diff --git a/modules/Makefile.am b/modules/Makefile.am
index bf4061d7f..2e58c3ca2 100644
--- a/modules/Makefile.am
+++ b/modules/Makefile.am
@@ -359,6 +359,7 @@ federation_federation_send_leave_la_SOURCES = federation/send_leave.cc
 federation_federation_backfill_la_SOURCES = federation/backfill.cc
 federation_federation_backfill_ids_la_SOURCES = federation/backfill_ids.cc
 federation_federation_event_auth_la_SOURCES = federation/event_auth.cc
+federation_federation_query_auth_la_SOURCES = federation/query_auth.cc
 federation_federation_publicrooms_la_SOURCES = federation/publicrooms.cc
 federation_federation_federation_la_SOURCES = federation/federation.cc
 
@@ -380,6 +381,7 @@ federation_module_LTLIBRARIES = \
 	federation/federation_backfill.la \
 	federation/federation_backfill_ids.la \
 	federation/federation_event_auth.la \
+	federation/federation_query_auth.la \
 	federation/federation_publicrooms.la \
 	federation/federation_federation.la \
 	###
diff --git a/modules/federation/query_auth.cc b/modules/federation/query_auth.cc
new file mode 100644
index 000000000..beb95ce4d
--- /dev/null
+++ b/modules/federation/query_auth.cc
@@ -0,0 +1,72 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+using namespace ircd;
+
+mapi::header
+IRCD_MODULE
+{
+	"Federation 5.1.5.2 :Query Auth"
+};
+
+resource
+query_auth_resource
+{
+	"/_matrix/federation/v1/query_auth/",
+	{
+		"federation query_auth",
+		resource::DIRECTORY,
+	}
+};
+
+static resource::response
+post__query_auth(client &client,
+                 const resource::request &request);
+
+resource::method
+method_post
+{
+	query_auth_resource, "POST", post__query_auth,
+	{
+		method_post.VERIFY_ORIGIN
+	}
+};
+
+resource::response
+post__query_auth(client &client,
+                 const resource::request &request)
+{
+	if(request.parv.size() < 1)
+		throw m::NEED_MORE_PARAMS
+		{
+			"room_id path parameter required"
+		};
+
+	m::room::id::buf room_id
+	{
+		url::decode(room_id, request.parv[0])
+	};
+
+	if(request.parv.size() < 2)
+		throw m::NEED_MORE_PARAMS
+		{
+			"event_id path parameter required"
+		};
+
+	m::event::id::buf event_id
+	{
+		url::decode(event_id, request.parv[1])
+	};
+
+	return resource::response
+	{
+		client, http::NOT_FOUND
+	};
+}