diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..6d8be14
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+/hans
+/build
diff --git a/gpl.txt b/LICENSE
similarity index 100%
rename from gpl.txt
rename to LICENSE
diff --git a/Makefile b/Makefile
index ab853d0..cf4b2dc 100644
--- a/Makefile
+++ b/Makefile
@@ -4,50 +4,59 @@ TUN_DEV_FILE = `sh osflags dev $(MODE)`
 GCC = gcc
 GPP = g++
 
+.PHONY: directories
+
 all: hans
 
-hans: tun.o sha1.o main.o client.o server.o auth.o worker.o time.o tun_dev.o echo.o exception.o utility.o
-    $(GPP) -o hans tun.o sha1.o main.o client.o server.o auth.o worker.o time.o tun_dev.o echo.o exception.o utility.o $(LDFLAGS)
+directories: build_dir
 
-utility.o: utility.cpp utility.h
-    $(GPP) -c utility.cpp $(CFLAGS)
+build_dir:
+	mkdir -p build
 
-exception.o: exception.cpp exception.h
-    $(GPP) -c exception.cpp $(CFLAGS)
+tunemu.o: directories build/tunemu.o
 
-echo.o: echo.cpp echo.h exception.h
-    $(GPP) -c echo.cpp $(CFLAGS)
+hans: directories build/tun.o build/sha1.o build/main.o build/client.o build/server.o build/auth.o build/worker.o build/time.o build/tun_dev.o build/echo.o build/exception.o build/utility.o
+	$(GPP) -o hans build/tun.o build/sha1.o build/main.o build/client.o build/server.o build/auth.o build/worker.o build/time.o build/tun_dev.o build/echo.o build/exception.o build/utility.o $(LDFLAGS)
 
-tun.o: tun.cpp tun.h exception.h utility.h tun_dev.h
-    $(GPP) -c tun.cpp $(CFLAGS)
+build/utility.o: src/utility.cpp src/utility.h
+	$(GPP) -c src/utility.cpp -o $@ -o $@ $(CFLAGS)
 
-tun_dev.o:
-    $(GCC) -c $(TUN_DEV_FILE) -o tun_dev.o $(CFLAGS)
+build/exception.o: src/exception.cpp src/exception.h
+	$(GPP) -c src/exception.cpp -o $@ $(CFLAGS)
 
-sha1.o: sha1.cpp sha1.h
-    $(GPP) -c sha1.cpp $(CFLAGS)
+build/echo.o: src/echo.cpp src/echo.h src/exception.h
+	$(GPP) -c src/echo.cpp -o $@ $(CFLAGS)
 
-main.o: main.cpp client.h server.h exception.h worker.h auth.h time.h echo.h tun.h tun_dev.h
-    $(GPP) -c main.cpp $(CFLAGS)
+build/tun.o: src/tun.cpp src/tun.h src/exception.h src/utility.h src/tun_dev.h
+	$(GPP) -c src/tun.cpp -o $@ $(CFLAGS)
 
-client.o: client.cpp client.h server.h exception.h config.h worker.h auth.h time.h echo.h tun.h tun_dev.h
-    $(GPP) -c client.cpp $(CFLAGS)
+build/tun_dev.o:
+	$(GCC) -c $(TUN_DEV_FILE) -o build/tun_dev.o -o $@ $(CFLAGS)
 
-server.o: server.cpp server.h client.h utility.h config.h worker.h auth.h time.h echo.h tun.h tun_dev.h
-    $(GPP) -c server.cpp $(CFLAGS)
+build/sha1.o: src/sha1.cpp src/sha1.h
+	$(GPP) -c src/sha1.cpp -o $@ $(CFLAGS)
 
-auth.o: auth.cpp auth.h sha1.h utility.h
-    $(GPP) -c auth.cpp $(CFLAGS)
+build/main.o: src/main.cpp src/client.h src/server.h src/exception.h src/worker.h src/auth.h src/time.h src/echo.h src/tun.h src/tun_dev.h
+	$(GPP) -c src/main.cpp -o $@ $(CFLAGS)
 
