diff --git a/app/models/auth_source_ldap.rb b/app/models/auth_source_ldap.rb
index d009ae33..3536b4f6 100644
--- a/app/models/auth_source_ldap.rb
+++ b/app/models/auth_source_ldap.rb
@@ -21,6 +21,7 @@ class AuthSourceLdap < AuthSource
   validates_length_of :account, :account_password, :base_dn, :maximum => 255, :allow_nil => true
   validates_length_of :attr_login, :attr_firstname, :attr_lastname, :attr_mail, :maximum => 30, :allow_nil => true
   validates_numericality_of :port, :only_integer => true
+  validate :custom_filter_should_be_valid_ldap_filter_syntax
 
   before_validation :strip_ldap_attributes
 
@@ -101,10 +102,17 @@ class AuthSourceLdap < AuthSource
     ldap_con = initialize_ldap_con(self.account, self.account_password)
     login_filter = Net::LDAP::Filter.eq( self.attr_login, login )
     object_filter = Net::LDAP::Filter.eq( "objectClass", "*" )
-    attrs = {}
+    custom_ldap_filter = custom_filter_to_ldap
 
-    ldap_con.search( :base => self.base_dn,
-                     :filter => object_filter & login_filter,
+    if custom_ldap_filter.present?
+      search_filters = object_filter & login_filter & custom_ldap_filter
+    else
+      search_filters = object_filter & login_filter
+    end
+    attrs = {}
+    
+    ldap_con.search( :base => self.base_dn, 
+                     :filter => search_filters, 
                      :attributes=> search_attributes) do |entry|
 
       if onthefly_register?
@@ -119,6 +127,27 @@ class AuthSourceLdap < AuthSource
     attrs
   end
 
+  def custom_filter_to_ldap
+    return nil unless custom_filter.present?
+    
+    begin
+      return Net::LDAP::Filter.construct(custom_filter)
+    rescue Net::LDAP::LdapError # Filter syntax error
+      logger.debug "LDAP custom filter syntax error for: #{custom_filter}" if logger && logger.debug?
+      return nil
+    end
+  end
+
+  def custom_filter_should_be_valid_ldap_filter_syntax
+    return true unless custom_filter.present?
+
+    begin
+      return Net::LDAP::Filter.construct(custom_filter)
+    rescue Net::LDAP::LdapError # Filter syntax error
+      errors.add(:custom_filter, :invalid)
+    end
+  end
+  
   def self.get_attr(entry, attr_name)
     if !attr_name.blank?
       entry[attr_name].is_a?(Array) ? entry[attr_name].first : entry[attr_name]
diff --git a/app/views/ldap_auth_sources/_form.rhtml b/app/views/ldap_auth_sources/_form.rhtml
index 9ffffafc..8699a2cd 100644
--- a/app/views/ldap_auth_sources/_form.rhtml
+++ b/app/views/ldap_auth_sources/_form.rhtml
@@ -25,6 +25,9 @@
 
 <p><label for="auth_source_onthefly_register"><%=l(:field_onthefly)%></label>
 <%= check_box 'auth_source', 'onthefly_register' %></p>
+
+<p><label for="auth_source_custom_filter"><%=l(:field_custom_filter)%></label>
+<%= text_field 'auth_source', 'custom_filter', :size => 60 %></p>
 </div>
 
 <fieldset class="box"><legend><%=l(:label_attribute_plural)%></legend>
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 8560fc8f..afce4f4c 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -307,6 +307,7 @@ en:
   field_text: Text field
   field_visible: Visible
   field_warn_on_leaving_unsaved: "Warn me when leaving a page with unsaved text"
+  field_custom_filter: Custom LDAP filter
 
