diff --git a/src/msp.erl b/src/msp.erl
index c94eb4c..98978ed 100644
--- a/src/msp.erl
+++ b/src/msp.erl
@@ -9,7 +9,17 @@ start() -> application:start(hakuzaru).
 stop() -> application:stop(hakuzaru).
 
 start(normal, _Args) ->
-	msp_sup:start_link().
+	{ok, Sup} = msp_sup:start_link(),
+	case init:get_plain_arguments() of
+		[_] ->
+			io:format("MSP started as idle process.~n");
+		[_, "test"] ->
+			io:format("Running tests.~n", []),
+			msp_tests:spawn_tests();
+		[_ | CLArgs] ->
+			io:format("Unknown args ~p~n", [CLArgs])
+	end,
+	{ok, Sup}.
 
 stop(_State) ->
 	ok.
diff --git a/src/msp_connection.erl b/src/msp_connection.erl
new file mode 100644
index 0000000..e69d79b
--- /dev/null
+++ b/src/msp_connection.erl
@@ -0,0 +1,118 @@
+%%% @doc
+%%% Minimal Stream Protocol: Connection Worker
+%%% @end
+
+-module(msp_connection).
+-vsn("0.1.0").
+-behavior(gen_server).
+-author("Jarvis Carroll <spiveehere@gmail.com>").
+-copyright("Jarvis Carroll <spiveehere@gmail.com>").
+-license("MIT").
+
+-export([begin_msp/5]).
+
+%% gen_server
+-export([start_link/0]).
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
+         code_change/3, terminate/2]).
+-include("$zx_include/zx_logger.hrl").
+
+
+%%% Type and Record Definitions
+
+-type endpoint() :: {inet:ip_address(), inet:port_number()}.
+
+% msp_channel server.
+-type channel() :: pid().
+
+-record(s,
+	{socket            :: gen_udp:socket(),
+	 peer              :: endpoint(),
+	 side              :: 0 | 1,
+	 connections = #{} :: #{integer() => channel()}}).
+
+-type state() :: none | #s{}.
+
+%%% Interface
+
+% msp does not negotiate new connections, but once you have a
+% socket, and a host that knows you will be talking MSP, then a
+% new msp_connection can be initialized.
+begin_msp(Connection, OurSock, TheirIP, TheirPort, OurSide) ->
+	% Transfer the socket to the gen_server. If it is
+	% active then a bunch of messages will be received
+	% at once, but that is fine.
+	case gen_udp:controlling_process(OurSock, Connection) of
+		ok ->
+			gen_server:cast(Connection, {begin_msp, OurSock, {TheirIP, TheirPort}, OurSide});
+		{error, Reason} ->
+			{error, Reason}
+	end.
+
+%%% gen_server
+
+-spec start_link() -> Result
+    when Result :: {ok, pid()}
+                 | {error, Reason :: term()}.
+
+start_link() ->
+    gen_server:start_link(?MODULE, none, []).
+
+
+% TODO: Ask msp_connection_man for the socket and endpoint
+init(none) ->
+    {ok, none}.
+
+
+handle_call(Unexpected, From, State) ->
+    ok = log(warning, "Unexpected call from ~tp: ~tp", [From, Unexpected]),
+    {reply, undef, State}.
+
+
+handle_cast({begin_msp, Sock, Peer, Side}, none) ->
+	State = do_begin_msp(Sock, Peer, Side),
+	{noreply, State};
+handle_cast(Unexpected, State) ->
+    ok = log(warning, "Unexpected cast: ~tp", [Unexpected]),
+    {noreply, State}.
+
+
+handle_info({udp, Sock, IP, Port, Packet}, State = #s{socket = Sock, peer = {IP, Port}}) ->
+	NewState = do_dispatch(State, Packet),
+	{noreply, NewState};
+handle_info(Unexpected, State) ->
+    ok = io:format(warning, "Unexpected info: ~tp", [Unexpected]),
+    {noreply, State}.
+
+
+-spec code_change(OldVersion, State, Extra) -> {ok, NewState} | {error, Reason}
+    when OldVersion :: Version | {old, Version},
+         Version    :: term(),
+         State      :: state(),
+         Extra      :: term(),
+         NewState   :: term(),
+         Reason     :: term().
+
+code_change(_, State, _) ->
+    {ok, State}.
+
+
+terminate(_, _) ->
+    ok.
+
+
+
+%%% Doer Functions
+
+do_begin_msp(Sock, Peer, Side) ->
+	ok = inet:setopts(Sock, [{active, once}]),
+	State = #s{socket = Sock,
+		   peer = Peer,
+		   side = Side},
+	State.
+
+do_dispatch(State = #s{socket = Sock}, Packet) ->
+	io:format("Got data: ~p~n", [Packet]),
+	ok = inet:setopts(Sock, [{active, once}]),
+	State.
+
diff --git a/src/msp_tests.erl b/src/msp_tests.erl
new file mode 100644
index 0000000..6fdd7e1
--- /dev/null
+++ b/src/msp_tests.erl
@@ -0,0 +1,42 @@
+-module(msp_tests).
+-export([spawn_tests/0, run_tests_and_halt/0, run_tests_protected/0, run_tests/0]).
+
+spawn_tests() ->
+	spawn(?MODULE, run_tests_and_halt, []),
+	ok.
+
+run_tests_and_halt() ->
+	Result = run_tests_protected(),
+	io:format("Tests returned ~p~n", [Result]),
+	halt().
+
+run_tests_protected() ->
+	try
+		run_tests()
+	catch
+		_:Reason:Stack -> {error, Reason, Stack}
+	end.
+
+run_tests() ->
+	ok = send_test(),
+	ok.
+
+make_connection(OurPort, TheirIP, TheirPort, Side) ->
+	{ok, Sock} = gen_udp:open(OurPort),
+	{ok, Pid} = msp_connection:start_link(),
+	ok = msp_connection:begin_msp(Pid, Sock, TheirIP, TheirPort, Side),
+	{Pid, Sock}.
+
+
+send_test() ->
+	IP = {127, 0, 0, 1},
+	PortA = 5555,
+	PortB = 6666,
+	{A, SockA} = make_connection(PortA, IP, PortB, 0),
+	{B, SockB} = make_connection(PortB, IP, PortA, 1),
+	gen_udp:send(SockA, {IP, PortB}, <<"message sent from A to B">>),
+	gen_udp:send(SockB, {IP, PortA}, <<"message sent from B to A">>),
+	timer:sleep(10),
+	ok.
+
+