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(PHP 4, PHP 5, PHP 7, PHP 8)

ldap_connectVerbindet mit einem LDAP-Server


ldap_connect(?string $uri = null): LDAP\Connection|false

Seit PHP 8.3.0 ist die folgende Signatur veraltet.

ldap_connect(?string $host = null, int $port = 389): LDAP\Connection|false

Erzeugt eine LDAP\Connection-Verbindung und prüft, ob der angegebene uri plausibel ist.

Hinweis: Es ist zu beachten, dass diese Funktion keine Verbindung öffnet. Sie prüft, ob die übergebenen Parameter plausibel sind, und kann verwendet werden, um eine Verbindung zu öffnen, sobald eine benötigt wird.



Ein vollständiger LDAP-URI der Form ldap://hostname:port oder ldaps://hostname:port für SSL-Verschlüsselung.

Es können auch mehrere LDAP-URIs, getrennt durch ein Leerzeichen, als eine Zeichenkette angegeben werden.

Es muss beachtet werden, dass hostname:port kein unterstützter LDAP-URI ist, da das Schema fehlt.


Der Hostname, zu dem eine Verbindung aufgebaut werden soll.


Der Port, zu dem eine Verbindung aufgebaut werden soll.


Gibt eine LDAP\Connection-Instanz zurück, wenn der angegebene LDAP-URI plausibel scheint. Es handelt sich um eine Syntaxprüfung der übergebenen Parameter, aber Server werden nicht kontaktiert! Schlägt die Syntaxprüfung fehl, wird false zurückgegeben. Andernfalls gibt ldap_connect() immer eine gültige LDAP\Connection-Instanz mit positiver Verbindungskennung zurück. Die Verbindung zum LDAP-Server wird noch nicht hergestellt, sie wird lediglich initialisiert. Der Verbindungsaufbau erfolgt bei der nächsten Nutzung einer ldap_*-Funktion; normalerweise ist dies ldap_bind().

Wird kein Argumente angegeben, wird die LDAP\Connection-Instanz einer bereits geöffneten Verbindung zurückgegeben.


Version Beschreibung
8.3.0 Der Aufruf von ldap_connect() mit separaten hostname und port ist nun veraltet.
8.1.0 Gibt nun eine LDAP\Connection-Instanz zurück; vorher wurde eine Ressource zurückgegeben.


Beispiel #1 Verbindung zu einem LDAP-Server


// LDAP-Variablen
$ldapuri = "ldap://"; // Ihr LDAP-URI

// Verbindung zu LDAP
$ldapconn = ldap_connect($ldapuri)
or die(
"Der LDAP-URI konnte nicht geparst werden" );


Beispiel #2 Sichere Verbindung zu einem LDAP-Server


// Stellen Sie sicher, dass Sie den korrekten Host angeben,
// für den das Zertifikat ausgestellt wurde
$ldaphost = "ldaps://";

// Verbindung zu LDAP
$ldapconn = ldap_connect($ldaphost)
or die(
"Der LDAP-URI konnte nicht geparst werden" );


Siehe auch

add a note

User Contributed Notes 29 notes

nemanja at prolux-universal dot com
9 years ago
If you don't want your PHP program to wait XXX seconds before giving up in a case when one of your corporate DC have failed, and since ldap_connect() does not have a mechanism to timeout on a user specified time, this is my workaround which shows excellent practical results.

function serviceping($host, $port=389, $timeout=1)
$op = fsockopen($host, $port, $errno, $errstr, $timeout);
if (!$op) return 0; //DC is N/A
else {
fclose($opanak); //explicitly close open socket connection
return 1; //DC is up & running, we can safely connect with ldap_connect

// ##### STATIC DC LIST, if your DNS round robin is not setup
//$dclist = array('', '', '');

// ##### DYNAMIC DC LIST, reverse DNS lookup sorted by round-robin result
$dclist = gethostbynamel('');

foreach ($dclist as $k => $dc) if (serviceping($dc) == true) break; else $dc = 0;
//after this loop, either there will be at least one DC which is available at present, or $dc would return bool false while the next line stops program from further execution


