I have followed these instructions: https://help.ubuntu.com/12.04/serverguide/openldap-server.html#openldap-auth-config

The ldap server works fine. I can log into it using an ldap account.

However, I configured another Ubuntu 12.04 server as a ldap client for authentication but I cannot contact the server. Here is the error:

On the client:

# ldapsearch -Q -LLL -Y EXTERNAL -H ldapi://ldap01.domain.local -b cn=config dn
ldap_sasl_interactive_bind_s: Can't contact LDAP server (-1)

The server can receive requests:

On the client:

# telnet ldap01.domain.local 389
Trying 10.3.17.10...
Connected to sisn01.domain.local.
Escape character is '^]'.

On the client:

# ldapsearch -x -h ldap01.domain.local -b cn=config dn
# extended LDIF
#
# LDAPv3
# base <cn=config> with scope subtree
# filter: (objectclass=*)
# requesting: dn 
#

# search result
search: 2
result: 32 No such object

# numResponses: 1

On the server:

# ps aux | grep slapd
openldap  3759  0.0  0.2 564820  8228 ?        Ssl  08:39   0:00 /usr/sbin/slapd -h     ldap:/// ldapi:/// -g openldap -u openldap -F /etc/ldap/slapd.d

I suspect I am missing a configuration parameter either on the server or on the client. I just cannot figure out what. Any help here would be appreciated.