diff --git a/conntrackt/migrations/0004_auto__add_unique_interface_netmask_address_entity.py b/conntrackt/migrations/0004_auto__add_unique_interface_netmask_address_entity.py
new file mode 100644
--- /dev/null
+++ b/conntrackt/migrations/0004_auto__add_unique_interface_netmask_address_entity.py
@@ -0,0 +1,61 @@
+# -*- coding: utf-8 -*-
+import datetime
+from south.db import db
+from south.v2 import SchemaMigration
+from django.db import models
+
+
+class Migration(SchemaMigration):
+
+    def forwards(self, orm):
+        # Adding unique constraint on 'Interface', fields ['netmask', 'address', 'entity']
+        db.create_unique(u'conntrackt_interface', ['netmask', 'address', 'entity_id'])
+
+
+    def backwards(self, orm):
+        # Removing unique constraint on 'Interface', fields ['netmask', 'address', 'entity']
+        db.delete_unique(u'conntrackt_interface', ['netmask', 'address', 'entity_id'])
+
+
+    models = {
+        u'conntrackt.communication': {
+            'Meta': {'unique_together': "(('source', 'destination', 'protocol', 'port'),)", 'object_name': 'Communication'},
+            'description': ('django.db.models.fields.TextField', [], {'blank': 'True'}),
+            'destination': ('django.db.models.fields.related.ForeignKey', [], {'related_name': "'destination_set'", 'to': u"orm['conntrackt.Interface']"}),
+            u'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'port': ('django.db.models.fields.IntegerField', [], {'default': '0'}),
+            'protocol': ('django.db.models.fields.CharField', [], {'max_length': '10'}),
+            'source': ('django.db.models.fields.related.ForeignKey', [], {'related_name': "'source_set'", 'to': u"orm['conntrackt.Interface']"})
+        },
+        u'conntrackt.entity': {
+            'Meta': {'unique_together': "(('name', 'project'),)", 'object_name': 'Entity'},
+            'description': ('django.db.models.fields.TextField', [], {'blank': 'True'}),
+            u'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'location': ('django.db.models.fields.related.ForeignKey', [], {'to': u"orm['conntrackt.Location']"}),
+            'name': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'project': ('django.db.models.fields.related.ForeignKey', [], {'to': u"orm['conntrackt.Project']"})
+        },
+        u'conntrackt.interface': {
+            'Meta': {'unique_together': "(('name', 'entity'), ('entity', 'address', 'netmask'))", 'object_name': 'Interface'},
+            'address': ('django.db.models.fields.IPAddressField', [], {'max_length': '15'}),
+            'description': ('django.db.models.fields.TextField', [], {'default': "'Main network interface.'", 'blank': 'True'}),
+            'entity': ('django.db.models.fields.related.ForeignKey', [], {'to': u"orm['conntrackt.Entity']"}),
+            u'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'default': "'eth0'", 'max_length': '100'}),
+            'netmask': ('django.db.models.fields.IPAddressField', [], {'default': "'255.255.255.255'", 'max_length': '15'})
+        },
+        u'conntrackt.location': {
+            'Meta': {'object_name': 'Location'},
+            'description': ('django.db.models.fields.TextField', [], {'blank': 'True'}),
+            u'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'unique': 'True', 'max_length': '100'})
+        },
+        u'conntrackt.project': {
+            'Meta': {'object_name': 'Project'},
+            'description': ('django.db.models.fields.TextField', [], {'blank': 'True'}),
+            u'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'unique': 'True', 'max_length': '100'})
+        }
+    }
+
+    complete_apps = ['conntrackt']
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