geert@boskant.nl wrote:

Full_Name: Geert Jansen Version: 2.4 OS: Linux URL: ftp://ftp.openldap.org/incoming/geert-jansen-081115.patch Submission from: (NULL) (12.230.186.195)

This is a resubmission of my earlier patch in [1]. I'm asking for this patch to be included into OpenLDAP.

The patch adds an LDAP option called LDAP_OPT_X_SASL_NOCANON to disable host name canonicalization using reverse DNS for the host name that is passed into SASL. Instead, it passes verbatim the host name part from the LDAP URI and lets SASL do the canonicalization. The option is disabled by default.

Since some time MIT Kerberos has support for server-side canonicalization which is an alternative for the DNS based scheme. By default it uses both, but with an option "rdns = no", reverse DNS can be disabled.

The use case for this is environments that do not have reverse DNS set up correctly. Especially in Windows Active Directory environments this is very common. Administrators are afraid to enable scavenging for their zones, and therefore any server IP change will leave a stale PTR record in place. This breaks reverse DNS based canonicalization if the IP adress is reassigned.

The behaviour enabled by this patch should remain optional and cannot become the default. It breaks the use case when multiple LDAP servers are load balanced using a CNAME record.

In reviewing this patch, I see some technical issues to resolve:

1) You seem to be making the ldap_set_option "arg" parameter optional; there appears to be no justification for this (significant) behavioral change.

2) If you're dealing with a KDC that supports this feature, then it would make the most sense for this to be a site-wide option. As such, it should be possible for the setting to become the default, and an ldap.conf keyword should exist to control that setting.

3) Your addition of the option to the command line tools is boolean; if the command line option is present the option will be turned on, otherwise it will be turned off. This requires too much knowledge on the part of the user running the tool, to decide whether they need the option or not. Again, it should allow a system-wide setting, and the command-line option should be tri-state: on / off / default.

Users should not be required to learn about this option before using the commandline tools, the sysadmin should set it site-wide when the KDC is known to support it.