Chapter 5. Configuring SSSD to use LDAP and require TLS authentication Complete this procedure to configure your Red Hat Enterprise Linux (RHEL) system as an OpenLDAP client. Use the following client configuration: The RHEL system authenticates users stored in an OpenLDAP user account database. The RHEL system uses the System Security Services Daemon (SSSD) service to retrieve user data. The RHEL system communicates with the OpenLDAP server over a TLS-encrypted connection. Note You can alternatively use this procedure to configure your RHEL system as a client of a Red Hat Directory Server. Prerequisites The OpenLDAP server is installed and configured with user information. You have root permissions on the host you are configuring as the LDAP client. On the host you are configuring as the LDAP client, the /etc/sssd/sssd.conf file has been created and configured to specify ldap as the autofs_provider and the id_provider . You have a PEM-formatted copy of the root CA signing certificate chain from the Certificate Authority that issued the OpenLDAP server certificate, stored in a local file named core-dirsrv.ca.pem . Procedure Install the requisite packages: Switch the authentication provider to sssd : Copy the core-dirsrv.ca.pem file containing the root CA signing certificate chain from the Certificate Authority that issued the OpenLDAP server's SSL/TLS certificate into the /etc/openldap/certs folder. Add the URL and suffix of your LDAP server to the /etc/openldap/ldap.conf file: In the /etc/openldap/ldap.conf file, add a line pointing the TLS_CACERT parameter to /etc/openldap/certs/core-dirsrv.ca.pem : In the /etc/sssd/sssd.conf file, add your environment values to the ldap_uri and ldap_search_base parameters and set the ldap_id_use_start_tls to True : In /etc/sssd/sssd.conf , specify the TLS authentication requirement by modifying the ldap_tls_cacert and ldap_tls_reqcert values in the [domain] section: Change the permissions on the /etc/sssd/sssd.conf file: Restart and enable the SSSD service and the oddjobd daemon: Optional: If your LDAP server uses the deprecated TLS 1.0 or TLS 1.1 protocols, switch the system-wide cryptographic policy on the client system to the LEGACY level to allow RHEL to communicate using these protocols: For more details, see the Strong crypto defaults in RHEL 8 and deprecation of weak crypto algorithms Knowledgebase article on the Red Hat Customer Portal and the update-crypto-policies(8) man page on your system. Verification Verify you can retrieve user data from your LDAP server by using the id command and specifying an LDAP user: The system administrator can now query users from LDAP using the id command. The command returns a correct user ID and group membership.

Commands:
dnf -y install openldap-clients sssd sssd-ldap oddjob-mkhomedir
authselect select sssd with-mkhomedir
cp core-dirsrv.ca.pem /etc/openldap/certs
URI ldap://ldap-server.example.com/ BASE dc=example,dc=com
When no CA certificates are specified the Shared System Certificates are in use. In order to have these available along with the ones specified by TLS_CACERTDIR one has to include them explicitly: TLS_CACERT /etc/openldap/certs/core-dirsrv.ca.pem
[domain/default] id_provider = ldap autofs_provider = ldap auth_provider = ldap chpass_provider = ldap ldap_uri = ldap://ldap-server.example.com/ ldap_search_base = dc=example,dc=com ldap_id_use_start_tls = True cache_credentials = True ldap_tls_cacertdir = /etc/openldap/certs ldap_tls_reqcert = allow [sssd] services = nss, pam, autofs domains = default [nss] homedir_substring = /home ...
... cache_credentials = True ldap_tls_cacert = /etc/openldap/certs/core-dirsrv.ca.pem ldap_tls_reqcert = hard ...
chmod 600 /etc/sssd/sssd.conf
systemctl restart sssd oddjobd systemctl enable sssd oddjobd
update-crypto-policies --set LEGACY
id ldap_user uid=17388(ldap_user) gid=45367(sysadmins) groups=45367(sysadmins),25395(engineers),10(wheel),1202200000(admins)