authelia/docs/configuration/authentication/ldap.md

layout	title	parent	grand_parent	nav_order
default	LDAP	Authentication Backends	Configuration	2

LDAP

Authelia supports using a LDAP server as the users database.

Configuration

authentication_backend:
  disable_reset_password: false
  refresh_interval: 5m
  ldap:
    implementation: custom
    url: ldap://127.0.0.1
    timeout: 5s
    start_tls: false
    tls:
      server_name: ldap.example.com
      skip_verify: false
      minimum_version: TLS1.2
    base_dn: DC=example,DC=com
    username_attribute: uid
    additional_users_dn: ou=users
    users_filter: (&({username_attribute}={input})(objectClass=person))
    additional_groups_dn: ou=groups
    groups_filter: (&(member={dn})(objectClass=groupOfNames))
    group_name_attribute: cn
    mail_attribute: mail
    display_name_attribute: displayName
    permit_referrals: false
    user: CN=admin,DC=example,DC=com
    password: password

Options

implementation

type: string {: .label .label-config .label-purple } default: custom {: .label .label-config .label-blue } required: no {: .label .label-config .label-green }

Configures the LDAP implementation used by Authelia.

See the Implementation Guide for information.

url

type: string {: .label .label-config .label-purple } required: yes {: .label .label-config .label-red }

The LDAP URL which consists of a scheme, address, and port. Format is <scheme>://<address>:<port> or <scheme>://<address> where scheme is either ldap or ldaps.

If utilising an IPv6 literal address it must be enclosed by square brackets:

url: ldap://[fd00:1111:2222:3333::1]

timeout

type: duration {: .label .label-config .label-purple } default: 5s {: .label .label-config .label-blue } required: no {: .label .label-config .label-green }

The timeout for dialing an LDAP connection.

start_tls

type: boolean {: .label .label-config .label-purple } default: false {: .label .label-config .label-blue } required: no {: .label .label-config .label-green }

Enables use of the LDAP StartTLS process which is not commonly used. You should only configure this if you know you need it. The initial connection will be over plain text, and Authelia will try to upgrade it with the LDAP server. LDAPS URL's are slightly more secure.

tls

Controls the TLS connection validation process. You can see how to configure the tls section here.

base_dn

type: string {: .label .label-config .label-purple } required: yes {: .label .label-config .label-red }

Sets the base distinguished name container for all LDAP queries. If your LDAP domain is example.com this is usually dc=example,dc=com, however you can fine tune this to be more specific for example to only include objects inside the authelia OU: ou=authelia,dc=example,dc=com. This is prefixed with the additional_users_dn for user searches and additional_groups_dn for groups searches.

username_attribute

type: string {: .label .label-config .label-purple } required: yes {: .label .label-config .label-red }

Note: While this option is required, an implementation may set a default value implicitly negating this requirement. Refer to the attribute defaults for more information.

The LDAP attribute that maps to the username in Authelia.

additional_users_dn

type: string {: .label .label-config .label-purple } required: no {: .label .label-config .label-green }

Additional LDAP path to append to the base_dn when searching for users. Useful if you want to restrict exactly which OU to get users from for either security or performance reasons. For example setting it to ou=users,ou=people with a base_dn set to dc=example,dc=com will mean user searches will occur in ou=users,ou=people,dc=example,dc=com. The default value is dependent on the implementation, refer to the attribute defaults for more information.

users_filter

type: string {: .label .label-config .label-purple } required: yes {: .label .label-config .label-red }

Note: While this option is required, an implementation may set a default value implicitly negating this requirement. Refer to the attribute defaults for more information.

The LDAP filter to narrow down which users are valid. This is important to set correctly as to exclude disabled users.

group_name_attribute

type: string {: .label .label-config .label-purple } required: yes {: .label .label-config .label-red }

Note: While this option is required, an implementation may set a default value implicitly negating this requirement. Refer to the attribute defaults for more information.

The LDAP attribute that is used by Authelia to determine the group name.

additional_groups_dn

type: string {: .label .label-config .label-purple } required: no {: .label .label-config .label-green }

Similar to additional_users_dn but it applies to group searches.

groups_filter

type: string {: .label .label-config .label-purple } required: yes {: .label .label-config .label-red }

Note: While this option is required, an implementation may set a default value implicitly negating this requirement. Refer to the attribute defaults for more information.

Similar to users_filter but it applies to group searches. In order to include groups the member is not a direct member of, but is a member of another group that is a member of those (i.e. recursive groups), you may try using the following filter which is currently only tested against Microsoft Active Directory:

(&(member:1.2.840.113556.1.4.1941:={dn})(objectClass=group)(objectCategory=group))

mail_attribute

type: string {: .label .label-config .label-purple } required: yes {: .label .label-config .label-red }

Note: While this option is required, an implementation may set a default value implicitly negating this requirement. Refer to the attribute defaults for more information.

