Here is an SSSD configuration that is working in production against OIT LDAP. You will still need to manage certificates properly to use this in a secure manner. While you are testing, you can add "ldap_tls_reqcert = allow" as a line under the domain definition. This will help you debug by ruling out any certificate issues. DO NOT use that line in production!

The only real deviations from a standard config is the addition of "min_id = 1", as OIT has group IDs in the 10s-20s. "enumerate = true" will create a local precache, and allows tools such as finger to operate normally.

[sssd]
config_file_version = 2
reconnection_retries = 3
sbus_timeout = 30
services = nss, pam
domains = oit

[nss]
filter_groups = root
filter_users = root
reconnection_retries = 3

[pam]
reconnection_retries = 3

[domain/oit]
auth_provider = ldap
ldap_id_use_start_tls = True
chpass_provider = ldap
cache_credentials = True
krb5_realm = EXAMPLE.COM
ldap_search_base = o=Princeton University,c=US
id_provider = ldap
ldap_uri = ldap://ldap.princeton.edu/
krb5_kdcip = kerberos.example.com
ldap_tls_cacertdir = /etc/pki/tls/certs
min_id = 1
enumerate = true

Someone else once wrote this:

For authentication only (no user database) make sure you have nss-pam-ldapd rpm installed and then run:

authconfig --enableldapauth --ldapserver=ldaps://ldap.princeton.edu --ldapbasedn="o=Princeton University,c=US" --ldaploadcacert=​file:///etc/pki/tls/certs/ca-bundle.crt --disablesssdauth --disablesssd --updateall --enableforcelegacy