I ran netstat -a | egrep ":ldap" and found that the replication between my two test servers was not ldaps thus me reaching out to this forum.


If “ldap://” is secure already then I do not need to proceed further. These are the SLAPD_URLS in the /etc/sysconfig/slapd file:

SLAPD_URLS="ldapi:/// ldap:/// ldaps:///"


I have TLS enabled everywhere and have encrypted connections between clients and servers.


These are the ciphers running on both masters:




I am using simple binds so I’ll look at SASL/EXTERNAL with authz-regexp mapping.


Why is version 2.4.40 unsafe for multi-master replication? I can upgrade at a later time I just wanted to find out how to enable ldaps between the two servers.


Thank you,



From: Quanah Gibson-Mount <quanah@symas.com>
Reply-To: Quanah Gibson-Mount <quanah@symas.com>
Date: Saturday, May 6, 2017 at 1:02 PM
To: "Real, Elizabeth (392K)" <Elizabeth.Real@jpl.nasa.gov>, "openldap-technical@openldap.org" <openldap-technical@openldap.org>
Subject: Re: Secure replication


--On Saturday, May 06, 2017 1:56 AM +0000 "Real, Elizabeth (392K)"

<Elizabeth.Real@jpl.nasa.gov> wrote:


The olcSyncRepl directive on both systems needs to go from:


olcSyncRepl: rid=001 provider=ldap




olcSyncRepl: rid=001 provider=ldaps


The use of "ldap://" does not mean that you have insecure replication.  The

"ldaps" designation was developed to allow for SSL encrypted connections as

a part of LDAPv2, which did not have a formal design spec for allowing SSL

encryption.  The LDAPv3 spec, which is what OpenLDAP 2.4 (and much earlier

version) implement, specifically has startTLS as a part of that

specification, which uses "ldap:///".  I.e., ldaps is a bastardized hack

for LDAPv2.  The proper way to do TLS encryption with LDAPv3 capable

servers such as OpenLDAP 2.[1-4+] is to use the startTLS extended operation

over a "ldap:///" URI.


In addition, there are other ways to have an encrypted connection between

an LDAP client and server without involving TLS at all, such as SASL/GSSAPI.


As Michael noted, you can, in addition to enabling TLS encryption between

the client and servers, use client cert authentication (SASL/EXTERNAL) so

as to remove the requirement for clear text credentials to be stored in the

olcSyncRepl attribute (if using simple binds).  And again, the usage of

SASL/GSSAPI also precludes the neccessity of storing cleartext credentials

in the olcSyncRepl attribute.


As an aside, I would note that 2.4.40 is completely unsafe to use with

multimaster replication.


I would generally suggest forming a clear set of requirements for your

replication environment, and then asking how to implement them.  Your

current question is too vague/general to really be answered well.


Hope that helps!







Quanah Gibson-Mount

Product Architect

Symas Corporation

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