Authentication Commands

4-69

4
Authentication Sequence

authentication login

This command defines the login authentication method and precedence. Use the no
form to restore the default.
Syntax
authentication login {[local] [radius] [tacacs]}
no authentication login
•local - Use local password.
•radius - Use RADIUS server password.
•tacacs - Use TACACS server password.
Default Setting
Local
Command Mode
Global Configuration
Command Usage
• RADIUS uses UDP while TACACS+ uses TCP. UDP only offers best effort
delivery, while TCP offers a connection-oriented transport. Also, note that
RADIUS encrypts only the password in the access-request packet from the
client to the server, while TACACS+ encrypts the entire body of the packet.
• RADIUS and TACACS+ logon authentication assigns a specific privilege level
for each user name and password pair. The user name, password, and
privilege level must be configured on the authentication server.
• You can specify three authentication methods in a single command to indicate
the authentication sequence. For example, if you enter “authentication login
radius tacacs local,” the user name and password on the RADIUS server is
verified first. If the RADIUS server is not available, then authentication is
attempted on the TACACS+ server. If the TACACS+ server is not available,
the local user name and password is checked.
Example
Related Commands
username - for setting the local user names and passwords (4-26)
Table4-28 Authentication Sequence Commands
Command Function Mode Page
authentication login Defines logon authentication method and precedence GC 4-69
authentication enable Defines the authentication method and precedence for
command mode change
GC 4-70
Console(config)#authentication login radius
Console(config)#