FortiOS 5.6.6 Release Notes

Upgrade Information

Upgrading to FortiOS 5.6.6

Supported upgrade path information is available on the Fortinet Customer Service & Support site.

To view supported upgrade path information:

  1. Go to
  2. From the Download menu, select Firmware Images.
  3. Check that Select Product is FortiGate.
  4. Click the Upgrade Path tab and select the following:

l Current Product l Current FortiOS Version l Upgrade To FortiOS Version 5. Click Go.

If you are upgrading from version 5.6.2, this caution does not apply.

Before upgrading, ensure that port 4433 is not used for admin-port or admin-sport (in config system global), or for SSL VPN (in config vpn ssl settings). If you are using port 4433, you must change admin-port, admin-sport, or the SSL VPN port to another port number before upgrading.

After upgrading, if FortiLink mode is enabled, you must manually create an explicit firewall policy to allow RADIUS traffic for 802.1x authentication from the FortiSwitch (such as from the FortiLink interface) to the RADIUS server through the FortiGate.

Security Fabric upgrade

FortiOS 5.6.6 greatly increases the interoperability between other Fortinet products. This includes:

l FortiAnalyzer 5.6.1 l FortiClient 5.6.0 l FortiClient EMS 1.2.2 l FortiAP 5.4.2 and later l FortiSwitch 3.6.2 and later

Upgrade the firmware of each product in the correct order. This maintains network connectivity without the need to use manual steps.

Before upgrading any product, you must read the FortiOS Security Fabric Upgrade Guide.


FortiClient profiles

After upgrading from FortiOS 5.4.0 to 5.4.1 and later, your FortiClient profiles will be changed to remove a number of options that are no longer supported. After upgrading, review your FortiClient profiles to make sure they are configured appropriately for your requirements and either modify them if required or create new ones.

The following FortiClient Profile features are no longer supported by FortiOS 5.4.1 and later:

  • Advanced FortiClient profiles (XML configuration).
  • Advanced configuration, such as configuring CA certificates, unregister option, FortiManager updates, dashboard Banner, client-based logging when on-net, and Single Sign-on Mobility Agent.
  • VPN provisioning. l Advanced AntiVirus settings, such as Scheduled Scan, Scan with FortiSandbox, and Excluded Paths. l Client-side web filtering when on-net. l iOS and Android configuration by using the FortiOS GUI.

With FortiOS 5.6.6, endpoints in the Security Fabric require FortiClient 5.6.0. You can use FortiClient 5.4.3 for VPN (IPsec VPN, or SSL VPN) connections to FortiOS 5.6.2, but not for Security Fabric functions.

FortiGate-VM 5.6 for VMware ESXi

Upon upgrading to FortiOS 5.6.6, FortiGate-VM v5.6 for VMware ESXi (all models) no longer supports the VMXNET2 vNIC driver.

Downgrading to previous firmware versions

Downgrading to previous firmware versions results in configuration loss on all models. Only the following settings are retained:

l operation mode l interface IP/management IP l static route table l DNS settings l VDOM parameters/settings l admin user account l session helpers l system access profiles


If you have long VDOM names, you must shorten the long VDOM names (maximum 11 characters) before downgrading:

  1. Back up your configuration.
  2. In the backup configuration, replace all long VDOM names with its corresponding short VDOM name.

For example, replace edit <long_vdom_name>/<short_name> with edit <short_name>/<short_ name>.

  1. Restore the configuration.
  2. Perform the downgrade.

Amazon AWS enhanced networking compatibility issue

With this new enhancement, there is a compatibility issue with older AWS VM versions. After downgrading a 5.6.6 image to an older version, network connectivity is lost. Since AWS does not provide console access, you cannot recover the downgraded image.

When downgrading from 5.6.6 to older versions, running the enhanced nic driver is not allowed. The following AWS instances are affected:

  • C3 l C4 l R3
  • I2 l M4 l D2

Having trouble configuring your Fortinet hardware or have some questions you need answered? Ask your questions in the comments below!!! Want someone else to deal with it for you? Get some consulting from Fortinet GURU!

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