An LDAP database can be distributed over multiple servers. If the requested information is not on the current server, the LDAP v3 standard provides a mechanism for the server to return a referral to the client that informs the client of an alternate server. (This feature is also included in some LDAP v2-compliant servers.)

ColdFusion can handle referrals automatically. If you specify a nonzero referral attribute in the cfldap tag, ColdFusion sends the request to the server specified in the referral.

The referral attribute value specifies the number of referrals allowed for the request. For example, if the referral attribute is 1, and server A sends a referral to server B, which then sends a referral to server C, ColdFusion returns an error. If the referral attribute is 2, and server C has the information, the LDAP request succeeds. The value to use depends on the topology of the distributed LDAP directory, the importance of response speed, and the value of response completeness.

When ColdFusion follows a referral, the rebind attribute specifies whether ColdFusion uses the cfldap tag login information in the request to the new server. The default, No, sends an anonymous login to the server.

Managing LDAP security

When you consider how to implement LDAP security, you must consider server security and application security.

Server security

The cfldap tag supports secure socket layer (SSL) v2 security. This security provides certificate-based validation of the LDAP server. It also encrypts data transferred between the ColdFusion server and the LDAP server, including the user password, and ensures the integrity of data passed between the servers. To specify SSL v2 security, set the cfladap tag secure="cfssl_basic" attribute.

About LDAP Server Security

ColdFusion uses Java Native Directory Interface (JNDI), the LDAP provider, and an SSL package to create the client side of an SSL communication. The LDAP server provides the server side. The LDAP server that the cfldap tag connects to using SSL holds an SSL server certificate, a certificate that is securely "signed" by a trusted authority and identifies (authenticates) the sender. During the initial SSL connection, the LDAP server presents its server certificate to the client. If the client trusts this certificate, the SSL connection is established and secure LDAP communication can begin.

ColdFusion determines whether to trust the server by comparing the server's certificate with the information in the jre/lib/security/cacerts keystore of the JRE used by ColdFusion. The ColdFusion default cacerts file contains information about many certificate granting authorities. If you must update the file with additional information, you can use the keytool utility in the ColdFusion jre/bin directory to import certificates that are in X.509 format. For example, enter the following:

keytool -import -keystore cacerts -alias ldap -file ldap.crt -keypass bl19mq

The keytool utility initial keypass password is "change it". For more information on using the keytool utility, see the Sun JDK documentation.

Once ColdFusion establishes secure communication with the server, it must provide the server with login credentials. You specify the login credentials in the cfldap tag username and password attributes. When the server determines that the login credentials are valid, ColdFusion can access the directory.

Using LDAP security

To use security, first ensure that the LDAP server supports SSL v2 security.

Specify the cfldap tag secure attribute as follows:

secure = "cfssl_basic"

For example:

<cfldap action="modify"
    modifyType="add"
    atributes="cn=Lizzie"
    dn="uid=lborden, ou=People, o=Airius.com"
    server=#myServer#
    username=#myUserName#
    password=#myPassword#
    secure="cfssl_basic"
    port=636>

The port attribute specifies the server port used for secure LDAP communications, which is 636 by default. If you do not specify a port, ColdFusion attempts to connect to the default, nonsecure, LDAP port 389.

Application security

To ensure application security, you must prevent outsiders from gaining access to the passwords that you use in cfldap tags. The best way to do this is to use variables for your username and password attributes. You can set these variables on one encrypted application page. For more information on securing applications, see Securing Applications.