We have a couple of old ldap servers (Debian 7/openldap 2.4.31) on which we try to replace the certificates. On these servers we have a bundled configuration:

# config
dn: cn=config
olcTLSCACertificateFile: /etc/ldap/tls/multi.deverywa.re.pem
olcTLSCertificateFile: /etc/ldap/tls/multi.deverywa.re.pem
olcTLSCertificateKeyFile: /etc/ldap/tls/multi.deverywa.re.pem

The file is a bundle containing both the certificates (wildcard and it's issuer) and the key. Until this year we just had to upload the new bundle and restart slapd. This year Gandi changed their signing certificate but it is still issued by UserTrust. But OpenLDAP refuses to use it now.

We tried to set LogLevel to any, but nothing really showed in the log. On the server side:

slapd[9217]: connection_read(16): TLS accept failure error=-1 id=1041, closing

On the client side (localhost):

openssl s_client -connect localhost:636 -servername ldap.deverywa.re
140365161965224:error:140790E5:SSL routines:SSL23_WRITE:ssl handshake failure:s23_lib.c:177:
no peer certificate available
No client certificate CA names sent
SSL handshake has read 0 bytes and written 315 bytes
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
    Protocol  : TLSv1.2
    Cipher    : 0000
    Key-Arg   : None
    PSK identity: None
    PSK identity hint: None
    SRP username: None
    Start Time: 1695652388
    Timeout   : 300 (sec)
    Verify return code: 0 (ok)

We still use 2048 RSA key to generate the certificates. We have checked permissions and it is fine. How could I debug what's wrong on the server side ?

Thank you

Jérôme BECOT
Ingénieur DevOps Infrastructure

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