diff --git a/conf/ldapcherry.ini b/conf/ldapcherry.ini
index 7deacf9..ebc23e1 100644
--- a/conf/ldapcherry.ini
+++ b/conf/ldapcherry.ini
@@ -75,6 +75,9 @@ ldap.uri = 'ldaps://ldap.ldapcherry.org'
 ldap.ca = '/etc/dnscherry/TEST-cacert.pem'
 ldap.starttls = 'on'
 ldap.checkcert = 'off'
+ldap.user.filter.tmpl = '(uid=%(username)s)'
+ldap.group.filter.tmpl = '(member=%(userdn)s)'
+
 
 ad.module = 'ldapcherry.backend.samba4'
 ad.auth = 'Administrator'
diff --git a/ldapcherry/backend/__init__.py b/ldapcherry/backend/__init__.py
index c73186c..a671873 100644
--- a/ldapcherry/backend/__init__.py
+++ b/ldapcherry/backend/__init__.py
@@ -10,11 +10,14 @@ class Backend:
     def __init__(self):
         pass
 
-    def add_group(self):
+    def auth(self):
+        pass
+
+    def add_to_group(self):
         pass
 
     def set_attr(self):
         pass
 
-    def rm_group(self):
+    def rm_from_group(self):
         pass
diff --git a/ldapcherry/backend/ldap.py b/ldapcherry/backend/ldap.py
index 1ffc00c..b1d930f 100644
--- a/ldapcherry/backend/ldap.py
+++ b/ldapcherry/backend/ldap.py
@@ -5,9 +5,99 @@
 # LdapCherry
 # Copyright (c) 2014 Carpentier Pierre-Francois
 
+import cherrypy
+import ldap
+import logging
 import ldapcherry.backend
 
 class Backend(ldapcherry.backend.Backend):
 
     def __init__(self, config, logger):
+        self.config = config
+
+    def auth(self, username, password):
+
+        binddn = get_user(username)
+        if binddn:
+            ldap_client = self._connect()
+            try:
+                ldap_client.simple_bind_s(binddn, password)
+            except ldap.INVALID_CREDENTIALS:
+                ldap_client.unbind_s()
+                return False
+            ldap_client.unbind_s()
+            return True
+        else:
+            return False
+
+    def add_to_group(self):
         pass
+
+    def set_attrs(self, attrs):
+        pass
+
+    def rm_from_group(self):
+        pass
+
+    def add_user(self, username):
+        pass
+
+    def del_user(self, username):
+        pass
+
+    def get_user(self, username):
+        ldap_client = self._connect()
+        try:
+            ldap_client.simple_bind_s(self.binddn, self.bindpassword)
+        except ldap.INVALID_CREDENTIALS:
+            self._logger(
+                    logging.ERROR,
+                    "Configuration error, wrong credentials, unable to connect to ldap with '" + self.binddn + "'"
+                )
+            raise cherrypy.HTTPError("500", "Configuration Error, contact administrator")
+        except ldap.SERVER_DOWN:
+            self._logger(
+                    logging.ERROR,
+                    "Unable to contact ldap server '" + self.uri + "', check 'auth.ldap.uri' and ssl/tls configuration"
+                )
+            return False
+
+        user_filter = self.config['user_filter_tmpl'] % {
+            'login': username
+            }
+
+        r = ldap_client.search_s(self.userdn,
+                ldap.SCOPE_SUBTREE,
+                user_filter
+                 )
+        if len(r) == 0:
+            ldap_client.unbind_s()
+            return False
+
+        dn_entry = r[0][0]
+        return dn_entry
+
+    def _connect(self):
+        ldap_client = ldap.initialize(self.config['uri'])
+        ldap_client.set_option(ldap.OPT_REFERRALS, 0)
+        if self.config['starttls'] == 'on':
+           ldap.set_option(ldap.OPT_X_TLS_DEMAND, True)
+        if self.config['starttls'] == 'on':
+            ldap.set_option(ldap.OPT_X_TLS_DEMAND, True)
+        if self.ca:
+            ldap.set_option(ldap.OPT_X_TLS_CACERTFILE, self.config['ca'])
+        if self.checkcert == 'off':
+            ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, ldap.OPT_X_TLS_ALLOW)
+        else:
+            ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT,ldap.OPT_X_TLS_DEMAND)
+
+        if self.config['starttls'] == 'on':
+            try:
+                ldap_client.start_tls_s()
+            except ldap.OPERATIONS_ERROR:
+                self._logger(
+                    logging.ERROR,
+                    "cannot use starttls with ldaps:// uri (uri: " + self.uri + ")"
+                )
+                raise cherrypy.HTTPError("500", "Configuration Error, contact administrator")
+        return ldap_client