diff --git a/Site.rb b/Site.rb
index 313166a..133ccbe 100644
--- a/Site.rb
+++ b/Site.rb
@@ -1,9 +1,11 @@
 require 'SystemData'
 
 class Site < SystemData
-	attr_accessor :name, :mailAccounts, :mailAliases
+	attr_accessor :name
 
 	def initialize(args = {})
+		super(args)
+
 		@name = args[:name]
 	end
 end
diff --git a/SystemDataBackendLdap.rb b/SystemDataBackendLdap.rb
index dc906f0..5fcca2e 100644
--- a/SystemDataBackendLdap.rb
+++ b/SystemDataBackendLdap.rb
@@ -43,8 +43,7 @@ class SystemDataBackendLdap
   LDAP_LAMBDA_USER = lambda do |entry|
     entry[:cn]               = entry[:uid]
     entry[:shadowlastchange] = (Time::now.to_i/60/60/24).to_s
-    entry[:shadowmax]        = '99999'
-    entry[:shadowwarning]    = '7'
+    entry[:replace]         += ['shadowreplace'] if entry[:replace]
   end
 
   LDAP_LAMBDA = {
@@ -64,7 +63,9 @@ class SystemDataBackendLdap
   end
 
   def load!(kind)
-    @ldapData[kind] = @ldap.search(
+    @ldapData[kind] = Hash.new if ! @ldapData[kind]
+
+    @ldapData[kind][:internal] = @ldap.search(
       :base   => ldapBase(kind),
       :filter => LDAP_FILTER[kind]
     )
@@ -73,7 +74,7 @@ class SystemDataBackendLdap
   def load(kind)
     load!(kind) if ! @ldapData[kind]
 
-    @ldapData[kind].each do |data|
+    @ldapData[kind][:external] = @ldapData[kind][:internal].map do |data|
       map = { :dn => :id }
       map.merge!(LDAP_MAP[kind]) if LDAP_MAP[kind]
 
@@ -81,9 +82,10 @@ class SystemDataBackendLdap
       data.each do |key,value|
         ydata.merge!({ map[key] || key => value.size==1?value[0]:value.to_a })
       end
+      ydata
+    end if ! @ldapData[kind][:external]
 
-      yield ydata
-    end
+    @ldapData[kind][:external].each{|ydata| yield ydata}
   end
 
   def update(kind, data)
@@ -91,19 +93,27 @@ class SystemDataBackendLdap
     map.merge!(LDAP_MAP[kind].invert) if LDAP_MAP[kind]
 
     entry = Net::LDAP::Entry.new(data[:id])
-    data.delete(:id)
 
-    entry[:changetype]  = 'add'
-    entry[:objectclass] = LDAP_OBJECTCLASS[kind]
+    odata = @ldapData[kind][:external].find{|edata| edata[:id] == data[:id]}
+    data = data.find_all{|key,value| value != odata[key]}
+    data.delete(:id)
 
+    replace = Array.new
     data.each do |key,value|
       key = map[key] if map[key]
+      replace.push(key.to_s)
       entry[key] = value
     end
-    
-    LDAP_LAMBDA[kind].call(entry) if LDAP_LAMBDA[kind]
 
-    puts entry.to_ldif
+    if not replace.empty?
+      entry[:changetype]  = 'modify'
+      entry[:replace]     = replace
+      LDAP_LAMBDA[kind].call(entry) if LDAP_LAMBDA[kind]
+
+      puts entry.to_ldif
+    else
+      puts 'INFO: no changes'
+    end
   end
 
   private
diff --git a/User.rb b/User.rb
index 68bb781..6f55ccd 100644
--- a/User.rb
+++ b/User.rb
@@ -6,11 +6,13 @@ class User < SystemData
 	def initialize(args = {})
 		super(args)
 
-		@name  = args[:name]
-		@pass  = args[:pass]
-		@uid   = args[:uid]
-		@gid   = args[:gid]
-		@shell = args[:shell]
-		@home  = args[:home]
+		@name          = args[:name]
+		@pass          = args[:pass]
+		@uid           = args[:uid]
+		@gid           = args[:gid]
+		@shell         = args[:shell]
+		@home          = args[:home]
+		@shadowmax     = args[:shadowmax]
+		@shadowwarning = args[:shadowwarning]
 	end
 end
diff --git a/test_dummy.rb b/test_dummy.rb
index 2a0e348..d69dfd2 100644
--- a/test_dummy.rb
+++ b/test_dummy.rb
@@ -46,8 +46,30 @@ end
 
 puts
 
-backend.userByName('georg').save
+georg = backend.userByName('georg')
+georg.save
 
 puts
 
-backend.groupByName('wheel').save
+georg.uid = 1001
+georg.save
+
+puts
+
+wheel = backend.groupByName('wheel')
+wheel.save
+
+puts
+
+wheel.gid = 100
+wheel.save
+
+puts
+
+site = backend.siteByName('kommandozeilenchef.de')
+site.save
+
+puts
+
+site.name = 'wumbaba.de'
+site.save