Chapter 10 Configuring IEEE 802.1x Port-Based Authentication

Understanding IEEE 802.1x Port-Based Authentication

Until a device is authorized, the port drops its traffic. Non-Cisco IP phones or voice devices are allowed into both the data and voice VLANs. The data VLAN allows the voice device to contact a DHCP server to obtain an IP address and acquire the voice VLAN information. After the voice device starts sending on the voice VLAN, its access to the data VLAN is blocked.

A voice device MAC address that is binding on the data VLAN is not counted towards the port security MAC address limit.

You can use dynamic VLAN assignment from a RADIUS server only for data devices.

MDA can use MAC authentication bypass as a fallback mechanism to allow the switch port to connect to devices that do not support IEEE 802.1x authentication. For more information, see the “MAC Authentication Bypass” section on page 10-25.

When a data or a voice device is detected on a port, its MAC address is blocked until authorization succeeds. If the authorization fails, the MAC address remains blocked for 5 minutes.

If more than five devices are detected on the data VLAN or more than one voice device is detected on the voice VLAN while a port is unauthorized, the port is error disabled.

When a port host mode is changed from single- or multihost to multidomain mode, an authorized data device remains authorized on the port. However, a Cisco IP phone that has been allowed on the port voice VLAN is automatically removed and must be reauthenticated on that port.

Active fallback mechanisms such as guest VLAN and restricted VLAN remain configured after a port changes from single- or multihost mode to multidomain mode.

Switching a port host mode from multidomain to single- or multihost mode removes all authorized devices from the port.

If a data domain is authorized first and placed in the guest VLAN, non-IEEE 802.1x-capable voice devices need to tag their packets on the voice VLAN to trigger authentication.

We do not recommend per-user ACLs with an MDA-enabled port. An authorized device with a per-user ACL policy might impact traffic on both the voice and data VLANs of the port. If used, only one device on the port should enforce per-user ACLs.

Using Web Authentication

You can use a web browser to authenticate a client that does not support IEEE 802.1x functionality.

You can configure a port to use only web authentication. You can also configure the port to first try and use IEEE 802.1x authentication and then to use web authorization if the client does not support IEEE 802.1x authentication.

Web authentication requires two Cisco Attribute-Value (AV) pair attributes:

The first attribute, priv-lvl=15, must always be set to 15. This sets the privilege level of the user who is logging into the switch.

The second attribute is an access list to be applied for web authenticated hosts. The syntax is similar to IEEE 802.1X per-user ACLs. However, instead of ip:inacl, this attribute must begin with proxyacl, and the source field in each entry must be any. (After authentication, the client IP address replaces the any field when the ACL is applied.)

 

 

 

For example:

 

 

 

proxyacl# 10=permit ip any 10.0.0.0 255.0.0.0

 

 

 

proxyacl# 20=permit ip any 11.1.0.0 255.255.0.0

 

 

 

proxyacl# 30=permit udp any any eq syslog

 

 

 

proxyacl# 40=permit udp any any eq tftp

 

 

 

Catalyst 3750-E and 3560-E Switch Software Configuration Guide

 

 

 

 

10-20

 

OL-9775-02

 

 

 

 

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Cisco Systems 3750E manual Using Web Authentication, For example, 10-20