//now, ldap_connect would certainly connect succesfully to DC tested previously and no timeout will occur
$ldapconn = ldap_connect($dc) or die("DC N/A, PLEASE TRY AGAIN LATER.");

Also with this approach, you get a real nice failover functionality, take for an example a company with a dozen of DC-a distributed along distant places, this way your PHP program will always have high availability if at least one DC is active at present.
lee at lareck70 dot net
9 years ago
To use LDAPS on Windows whitout "c:\openldap\sysconf\ldap.conf":
Generate a file like ldap.conf, name it "ldaprc".
For PHP script running on command line put the file to the script.
For PHP script running on webserver put the file in home directory of PHP.
Andrew (a.whyte at
20 years ago
To be able to make modifications to Active Directory via the LDAP connector you must bind to the LDAP service over SSL. Otherwise Active Directory provides a mostly readonly connection. You cannot add objects or modify certain properties without LDAPS, e.g. passwords can only be changed using LDAPS connections to Active Directory.

Therefore, for those wishing to securely connect to Active Directory, from a Unix host using PHP+OpenLDAP+OpenSSL I spent some time getting this going myself, and came across a few gotcha's. Hope this proves fruitfull for others like me when you couldn't find answers out there.

Make sure you compile OpenLDAP with OpenSSL support, and that you compile PHP with OpenLDAP and OpenSSL.

This provides PHP with what it needs to make use of ldaps:// connections.

Configure OpenSSL:

Extract your Root CA certificate from Active Directory, this is achived through the use of Certificate Services, a startard component of Windows 2000 Server, but may not be installed by default, (The usual Add/Remove Software method will work here). I extracted this in Base64 not DER format.

Place the extracted CAcert into the certs folder for openssl. (e.g. /usr/local/ssl/certs) and setup the hashed symlinks. This is easily done by simply running:


Once this is done you can test it is worked by running:

/usr/local/ssl/bin/openssl verify -verbose -CApath /usr/local/ssl/certs /tmp/exported_cacert.pem

(Should return: OK).

Configure OpenLDAP:

Add the following to your ldap.conf file.
(found as /usr/local/openldap/etc/openldap/ldap.conf)


# Instruct client to NOT request a server's cert.
# WARNING: This will open up the server vor Man-in-the-middle
# attacs and should *not* be used on production systems or outside
# of test-scenarios!
# If you use this setting you will not need any other settings as
# no certificate is requested and therefore will not be validated
# For a proper solution check out

# Define location of CA Cert
TLS_CACERT /usr/local/ssl/certs/AD_CA_CERT.pem
TLS_CACERTDIR /usr/local/ssl/certs


You also need to place those same settings in a file within the Apache Web user homedir called .ldaprc


cp /usr/local/openldap/etc/openldap/ldap.conf ~www/.ldaprc )

You can then test that you're able to establish a LDAPS connection to Active Directory from the OpenLDAP command tools:

/usr/local/openldap/bin/ldapsearch -H "ldaps://"

This should return some output in extended LDIF format and will indicate no matching objects, but it proves the connection works.

The name of the server you're connecting to is important. If they server name you specify in the "ldaps://" URI does not match the name of the server in it's certificate, it will complain like so:

ldap_bind: Can't contact LDAP server (81)
additional info: TLS: hostname does not match CN in peer certificate

Once you've gotten the ldapsearch tool working correctly PHP should work also.

One important gotcha however is that the Web user must be able to locate it's HOME folder. You must check that Apache is providing a HOME variable set to the Web users home directory, so that php can locate the .ldaprc file and the settings contained within. This may well be different between Unix variants but it is such a simple and stupid thing if you miss it and it causes you grief. Simply use a SetEnv directive in Apache's httpd.conf:

SetEnv HOME /usr/local/www

With all that done, you can now code up a simple connect function:

function connect_AD()
$ldap_server = "ldaps://" ;
$ldap_user = "CN=web service account,OU=Service Accounts,DC=ad,DC=com" ;
$ldap_pass = "password" ;

$ad = ldap_connect($ldap_server) ;
ldap_set_option($ad, LDAP_OPT_PROTOCOL_VERSION, 3) ;
$bound = ldap_bind($ad, $ldap_user, $ldap_pass);

return $ad ;

Optionally you can avoid the URI style server string and use something like ldap_connect("", 636) ; But work fine with Active Directory servers.

