diff --git a/src/opnsense/mvc/app/models/OPNsense/Base/Constraints/BaseConstraint.php b/src/opnsense/mvc/app/models/OPNsense/Base/Constraints/BaseConstraint.php
new file mode 100644
index 000000000..ac7c64686
--- /dev/null
+++ b/src/opnsense/mvc/app/models/OPNsense/Base/Constraints/BaseConstraint.php
@@ -0,0 +1,54 @@
+<?php
+/**
+ *    Copyright (C) 2016 Deciso B.V.
+ *
+ *    All rights reserved.
+ *
+ *    Redistribution and use in source and binary forms, with or without
+ *    modification, are permitted provided that the following conditions are met:
+ *
+ *    1. Redistributions of source code must retain the above copyright notice,
+ *       this list of conditions and the following disclaimer.
+ *
+ *    2. Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *
+ *    THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ *    INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ *    AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ *    AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
+ *    OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ *    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ *    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ *    POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+namespace OPNsense\Base\Constraints;
+
+use \Phalcon\Validation\Validator;
+use \Phalcon\Validation\ValidatorInterface;
+
+use \Phalcon\Validation\Message;
+
+abstract class BaseConstraint extends Validator implements ValidatorInterface
+{
+    /**
+     * @param \Phalcon\Validation $validator
+     * @param $attribute
+     */
+    protected function appendMessage(\Phalcon\Validation $validator, $attribute)
+    {
+        $message = $this->getOption('message');
+        $name = $this->getOption('name');
+        if (empty($message)) {
+            $message = 'validation failure ' . get_class($this);
+        }
+        if (empty($name)) {
+            $name =  get_class($this);
+        }
+        $validator->appendMessage(new Message($message, $attribute, $name));
+    }
+}
\ No newline at end of file
diff --git a/src/opnsense/mvc/app/models/OPNsense/Base/Constraints/UniqueConstraint.php b/src/opnsense/mvc/app/models/OPNsense/Base/Constraints/UniqueConstraint.php
new file mode 100644
index 000000000..50062f75a
--- /dev/null
+++ b/src/opnsense/mvc/app/models/OPNsense/Base/Constraints/UniqueConstraint.php
@@ -0,0 +1,92 @@
+<?php
+/**
+ *    Copyright (C) 2016 Deciso B.V.
+ *
+ *    All rights reserved.
+ *
+ *    Redistribution and use in source and binary forms, with or without
+ *    modification, are permitted provided that the following conditions are met:
+ *
+ *    1. Redistributions of source code must retain the above copyright notice,
+ *       this list of conditions and the following disclaimer.
+ *
+ *    2. Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *
+ *    THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ *    INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ *    AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ *    AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
+ *    OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ *    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ *    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ *    POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+namespace OPNsense\Base\Constraints;
+
+
+/**
+ * Class UniqueConstraint, add a unique constraint to this field and optional additional fields.
+ * @package OPNsense\Base\Constraints
+ */
+class UniqueConstraint extends BaseConstraint
+{
+    /**
+     * Executes validation
+     *
+     * @param \Phalcon\Validation $validator
+     * @param string $attribute
+     * @return boolean
+     */
+    public function validate(\Phalcon\Validation $validator, $attribute)
+    {
+        $node = $this->getOption('node');
+        $addFields = $this->getOption('addFields');
+        $fieldSeparator = chr(10) . chr(0);
+        if ($node) {
+            $containerNode = $node;
+            $nodeName = $node->getInternalXMLTagName();
+            $parentNode = $node->getParentNode();
+            $level = 0;
+            // dive into parent
+            while ($containerNode != null &&
+                get_class($containerNode) != 'OPNsense\Base\FieldTypes\ArrayField') {
+                $containerNode = $containerNode->getParentNode();
+                $level++;
+            }
+            if ($containerNode != null && $level == 2) {
+                // collect (additional) key fields
+                $keyFields = array($nodeName);
+                if (!empty($addFields)) {
+                    foreach ($addFields as $field) {
+                        $keyFields[] = $field;
+                    }
+                }
+                // calculate the key for this node
+                $nodeKey = '';
+                foreach ($keyFields as $field) {
+                    $nodeKey .= $fieldSeparator . $parentNode->$field;
+                }
+                // when an ArrayField is found in range, traverse nodes and compare keys
+                foreach ($containerNode->__items as $item) {
+                    if ($item !== $parentNode) {
+                        $itemKey = '';
+                        foreach ($keyFields as $field) {
+                            $itemKey .= $fieldSeparator . $item->$field;
+                        }
+                        if ($itemKey == $nodeKey) {
+                            $this->appendMessage($validator, $attribute);
+                            return false;
+                        }
+                    }
+                }
+            }
+        }
+        return true;
+    }
+
+}
\ No newline at end of file
diff --git a/src/opnsense/mvc/app/models/OPNsense/Base/FieldTypes/BaseField.php b/src/opnsense/mvc/app/models/OPNsense/Base/FieldTypes/BaseField.php
index 5398b3376..f3ec820f1 100644
--- a/src/opnsense/mvc/app/models/OPNsense/Base/FieldTypes/BaseField.php
+++ b/src/opnsense/mvc/app/models/OPNsense/Base/FieldTypes/BaseField.php
@@ -47,6 +47,11 @@ abstract class BaseField
      */
     protected $internalChildnodes = array();
 
