LDAP servers

Lightweight Directory Access Protocol (LDAP) is an Internet protocol used to maintain authentication data that may include departments, people, groups of people, passwords, email addresses, and printers. LDAP consists of a data-representation scheme, a set of defined operations, and a request/response network.

The scale of LDAP servers range from big public servers such as BigFoot and Infospace, to large organizational servers at universities and corporations, to small LDAP servers for workgroups that may be using OpenLDAP. This document focuses on the institutional and workgroup applications of LDAP.

This section includes:

• Components and topology
• LDAP directory organization
• Configuring the FortiGate unit to use an LDAP server
• Example — wildcard admin accounts – CLI
• Example of LDAP to allow Dial-in through member-attribute – CLI
• Troubleshooting LDAP

Components and topology

LDAP organization starts with directories. A directory is a set of objects with similar attributes organized in a logical and hierarchical way. Generally, an LDAP directory tree reflects geographic and organizational boundaries, with the Domain name system (DNS) names to structure the top level of the hierarchy. The common name identifier for most LDAP servers is cn, however some servers use other common name identifiers such as uid.

When LDAP is configured and a user is required to authenticate the general steps are:

1. The FortiGate unit contacts the LDAP server for authentication.

2. To authenticate with the FortiGate unit, the user enters a username and password.

3. The FortiGate unit sends this username and password to the LDAP server.

4. If the LDAP server can authenticate the user, the user is successfully authenticated with the FortiGate unit.

5. If the LDAP server cannot authenticate the user, the connection is refused by the FortiGate unit.

Binding

Binding is the step where the LDAP server authenticates the user. If the user is successfully authenticated, binding allows the user access to the LDAP server based on that user’s permissions.

The FortiGate unit can be configured to use one of three types of binding:

• anonymous – bind using anonymous user search
• regular – bind using username/password and then search
• simple – bind using a simple password authentication without a search

You can use simple authentication if the user records all fall under one domain name (dn). If the users are under more than one dn, use the anonymous or regular type, which can search the entire LDAP database for the required username.

If your LDAP server requires authentication to perform searches, use the regular type and provide values for username and password.