10. Security Considerations
OpenLDAP Software is designed to run in a wide variety of computing environments from tightly-controlled closed networks to the global Internet. Hence, OpenLDAP Software supports many different security mechanisms. This chapter describes these mechanisms and discusses security considerations for using OpenLDAP Software.
10.1. Network Security
10.1.1. Selective Listening
By default, slapd(8) will listen on both the IPv4 and IPv6 "any" addresses. It is often desirable to have slapd listen on select address/port pairs. For example, listening only on the IPv4 address 127.0.0.1 will disallow remote access to the directory server. E.g.:
slapd -h ldap://127.0.0.1
While the server can be configured to listen on a particular interface address, this doesn't necessarily restrict access to the server to only those networks accessible via that interface. To selective restrict remote access, it is recommend that an IP Firewall be used to restrict access.
See
10.1.2. IP Firewall
Generally, slapd(8) listens on port 389/tcp for ldap:// sessions and port 636/tcp for ldaps://) sessions. slapd(8) may be configured to listen on other ports.
As specifics of how to configure IP firewall are dependent on the particular kind of IP firewall used, no examples are provided here. See the document associated with your IP firewall.
10.1.3. TCP Wrappers
slapd(8) supports
slapd: 10.0.0.0/255.0.0.0 127.0.0.1 : ALLOW
slapd: ALL : DENY
allows only incoming connections from the private network 10.0.0.0 and localhost (127.0.0.1) to access the directory service. Note that IP addresses are used as slapd(8) is not normally configured to perform reverse lookups.
It is noted that TCP wrappers require the connection to be accepted. As significant processing is required just to deny a connection, it is generally advised that IP firewall protection be used instead of TCP wrappers.
See hosts_access(5) for more information on TCP wrapper rules.
10.2. Data Integrity and Confidentiality Protection
A number of
10.2.1. Security Strength Factors
The server uses
A number of administrative controls rely on SSFs associated with TLS and SASL protection in place on an LDAP session.
security controls disallow operations when appropriate protections are not in place. For example:
security ssf=1 update_ssf=112
requires integrity protection for all operations and encryption protection, 3DES equivalent, for update operations (e.g. add, delete, modify, etc.). See slapd.conf(5) for details.
For fine-grained control, SSFs may be used in access controls. See Access Control section of the The slapd Configuration File for more information.
10.3. Authentication Methods
10.3.1. "simple" method
The LDAP "simple" method has three modes of operation:
- anonymous,
- unauthenticated, and
- user/password authenticated.
Anonymous access is requested by providing no name and no password to the "simple" bind operation. Unauthenticated access is requested by providing a name but no password. Authenticated access is requested by providing a valid name and password.
An anonymous bind results in an anonymous authorization association. Anonymous bind mechanism is enabled by default, but can be disabled by specifying "disallow bind_anon" in slapd.conf(5). Note that disabling the anonymous bind mechanism does not prevent anonymous access to the directory. To require authentication to access the directory, one should instead specify "require authc".
An unauthenticated bind also results in an anonymous authorization association. Unauthenticated bind mechanism is disabled by default, but can be enabled by specifying "allow bind_anon_cred" in slapd.conf(5). As a number of LDAP applications mistakenly generate unauthenticated bind request when authenticated access was intended (that is, they do not ensure a password was provided), this mechanism should generally remain disabled.
A successful user/password authenticated bind results in a user authorization identity, the provided name, being associated with the session. User/password authenticated bind is enabled by default. However, as this mechanism itself offers no evesdropping protection (e.g., the password is set in the clear), it is recommended that it be used only in tightly controlled systems or when the LDAP session is protected by other means (e.g., TLS,
The user/password authenticated bind mechanism can be completely disabled by setting "disallow bind_simple".
Note: An unsuccessful bind always results in the session having an anonymous authorization association.
10.3.2. SASL method
The LDAP