Several files need editing to enable ldap access, lines or blocks of directives which require changing are shown below, lines which are left alone are not shown for clarity:-

[root@inet03 pam.d]# more /etc/ldap.conf
# This is the configuration file for the LDAP nameservice
# switch library and the LDAP PAM module.
#
host inet02 inet01

# The distinguished name of the search base.
#base dc=example,dc=com
base dc=prod,dc=company,dc=net

[root@inet03 pam.d]# more /etc/nsswitch.conf
#
# /etc/nsswitch.conf

passwd:     files ldap
shadow:     files ldap
group:      files ldap

#hosts:     db files nisplus nis dns
hosts:      files dns


ethers:     files
netmasks:   files
networks:   files
protocols:  files ldap
rpc:        files
services:   files ldap

netgroup:   files ldap

publickey:  nisplus

automount:  files ldap
aliases:    files

[root@inet03 pam.d]# cat /etc/openldap/ldap.conf
#BASE   dc=example, dc=com
#URI    ldap://ldap.example.com ldap://ldap-master.example.com:666

#SIZELIMIT      12
#TIMELIMIT      15
#DEREF          never
#URI ldap://127.0.0.1/
URI ldap://inet02 ldap://inet01

#BASE dc=example,dc=com
BASE dc=prod,dc=company,dc=net

TLS_CACERTDIR /etc/openldap/cacerts
[root@inet03 pam.d]#

Add the pam module to /etc/pam.d/sshd to auto create home directories:-

[root@inet03 pam.d]# cat sshd
#%PAM-1.0
auth       include      system-auth
account    required     pam_nologin.so
account    include      system-auth
password   include      system-auth
session    optional     pam_keyinit.so force revoke
session    include      system-auth
session    required     pam_mkhomedir.so skel=/etc/skel/ umask=0077
session    required     pam_loginuid.so

Also you can add this line to a pam file like /etc/pam.d/sshd:-

account    required     pam_access.so accessfile=/etc/security/access-login.conf

Users must additionally be listed in /etc/security/access-login.conf to allow logins.

Test LDAP access with ldapsearch -x.

https://serverfault.com/questions/653792/ssh-key-authentication-using-ldap