I want to set up an architecture that allows a client to query an LDAP backend via an LDAP proxy. I want the query from the client to be unsecured, but the proxied communication between the LDAP proxy and the LDAP backend to be secured through mutual TLS authentication via SASL EXTERNAL. What configurations need to be implemented on the LDAP proxy and the LDAP backend?
I saw in the slapd-ldap(5) documentation that the idassert-bind parameter could be used on the LDAP proxy for the TLS connection via SASL EXTERNAL, and in the slapd.conf(5) documentation that the authz-regexp parameter could be used on the LDAP backend to allow querying with a DN extracted from the certificate on this LDAP backend. However, I am struggling to set it up. I use openldap 2.4. slapd.conf on proxy server: [...] Database ldap suffix dc=test,dc=com uri ldaps://mytest.com:636 idassert-bind mode=self bindmethod=sasl saslmech=EXTERNAL tls_cert=/etc/openldap/certs/server.crt tls_key=/etc/openldap/certs/server.key tls_cacert=/etc/ssl/certs/ca-bundle.crt tls_cacertdir=/etc/ssl/certs tls_crlcheck=none tls_reqcert=allow [...] slapd.conf on backend server: [...] # Modules moduleload back_mdb moduleload authz-regexp # TLS TLSCACertificateFile /opt/openldap/etc/openldap/certs/ca-certificates.crt TLSCertificateFile /opt/openldap/etc/openldap/certs/backend.crt TLSCertificateKeyFile /opt/openldap/etc/openldap/certs/backend.key TLSCipherSuite HIGH TLSVerifyClient demand sasl-Host mytest.com sasl-realm EXTERNAL authz-regexp ".*" "cn=user1,dc=test,dc=com" [...] proxy: ldapsearch -H ldaps://mytest.com -b "dc=appli,dc=test,dc=com" -Y EXTERNAL -ZZ ldap_start_tls: Can't contact LDAP server (-1) backend: 67895427.2b4074ce 0x7f7e6bffe6c0 TLS: can't accept: error:0A0000C7:SSL routines::peer did not return a certificate. Any help would be appreciated.
