ldap_set_option

As john.hallam@compaq.com above mentioned ,one has to set option LDAP_OPT_PROTOCOL_VERSION=3
ldap_set_option($ds,LDAP_OPT_PROTOCOL_VERSION,3);
to use the ldap_rename function.
However, the ldap_set_option() line has to be written immediately after ldap_connect() and before ldap_bind() statements.
Christos Soulios

If you want to disable the TLS cert check (e.g. because you are doing an SSH port-forward, and ldaps is pointing to localhost), then you must invoke:
ldap_set_option(NULL, LDAP_OPT_X_TLS_REQUIRE_CERT,0)
*before* calling ldap_connect()
If you try: 
$ds = ldap_connect(...)
ldap_set_option($ds, LDAP_OPT_X_TLS_REQUIRE_CERT,0)
then the option won't actually take effect, and the certificate will be checked anyway, and a TLS failure will happen..

Luckily you can turn on debugging before you open a connection:
 ldap_set_option(NULL, LDAP_OPT_DEBUG_LEVEL, 7);
This way you at least can see in the logs if the connection fails...

The following flags are valid integer values for the LDAP_OPT_DEREF (as taken from the documentation for ldap_read()):
LDAP_DEREF_NEVER (int 0) - (default) aliases are never dereferenced.
LDAP_DEREF_SEARCHING (int 1) - aliases should be dereferenced during the search but not when locating the base object of the search.
LDAP_DEREF_FINDING (int 2) - aliases should be dereferenced when locating the base object but not during the search.
LDAP_DEREF_ALWAYS (int 3) - aliases should be dereferenced always.
Example:
<?php
ldap_set_option($ds, LDAP_OPT_DEREF, LDAP_DEREF_ALWAYS);
?> 
These are defined in the draft C API (presumably from the original LDAP API). See draft-ietf-ldapext-ldap-c-api-xx.txt included in the OpenLDAP source code distribution.

PHP 7.1 added support for configuring the LDAP CA/Cert environment directly, rather than relying on the environment variables. I noticed that a lot of people are having trouble getting this to work.
The correct way is:
$ds=ldap_connect("ldap.google.com"); 
ldap_set_option(NULL, LDAP_OPT_X_TLS_CERTFILE, "/path/file.crt");
ldap_set_option(NULL, LDAP_OPT_X_TLS_KEYFILE, "/path/file.key");
ldap_set_option($ds, LDAP_OPT_PROTOCOL_VERSION, 3);
ldap_set_option($ds, LDAP_OPT_REFERRALS, 0);
ldap_start_tls($ds);
...
ldap_close($ds);

I have the following code, but you do not rename the cn, that may be?
 $TheDN = "cn=Nombre,ou=Addressbook,dc=axia-ldap,dc=net";
 $newRDN = "cn=bill";
 $newParent = "ou=Addressbook,dc=axia-ldap,dc=net";
 ldap_set_option($ds,LDAP_OPT_PROTOCOL_VERSION,3);
 $result = ldap_rename($ds, $TheDN, $newRDN, $newParent, TRUE);

it seems that ldap_set_option returns 1 for bogus ldap_connect -ions also.
ldap_connect always returns a resource (documented in the
comments of ldap_connect) so it is not possible to check if the
ldap server is there or alive or what. and because ldap_set_option
must be between ldap_connect and ldap_bind, there seems to
be no sense in checking the return value.
it is a bit strange that ldap_bind is the first function which can
really check if a ldap resource is usable because it is the third
function in line to use when working with openldap.
<?php
$connect = ldap_connect("whatever");
$set = ldap_set_option($connect, LDAP_OPT_PROTOCOL_VERSION, 3);
echo $set;
?>

To get this to work I had to set the LDAP version to 3 using ldap_set_option. Here is an example that might help:
$TheDN = "cn=john smith,ou=users,dc=acme,dc=com";
$newRDN = "cn=bill brown";
$newParent = "ou=users,dc=acme,dc=com";
ldap_set_option($ds,LDAP_OPT_PROTOCOL_VERSION,3);
@$result = ldap_rename($ds, $TheDN, $newRDN, $newParent, TRUE);