Combination of authentication schemes

This backend allows one to chain authentication method, for example to failback to LDAP authentication if Remote authentication failed…

You have to use Combination as authentication module (users module must be set to “Same”). Then go in Combination parameters to :

• declare the modules that will be used
• set the rule chain

Each module that will be used in combination rule must be declared. You must set:

• the name used in the rule (a uniq string)
• the type (LDAP, DBI,...)
• the scope:
  • authentication and user DB
  • authentication only
  • user DB only
• overloaded parameters: you can redefine any LLNG string parameters. For example, if you use 2 different LDAP, the first can use normal configuration and for the second, overwritten parameter can redefine ldapServer,...

For example:

Usually, you can't declare two modules of the same type if they don't have the same parameters. For example, usually you can't declare a MySQL DBI and a PostgreSQL DBI, because there is no extra field for PostgreSQL parameters. Now with Combination, you can declare some overloaded parameters.

For example, if DBI is configured to use PostgreSQL but DB2 is a MySQL DB, you can override the “dbiChain” parameter.

You can also override a complex key like ldapExportedVars, by setting a JSON value:

{"cn" => "cn", "uid" => "sAMAccounName", "mail" => "mail"}

Combination allows:

• to chain schemes (example: [LDAP] and [DBI])
• to test different schemes (example: [LDAP] or [DBI])
• to mix schemes (example: [Kerberos,LDAP] or [LDAP,LDAP])
• to choose authentication scheme depending on some request values

Each scheme must be enclose in []. A comma separates auth and user DB modules. If only one value is set, the same is used for both.

Remember that schemes in rules are the names declared above.

Test can use only the $env variable. It contains the FastCGI environment variables.

The following rule is valid:

if($env->{REMOTE_ADDR} =~ /^192\./) then [mySSL, myLDAP] or [myLDAP] else [myLDAP and myDBI, myLDAP]

Imagine you want to authenticate users either by SSL or LDAP+U2F, you can't directly write this rule: this is done in 2 steps:

• use this combination rule: [SSL,LDAP] or [LDAP]
• enable U2F with this rule: $_auth eq “LDAP” or $_authenticationLevel < 4 (and adapt U2F authentication level)

Now if you want to authenticate users either by LDAP or LDAP+U2F (to have 2 different authentication level), 2 possibilities:

• configure 2 portals and overwrite U2F activation in the second
• Modify login template to propose the choice (add a “submit” button that points to the second portal)

Combination module returns the form corresponding to the first authentication scheme available for the current request. You can force it to display the forms chosen using combinationForms in lemonldap-ng.ini. Example:

[portal]
combinationForms = standardform, openidform

SAML, OpenID-Connect, CAS or old OpenID can't be chained with a “and” for authentication part. So “[SAML] and [LDAP]” isn't valid. This is because their authentication kinematic don't use the same steps.

When using this module, LL::NG portal will be called only if Apache does not return “401 Authentication required”, but this is not the Apache behaviour: if the auth module fails, Apache returns 401. So it can be used only with a “and” boolean expression.

Example: [ Apache and LDAP, LDAP ]

To bypass this, follow the documentation of AuthApache module

To chain SSL, you have to set “SSLRequire optional” in Apache configuration, else users will be authenticated by SSL only.

Old Multiple backends stack implemented only `if` and `or` keywords. Examples: