diff --git a/datasrc/network.dts b/datasrc/network.dts
new file mode 100644
index 000000000..ffa6dea44
--- /dev/null
+++ b/datasrc/network.dts
@@ -0,0 +1,2 @@
+const array:int sound = sounds.*
+const array:int weapon = weapons.*
diff --git a/default.bam b/default.bam
index ef544015e..537edaf62 100644
--- a/default.bam
+++ b/default.bam
@@ -10,11 +10,26 @@ if family == "windows" then
 	dat2c_compiler = "scripts\\dat2c.py"
 end
 
+cmd5_tool = "python scripts/cmd5.py"
+if family == "windows" then
+	cmd5_tool = "scripts\\cmd5.py"
+end
+
 function rc(output, input)
 	print("rc " .. PathFilename(input))
 	return os.execute("rc /fo " .. output .. " " .. input)
 end
 
+function cmd5(output, inputs)
+	print("cmd5 " .. PathFilename(output))
+	cmd = cmd5_tool .. " "
+	for i,v in inputs do
+		cmd = cmd .. v .. " " 
+	end
+	cmd = cmd .. " > " .. output
+	return os.execute(cmd)
+end
+
 function dat2c(output, data, name)
 	print("dat2c " .. PathFilename(output) .. " = " .. PathFilename(data))
 	return os.execute(dat2c_compiler .. " " .. data .. " " .. name .. " > " .. output)
@@ -40,6 +55,25 @@ function dc_cdata(output, data, script)
 	return os.execute(dc_compiler .. " " .. data .. " " .. script .. " -c " .. output)
 end
 
+
+function CHash(output, ...)
+	local inputs = {}
+	local ih = collect_input(arg)
+	
+	output = Path(output)
+	
+	-- compile all the files
+	for index, inname in ih do
+		table.insert(inputs, Path(inname))
+	end
+	
+	bam_add_job("cmd5", output, inputs)
+	for index, inname in inputs do
+		bam_add_dependency(output, inname)
+	end
+	return output
+end
+
 function ResCompile(scriptfile)
 	scriptfile = Path(scriptfile)
 	output = PathBase(scriptfile) .. ".res"
@@ -60,18 +94,26 @@ function DataCompile(datafile, scriptfile, headerfile, sourcefile, outputdatafil
 	datafile = Path(datafile)
 	scriptfile = Path(scriptfile)
 	headerfile = Path(headerfile)
-	sourcefile = Path(sourcefile)
-	outputdatafile = Path(outputdatafile)
-	bam_add_job("dc_source", sourcefile, datafile, scriptfile)
+	
 	bam_add_job("dc_header", headerfile, datafile, scriptfile)
-	bam_add_job("dc_cdata", outputdatafile, datafile, scriptfile)
-	bam_add_dependency(sourcefile, datafile)
-	bam_add_dependency(sourcefile, scriptfile)
-	bam_add_dependency(sourcefile, headerfile)
 	bam_add_dependency(headerfile, datafile)
 	bam_add_dependency(headerfile, scriptfile)
-	bam_add_dependency(outputdatafile, datafile)
-	bam_add_dependency(outputdatafile, scriptfile)
+	
+	if sourcefile then
+		sourcefile = Path(sourcefile)
+		bam_add_job("dc_source", sourcefile, datafile, scriptfile)
+		bam_add_dependency(sourcefile, datafile)
+		bam_add_dependency(sourcefile, scriptfile)
+		bam_add_dependency(sourcefile, headerfile)
+	end
+		
+	if outputdatafile then
+		outputdatafile = Path(outputdatafile)
+		bam_add_job("dc_cdata", outputdatafile, datafile, scriptfile)
+		bam_add_dependency(outputdatafile, datafile)
+		bam_add_dependency(outputdatafile, scriptfile)
+	end
+		
 	return {cdata = outputdatafile, header=headerfile, source=sourcefile}
 end
 
@@ -89,6 +131,13 @@ clientdata = DataCompile(
 		"src/game/client/data/client_data.cpp",
 		"src/game/client/data/client_internal.cpp")
 