-worker.o: worker.cpp worker.h tun.h exception.h time.h echo.h tun_dev.h config.h
-    $(GPP) -c worker.cpp $(CFLAGS)
+build/client.o: src/client.cpp src/client.h src/server.h src/exception.h src/config.h src/worker.h src/auth.h src/time.h src/echo.h src/tun.h src/tun_dev.h
+	$(GPP) -c src/client.cpp -o $@ $(CFLAGS)
 
-time.o: time.cpp time.h
-    $(GPP) -c time.cpp $(CFLAGS)
+build/server.o: src/server.cpp src/server.h src/client.h src/utility.h src/config.h src/worker.h src/auth.h src/time.h src/echo.h src/tun.h src/tun_dev.h
+	$(GPP) -c src/server.cpp -o $@ $(CFLAGS)
+
+build/auth.o: src/auth.cpp src/auth.h src/sha1.h src/utility.h
+	$(GPP) -c src/auth.cpp -o $@ $(CFLAGS)
+
+build/worker.o: src/worker.cpp src/worker.h src/tun.h src/exception.h src/time.h src/echo.h src/tun_dev.h src/config.h
+	$(GPP) -c src/worker.cpp -o $@ $(CFLAGS)
+
+build/time.o: src/time.cpp src/time.h
+	$(GPP) -c src/time.cpp -o $@ $(CFLAGS)
 
 clean:
-    rm -f tun.o sha1.o main.o client.o server.o auth.o worker.o time.o tun_dev.o echo.o exception.o utility.o tunemu.o hans
+	rm -f build/tun.o build/sha1.o build/main.o build/client.o build/server.o build/auth.o build/worker.o build/time.o build/tun_dev.o build/echo.o build/exception.o build/utility.o build/tunemu.o hans
+	rm -df build
 
