IEEE 802.1X Open Authentication
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IEEE 802.1X Open Authentication

Last Updated: July 17, 2012

IEEE 802.1X Open Authentication allows a host to have network access without having to go through IEEE 802.1X authentication. Open authentication is useful in an applications such as the Preboot Execution Environment (PXE), where a device must access the network to download a bootable image containing an authentication client.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for IEEE 802.1X Open Authentication

IEEE 802.1X Port-Based Network Access Control

You should understand the concepts of port-based network access control and have an understanding of how to configure port-based network access control on your Cisco platform. For more information, see the Configuring IEEE 802.1X Port-Based Authentication module.

The switch must be connected to a Cisco secure Access Control System (ACS) and RADIUS authentication, authorization, and accounting (AAA) must be configured for Web authentication. If appropriate, you must enable ACL download.

If the authentication order includes the 802.1X port authentication method, you must enable IEEE 802.1X authentication on the switch.

If the authentication order includes web authentication, configure a fallback profile that enables web authentication on the switch and the interface.

Note
The web authentication method is not supported on Cisco integrated services routers (ISRs) or Integrated Services Routers Generation 2 (ISR G2s) in Cisco IOS Release 15.2(2)T.

You should understand the concepts of the RADIUS protocol and have an understanding of how to create and apply access control lists (ACLs). For more information, see the documentation for your Cisco platform and the Cisco IOS Security Configuration Guide: Securing User Services.

The switch must have a RADIUS configuration and be connected to the Cisco secure access control server (ACS). For more information, see the Configuration Guide for CISCO Secure ACS.

Restrictions for IEEE 802.1X Open Authentication

  • This feature does not support standard ACLs on the switch port.
  • If you configure Open Authentication by using the authentication open interface configuration command, any new MAC address detected on the port will be allowed unrestricted Layer 2 access to the network even before any authentication has succeeded. If you use this command, you should use static default ACLs to restrict Layer 3 traffic.

Information About IEEE 802.1X Open Authentication

IEEE 802.1X Open Authentication and Host Modes

Any of the four host modes (single-host mode, multiple-host mode, multi-domain authentication mode, and multiauthentication mode) may be configured to allow a device to gain network access before authentication. For information about configuring IEEE 802.1X host modes, see the "Configuring the Host Mode" section of the "Configuring IEEE 802.1X Port-Based Authentication" chapter.

Open authentication is enabled by entering the authentication open command after host mode configuration, and acts as an extension to the configured host mode. For example, if open authentication is enabled with single-host mode, then the port will allow only one MAC address. When preauthentication open access is enabled, initial traffic on the port is restricted only by whatever other access restriction, independent of 802.1X, is configured on the port. If no access restriction other than 802.1X is configured on the port, then a client device will have full access on the configured VLAN.

How to Configure IEEE 802.1X Open Authentication

Configuring IEEE 802.1X Open Authentication

Before You Begin

Note
To configure open authentication you must have configured one of the four 802.1X host modes. For information about configuring IEEE 802.1X host modes, see the "Configuring the Host Mode" section of the "Configuring IEEE 802.1X Port-Based Authentication" chapter.

SUMMARY STEPS

1.    configure terminal

2.    interface type slot/port

3.   authentication port-control-auto

4.   authentication host-mode {single-host | multi-auth | multi-domain | multi-host} [open]

5.   authentication open

6.   end


DETAILED STEPS
 Command or ActionPurpose
Step 1
configure terminal


Example:

Switch# configure terminal

 

Enters global configuration mode.

 
Step 2
interface type slot/port


Example:

Switch(config)# interface gigabitethernet0/1

 

Specifies the port to be configured, and enters interface configuration mode. For the supported port types, see the "802.1x Authentication Configuration Guidelines" section of the "Configuring IEEE 1802.1X Port-Based Authentication" module.

 
Step 3
authentication port-control-auto


Example:

Switch(config-if)# authentication port-control-auto

 
 Enables port-based authentication on the interface.  
Step 4
authentication host-mode {single-host | multi-auth | multi-domain | multi-host} [open]

Example:

Switch(config-if)# authentication host-mode single-host

 
 Configures the host mode (single-host mode, multiple-host mode, multidomain authentication mode, and multiauthentication mode) on the authorized port or allows open access (no access restrictions).  
Step 5
authentication open


Example:

Switch(config-if)# authentication open

 
 Enables open authentication.
Note   This command overrides the authentication host-mode {single-host | multi-auth | multi-domain | multi-host} [open] command for the port only.
 
Step 6
end


Example:

Switch(config-if)# end

 
 Returns to privileged EXEC mode.  

Configuration Examples for IEEE 802.1X Open Authentication

Example: Configuring IEEE 802.1X Open Authentication

The following example shows how to enable the Open Authentication feature on a port that has been configured in single-host mode: 

Switch(config)# interface gigabitethernet0/1
Switch(config-if)# authentication port-control auto
Switch(config-if)# authentication host-mode single-host
Switch(config-if)# authentication open

Additional References

Related Documents

Related Topic Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

IEEE 802.1X commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples

  • Catalyst 4500 Series Switch Cisco IOS Command Reference, Release 12.2(25)SGA
  • Catalyst 3750 Switch Command Reference , Cisco IOS Release 12.2(25)SEE
Configuring host modes "Configuring the Host Mode" section of the "Configuring IEEE 802.1X Port-Based Authentication" chapter.

Standards and RFCs

Standard/RFC Title
IEEE 802.1X

Port Based Network Access Control

Technical Assistance

Description Link

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http://www.cisco.com/cisco/web/support/index.html

Feature Information for IEEE 802.1X Open Authentication

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Table 1Feature Information for IEEE 802.1X Open Authentication
Feature Name Releases Feature Information

IEEE 802.1X Open Authentication

15.2(2)T

IEEE 802.1X Open Authentication allows a host to have network access without having to go through IEEE 802.1X authentication.

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Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

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