+networkdata = DataCompile(
+		"datasrc/teewars.ds", 
+		"datasrc/network.dts", 
+		"src/game/protocol_ids.h")
+
+nethash = CHash("src/game/nethash.c", "src/engine/protocol.h", "src/game/game_protocol.h", networkdata.header)
+
 client_link_other = {}
 if family == "windows" then
 	client_link_other = {ResCompile("other/icons/teewars.rc")}
@@ -171,7 +220,7 @@ function build(settings)
 	server = Compile(engine_settings, Collect("src/engine/server/*.c"))
 	
 	masterserver = Compile(settings, Collect("src/mastersrv/*.cpp"))
-	game_shared = Compile(settings, Collect("src/game/*.cpp"))
+	game_shared = Compile(settings, Collect("src/game/*.cpp"), nethash)
 	game_client = Compile(settings, Collect("src/game/client/*.cpp"), clientdata.source, clientdata.cdata)
 	game_server = Compile(settings, Collect("src/game/server/*.cpp"), serverdata.source, serverdata.cdata)
 	editor = Compile(settings, Collect("src/editor/*.cpp"))
diff --git a/scripts/cmd5.py b/scripts/cmd5.py
new file mode 100644
index 000000000..2e20ff5be
--- /dev/null
+++ b/scripts/cmd5.py
@@ -0,0 +1,32 @@
+import md5, sys, re
+m = md5.new()
+
+alphanum = "0123456789abcdefghijklmnopqrstuvwzyxABCDEFGHIJKLMNOPQRSTUVWXYZ_"
+
+def cstrip(lines):
+	d = ""	
+	for l in lines:
+		l = re.sub("#.*", "", l)
+		l = re.sub("//.*", "", l)
+		d += l + " "
+	d = re.sub("\/\*.*?\*/", "", d) # remove /* */ comments
+	d = d.replace("\t", " ") # tab to space
+	d = re.sub("  *", " ", d) # remove double spaces
+	d = re.sub("", "", d) # remove /* */ comments
+	
+	d = d.strip()
+	
+	# this eats up cases like 'n {'
+	i = 1
+	while i < len(d)-2:
+		if d[i] == ' ':
+			if not (d[i-1] in alphanum and d[i+1] in alphanum):
+				d = d[:i] + d[i+1:]
+		i += 1
+	return d
+
+f = ""
+for filename in sys.argv[1:]:
+	f += cstrip([l.strip() for l in file(filename)])
+
+print '#define TEEWARS_NETVERSION_HASH "%s"' % md5.new(f).hexdigest().lower()[16:]
diff --git a/src/engine/client/client.c b/src/engine/client/client.c
index ab4b71091..fe8a73054 100644
--- a/src/engine/client/client.c
+++ b/src/engine/client/client.c
@@ -9,8 +9,6 @@
 #include <engine/interface.h>
 #include "ui.h"
 
-#include <engine/versions.h>
-
 #include <engine/protocol.h>
 #include <engine/snapshot.h>
 #include <engine/compression.h>
@@ -152,7 +150,7 @@ static void client_send_info()
 	game_start_time = -1;
 
 	msg_pack_start_system(NETMSG_INFO, MSGFLAG_VITAL);
-	msg_pack_string(TEEWARS_NETVERSION_STRING, 64);
+	msg_pack_string(modc_net_version(), 128);
 	msg_pack_string(config.player_name, 128);
 	msg_pack_string(config.clan_name, 128);
 	msg_pack_string(config.password, 128);
@@ -717,6 +715,7 @@ static void client_run(const char *direct_connect_server)
 	
 	// init the mod
 	modc_init();
+	dbg_msg("client", "version %s", modc_net_version());
 	
 	// open socket
 	NETADDR4 bindaddr;
diff --git a/src/engine/interface.h b/src/engine/interface.h
index 010a393e4..a46b826f5 100644
--- a/src/engine/interface.h
+++ b/src/engine/interface.h
@@ -708,6 +708,13 @@ int modmenu_render(int ingame);
 void modc_message(int msg);
 void mods_message(int msg, int client_id);
 