Hope this proves usefull.
harrison at glsan dot com
9 years ago
To override the ssl ca file can be done by setting an environmental variable within php.

I found using saving the ca certificate (and intermediate ca's) to a file called ca.pem and then adding


before ldap_connect works for me.
Code example:
ldap_set_option(NULL, LDAP_OPT_DEBUG_LEVEL, 7);
$l = ldap_connect("ldaps://ldap/");
ldap_set_option($l, LDAP_OPT_PROTOCOL_VERSION, 3);
ldap_bind($l, "cn=apache,dc=example", "xxxxxxx");
$s = ldap_search($l, "dc=example", "uid=test");
ldap_count_entries($l, $s)."\n");
in the file ca.pem in the same directory we have our ca's:
<cert here>
nateshull at gmail dot com
4 years ago
Implementing LDAPS on a WISP stack - Win, IIS, SQL, PHP
PHP 7.0.19:

Had some issues with some of the instructions and I needed LDAPS for an upcoming Active Directory update that removes insecure LDAP connections.

Enable modules for ldap and openssl in php.ini

Also ensure the extensions are in the ext folder

Verify the modules are loaded: phpinfo()

The ldap or openssl config file is not needed if the environment variables are set in the code. Also the ca path does not like double quotations around the path.

*** code sample:

= "domain\\user";
$ldappass = "Passsword";
$ldapserver = "ldaps://";

//options are require, never, allow
//require is most secure, the others could allow for man in the middle attacks

//tell ldap where the root ca certificate is
//note that the space is allowed in the path without escape or quotes
//I have not tested the permissions, but I would assume the service should have read.
putenv('LDAPTLS_CACERT=C:\\Program Files\\php\\certs\\rootca.pem');

//test to ensure the certificate is able to be read and path is right.
echo file_get_contents("LDAPTLS_CACERT=C:\\Program Files\\php\\certs\\rootca.pem");

// Set debugging
ldap_set_option(NULL, LDAP_OPT_DEBUG_LEVEL, 7);

// connect to ldap server
$ldapconn = ldap_connect($ldapserver) or die ("Couldn't connect");

// binding to ldap server
$ldapbind = false;
$ldapbind = ldap_bind($ldapconn, $ldapuser, $ldappass);

//easy view of success or failure
if ($ldapbind) {
"\n logged in! \n\n");
} else {
"\n log on failure \n\n");
peter dot burden at gmail dot com
15 years ago
The host name parameter can be a space separated list of host names. This means that the LDAP code will talk to a backup server if the main server is not operational. There will be a delay while the code times out trying to talk to the main server but things will still work. This is particularly useful with a typical Microsoft Active Directory setup of primary and backup domain controllers.
= "";
$ldapconn = ldap_connect($ldaphost);
blizzards at libero dot it
19 years ago
To complete questions about how to connect to a LDAP ACTIVE DIRECTORY 2000/2003 server with SASL on port 636, you can refer to prevous notes, and the following directives:

A)Create CA certificates from AD;
B)Export in .pem (DER) format;
D)Copy exported AD ca cert into openssl certs dir on your unix system;
E)Reash with c_reash command;
F)Get a kerberos ticket form AD for your user;
G)Compile PHP with SSL and LDAP support;
H)Test with ldapsearch -D <binddn> -W -H ldaps:// -x

If all works right, create your php script.

Note: For writing parameters to AD you need to renew ticket each 10 hours or less (AD default lifetime ticket), for reading pourpose you can maintain expired ticket.
When querying a windows 2000/2003 AD you MUST use only SASL and not TLS (non supported).
mwilmes at avc dot edu
9 years ago
I support a LAMP stack with PHP-FPM on CentOS 7 that needs to connect to Active Directory over SSL. We have a root certificate for the domain. I was able to set this up in five steps.