The attribute to retrieve which contains the users email addresses. This is important for the device registration and password reset processes.

The user must have an email address in order for Authelia to perform identity verification when a user attempts to reset their password or register a second factor device.

display_name_attribute

type: string {: .label .label-config .label-purple } required: yes {: .label .label-config .label-red }

Note: While this option is required, an implementation may set a default value implicitly negating this requirement. Refer to the attribute defaults for more information.

The attribute to retrieve which is shown on the Web UI to the user when they log in.

permit_referrals

type: boolean {: .label .label-config .label-purple } default: false {: .label .label-config .label-blue } required: no {: .label .label-config .label-red }

Permits following referrals. This is useful if you have read-only servers in your architecture and thus require referrals to be followed when performing write operations. This is only implemented for password modifications, if you need this for searches please open a GitHub issue or contact us.

user

The distinguished name of the user paired with the password to bind with for lookup and password change operations.

password

The password of the user paired with the user to bind with for lookup and password change operations. Can also be defined using a secret which is the recommended for containerized deployments.

Implementation Guide

There are currently two implementations, custom and activedirectory. The activedirectory implementation must be used if you wish to allow users to change or reset their password as Active Directory uses a custom attribute for this, and an input format other implementations do not use. The long term intention of this is to have logical defaults for various RFC implementations of LDAP.

Filter replacements

Various replacements occur in the user and groups filter. The replacements either occur at startup or upon an LDAP search.

Users filter replacements

Placeholder	Phase	Replacement
{username_attribute}	startup	The configured username attribute
{mail_attribute}	startup	The configured mail attribute
{display_name_attribute}	startup	The configured display name attribute
{input}	search	The input into the username field

Groups filter replacements

Placeholder	Phase	Replacement
{input}	search	The input into the username field
{username}	search	The username from the profile lookup obtained from the username attribute
{dn}	search	The distinguished name from the profile lookup

Defaults

The below tables describes the current attribute defaults for each implementation.

Attribute defaults

This table describes the attribute defaults for each implementation. i.e. the username_attribute is described by the Username column.

Implementation	Username	Display Name	Mail	Group Name
custom	n/a	displayName	mail	cn
activedirectory	sAMAccountName	displayName	mail	cn

Filter defaults

The filters are probably the most important part to get correct when setting up LDAP. You want to exclude disabled accounts. The active directory example has two attribute filters that accomplish this as an example (more examples would be appreciated). The userAccountControl filter checks that the account is not disabled and the pwdLastSet makes sure that value is not 0 which means the password requires changing at the next login.

Implementation	Users Filter	Groups Filter
custom	n/a	n/a
activedirectory	(&(|({username_attribute}={input})({mail_attribute}={input}))(sAMAccountType=805306368)(!(userAccountControl:1.2.840.113556.1.4.803:=2))(!(pwdLastSet=0)))	(&(member={dn})(objectClass=group)(objectCategory=group))

Note: The Active Directory filter (sAMAccountType=805306368) is exactly the same as (&(objectCategory=person)(objectClass=user)) except that the former is more performant, you can read more about this and other Active Directory filters on the TechNet wiki.

Refresh Interval

This setting takes a duration notation that sets the max frequency for how often Authelia contacts the backend to verify the user still exists and that the groups stored in the session are up to date. This allows us to destroy sessions when the user no longer matches the user_filter, or deny access to resources as they are removed from groups.

In addition to the duration notation, you may provide the value always or disable. Setting to always is the same as setting it to 0 which will refresh on every request, disable turns the feature off, which is not recommended. This completely prevents Authelia from refreshing this information, and it would only be refreshed when the user session gets destroyed by other means like inactivity, session expiration or logging out and in.

This value can be any value including 0, setting it to 0 would automatically refresh the session on every single request. This means Authelia will have to contact the LDAP backend every time an element on a page loads which could be substantially costly. It's a trade-off between load and security that you should adapt according to your own security policy.

Important notes

Users must be uniquely identified by an attribute, this attribute must obviously contain a single value and be guaranteed by the administrator to be unique. If multiple users have the same value, Authelia will simply fail authenticating the user and display an error message in the logs.

In order to avoid such problems, we highly recommended you follow https://www.ietf.org/rfc/rfc2307.txt by using sAMAccountName for Active Directory and uid for other implementations as the attribute holding the unique identifier for your users.

As of versions > 4.24.0 the users_filter must include the username_attribute placeholder, not including this will result in Authelia throwing an error. In versions <= 4.24.0 not including the username_attribute placeholder will cause issues with the session refresh and will result in session resets when the refresh interval has expired, default of 5 minutes.