   setting_app_title: Application title
   setting_app_subtitle: Application subtitle
diff --git a/db/migrate/20100217010520_add_custom_filter_to_auth_sources.rb b/db/migrate/20100217010520_add_custom_filter_to_auth_sources.rb
new file mode 100644
index 00000000..8543c297
--- /dev/null
+++ b/db/migrate/20100217010520_add_custom_filter_to_auth_sources.rb
@@ -0,0 +1,9 @@
+class AddCustomFilterToAuthSources < ActiveRecord::Migration
+  def self.up
+    add_column :auth_sources, :custom_filter, :string
+  end
+
+  def self.down
+    remove_column :auth_sources, :custom_filter
+  end
+end
diff --git a/test/fixtures/ldap/backend.redmine.org.ldif b/test/fixtures/ldap/backend.redmine.org.ldif
new file mode 100644
index 00000000..b08dddbc
--- /dev/null
+++ b/test/fixtures/ldap/backend.redmine.org.ldif
@@ -0,0 +1,27 @@
+# This is a configuration for a new database to test the ldap plugin.
+# It is assumed that you have a ldap server up and running. Do not
+# use this file on a new openldap installation.
+
+# Database settings
+dn: olcDatabase=hdb,cn=config
+objectClass: olcDatabaseConfig
+objectClass: olcHdbConfig
+olcDatabase: hdb
+olcSuffix: dc=redmine,dc=org
+# WARNING: Do not use a directory that already contains a ldap database.
+# Each database has to be stored in a seperate directory. The directory
+# /var/lib/ldap is the default directory on Debian.
+olcDbDirectory: /var/lib/ldap/redmine
+olcRootDN: cn=Manager,dc=redmine,dc=org
+olcRootPW: secret
+olcDbConfig: set_cachesize 0 2097152 0
+olcDbConfig: set_lk_max_objects 1500
+olcDbConfig: set_lk_max_locks 1500
+olcDbConfig: set_lk_max_lockers 1500
+olcDbIndex: objectClass eq
+olcLastMod: TRUE
+olcDbCheckpoint: 512 30
+olcAccess: to attrs=userPassword by dn="cn=Manager,dc=redmine,dc=org" write by anonymous auth by self write by * none
+olcAccess: to attrs=shadowLastChange by self write by * read
+olcAccess: to dn.base="" by * read
+olcAccess: to * by dn="cn=Manager,dc=redmine,dc=org" write by * read
diff --git a/test/fixtures/ldap/test-ldap.ldif b/test/fixtures/ldap/test-ldap.ldif
index 7d9e109c..8a4ce5aa 100644
--- a/test/fixtures/ldap/test-ldap.ldif
+++ b/test/fixtures/ldap/test-ldap.ldif
@@ -4,39 +4,11 @@ objectClass: dcObject
 objectClass: organization
 o: redmine.org
 dc: redmine
-structuralObjectClass: organization
-entryUUID: 886f5fca-0a87-102e-8d06-67c361d9bd2d
-creatorsName:
-createTimestamp: 20090721211642Z
-entryCSN: 20090721211642.955188Z#000000#000#000000
-modifiersName:
-modifyTimestamp: 20090721211642Z
-
-dn: cn=admin,dc=redmine,dc=org
-objectClass: simpleSecurityObject
-objectClass: organizationalRole
-cn: admin
-description: LDAP administrator
-userPassword:: e2NyeXB0fWlWTU9DcUt6WWxXRDI=
-structuralObjectClass: organizationalRole
-entryUUID: 88704e44-0a87-102e-8d07-67c361d9bd2d
-creatorsName:
-createTimestamp: 20090721211642Z
-entryCSN: 20090721211642.961418Z#000000#000#000000
-modifiersName:
-modifyTimestamp: 20090721211642Z
 
 dn: ou=Person,dc=redmine,dc=org
 ou: Person
 objectClass: top
 objectClass: organizationalUnit
-structuralObjectClass: organizationalUnit
-entryUUID: d39dd388-0c84-102e-82fa-dff86c63a7d6
-creatorsName: cn=admin,dc=redmine,dc=org
-createTimestamp: 20090724100222Z
-entryCSN: 20090724100222.924226Z#000000#000#000000
-modifiersName: cn=admin,dc=redmine,dc=org
-modifyTimestamp: 20090724100222Z
 
