diff --git a/CMakeLists.txt b/CMakeLists.txt
index c4d457a7..c5c53a15 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -126,15 +126,8 @@ set(WITH_MBEDTLS 1)
 endif(EXISTS ${CMAKE_CURRENT_LIST_DIR}/third_party/mbedtls/mbedtls-2.6.0)
 
 if(WITH_MBEDTLS)
-include_directories(
-    ${CMAKE_CURRENT_LIST_DIR}/src/tls/mbedtls
-    ${CMAKE_CURRENT_LIST_DIR}/third_party/mbedtls/mbedtls-2.6.0/include
-)
-
-file(GLOB tls_SRCS ${CMAKE_CURRENT_LIST_DIR}/third_party/mbedtls/mbedtls-2.6.0/library/*.c)
 
 add_definitions(-DCONFIG_MMS_SUPPORT_TLS=1)
-add_definitions(-DMBEDTLS_CONFIG_FILE="mbedtls_config.h")
 
 endif(WITH_MBEDTLS)
 
diff --git a/hal/CMakeLists.txt b/hal/CMakeLists.txt
index a225a92b..1441d5ac 100644
--- a/hal/CMakeLists.txt
+++ b/hal/CMakeLists.txt
@@ -13,6 +13,14 @@ set(LIBHAL_VERSION_MAJOR "2")
 set(LIBHAL_VERSION_MINOR "0")
 set(LIBHAL_VERSION_PATCH "0")
 
+# feature checks
+include(CheckLibraryExists)
+check_library_exists(rt clock_gettime "time.h" CONFIG_SYSTEM_HAS_CLOCK_GETTIME)
+
+# check if we are on a little or a big endian
+include (TestBigEndian)
+test_big_endian(PLATFORM_IS_BIGENDIAN)
+
 if(WIN32)
 
 if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/../third_party/winpcap/Lib/wpcap.lib")
diff --git a/hal/filesystem/linux/file_provider_linux.c b/hal/filesystem/linux/file_provider_linux.c
index 23805da1..e9f03e87 100644
--- a/hal/filesystem/linux/file_provider_linux.c
+++ b/hal/filesystem/linux/file_provider_linux.c
@@ -31,7 +31,6 @@
 #include <unistd.h>
 
 #include "hal_filesystem.h"
-#include "stack_config.h"
 #include "lib_memory.h"
 
 struct sDirectoryHandle {
diff --git a/hal/filesystem/win32/file_provider_win32.c b/hal/filesystem/win32/file_provider_win32.c
index 8b9a8f98..1a08e8d1 100644
--- a/hal/filesystem/win32/file_provider_win32.c
+++ b/hal/filesystem/win32/file_provider_win32.c
@@ -32,7 +32,6 @@
 #include "hal_filesystem.h"
 
 #include "platform_endian.h"
-#include "stack_config.h"
 #include "lib_memory.h"
 
 #include <malloc.h>
diff --git a/hal/inc/hal_socket.h b/hal/inc/hal_socket.h
index 41ec55de..e1d02bb6 100644
--- a/hal/inc/hal_socket.h
+++ b/hal/inc/hal_socket.h
@@ -147,9 +147,21 @@ ServerSocket_listen(ServerSocket self);
 Socket
 ServerSocket_accept(ServerSocket self);
 
+/**
+ * \brief active TCP keep alive for socket and set keep alive parameters
+ *
+ * NOTE: implementation is mandatory for IEC 61850 MMS
+ *
+ * \param self server socket instance
+ * \param idleTime time (in s) between last received message and first keep alive message
+ * \param interval time (in s) between subsequent keep alive messages if no ACK received
+ * \param count number of not missing keep alive ACKs until socket is considered dead
+ */
+void
+Socket_activateTcpKeepAlive(Socket self, int idleTime, int interval, int count);
 
 /**
- * \brief set the maximum number of pending connection in the queue
+ * \brief set the maximum number of pending connections in the queue
  *
  * Implementation of this function is OPTIONAL.
  *
diff --git a/hal/inc/hal_time.h b/hal/inc/hal_time.h
index 12164901..5ac8080e 100644
--- a/hal/inc/hal_time.h
+++ b/hal/inc/hal_time.h
@@ -28,6 +28,8 @@
 extern "C" {
 #endif
 
+#include <stdint.h>
+
 /**
  * \file hal_time.h
  * \brief Abstraction layer for system time access
diff --git a/hal/inc/platform_endian.h b/hal/inc/platform_endian.h
index 9bc7a5af..76c410af 100644
--- a/hal/inc/platform_endian.h
+++ b/hal/inc/platform_endian.h
@@ -1,7 +1,7 @@
 /*
- *  endian.h
+ *  platform_endian.h
  *
- *  Copyright 2013 Michael Zillgith
+ *  Copyright 2013-2018 Michael Zillgith
  *
  *  This file is part of libIEC61850.
  *
@@ -24,8 +24,6 @@
 #ifndef ENDIAN_H_
 #define ENDIAN_H_
 
