diff --git a/boards/management/commands/sync_with_server.py b/boards/management/commands/sync_with_server.py
--- a/boards/management/commands/sync_with_server.py
+++ b/boards/management/commands/sync_with_server.py
@@ -17,12 +17,16 @@ class Command(BaseCommand):
     help = 'Send a sync or get request to the server.'
 
     def add_arguments(self, parser):
-        parser.add_argument('url', type=str)
-        parser.add_argument('--global_id', type=str, default='',
+        parser.add_argument('url', type=str, help='Server root url')
+        parser.add_argument('--global-id', type=str, default='',
                             help='Post global ID')
 
     def handle(self, *args, **options):
         url = options.get('url')
+
+        pull_url = url + 'api/sync/pull/'
+        get_url = url + 'api/sync/get/'
+
         global_id_str = options.get('global_id')
         if global_id_str:
             match = REGEX_GLOBAL_ID.match(global_id_str)
@@ -37,7 +41,7 @@ class Command(BaseCommand):
                 xml = GlobalId.objects.generate_request_get([global_id])
                 # body = urllib.parse.urlencode(data)
                 h = httplib2.Http()
-                response, content = h.request(url, method="POST", body=xml)
+                response, content = h.request(get_url, method="POST", body=xml)
 
                 SyncManager.parse_response_get(content)
             else:
@@ -45,9 +49,9 @@ class Command(BaseCommand):
         else:
             h = httplib2.Http()
             xml = GlobalId.objects.generate_request_pull()
-            response, content = h.request(url, method="POST", body=xml)
+            response, content = h.request(pull_url, method="POST", body=xml)
 
-            print(content)
+            print(content.decode() + '\n')
 
             root = ET.fromstring(content)
             status = root.findall('status')[0].text
@@ -57,15 +61,16 @@ class Command(BaseCommand):
                 models = root.findall('models')[0]
                 for model in models:
                     global_id, exists = GlobalId.from_xml_element(model)
-                    print(global_id)
                     if not exists:
+                        print(global_id)
                         ids_to_sync.append(global_id)
+                print()
 
                 if len(ids_to_sync) > 0:
                     xml = GlobalId.objects.generate_request_get(ids_to_sync)
                     # body = urllib.parse.urlencode(data)
                     h = httplib2.Http()
-                    response, content = h.request(url, method="POST", body=xml)
+                    response, content = h.request(get_url, method="POST", body=xml)
 
                     SyncManager.parse_response_get(content)
                 else:
diff --git a/boards/models/post/manager.py b/boards/models/post/manager.py
--- a/boards/models/post/manager.py
+++ b/boards/models/post/manager.py
@@ -142,10 +142,11 @@ class PostManager(models.Manager):
                            pub_time=pub_time,
                            poster_ip=NO_IP,
                            last_edit_time=pub_time,
-                           thread_id=thread.id,
                            global_id=global_id,
-                           opening=is_opening)
+                           opening=is_opening,
+                           thread=thread)
 
+        post.threads.add(thread)
         post.build_url()
         post.connect_replies()
         post.connect_notifications()
diff --git a/boards/models/post/sync.py b/boards/models/post/sync.py
--- a/boards/models/post/sync.py
+++ b/boards/models/post/sync.py
@@ -84,11 +84,14 @@ class SyncManager:
                 # the post is added? Need to add some on_save signal queue
                 # and add this there.
                 key = KeyPair.objects.get(public_key=post.global_id.key)
-                signatures = [Signature(
+                signature = Signature(
                     key_type=key.key_type,
                     key=key.public_key,
                     signature=key.sign(et.tostring(content_tag, ENCODING_UNICODE)),
-                )]
+                    global_id=post.global_id,
+                )
+                signature.save()
+                signatures = [signature]
             for signature in signatures:
                 signature_tag = et.SubElement(signatures_tag, TAG_SIGNATURE)
                 signature_tag.set(ATTR_TYPE, signature.key_type)
@@ -127,13 +130,18 @@ class SyncManager:
                     thread = tag_content.find(TAG_THREAD)
                     tags = []
                     if thread:
-                        opening_post = Post.objects.get(
-                            id=thread.find(TAG_ID).text)
+                        thread_id = thread.find(TAG_ID)
+                        op_global_id, exists = GlobalId.from_xml_element(thread_id)
+                        if exists:
+                            opening_post = Post.objects.get(global_id=op_global_id)
+                        else:
+                            raise Exception('Load the OP first')
                     else:
                         opening_post = None
                         tag_tags = tag_content.find(TAG_TAGS)
                         for tag_tag in tag_tags:
-                            tag, created = Tag.objects.get_or_create(name=tag_tag.text)
+                            tag, created = Tag.objects.get_or_create(
+                                name=tag_tag.text)
                             tags.append(tag)
 
                     # TODO Check that the replied posts are already present
@@ -181,10 +189,13 @@ class SyncManager:
             signature = Signature(key_type=signature_type,
                                   key=signature_key,
                                   signature=signature_value)
-            signatures.append(signature)
+
+            content = et.tostring(tag_content, ENCODING_UNICODE)
 
             if not KeyPair.objects.verify(
-                    signature, et.tostring(tag_content, ENCODING_UNICODE)):
-                raise Exception('Invalid model signature')
+                    signature, content):
+                raise Exception('Invalid model signature for {}'.format(content))
+
+            signatures.append(signature)
 
         return signatures