TLS negotiation failure: ldap_connect with port other than default

Question

running centos 6 on client

running centos 7 on server

openldap 2.4.44

php 5.3

certs are self signed

php program works before changing the default port and setting up TLS

php program

    $username = "uid=" . $userLogin . ",ou=Users,dc=XX,dc=XXX,dc=edu";

    $ldap_host = "XXX.XX.XXX.edu";
    $ldap_port = "1636";
    $ldap_dn = "dc=XX,dc=XXX,dc=edu";

    $filter = "(uid=".$userLogin.")";

    // limit attributes we want to look for
    $attr = array("uid","cn","givenName","sn","mail");
    // turn on debugging before you open a connection
    ldap_set_option(NULL, LDAP_OPT_DEBUG_LEVEL, 7);

    $ldap = @ldap_connect($ldap_host, $ldap_port) or die("Could not connect to $ldap_host");

ERROR on ldap server

 slapd[11651]: conn=1001 fd=12 closed (TLS negotiation failure)

error_log on client

ldap_create
ldap_bind_s
ldap_simple_bind_s
ldap_sasl_bind_s
ldap_sasl_bind
ldap_send_initial_request
ldap_new_connection 1 1 0
ldap_int_open_connection
ldap_connect_to_host: TCP XX.XX.XXX.edu:1636
ldap_new_socket: 21
ldap_prepare_socket: 21
ldap_connect_to_host: Trying XXX.XXX.XX.XXX:1636
ldap_pvt_connect: fd: 21 tm: -1 async: 0
attempting to connect: 
connect success
ldap_open_defconn: successful
ldap_send_server_request
ldap_result ld 0x7f1b0c78f6b0 msgid 1
wait4msg ld 0x7f1b0c78f6b0 msgid 1 (infinite timeout)
wait4msg continue ld 0x7f1b0c78f6b0 msgid 1 all 1
** ld 0x7f1b0c78f6b0 Connections:
* host: XXX.XX.XXX.edu  port: 1636  (default)
refcnt: 2  status: Connected
last used: Wed Jul 11 11:46:03 2018


** ld 0x7f1b0c78f6b0 Outstanding Requests:
* msgid 1,  origid 1, status InProgress
outstanding referrals 0, parent count 0
ld 0x7f1b0c78f6b0 request count 1 (abandoned 0)
** ld 0x7f1b0c78f6b0 Response Queue:
Empty
ld 0x7f1b0c78f6b0 response count 0
ldap_chkResponseList ld 0x7f1b0c78f6b0 msgid 1 all 1
ldap_chkResponseList returns ld 0x7f1b0c78f6b0 NULL
ldap_int_select
read1msg: ld 0x7f1b0c78f6b0 msgid 1 all 1
ldap_err2string
ldap_free_request (origid 1, msgid 1)
ldap_free_connection 1 1
ldap_free_connection: actually freed

messages log on client httpd: LOGIN FAILED: binding error#012Please try again.

ldap.conf file on server

# LDAP Defaults
#

# See ldap.conf(5) for details
# This file should be world readable but not world writable.

#BASE   dc=example,dc=com
#URI    ldap://ldap.example.com ldap://ldap-master.example.com:666

URI ldaps://XXX.XX.XX.edu:1636
BASE dc=XX,dc=XXX,dc=edu

#SIZELIMIT      12
#TIMELIMIT      15
#DEREF          never

# start TLS
SSL ON

TLS_CACERTDIR   /etc/openldap/certs
TLSCertificateFile /etc/openldap/certs/paldapcert.pem
TLSCertificateKeyFile /etc/openldap/certs/paldapkey.pem

TLSVerifyClient allow

# Turning this off breaks GSSAPI used with krb5 when rdns = false
#SASL_NOCANON   on

ldap.conf on client

# LDAP Defaults
#

# See ldap.conf(5) for details
# This file should be world readable but not world writable.

#BASE   dc=example,dc=com
#URI    ldap://ldap.example.com ldap://ldap-master.example.com:666

#SIZELIMIT      12
#TIMELIMIT      15
#DEREF          never

TLS_CACERTDIR /etc/openldap/certs
TLS_CERT /etc/openldap/certs/paldapcert.pem
TLS_KEY /etc/openldap/certs/paldapkey.pem
URI ldaps://XXX.XX.XXX.edu:1636
BASE dc=XX,dc=XXX,dc=edu