-#include "stack_config.h"
-
 #ifndef PLATFORM_IS_BIGENDIAN
 #ifdef __GNUC__
 #ifdef __BYTE_ORDER__
diff --git a/hal/socket/bsd/socket_bsd.c b/hal/socket/bsd/socket_bsd.c
index 6207c71a..18079db7 100644
--- a/hal/socket/bsd/socket_bsd.c
+++ b/hal/socket/bsd/socket_bsd.c
@@ -1,7 +1,8 @@
 /*
  *  socket_bsd.c
  *
- *  Copyright 2013, 2014 Michael Zillgith, contributions by Michael Clausen (School of engineering Valais).
+ *  Copyright 2013-2018 Michael Zillgith
+ *  contributions by Michael Clausen (School of engineering Valais).
  *
  *  This file is part of libIEC61850.
  *
@@ -36,8 +37,7 @@
 #include <netinet/tcp.h> // required for TCP keepalive
 
 #include "hal_thread.h"
-
-#include "libiec61850_platform_includes.h"
+#include "lib_memory.h"
 
 #ifndef DEBUG_SOCKET
 #define DEBUG_SOCKET 0
@@ -113,30 +113,28 @@ Handleset_destroy(HandleSet self)
    GLOBAL_FREEMEM(self);
 }
 
-#if (CONFIG_ACTIVATE_TCP_KEEPALIVE == 1)
-static void
-activateKeepAlive(int sd)
+void
+Socket_activateTcpKeepAlive(Socket self, int idleTime, int interval, int count)
 {
 #if defined SO_KEEPALIVE
     int optval;
     socklen_t optlen = sizeof(optval);
 
-    optval = CONFIG_TCP_KEEPALIVE_IDLE;
-    setsockopt(sd, SOL_SOCKET, SO_KEEPALIVE, &optval, optlen);
+    optval = idleTime;
+    setsockopt(self->fd, SOL_SOCKET, SO_KEEPALIVE, &optval, optlen);
     optval = 1;
-    setsockopt(sd, SOL_SOCKET, SO_NOSIGPIPE, &optval, optlen);
+    setsockopt(self->fd, SOL_SOCKET, SO_NOSIGPIPE, &optval, optlen);
 
 #if defined TCP_KEEPCNT
-    optval = CONFIG_TCP_KEEPALIVE_INTERVAL;
-    setsockopt(sd, IPPROTO_TCP, TCP_KEEPINTVL, &optval, optlen);
+    optval = interval;
+    setsockopt(self->fd, IPPROTO_TCP, TCP_KEEPINTVL, &optval, optlen);
 
-    optval = CONFIG_TCP_KEEPALIVE_CNT;
-    setsockopt(sd, IPPROTO_TCP, TCP_KEEPCNT, &optval, optlen);
+    optval = count;
+    setsockopt(self->fd, IPPROTO_TCP, TCP_KEEPCNT, &optval, optlen);
 #endif /* TCP_KEEPCNT */
 
 #endif /* SO_KEEPALIVE */
 }
-#endif /* (CONFIG_ACTIVATE_TCP_KEEPALIVE == 1) */
 
 static bool
 prepareServerAddress(const char* address, int port, struct sockaddr_in* sockaddr)
@@ -196,10 +194,6 @@ TcpServerSocket_create(const char* address, int port)
             return NULL ;
         }
 
-#if CONFIG_ACTIVATE_TCP_KEEPALIVE == 1
-        activateKeepAlive(fd);
-#endif
-
         setSocketNonBlocking((Socket) serverSocket);
     }
 
@@ -294,10 +288,6 @@ Socket_connect(Socket self, const char* address, int port)
 
     self->fd = socket(AF_INET, SOCK_STREAM, 0);
 
-#if CONFIG_ACTIVATE_TCP_KEEPALIVE == 1
-    activateKeepAlive(self->fd);
-#endif
-
     fd_set fdSet;
     FD_ZERO(&fdSet);
     FD_SET(self->fd, &fdSet);
diff --git a/hal/socket/linux/socket_linux.c b/hal/socket/linux/socket_linux.c
index 2dded754..69fca6a6 100644
--- a/hal/socket/linux/socket_linux.c
+++ b/hal/socket/linux/socket_linux.c
@@ -32,14 +32,10 @@
 #include <netdb.h>
 #include <errno.h>
 #include <stdio.h>
-
 #include <fcntl.h>
-
 #include <netinet/tcp.h> // required for TCP keepalive
 
 #include "hal_thread.h"
-
-#include "stack_config.h"
 #include "lib_memory.h"
 
 #ifndef DEBUG_SOCKET
@@ -115,25 +111,25 @@ Handleset_destroy(HandleSet self)
    GLOBAL_FREEMEM(self);
 }
 
-static void
-activateKeepAlive(int sd)
+void
+Socket_activateTcpKeepAlive(Socket self, int idleTime, int interval, int count)
 {
 #if defined SO_KEEPALIVE
     int optval;
     socklen_t optlen = sizeof(optval);
 
     optval = 1;
-    setsockopt(sd, SOL_SOCKET, SO_KEEPALIVE, &optval, optlen);
+    setsockopt(self->fd, SOL_SOCKET, SO_KEEPALIVE, &optval, optlen);
 