+const char *modc_net_version();
+const char *mods_net_version();
+
+// unused
+// const char *modc_version();
+// const char *mods_version();
+
 /* server */
 int server_getclientinfo(int client_id, CLIENT_INFO *info);
 int server_tick();
diff --git a/src/engine/server/server.c b/src/engine/server/server.c
index b31c2a6cb..2c568e07b 100644
--- a/src/engine/server/server.c
+++ b/src/engine/server/server.c
@@ -11,7 +11,6 @@
 #include <engine/snapshot.h>
 
 #include <engine/compression.h>
-#include <engine/versions.h>
 
 #include <engine/network.h>
 #include <engine/config.h>
@@ -366,11 +365,11 @@ static void server_process_client_packet(NETPACKET *packet)
 		{
 			char version[64];
 			strncpy(version, msg_unpack_string(), 64);
-			if(strcmp(version, TEEWARS_NETVERSION_STRING) != 0)
+			if(strcmp(version, mods_net_version()) != 0)
 			{
 				// OH FUCK! wrong version, drop him
 				char reason[256];
-				sprintf(reason, "wrong version. server is running %s.", TEEWARS_NETVERSION_STRING);
+				sprintf(reason, "wrong version. server is running %s.", mods_net_version());
 				netserver_drop(net, cid, reason);
 				return;
 			}
@@ -545,6 +544,7 @@ static int server_run()
 	}
 
 	mods_init();
+	dbg_msg("server", "version %s", mods_net_version());
 
 	int64 time_per_tick = time_freq()/SERVER_TICK_SPEED;
 	int64 time_per_heartbeat = time_freq() * 30;
@@ -657,3 +657,4 @@ int main(int argc, char **argv)
 	server_run();
 	return 0;
 }
+
diff --git a/src/engine/versions.h b/src/engine/versions.h
deleted file mode 100644
index 001542e33..000000000
--- a/src/engine/versions.h
+++ /dev/null
@@ -1,3 +0,0 @@
-#define TEEWARS_NETVERSION 0xffffffff
-#define TEEWARS_NETVERSION_STRING "development"
-#define TEEWARS_VERSION "development"
diff --git a/src/game/client/game_client.cpp b/src/game/client/game_client.cpp
index e5969fcfb..2e0933087 100644
--- a/src/game/client/game_client.cpp
+++ b/src/game/client/game_client.cpp
@@ -9,6 +9,7 @@ extern "C" {
 };
 
 #include "../game.h"
+#include "../version.h"
 #include "mapres_image.h"
 #include "mapres_tilemap.h"
 #include "data.h"
@@ -2204,3 +2205,6 @@ extern "C" void modc_message(int msg)
 		client_datas[cid].emoticon_start = client_tick();
 	}
 }
+
+
+extern "C" const char *modc_net_version() { return TEEWARS_NETVERSION; }
diff --git a/src/game/client/menu.cpp b/src/game/client/menu.cpp
index 1e7f1edc9..a307d1760 100644
--- a/src/game/client/menu.cpp
+++ b/src/game/client/menu.cpp
@@ -8,12 +8,12 @@
 extern "C" {
 	#include <engine/system.h>
 	#include <engine/interface.h>
-	#include <engine/versions.h>
 	#include <engine/config.h>
 	#include <engine/client/ui.h>
 }
 
 #include "../mapres.h"
+#include "../version.h"
 
 #include "mapres_image.h"
 #include "mapres_tilemap.h"
@@ -1289,7 +1289,7 @@ int render_popup(const char *caption, const char *text, const char *button_text)
 	ui_do_label(x+w/2-tw/2, y+20, caption, 48.0f);
 	
 	tw = gfx_pretty_text_width(32.0f, text, -1);
-	ui_do_label(x+w/2-tw/2, y+130, text, 32.0f);
+    gfx_pretty_text(x+w/2-tw/2, y+130, 32.0f, text, -1);
 
 	if(button_text)
 	{
@@ -1366,6 +1366,8 @@ static int menu_render(bool ingame)
 		{
 			ui_do_image(data->images[IMAGE_BANNER].id, 200, 20, 512, 128);
 			ui_do_label(20.0f, 600.0f-40.0f, "Version: " TEEWARS_VERSION, 36);
+			if(config.debug)
+				ui_do_label(20.0f, 600.0f-60.0f, "Nethash: " TEEWARS_NETVERSION_HASH, 24);
 		}
 	}
 	else
diff --git a/src/game/game.h b/src/game/game.h
index 45a19105c..5b860036e 100644
--- a/src/game/game.h
+++ b/src/game/game.h
@@ -4,6 +4,8 @@
 #include "../engine/interface.h"
 #include "mapres_col.h"
 
