and sudoers will be queried
for Defaults entries.
If the /etc/netsvc.conf file is not present or there is no sudoers line, the following default is
assumed:
sudoers = files
Integration with sssd
On systems with the System Security Services Daemon (SSSD) and where sudo has been built with SSSD
support, it is possible to use SSSD to cache LDAP sudoers rules. To use SSSD as the sudoers source, you
should use sss instead of ldap for the sudoers entry in /etc/nsswitch.conf. The /etc/sudo-ldap.conf file
is not used by the SSSD sudo back end. See sssd-sudo(5) for more information on configuring sudo to work
with SSSD.
FILES
/etc/sudo-ldap.conf LDAP configuration file
/etc/nsswitch.conf determines sudoers source order
/etc/netsvc.conf determines sudoers source order on AIX
EXAMPLES
Example ldap.conf
# Either specify one or more URIs or one or more host:port pairs.
# If neither is specified sudo will default to localhost, port 389.
#
#host ldapserver
#host ldapserver1 ldapserver2:390
#
# Default port if host is specified without one, defaults to 389.
#port 389
#
# URI will override the host and port settings.
uri ldap://ldapserver
#uri ldaps://secureldapserver
#uri ldaps://secureldapserver ldap://ldapserver
#
# The amount of time, in seconds, to wait while trying to connect to
# an LDAP server.
bind_timelimit 30
#
# The amount of time, in seconds, to wait while performing an LDAP query.
timelimit 30
#
# Must be set or sudo will ignore LDAP; may be specified multiple times.
sudoers_base ou=SUDOers,dc=my-domain,dc=com
#
# verbose sudoers matching from ldap
#sudoers_debug 2
#
# Enable support for time-based entries in sudoers.
#sudoers_timed yes
#
# optional proxy credentials
#binddn <who to search as>
#bindpw <password>
#rootbinddn <who to search as, uses /etc/ldap.secret for bindpw>
#
# LDAP protocol version, defaults to 3
#ldap_version 3
#
# Define if you want to use an encrypted LDAP connection.
# Typically, you must also set the port to 636 (ldaps).
#ssl on
#
# Define if you want to use port 389 and switch to
# encryption before the bind credentials are sent.
# Only supported by LDAP servers that support the start_tls
# extension such as OpenLDAP.
#ssl start_tls
#
# Additional TLS options follow that allow tweaking of the
# SSL/TLS connection.
#
#tls_checkpeer yes # verify server SSL certificate
#tls_checkpeer no # ignore server SSL certificate
#
# If you enable tls_checkpeer, specify either tls_cacertfile
# or tls_cacertdir. Only supported when using OpenLDAP.
#
#tls_cacertfile /etc/certs/trusted_signers.pem
#tls_cacertdir /etc/certs
#
# For systems that don't have /dev/random
# use this along with PRNGD or EGD.pl to seed the
# random number pool to generate cryptographic session keys.
# Only supported when using OpenLDAP.
#
#tls_randfile /etc/egd-pool
#
# You may restrict which ciphers are used. Consult your SSL
# documentation for which options go here.
# Only supported when using OpenLDAP.
#
#tls_ciphers <cipher-list>
#
# Sudo can provide a client certificate when communicating to
# the LDAP server.
# Tips:
# * Enable both lines at the same time.
# * Do not password protect the key file.
# * Ensure the keyfile is only readable by root.
#
# For OpenLDAP:
#tls_cert /etc/certs/client_cert.pem
#tls_key /etc/certs/client_key.pem
#
# For Netscape-derived LDAP, tls_cert and tls_key may specify either
# a directory, in which case the files in the directory must have the
# default names (e.g., cert8.db and key4.db), or the path to the cert
# and key files themselves. However, a bug in version 5.0 of the LDAP
# SDK will prevent specific file names from working. For this reason
# it is suggested that tls_cert and tls_key be set to a directory,
# not a file name.
#
# The certificate database specified by tls_cert may contain CA certs
# and/or the client's cert. If the client's cert is included, tls_key
# should be specified as well.
# For backward compatibility, "sslpath" may be used in place of tls_cert.
#tls_cert /var/ldap
#tls_key /var/ldap
#
# If using SASL authentication for LDAP (OpenSSL)
# use_sasl yes
# sasl_auth_id <SASL user name>
# rootuse_sasl yes
# rootsasl_auth_id <SASL user name for root access>
# sasl_secprops none
# krb5_ccname /etc/.ldapcache
Sudoers schema for OpenLDAP
The following schema, in OpenLDAP format, is included with sudo source and binary distributions as
schema.OpenLDAP. Simply copy it to the schema directory (e.g., /etc/openldap/schema), add the proper
include line in slapd.conf and restart slapd. Sites using the optional on-line configuration supported
by OpenLDAP 2.3 and higher should apply the schema.olcSudo file instead.