1. Get the domain's root SSL certificate in base64. (Must be an Enterprise Administrator - talk with your admin if you are not one.)
Run mmc.exe
File -> Add/Remove Snap-in
Select Certification Authority, then the server that generates certificates for your domain.
Expand the tree until you find the entry for the root certificate, then right click->Properties.
Click the "View Certificate" button, The "Details" tab, then the "Copy to File..." button.
Use the wizard to export the root certificate to your computer. Ensure you use the Base-64 format.

2. Copy the root cert to the Linux server. You can open the certificate in notepad and copy and paste the contents.

3. Convert the certificate to pem format. Substitute the names of files as needed.
openssl x509 -in <copied certificate file> -out /etc/openldap/certs/<cert>.pem

4. Add a line in ldap.conf to use new root cert.
vi /etc/openldap/ldap.conf
TLS_CACERT /etc/openldap/certs/<cert>.pem

5.Restart the PHP service.
systemctl restart php-fpm.service
avel at noc uoa gr
22 years ago
Note that hostname can be a space-separated list of LDAP host names. This is very useful for failover; if the first ldap host is down, ldap_connect will ask the second LDAP host. Of course, you _must_ have LDAP replicates before doing this. :) Read the LDAP API documentation for more information.

This can also be useful, apart from failover, for LDAP load balancing. Just use a random generator function that will return a different space-separated list every time. This is because the first host in the list is always tried first.

Be careful when doing LDAP writes; be sure to always connect to your master host when you are about to modify the database, so that the replicates will get the changes as expected.

Alexandros Vellis
9 years ago
I have spent a lot of time to make an LDAPS connection to a MS AD Global Catalog port 3269

My five Cents:

ldap_connect("ldaps://", 3269)
=> Connection to 636.... :(, DC only

=> Connection to 3269.... :), GC as expected

May it helps...
allie at lsu dot edu
17 years ago
I sure do wish there was some way I could get this information out to all programmers in the world about binding and searching MS AD. This is the second time I was bit by the "I need to search the entire tree" problem.

For php (and apache auth_ldap ) you need to specify port 3268 when you want to search the entire tree. Otherwise it will spit out the partial results error.


I'm just fortunate enough to have won this same battle with apache searching the whole directory. When I noticed our php application failing auth's for users, I was immediately able to fix the problem by adding this port specification (and the ldap_set_option($ldapserver, LDAP_OPT_REFERRALS, 0) option).

I really hope this helps someone else before they pull all their hair out. I know I miss mine.
heiglandreas at php dot net
5 months ago
If you have trouble using TLS on ldap-conjnect: Despite what a lot of people are saying: TLS_REQCERT=never is NEVER the correct answer.

Check out for the solution to do it with propper certificate checking!
titanrat at bk dot ru
7 years ago
I found some difference between php7.0 and php5.5 on this function

Php5 ldap_connect ('host', 0) try to connect default port - host:389
Php7 ldap_connect ('host', 0) try to connect host:0 and crashes.
antoine dot php dot net at bonnefoy dot eu
8 years ago

Little corrections to nemanja post.
- There was a warning if connection is denied by firewall (adding @ before fsockopen)
- fclose parameter was incorrect.

With this approach, you get a real nice failover functionality, take for an example a company with a dozen of DC-a distributed along distant places, this way your PHP program will always have high availability if at least one DC is active at present.
function serviceping($_host, $_port = 389, $_timeout = 1) {
$op = @fsockopen($_host, $_port, $errno, $errstr, $_timeout);
if (!
$op) {

//DC is N/A
else {
fclose($op); //explicitly close open socket connection
return 1; //DC is up & running, we can safely connect with ldap_connect

ldap_connect_failover($_domain) {
// ##### STATIC DC LIST, if your DNS round robin is not setup
//$dclist = array('', '', '');
// ##### DYNAMIC DC LIST, reverse DNS lookup sorted by round-robin result
$dclist = gethostbynamel($_domain);

foreach (
$dclist as $dc) {
if (
serviceping($dc) == true) {
} else {
$dc = 0;
//after this loop, either there will be at least one DC which is available at present, or $dc would return bool false while the next line stops program from further execution

if (!$dc) {
//user being notified

return ldap_connect($dc);
9 years ago
I have spent hours and hours trying to get an LDAPS connection happening with my local AD LDS instance (running on Windows 8.1 64bit).

