Single Sign-On to Windows AD

Single Sign-On to Windows AD

The FortiGate unit can authenticate users transparently and allow them network access based on their privileges in Windows AD. This means that users who have logged on to the network are not asked again for their credentials to access network resources through the FortiGate unit, hence the term “Single Sign-On”.

The following topics are included:

  • Introduction to Single Sign-On with Windows AD
  • Configuring Single Sign On to Windows AD
  • FortiOS FSSO log messages
  • Testing FSSO
  • Troubleshooting FSSO


Introduction to Single Sign-On with Windows AD

Introduced in FortiOS 5.0, Single Sign-On (SSO) support provided by FortiGate polling of domain controllers is simpler than the earlier method that relies on agent software installed on Windows AD network servers. No Fortinet software needs to be installed on the Windows network. The FortiGate unit needs access only to the Windows AD global catalog and event log.

When a Windows AD user logs on at a workstation in a monitored domain, the FortiGate unit

  • detects the logon event in the domain controller’s event log and records the workstation name, domain, and user,
  • resolves the workstation name to an IP address,
  • uses the domain controller’s LDAP server to determine which groups the user belongs to,
  • creates one or more log entries on the FortiGate unit for this logon event as appropriate.

When the user tries to access network resources, the FortiGate unit selects the appropriate security policy for the destination. The selection consist of matching the FSSO group or groups the user belongs to with the security policy or policies that match that group. If the user belongs to one of the permitted user groups associated with that policy, the connection is allowed. Otherwise the connection is denied.

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