2. Enter a password.3. Assign an access class.4. Enter a privilege level.You can assign line authentication on a per-VTY basis; it is a simple password authentication, using an access-class as authorization.Configure local authentication globally and configure access classes on a per-user basis.Dell Networking OS can assign different access classes to different users by username. Until users attempt to log in, Dell NetworkingOS does not know if they will be assigned a VTY line. This means that incoming users always see a login prompt even if you haveexcluded them from the VTY line with a deny-all access class. After users identify themselves, Dell Networking OS retrieves theaccess class from the local database and applies it. (Dell Networking OS then 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 youconfigure RADIUS authentication.The following example shows how to allow or deny a Telnet connection to a user. Users see a login prompt even if they cannot log in.No access class is configured for the VTY line. It defaults from the local database.Example of Configuring VTY Authorization Based on Access Class Retrieved from a Local Database (Per User)Dell(conf)#user gooduser password abc privilege 10 access-class permitallDell(conf)#user baduser password abc privilege 10 access-class denyallDell(conf)#Dell(conf)#aaa authentication login localmethod localDell(conf)#Dell(conf)#line vty 0 9Dell(config-line-vty)#login authentication localmethodDell(config-line-vty)#endVTY Line Remote Authentication and AuthorizationDell Networking OS retrieves the access class from the VTY line.The Dell Networking OS takes the access class from the VTY line and applies it to ALL users. Dell Networking OS does not need toknow 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, Dell Networking OS immediately applies it. If theaccess-class is set to deny all or deny for the incoming subnet, Dell Networking OS closes the connection without displaying thelogin prompt. The following example shows how to deny incoming connections from subnet 10.0.0.0 without displaying a loginprompt. The example uses TACACS+ as the authentication mechanism.Example of Configuring VTY Authorization Based on Access Class Retrieved from the Line (Per Network Address)Dell(conf)#ip access-list standard deny10Dell(conf-ext-nacl)#permit 10.0.0.0/8Dell(conf-ext-nacl)#deny anyDell(conf)#Dell(conf)#aaa authentication login tacacsmethod tacacs+Dell(conf)#tacacs-server host 256.1.1.2 key Force10Dell(conf)#Dell(conf)#line vty 0 9Dell(config-line-vty)#login authentication tacacsmethodDell(config-line-vty)#Dell(config-line-vty)#access-class deny10Dell(config-line-vty)#end(same applies for radius and line authentication)VTY MAC-SA Filter SupportDell Networking OS supports MAC access lists which permit or deny users based on their source MAC address.With this approach, you can implement a security policy based on the source MAC address.To apply a MAC ACL on a VTY line, use the same access-class command as IP ACLs.The following example shows how to deny incoming connections from subnet 10.0.0.0 without displaying a login prompt.Security 759