I tried certificate after certificate. OpenSSL, Thawte and Self-signed - all with no success.

I ended up deleting all of my certificates and created a Self-signed certificate using IIS 7 (running on Windows 8.1).

I then downloaded the Softerra LDAP browser and it was able to connect to my AD LDS instance via SSL with no problems.

Sure if it could PHP could.

I used the following code to connect:
= "ldaps://delllappy:636";
$ldap_conn = ldap_connect($ldap_server) or die("Failed to connect to LDAP server.");
I added the following above the ldap_connect:

That did nothing.

The ldap_bind command I used was:
if (!ldap_bind($ldap_conn, $ldap_user, $ldap_pass)) {
BTW: I added a heap of debug in the code too - which is referenced elsewhere - so I didn't add it in here.

The error that I kept on getting was:
Error Binding to LDAP: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

I then ran ProcMon (Process Monitor from Microsoft).

I monitored when I restarted my web server (Z-WAMP). At that point there was no attempt to read ldap.conf.

I then loaded up my web page with my test.php file.

At that point I noticed that it was ldap.conf that was being read but openldap.conf.

Of course as my file was called ldap.conf, openldap.conf failed. I renamed my ldap.conf to openldap.conf and everything worked.

On Z-WAMP running OpenLDAP don't used ldap.conf, use openldap.conf.

The openldap.conf file was placed in C:\openldap\sysconf\.

As the PUTENV values did not do anything, I removed them.
ac dot russell at live dot com
11 years ago
In order to connect to an ldap server via ssl I needed to use a certificate. For this to work the ldap admin sent me a .der file which I put into /etc/openldap/cacerts.
cp ldap-server.der /etc/openldap/cacerts
That directory must be chmod 755. Then the following entries had to be in /etc/openldap/ldap.conf

# Make the connection vulnerable to MITM-Attacks
# by not checking any certificates
# For a better solution see
TLS_CACERTDIR /etc/openldap/cacerts
"TLS_REQCERT never" should only be required if there is a self-signed certificate in the certificate chain.
csnyder at fcny dot org
15 years ago
It bears repeating (and the examples should probably be updated) that ldap_connect() doesn't actually test the connection to the specified ldap server. This is important if you're trying to build failover into your ldap-based authentication routine.

The only way to test the connection is to actually call ldap_bind( $ds, $username, $password ). But if that fails, is it because you have the wrong username/password or is it because the connection is down? As far as I can see there isn't any way to tell.

It seems that if ldap_bind() fails against your primary server, you have no choice but to try ldap_bind() with the same credentials against the backup. And yet, if your organization limits failed login attempts, a single bad password counts as two failed login attempts. Not good.

One possible workaround is to try an anonymous bind first:

// connect to primary
$ds = ldap_connect( 'ldap://' );
// note: $ds is always a resource even if primary is down

// try anonymous login to test connection
$anon = @ldap_bind( $ds );
if ( !
$anon ) {
// test failed, connect to failover host
$ds = ldap_connect( 'ldap://' );
else {
// test passed, unbind anonymous and reconnect to primary
ldap_unbind( $ds );
$ds = ldap_connect( 'ldap://' );

// now try a real login
$login = @ldap_bind( $ds, $username, $password );

Note that this workaround relies on anonymous login being enabled, which may not always be the case. It's a little sad that there is no other way to test the connection. Hopefully this can be remedied in some future implementation of ldap_connect().
geigers at binghamton dot edu
16 years ago
If you have oci8 and are trying to use openldap for ldap you *may* run into a problem. I have an Oracle database that I connect to from apache. Oracle also has ldap libs which were taking precedence over the openldap libs. This would cause a seg fault when calling ldap_connect with a uri style connect string; e.g. ldap_connect("ldaps://");

After using gdb to debug a core dump and a lot of googling I found that the solution was to add an env-var to apachectl startup.

