| 4.1 |  | AAA Secure Network Access |
| 4.1.3 |  | Authentication methods |

| Overview Authentication is the first step in the AAA security process. By definition, authentication asks users to prove that they are who they say they are. There are a number of authentication methods available, but the most common method is to use usernames and passwords. Username/password methods range from weak to strong in authentication power. Simple authentication methods use a database of usernames and passwords, while methods that are more complex use one-time passwords or token cards. It is important to recognize that when choosing an authentication method, there is a trade-off between the security that the authentication method provides and its ease of use. This is illustrated in Figure .

The most common authentication methods are discussed in Figure . Each method will be discussed in greater detail throughout the rest of this section.

| Web Links s/key http://www.ietf.org/rfc/rfc1760.txt?number=1760 one-time password http://www.ietf.org/rfc/rfc2289.txt