Configuring Port-Based and Client-Based Access Control (802.1X)

Terminology

EAPOL: Extensible Authentication Protocol Over LAN, as defined in the

802.1X standard.

Friendly Client: A client that does not pose a security risk if given access to the switch and your network.

MD5: An algorithm for calculating a unique digital signature over a stream of bytes. It is used by CHAP to perform authentication without revealing the shared secret (password).

PVID (Port VID): This is the VLAN ID for the untagged VLAN to which an 802.1X port belongs.

Port-Based Authentication: In this operation, the first client on a port to authenticate itself unblocks the port for the duration of the client’s 802.1X- authenticated session. The switches covered in this guide use port-based authentication.

Static VLAN: A VLAN that has been configured as “permanent” on the switch by using the CLI vlan < vid > command or the Menu interface.

Supplicant: The entity that must provide the proper credentials to the switch before receiving access to the network. This is usually an end-user work- station, but it can be a switch, router, or another device seeking network services.

Tagged Membership in a VLAN: This type of VLAN membership allows a port to be a member of multiple VLANs simultaneously. If a client connected to the port has an operating system that supports 802.1Q VLAN tagging, then the client can access VLANs for which the port is a tagged member. If the client does not support VLAN tagging, then it can access only a VLAN for which the port is an untagged member. (A port can be an untagged member of only one port-based VLAN at a time.) Where a port is a tagged member of a VLAN, 802.1X Open VLAN mode does not affect the port’s access to the VLAN unless the port is statically configured as a member of a VLAN that is also configured as the Unauthorized-Client or Authorized-Client VLAN. See also “Untagged Membership in a VLAN”.

Unauthorized-Client VLAN: A conventional, static VLAN statically configured on the switch. It is used to provide access to a client prior to authentication, and is sometimes termed a guest VLAN. It should be set up to allow an unauthenticated client to access only the initialization services necessary to establish an authenticated connection, plus any other desirable services whose use by an unauthenticated client poses no security threat to your network. (Note that an unauthenticated client has access to all network resources that have membership in the VLAN you

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