 dn: uid=example1,ou=Person,dc=redmine,dc=org
 objectClass: posixAccount
@@ -48,16 +20,9 @@ sn: One
 uid: example1
 homeDirectory: /home/example1
 cn: Example One
-structuralObjectClass: inetOrgPerson
-entryUUID: 285d304e-0c8a-102e-82fc-dff86c63a7d6
-creatorsName: cn=admin,dc=redmine,dc=org
-createTimestamp: 20090724104032Z
 uidNumber: 0
 mail: example1@redmine.org
 userPassword:: e1NIQX1mRXFOQ2NvM1lxOWg1WlVnbEQzQ1pKVDRsQnM9
-entryCSN: 20090724105945.375801Z#000000#000#000000
-modifiersName: cn=admin,dc=redmine,dc=org
-modifyTimestamp: 20090724105945Z
 
 dn: uid=edavis,ou=Person,dc=redmine,dc=org
 objectClass: posixAccount
@@ -68,15 +33,8 @@ givenName: Eric
 sn: Davis
 uid: edavis
 mail: edavis@littlestreamsoftware.com
-structuralObjectClass: inetOrgPerson
-entryUUID: 9c5f0502-0c8b-102e-82fe-dff86c63a7d6
-creatorsName: cn=admin,dc=redmine,dc=org
-createTimestamp: 20090724105056Z
 homeDirectory: /home/edavis
 cn: Eric Davis
 uidNumber: 0
 userPassword:: e1NIQX1mRXFOQ2NvM1lxOWg1WlVnbEQzQ1pKVDRsQnM9
-entryCSN: 20090724105937.734480Z#000000#000#000000
-modifiersName: cn=admin,dc=redmine,dc=org
-modifyTimestamp: 20090724105937Z
 
diff --git a/test/unit/auth_source_ldap_test.rb b/test/unit/auth_source_ldap_test.rb
index b383b906..0effa103 100644
--- a/test/unit/auth_source_ldap_test.rb
+++ b/test/unit/auth_source_ldap_test.rb
@@ -31,6 +31,20 @@ class AuthSourceLdapTest < ActiveSupport::TestCase
     assert_equal 'givenName', a.reload.attr_firstname
   end
 
+  context "validations" do
+    should "validate that custom_filter is a valid LDAP filter" do
+      @auth = AuthSourceLdap.new(:name => 'Validation', :host => 'localhost', :port => 389, :attr_login => 'login')
+      @auth.custom_filter = "(& (homeDirectory=*) (sn=O*" # Missing ((
+      assert @auth.invalid?
+      assert_equal "is invalid", @auth.errors.on(:custom_filter)
+
+      @auth.custom_filter = "(& (homeDirectory=*) (sn=O*))"
+      assert @auth.valid?
+      assert_equal nil, @auth.errors.on(:custom_filter)
+      
+    end
+  end
+  
   if ldap_configured?
     context '#authenticate' do
       setup do
@@ -69,6 +83,32 @@ class AuthSourceLdapTest < ActiveSupport::TestCase
         end
       end
 
+      context "using a valid custom filter" do
+        setup do
+          @auth.update_attributes(:custom_filter => "(& (homeDirectory=*) (sn=O*))")
+        end
+
+        should "find a user who authenticates and matches the custom filter" do
+          assert_not_nil @auth.authenticate('example1', '123456')
+        end
+
+        should "be nil for users who don't match the custom filter" do
+          assert_nil @auth.authenticate('edavis', '123456')
+        end
+      end
+
+      context "using an invalid custom filter" do
+        setup do
+          # missing )) at the end
+          @auth.update_attributes(:custom_filter => "(& (homeDirectory=*) (sn=O*")
+        end
+
+        should "skip the custom filter" do
+          assert_not_nil @auth.authenticate('example1', '123456')
+          assert_not_nil @auth.authenticate('edavis', '123456')
+        end
+      end
+
     end
   else
     puts '(Test LDAP server not configured)'