+#include "game_protocol.h"
+
 inline vec2 get_direction(int angle)
 {
 	float a = angle/256.0f;
@@ -25,161 +27,6 @@ inline float get_angle(vec2 dir)
 inline bool col_check_point(float x, float y) { return col_check_point((int)x, (int)y) != 0; }
 inline bool col_check_point(vec2 p) { return col_check_point(p.x, p.y); }
 
-// Network stuff
-
-enum
-{
-	OBJTYPE_NULL=0,
-	OBJTYPE_GAME,
-	OBJTYPE_PLAYER,
-	OBJTYPE_PROJECTILE,
-	OBJTYPE_POWERUP,
-	OBJTYPE_FLAG,
-	EVENT_EXPLOSION,
-	EVENT_DAMAGEINDICATION,
-	EVENT_SOUND,
-	EVENT_SMOKE,
-	EVENT_SPAWN,
-	EVENT_DEATH,
-};
-
-enum
-{
-	MSG_NULL=0,
-	MSG_SAY,
-	MSG_CHAT,
-	MSG_SETNAME,
-	MSG_KILLMSG,
-	MSG_SWITCHTEAM,
-	MSG_JOIN,
-	MSG_QUIT,
-	MSG_EMOTICON,
-	MSG_CHANGENAME,
-};
-
-enum
-{
-	EMOTE_NORMAL=0,
-	EMOTE_PAIN,
-	EMOTE_HAPPY,
-	EMOTE_SURPRISE,
-	EMOTE_ANGRY,
-	EMOTE_BLINK,
-};
-
-enum
-{
-	STATE_UNKNOWN=0,
-	STATE_PLAYING,
-	STATE_IN_MENU,
-	STATE_CHATTING,
-};
-
-struct player_input
-{
-	int left;
-	int right;
-	
-	int target_x;
-	int target_y;
-	
-	int jump;
-	int fire;
-	int hook;
-	int blink;
-	int activeweapon;
-	int state;
-};
-
-
-struct ev_explosion
-{
-	int x, y;
-};
-
-struct ev_spawn
-{
-	int x, y;
-};
-
-struct ev_death
-{
-	int x, y;
-};
-
-struct ev_sound
-{
-	int x, y;
-	int sound; // if (0x80000000 flag is set -> looping) if (0x40000000 is set -> stop looping
-};
-
-struct ev_damageind
-{
-	int x, y;
-	int angle;
-};
-
-struct obj_game
-{
-	int round_start_tick;
-	int game_over;
-	int sudden_death;
-	int paused;
-	
-	int score_limit;
-	int time_limit;
-	int gametype;
-};
-
-struct obj_projectile
-{
-	int type;
-	int x, y;
-	int vx, vy; // should be an angle instead
-};
-
-struct obj_powerup
-{
-	int x, y;
-	int type; // why do we need two types?
-	int subtype;
-};
-
-struct obj_flag
-{
-	int x, y;
-	int team;
-};
-
-struct obj_player
-{
-	int local;
-	int clientid;
-	int state;
-
-	int health;
-	int armor;
-	int ammocount;
-	
-	int x, y;
-	int vx, vy;
-	int angle;
-	
-	int weapon; // current active weapon
-
-	int attacktick; // num attack ticks left of current attack
-	
-	int score;
-	int latency;
-	int latency_flux;
-	int emote;
-	
-	int hook_active;
-	int hook_x, hook_y;
-	int team;
-};
-
-
 struct mapres_spawnpoint
 {
 	int x, y;
diff --git a/src/game/game_protocol.h b/src/game/game_protocol.h
new file mode 100644
index 000000000..f04df1483
--- /dev/null
+++ b/src/game/game_protocol.h
@@ -0,0 +1,154 @@
+// NOTE: Be very careful when editing this file as it will change the network version
+
+// Network stuff
+enum
+{
+	OBJTYPE_NULL=0,
+	OBJTYPE_GAME,
+	OBJTYPE_PLAYER,
