5. Security Considerations

The general URL security considerations discussed in [RFC3986] are relevant for LDAP URLs.

The use of security mechanisms when processing LDAP URLs requires particular care, since clients may encounter many different servers via URLs, and since URLs are likely to be processed automatically, without user intervention. A client SHOULD have a user-configurable policy that controls which servers the client will establish LDAP sessions with and with which security mechanisms, and SHOULD NOT establish LDAP sessions that are inconsistent with this policy. If a client chooses to reuse an existing LDAP session when resolving one or more LDAP URLs, it MUST ensure that the session is compatible with the URL and that no security policies are violated.

Sending authentication information, no matter the mechanism, may violate a user's privacy requirements. In the absence of specific policy permitting authentication information to be sent to a server, a client should use an anonymous LDAP session. (Note that clients conforming to previous LDAP URL specifications, where all LDAP sessions are anonymous and unprotected, are consistent with this specification; they simply have the default security policy.) Simply opening a transport connection to another server may violate some users' privacy requirements, so clients should provide the user with a way to control URL processing.

Some authentication methods, in particular, reusable passwords sent to the server, may reveal easily-abused information to the remote server or to eavesdroppers in transit and should not be used in URL processing unless they are explicitly permitted by policy. Confirmation by the human user of the use of authentication information is appropriate in many circumstances. Use of strong authentication methods that do not reveal sensitive information is much preferred. If the URL represents a referral for an update operation, strong authentication methods SHOULD be used. Please refer to the Security Considerations section of [RFC4513] for more information.

The LDAP URL format allows the specification of an arbitrary LDAP search operation to be performed when evaluating the LDAP URL. Following an LDAP URL may cause unexpected results, for example, the retrieval of large amounts of data or the initiation of a long-lived

search. The security implications of resolving an LDAP URL are the same as those of resolving an LDAP search query.