I am using Apache 2.2.8 with PHP 5.2.5 on RHEL. I added:


in /usr/sbin/envvars which is read when apachectl starts. You can read more on this here:

Scott Geiger
bleathem at gmail dot com
16 years ago
Everyone is posting about getting ldaps:// working in a WAMP/AD stack, I had a tough time finding how to get it going in RHEL 5.1 (w/ all stock rpms). Good old strace did the trick and helped me find the problem...

Turns out php was looking for the CA file in /etc/pki/CA, and I didn't have the correct permissions on the folder. chmod'ing it to 755 solved my "Can't contact LDAP server" message.
andreas dot a dot sandberg at gmail dot com
17 years ago
Be careful when using ldap_connect with the sun client libraries that come bundled with solaris. When specifyng the host with the ldap protocol, my connection failed and it took me a good day to trouble shoot. ie. ldap_connect("ldap://"); Just remove the 'ldap://' and specify the host. This was on Solaris 10 sparc.
elsint at yahoo dot com
17 years ago
Be careful about the certificate's permission if you are using Windows.

Set certificates' permissions for everyone to Read and Read&Execute or you may get binding errors because of this.
Srivathsa M
19 years ago
Using LDAP over SSL on NetWare:

1. Copy the server certificates to sys:/php5/cert directory. This location is configurable in php.ini file.

2. Use "ldaps://" prefix for host name argument or a value of 636 for port number argument in ldap_connect call.

For more details, visit, NetWare specific PHP documentation at
nigelf at esp dot co dot uk
19 years ago
As mentioned above, openLDAP will always return a resource, even if the server name isn't valid.

If you then bind with errors suppressed (@ldap_bind) and it fails, it's not obvious what caused the failure (ie: connection or credentials). As the bind doesn't return a resource you can't get the last error from ldap_error etc. either.

If you display just a message about login failure to the user they may get frustrated re-typing a valid username/password when it's the connection that's at fault.
vandervoord at planet dot nl
17 years ago
The previous note concerning searching the whole AD tree works fully. Though you must be sure that the server you're authenticating/searching is a Global Catalog server. If not, connecting and binding will fail. Usually there is at least one Global Catalog server in your domain, so if the connect fails try another server it will work. The reason it works is that the Global Catalog server searches the whole domain as where the domain catalog only searches a given OU, offcourse this opposes a security threat as well :)...
22 years ago
A resource ID is always returned when using URLs for the host parameter
even if the host does not exist.

"When using an URI to describe the connection, the (open)ldap library
only parses the url and checks if it's valid, _no connection_ is
established in that case."
mharting at micahtek dot com
14 years ago
An addition to trying to setup failover. After doing the ldap_connect, do the ldap_bind. If ldap_bind fails, use the command ldap_errno to get the error number. If the error number is 81, that represents the server is down. That is the only time we do a failover to our backup ldap server.

Another thing to consider is the error could be 49, then do
ldap_get_option($this->ds,LDAP_OPT_ERROR_NUMBER,$optErrorNumber);. This will return extended data and if the data code in that is 532 or 773, the bind failure will be caused by the password being expired and requiring a password update before the bind will succeed.
baroque at citromail dot hu
18 years ago
This code sample shows how to connect and bind to eDirectory in PHP using LDAP for Netware.



$ds=ldap_connect($server); // assuming the LDAP server is on this host

if ($ds) {
// bind with appropriate dn to give update access
$r=ldap_bind($ds, $admin, $passwd);
$r) die("ldap_bind failed<br>");

"ldap_bind success";
} else {
"Unable to connect to LDAP server";
13 years ago
PHP:LDAP does not support persistent connections.
miki at qex dot cz
14 years ago
I had terrible problems with "Unable to bind to server: Invalid credentials" error - everything seemed to be OK (login/pwd used in other apps).
Solved by adding domain to login (instead "username" I used "").
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