sssd_be[24065]: Could not start TLS encryption. unknown error

This document (000021149) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server All Service Packs

Situation

Following message is found in journalctl

2023-06-29T07:07:17.350846+02:00 server1 sssd_be[24065]: Could not start TLS encryption. unknown error

Resolution

To get more descriptive message than "unknown error" one can enable libldap debugging.
In /etc/sssd/sssd.conf under [domain/$DOMAIN] add option:

 ldap_library_debug_level = -1

and restart sssd:

systemctl restart sssd

after the error appears in journalctl, inspect /var/log/sssd/sssd_$DOMAIN.log for further details.

Cause

The message itself is harmless and might occasionally show up in journalctl.
However, if it floods the logs, it might indicate an underlying system/network problem.
In this example case, /var/log/sssd/sssd_$DOMAIN.log shows:

(2023-07-20 11:47:25): [be[DOMAIN]] [sss_ldap_debug] (0x4000): [RID#19241] libldap: tls_read: want=5252, got=3930
(2023-07-20 11:47:25): [be[DOMAIN]] [sss_ldap_debug] (0x4000): [RID#19241] libldap: tls_read: want=1322 error=Interrupted system call
(2023-07-20 11:47:25): [be[DOMAIN]] [sss_ldap_debug] (0x4000): [RID#19241] libldap: TLS trace: SSL_connect:error in TLSv1.3 read encrypted extensions
(2023-07-20 11:47:25): [be[DOMAIN]] [sss_ldap_debug] (0x4000): [RID#19241] libldap: TLS: can't connect: .
(2023-07-20 11:47:25): [be[DOMAIN]] [sss_ldap_debug] (0x4000): [RID#19241] libldap: ldap_err2string
(2023-07-20 11:47:25): [be[DOMAIN]] [sss_ldap_init_sys_connect_done] (0x0020): [RID#19241] ldap_install_tls failed: [Connect error] [unknown error]

indicates network related problem and packets analysis is required.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.