#start TLS
SSL ON
TLS_REQCERT allow
#TLS_CACERTDIR /etc/openldap/cacerts

pwd

/etc/openldap/certs

on server

-rw-r--r--. 1 ldap ldap 1472 Mar 16 10:36 paldapcert.pem
-rw-r--r--. 1 ldap ldap 1704 Mar 16 10:36 paldapkey.pem

on client

-rw-r--r--. 1 root root 65536 Aug 11  2014 cert8.db
-rw-r--r--. 1 root root 16384 Aug 11  2014 key3.db
-rw-r--r--. 1 root root  1472 Jul  6 11:05 paldapcert.pem
-rw-r--r--. 1 root root  1704 Jul  6 11:05 paldapkey.pem
-r--------. 1 root root    45 Aug 11  2014 password
-rw-r--r--. 1 root root 16384 Aug 11  2014 secmod.db

cat certs.ldif

dn: cn=config
changetype: modify
replace: olcTLSCertificateFile
olcTLSCertificateFile: /etc/openldap/certs/paldapcert.pem

dn: cn=config
changetype: modify
replace: olcTLSCertificateKeyFile
olcTLSCertificateKeyFile: /etc/openldap/certs/paldapkey.pem

cat /etc/sysconfig/slapd

# OpenLDAP server configuration
# see 'man slapd' for additional information

# Where the server will run (-h option)
# - ldapi:/// is required for on-the-fly configuration using client tools
#   (use SASL with EXTERNAL mechanism for authentication)
# - default: ldapi:/// ldap:///
# - example: ldapi:/// ldap://127.0.0.1/ ldap://10.0.0.1:1389/ ldaps:///
# - SLAPD_URLS="ldapi:/// ldap://127.0.0.1/ 
ldap://XXX.XXX.XXX.XXX:1389/ ldaps://XXX.XXX.XXX.XXX:1636/"
SLAPD_URLS="ldapi:/// ldap:/// ldaps://XXX.XXX.XXX.XXX:1636/"

# Any custom options
#SLAPD_OPTIONS=""

# Keytab location for GSSAPI Kerberos authentication
#KRB5_KTNAME="FILE:/etc/openldap/ldap.keytab"

netstat -antup | grep -i 1636 tcp 0 0 XXX.XXX.XX.XXX:1636 0.0.0.0:*
LISTEN 11651/slapd

on client:

/etc/nslcd.conf

tls_reqcert allow
uid nslcd
gid ldap
# This comment prevents repeated auto-migration of settings.
uri ldaps://XXX.XX.XX.XX:1636
base dc=XX,dc=XXX,dc=edu
ssl yes
tls_cacertdir /etc/openldap/certs

ldapsearch -p 1636 -D "cn=ldapadmin,dc=XX,dc=XXX,dc=edu" -W -h ldaps://XXX.XX.XXX.edu -b "dc=XX,dc=XX,dc=edu" -s sub "cn=Bricks *"

ldapsearch from the client works

Also run openssl on client to test connection

openssl s_client -connect xxx.xx.xxx.edu:1636 -servername xxx.xx.xxx.edu -showcerts |openssl x509 -text -noout

verify error:num=18:self signed certificate verify return:1 did not see any errors except this note about a self signed cert

Thank you in advance for any help.

Answer 1

The use of ldap_connect with two parameters is discouraged by now. It can only create an unencrypted LDAP-connection to the server(s) given as $host and on the port given in $port .

By now you should use an LDAP-URI containing a scheme ( ldap or ldaps ), a server and optionally a port if it's not the default one for the scheme. The second parameter is then ignored.

So in our case you should use something like this:

$ldap_uri = "ldap://XXX.XX.XXX.edu:1636";

$ldap = @ldap_connect($ldap_uri);

Please also note the information about the return value in the docs that states:

When OpenLDAP 2.xx is used, ldap_connect() will always return a resource as it does not actually connect but just initializes the connecting parameters. The actual connect happens with the next calls to ldap_* funcs, usually with ldap_bind()

Answer extends my helpful question ;-)