+    /**
+     * @var array constraints for this field, additional to fieldtype
+     */
+    protected $internalConstraints = array();
+
     /**
      * @var null pointer to parent
      */
@@ -211,6 +216,15 @@ abstract class BaseField
         $this->internalParentNode = $node;
     }
 
+    /**
+     * return this nodes parent (or null if not found)
+     * @return null|BaseField
+     */
+    public function getParentNode()
+    {
+        return $this->internalParentNode;
+    }
+
     /**
      * Reflect default getter to internal child nodes.
      * Implements the special attribute __items to return all items and __reference to identify the field in this model.
@@ -347,13 +361,35 @@ abstract class BaseField
         }
     }
 
+    /**
+     * fetch all additional validators
+     */
+    private function getConstraintValidators()
+    {
+        $result = array();
+        foreach ($this->internalConstraints as $name => $constraint) {
+            if (!empty($constraint['type'])) {
+                try {
+                    $constr_class = new \ReflectionClass($constraint['type']);
+                    if ($constr_class->getParentClass()->name == 'OPNsense\Base\Constraints\BaseConstraint') {
+                        $constraint['name'] = $name;
+                        $constraint['node'] = $this;
+                        $result[] = $constr_class->newInstance($constraint);
+                    }
+                } catch (\ReflectionException $e) {
+                    null; // ignore configuration errors, if the constraint can't be found, skip.
+                }
+            }
+        }
+        return $result;
+    }
     /**
      * return field validators for this field
      * @return array returns validators for this field type (empty if none)
      */
     public function getValidators()
     {
-        $validators = array();
+        $validators = $this->getConstraintValidators();
         if ($this->isEmptyAndRequired()) {
             $validators[] = new PresenceOf(array('message' => $this->internalValidationMessage)) ;
         }
@@ -561,6 +597,15 @@ abstract class BaseField
         }
     }
 
+    /**
+     * set additional constraints
+     * @param $constraints
+     */
+    public function setConstraints($constraints)
+    {
+        $this->internalConstraints = $constraints;
+    }
+
     /**
      * apply change case to this node, called by setValue
      */
diff --git a/src/opnsense/mvc/tests/app/models/OPNsense/Base/BaseModel/TestModel.xml b/src/opnsense/mvc/tests/app/models/OPNsense/Base/BaseModel/TestModel.xml
index 8494e96cc..d0023c3e4 100644
--- a/src/opnsense/mvc/tests/app/models/OPNsense/Base/BaseModel/TestModel.xml
+++ b/src/opnsense/mvc/tests/app/models/OPNsense/Base/BaseModel/TestModel.xml
@@ -20,7 +20,18 @@
                     <MaximumValue>65535</MaximumValue>
                     <ValidationMessage>not a valid number</ValidationMessage>
                     <Required>Y</Required>
+                    <Constraints>
+                        <check001>
+                            <message>number should be unique</message>
+                            <type>OPNsense\Base\Constraints\UniqueConstraint</type>
+                            <addFields>
+                                <field1>optfield</field1>
+                            </addFields>
+                        </check001>
+                    </Constraints>
                 </number>
+                <optfield type="TextField">
+                </optfield>
             </item>
         </arraytypes>
     </items>
diff --git a/src/opnsense/mvc/tests/app/models/OPNsense/Base/BaseModelTest.php b/src/opnsense/mvc/tests/app/models/OPNsense/Base/BaseModelTest.php
index cfbde9c37..3292b1811 100644
--- a/src/opnsense/mvc/tests/app/models/OPNsense/Base/BaseModelTest.php
+++ b/src/opnsense/mvc/tests/app/models/OPNsense/Base/BaseModelTest.php
@@ -234,4 +234,34 @@ class BaseModelTest extends \PHPUnit_Framework_TestCase
         $data = BaseModelTest::$model->arraytypes->item->getNodes();
         $this->assertEquals(count($data), 9);
     }
+
+    /**
+     * @depends testGetNodes
+     * @expectedException \Phalcon\Validation\Exception
+     * @expectedExceptionMessage number should be unique
+     */
+    public function testConstraintsNok()
+    {
+        $count = 2;
+        foreach (BaseModelTest::$model->arraytypes->item->__items as $nodeid => $node) {
+            $count-- ;
+            if ($count >= 0) {
+                $node->number = 999;
+            }
+        }
+        BaseModelTest::$model->serializeToConfig();
+    }
+
+    /**
+     * @depends testConstraintsNok
+     */
+    public function testConstraintsOk()
+    {
+        $count = 1;
+        foreach (BaseModelTest::$model->arraytypes->item->__items as $nodeid => $node) {
+            $count++ ;
+            $node->number = $count;
+        }
+        BaseModelTest::$model->serializeToConfig();
+    }
 }