-
-tunemu.o: tunemu.h tunemu.c
-    $(GCC) -c tunemu.c -o tunemu.o
+build/tunemu.o: src/tunemu.h src/tunemu.c
+	$(GCC) -c src/tunemu.c -o build/tunemu.o
diff --git a/osflags b/osflags
index a0dacb6..80b117b 100644
--- a/osflags
+++ b/osflags
@@ -8,7 +8,7 @@ ld)
     case $OS in
         DARWIN)
             if [ "$MODE" == TUNEMU ]; then
-                echo tunemu.o -lpcap
+                echo build/tunemu.o -lpcap
             fi
         ;;
     esac
@@ -28,23 +28,23 @@ c)
 dev)
     case $OS in
         LINUX)
-            echo tun_dev_linux.c
+            echo src/tun_dev_linux.c
         ;;
         FREEBSD)
-            echo tun_dev_freebsd.c
+            echo src/tun_dev_freebsd.c
         ;;
         OPENBSD)
-            echo tun_dev_openbsd.c
+            echo src/tun_dev_openbsd.c
         ;;
         DARWIN)
             if [ "$MODE" == TUNEMU ]; then
-                echo tun_dev_darwin_emu.c
+                echo src/tun_dev_darwin_emu.c
             else
-                echo tun_dev_generic.c
+                echo src/tun_dev_generic.c
             fi
         ;;
         *)
-            echo tun_dev_generic.c
+            echo src/tun_dev_generic.c
         ;;
     esac
     ;;
diff --git a/auth.cpp b/src/auth.cpp
similarity index 100%
rename from auth.cpp
rename to src/auth.cpp
diff --git a/auth.h b/src/auth.h
similarity index 100%
rename from auth.h
rename to src/auth.h
diff --git a/client.cpp b/src/client.cpp
similarity index 100%
rename from client.cpp
rename to src/client.cpp
diff --git a/client.h b/src/client.h
similarity index 100%
rename from client.h
rename to src/client.h
diff --git a/config.h b/src/config.h
similarity index 100%
rename from config.h
rename to src/config.h
diff --git a/echo.cpp b/src/echo.cpp
similarity index 100%
rename from echo.cpp
rename to src/echo.cpp
diff --git a/echo.h b/src/echo.h
similarity index 100%
rename from echo.h
rename to src/echo.h
diff --git a/exception.cpp b/src/exception.cpp
similarity index 100%
rename from exception.cpp
rename to src/exception.cpp
diff --git a/exception.h b/src/exception.h
similarity index 100%
rename from exception.h
rename to src/exception.h
diff --git a/main.cpp b/src/main.cpp
similarity index 100%
rename from main.cpp
rename to src/main.cpp
diff --git a/server.cpp b/src/server.cpp
similarity index 100%
rename from server.cpp
rename to src/server.cpp
diff --git a/server.h b/src/server.h
similarity index 100%
rename from server.h
rename to src/server.h
diff --git a/sha1.cpp b/src/sha1.cpp
similarity index 100%
rename from sha1.cpp
rename to src/sha1.cpp
diff --git a/sha1.h b/src/sha1.h
similarity index 100%
rename from sha1.h
rename to src/sha1.h
diff --git a/sha1 license.txt b/src/sha1_license.txt
similarity index 100%
rename from sha1 license.txt
rename to src/sha1_license.txt
diff --git a/time.cpp b/src/time.cpp
similarity index 100%
rename from time.cpp
rename to src/time.cpp
diff --git a/time.h b/src/time.h
similarity index 100%
rename from time.h
rename to src/time.h
diff --git a/tun.cpp b/src/tun.cpp
similarity index 100%
rename from tun.cpp
rename to src/tun.cpp
diff --git a/tun.h b/src/tun.h
similarity index 100%
rename from tun.h
rename to src/tun.h
diff --git a/tun_dev.h b/src/tun_dev.h
similarity index 100%
rename from tun_dev.h
rename to src/tun_dev.h
diff --git a/tun_dev_darwin_emu.c b/src/tun_dev_darwin_emu.c
similarity index 100%
rename from tun_dev_darwin_emu.c
rename to src/tun_dev_darwin_emu.c
diff --git a/tun_dev_freebsd.c b/src/tun_dev_freebsd.c
similarity index 100%
rename from tun_dev_freebsd.c
rename to src/tun_dev_freebsd.c
diff --git a/tun_dev_generic.c b/src/tun_dev_generic.c
similarity index 100%
rename from tun_dev_generic.c
rename to src/tun_dev_generic.c
diff --git a/tun_dev_linux.c b/src/tun_dev_linux.c
similarity index 100%
rename from tun_dev_linux.c
rename to src/tun_dev_linux.c
diff --git a/tun_dev_openbsd.c b/src/tun_dev_openbsd.c
similarity index 100%
rename from tun_dev_openbsd.c
rename to src/tun_dev_openbsd.c
diff --git a/tun_dev_svr4.c b/src/tun_dev_svr4.c
similarity index 100%
rename from tun_dev_svr4.c
rename to src/tun_dev_svr4.c
diff --git a/tunemu.c b/src/tunemu.c
similarity index 100%
rename from tunemu.c
rename to src/tunemu.c
diff --git a/tunemu.h b/src/tunemu.h
similarity index 100%
rename from tunemu.h
rename to src/tunemu.h
diff --git a/utility.cpp b/src/utility.cpp
similarity index 100%
rename from utility.cpp
rename to src/utility.cpp
diff --git a/utility.h b/src/utility.h
similarity index 100%
rename from utility.h
rename to src/utility.h
diff --git a/worker.cpp b/src/worker.cpp
similarity index 100%
rename from worker.cpp
rename to src/worker.cpp
diff --git a/worker.h b/src/worker.h
similarity index 100%
rename from worker.h
rename to src/worker.h