attributetype ( 1.3.6.1.4.1.15953.9.1.1
NAME 'sudoUser'
DESC 'User(s) who may run sudo'
EQUALITY caseExactMatch
SUBSTR caseExactSubstringsMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 )
attributetype ( 1.3.6.1.4.1.15953.9.1.2
NAME 'sudoHost'
DESC 'Host(s) who may run sudo'
EQUALITY caseExactIA5Match
SUBSTR caseExactIA5SubstringsMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )
attributetype ( 1.3.6.1.4.1.15953.9.1.3
NAME 'sudoCommand'
DESC 'Command(s) to be executed by sudo'
EQUALITY caseExactIA5Match
SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )
attributetype ( 1.3.6.1.4.1.15953.9.1.4
NAME 'sudoRunAs'
DESC 'User(s) impersonated by sudo'
EQUALITY caseExactIA5Match
SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )
attributetype ( 1.3.6.1.4.1.15953.9.1.5
NAME 'sudoOption'
DESC 'Options(s) followed by sudo'
EQUALITY caseExactIA5Match
SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )
attributetype ( 1.3.6.1.4.1.15953.9.1.6
NAME 'sudoRunAsUser'
DESC 'User(s) impersonated by sudo'
EQUALITY caseExactMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 )
attributetype ( 1.3.6.1.4.1.15953.9.1.7
NAME 'sudoRunAsGroup'
DESC 'Group(s) impersonated by sudo'
EQUALITY caseExactMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 )
attributetype ( 1.3.6.1.4.1.15953.9.1.8
NAME 'sudoNotBefore'
DESC 'Start of time interval for which the entry is valid'
EQUALITY generalizedTimeMatch
ORDERING generalizedTimeOrderingMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.24 )
attributetype ( 1.3.6.1.4.1.15953.9.1.9
NAME 'sudoNotAfter'
DESC 'End of time interval for which the entry is valid'
EQUALITY generalizedTimeMatch
ORDERING generalizedTimeOrderingMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.24 )
attributetype ( 1.3.6.1.4.1.15953.9.1.10
NAME 'sudoOrder'
DESC 'an integer to order the sudoRole entries'
EQUALITY integerMatch
ORDERING integerOrderingMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.27 )
objectclass ( 1.3.6.1.4.1.15953.9.2.1 NAME 'sudoRole' SUP top STRUCTURAL
DESC 'Sudoer Entries'
MUST ( cn )
MAY ( sudoUser $ sudoHost $ sudoCommand $ sudoRunAs $ sudoRunAsUser $
sudoRunAsGroup $ sudoOption $ sudoNotBefore $ sudoNotAfter $
sudoOrder $ description )
)
SEE ALSO
cvtsudoers(1), ldap.conf(5), sssd-sudo(5), sudo.conf(5), sudoers(5)
AUTHORS
Many people have worked on sudo over the years; this version consists of code written primarily by:
Todd C. Miller
See the CONTRIBUTORS.md file in the sudo distribution (https://www.sudo.ws/about/contributors/) for an
exhaustive list of people who have contributed to sudo.
CAVEATS
There are differences in the way that LDAP-based sudoers is parsed compared to file-based sudoers. See
the “Differences between LDAP and non-LDAP sudoers” section for more information.
BUGS
If you believe you have found a bug in sudo, you can submit a bug report at https://bugzilla.sudo.ws/
SUPPORT
Limited free support is available via the sudo-users mailing list, see
https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search the archives.
DISCLAIMER
sudo is provided “AS IS” and any express or implied warranties, including, but not limited to, the
implied warranties of merchantability and fitness for a particular purpose are disclaimed. See the
LICENSE.md file distributed with sudo or https://www.sudo.ws/about/license/ for complete details.
Sudo 1.9.15p5 June 7, 2023 SUDOERS.LDAP(5)