+	OBJTYPE_PROJECTILE,
+	OBJTYPE_POWERUP,
+	OBJTYPE_FLAG,
+	EVENT_EXPLOSION,
+	EVENT_DAMAGEINDICATION,
+	EVENT_SOUND,
+	EVENT_SMOKE,
+	EVENT_SPAWN,
+	EVENT_DEATH,
+};
+
+enum
+{
+	MSG_NULL=0,
+	MSG_SAY,
+	MSG_CHAT,
+	MSG_SETNAME,
+	MSG_KILLMSG,
+	MSG_SWITCHTEAM,
+	MSG_JOIN,
+	MSG_QUIT,
+	MSG_EMOTICON,
+	MSG_CHANGENAME,
+};
+
+enum
+{
+	EMOTE_NORMAL=0,
+	EMOTE_PAIN,
+	EMOTE_HAPPY,
+	EMOTE_SURPRISE,
+	EMOTE_ANGRY,
+	EMOTE_BLINK,
+};
+
+enum
+{
+	STATE_UNKNOWN=0,
+	STATE_PLAYING,
+	STATE_IN_MENU,
+	STATE_CHATTING,
+};
+
+struct player_input
+{
+	int left;
+	int right;
+	
+	int target_x;
+	int target_y;
+	
+	int jump;
+	int fire;
+	int hook;
+	int blink;
+	int activeweapon;
+	int state;
+};
+
+
+struct ev_explosion
+{
+	int x, y;
+};
+
+struct ev_spawn
+{
+	int x, y;
+};
+
+struct ev_death
+{
+	int x, y;
+};
+
+struct ev_sound
+{
+	int x, y;
+	int sound; // if (0x80000000 flag is set -> looping) if (0x40000000 is set -> stop looping
+};
+
+struct ev_damageind
+{
+	int x, y;
+	int angle;
+};
+
+struct obj_game
+{
+	int round_start_tick;
+	int game_over;
+	int sudden_death;
+	int paused;
+	
+	int score_limit;
+	int time_limit;
+	int gametype;
+};
+
+struct obj_projectile
+{
+	int type;
+	int x, y;
+	int vx, vy; // should be an angle instead
+};
+
+struct obj_powerup
+{
+	int x, y;
+	int type; // why do we need two types?
+	int subtype;
+};
+
+struct obj_flag
+{
+	int x, y;
+	int team;
+};
+
+struct obj_player
+{
+	int local;
+	int clientid;
+	int state;
+
+	int health;
+	int armor;
+	int ammocount;
+	
+	int x, y;
+	int vx, vy;
+	int angle;
+	
+	int weapon; // current active weapon
+
+	int attacktick; // num attack ticks left of current attack
+	
+	int score;
+	int latency;
+	int latency_flux;
+	int emote;
+	
+	int hook_active;
+	int hook_x, hook_y;
+	int team;
+};
diff --git a/src/game/server/game_server.cpp b/src/game/server/game_server.cpp
index f7bf976ea..711a0d1b9 100644
--- a/src/game/server/game_server.cpp
+++ b/src/game/server/game_server.cpp
@@ -3,6 +3,7 @@
 #include <string.h>
 #include <engine/config.h>
 #include "../game.h"
+#include "../version.h"
 #include "data.h"
 #include "game_server.h"
 
@@ -2189,3 +2190,5 @@ void mods_init()
 void mods_shutdown() {}
 void mods_presnap() {}
 void mods_postsnap() {}
+
+extern "C" const char *mods_net_version() { return TEEWARS_NETVERSION; }
diff --git a/src/game/version.h b/src/game/version.h
new file mode 100644
index 000000000..10a03af0a
--- /dev/null
+++ b/src/game/version.h
@@ -0,0 +1,3 @@
+#include "nethash.c"
+#define TEEWARS_VERSION "0.3.0-dev"
+#define TEEWARS_NETVERSION "0.3 " TEEWARS_NETVERSION_HASH