Dell Force10 MXL Blade MXL 10/40GbE Switch IO Module Configuration Guide - Page 503

You can assign line authentication on a per-VTY basis; it is a simple password authentication using an access-class as authorization. Local authentication is configured globally. You configure access classes on a per-user basis. FTOS can assign different access classes to different users by username. Until users attempt to log in, FTOS does not know if they will be assigned a VTY line. This means that incoming users always see a login prompt even if you have excluded them from the VTY line with a deny-all access class. After users identify themselves, FTOS retrieves the access class from the local database and applies it. (FTOS also subsequently can close the connection if a user is denied access.) Note: If a VTY user logs in with RADIUS authentication, the privilege level is applied from the RADIUS server only if you configure RADIUS authentication. Figure 28-16 shows how to allow or deny a Telnet connection to a user. Users see a login prompt, even if they cannot login. No access class is configured for the VTY line. It defaults from the local database. Figure 28-16. Example Access-Class Configuration Using Local Database FTOS(conf)#user gooduser password abc privilege 10 access-class permitall FTOS(conf)#user baduser password abc privilege 10 access-class denyall FTOS(conf)# FTOS(conf)#aaa authentication login localmethod local FTOS(conf)# FTOS(conf)#line vty 0 9 FTOS(conf-line-vty)#login authentication localmethod FTOS(conf-line-vty)#end Note: For more information, refer to Access Control Lists (ACLs). VTY Line Remote Authentication and Authorization FTOS takes the access class from the VTY line and applies it to ALL users. FTOS does not need to know the identity of the incoming user and can immediately apply the access class. If the authentication method is radius, TACACS+, or line, and you have configured an access class for the VTY line, FTOS immediately applies it. If the access-class is deny all or deny for the incoming subnet, FTOS closes the connection without displaying the login prompt. Figure 28-17 shows how to deny incoming connections from subnet 10.0.0.0 without displaying a login prompt. The example uses TACACS+ as the authentication mechanism. Security | 501