8. Security Considerations

8. Security Considerations

Security issues are the primary topic of this document.

In practice, within or associated with each RADIUS server, there is a database which associates "user" names with authentication information ("secrets"). It is not anticipated that a particular named user would be authenticated by multiple methods. This would make the user vulnerable to attacks which negotiate the least secure method from among a set. Instead, for each named user there should be an indication of exactly one method used to authenticate that user name. If a user needs to make use of different authentication methods under different circumstances, then distinct user names SHOULD be employed, each of which identifies exactly one authentication method.

Passwords and other secrets should be stored at the respective ends such that access to them is as limited as possible. Ideally, the secrets should only be accessible to the process requiring access in order to perform the authentication.

The secrets should be distributed with a mechanism that limits the number of entities that handle (and thus gain knowledge of) the secret. Ideally, no unauthorized person should ever gain knowledge of the secrets. It is possible to achieve this with SNMP Security Protocols [14], but such a mechanism is outside the scope of this specification.

Other distribution methods are currently undergoing research and experimentation. The SNMP Security document [14] also has an excellent overview of threats to network protocols.

The User-Password hiding mechanism described in Section 5.2 has not been subjected to significant amounts of cryptanalysis in the published literature. Some in the IETF community are concerned that this method might not provide sufficient confidentiality protection [15] to passwords transmitted using RADIUS. Users should evaluate their threat environment and consider whether additional security mechanisms should be employed.