CISC-L2-000020 - The Cisco switch must uniquely identify all network-connected endpoint devices before establishing any connection - dot1x port-control auto


Controlling LAN access via 802.1x authentication can assist in preventing a malicious user from connecting an unauthorized PC to a switch port to inject or receive data from the network without detection.


Configure 802.1 x authentications on all host-facing access switch ports. To authenticate those devices that do not support 802.1x, MAC Authentication Bypass must be configured.

Step 1: Configure the radius servers as shown in the example below:

SW1(config)# radius-server host key xxxx
SW1(config)# radius-server host key xxxx

Step 2: Enable 802.1x authentication on the switch.

SW1(config)# aaa group server radius RADIUS_GROUP
SW1(config-radius)# server
SW1(config-radius)# server
SW1(config-radius)# exit
SW1(config)# aaa authentication dot1x default group RADIUS_GROUP
SW1(config)# exit

Step 3: Enable 802.1x on all host-facing interfaces as shown in the example below:

SW1(config)# int e1/1 - 80
SW1(config-if-range)# dot1x port-control auto
SW1(config-if-range)# dot1x host-mode single-host
SW1(config-if-range)# end

Note: Host-mode must be set to single-host, multi-domain (for VoIP phone + PC), or multi-auth (multiple PCs connected to a hub). Host-mode multi-host is not compliant with this requirement.

Supportive Information

The following resource is also helpful.

This security hardening control applies to the following category of controls within NIST 800-53: Identification and Authentication.This control applies to the following type of system Cisco.