 #if defined TCP_KEEPCNT
-    optval = CONFIG_TCP_KEEPALIVE_IDLE;
-    setsockopt(sd, IPPROTO_TCP, TCP_KEEPIDLE, &optval, optlen);
+    optval = idleTime;
+    setsockopt(self->fd, IPPROTO_TCP, TCP_KEEPIDLE, &optval, optlen);
 
-    optval = CONFIG_TCP_KEEPALIVE_INTERVAL;
-    setsockopt(sd, IPPROTO_TCP, TCP_KEEPINTVL, &optval, optlen);
+    optval = interval;
+    setsockopt(self->fd, IPPROTO_TCP, TCP_KEEPINTVL, &optval, optlen);
 
-    optval = CONFIG_TCP_KEEPALIVE_CNT;
-    setsockopt(sd, IPPROTO_TCP, TCP_KEEPCNT, &optval, optlen);
+    optval = count;
+    setsockopt(self->fd, IPPROTO_TCP, TCP_KEEPCNT, &optval, optlen);
 #endif /* TCP_KEEPCNT */
 
 #endif /* SO_KEEPALIVE */
@@ -217,10 +213,6 @@ TcpServerSocket_create(const char* address, int port)
             close(fd);
             return NULL ;
         }
-
-#if CONFIG_ACTIVATE_TCP_KEEPALIVE == 1
-        activateKeepAlive(fd);
-#endif
     }
 
     return serverSocket;
@@ -326,10 +318,6 @@ Socket_connect(Socket self, const char* address, int port)
 
     activateTcpNoDelay(self);
 
-#if (CONFIG_ACTIVATE_TCP_KEEPALIVE == 1)
-    activateKeepAlive(self->fd);
-#endif
-
     fcntl(self->fd, F_SETFL, O_NONBLOCK);
 
     if (connect(self->fd, (struct sockaddr *) &serverAddress, sizeof(serverAddress)) < 0) {
diff --git a/hal/socket/win32/socket_win32.c b/hal/socket/win32/socket_win32.c
index 9cfc02c6..c686ddc7 100644
--- a/hal/socket/win32/socket_win32.c
+++ b/hal/socket/win32/socket_win32.c
@@ -1,7 +1,7 @@
 /*
  *  socket_win32.c
  *
- *  Copyright 2013, 2014 Michael Zillgith
+ *  Copyright 2013-2018 Michael Zillgith
  *
  *	This file is part of libIEC61850.
  *
@@ -116,25 +116,26 @@ Handleset_destroy(HandleSet self)
 static bool wsaStartupCalled = false;
 static int socketCount = 0;
 
-static void
-activateKeepAlive(SOCKET s)
+void
+Socket_activateTcpKeepAlive(Socket self, int idleTime, int interval, int count)
 {
-	struct tcp_keepalive keepalive;
-	DWORD retVal=0;
+    struct tcp_keepalive keepalive;
+    DWORD retVal=0;
 
-	keepalive.onoff = 1;
-	keepalive.keepalivetime = CONFIG_TCP_KEEPALIVE_IDLE * 1000;
-	keepalive.keepaliveinterval = CONFIG_TCP_KEEPALIVE_INTERVAL * 1000;
+    keepalive.onoff = 1;
+    keepalive.keepalivetime = CONFIG_TCP_KEEPALIVE_IDLE * 1000;
+    keepalive.keepaliveinterval = CONFIG_TCP_KEEPALIVE_INTERVAL * 1000;
 
-	 if (WSAIoctl(s, SIO_KEEPALIVE_VALS, &keepalive, sizeof(keepalive),
-	            NULL, 0, &retVal, NULL, NULL) == SOCKET_ERROR)
-	 {
-	     if (DEBUG_SOCKET)
+     if (WSAIoctl(self->fd, SIO_KEEPALIVE_VALS, &keepalive, sizeof(keepalive),
+                NULL, 0, &retVal, NULL, NULL) == SOCKET_ERROR)
+     {
+         if (DEBUG_SOCKET)
                 printf("WIN32_SOCKET: WSAIotcl(SIO_KEEPALIVE_VALS) failed: %d\n",
                     WSAGetLastError());
-	 }
+     }
 }
 
+
 static void
 setSocketNonBlocking(Socket self)
 {
@@ -223,10 +224,6 @@ TcpServerSocket_create(const char* address, int port)
 
 	listen_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
 
-#if CONFIG_ACTIVATE_TCP_KEEPALIVE == 1
-    activateKeepAlive(listen_socket);
-#endif
-
 	if (listen_socket == INVALID_SOCKET) {
 	    if (DEBUG_SOCKET)
 	        printf("WIN32_SOCKET: socket failed with error: %i\n", WSAGetLastError());
@@ -335,10 +332,6 @@ Socket_connect(Socket self, const char* address, int port)
 
 	self->fd = socket(AF_INET, SOCK_STREAM, 0);
 
-#if CONFIG_ACTIVATE_TCP_KEEPALIVE == 1
-    activateKeepAlive(self->fd);
-#endif
-
     setSocketNonBlocking(self);
 
     fd_set fdSet;
diff --git a/hal/time/unix/time.c b/hal/time/unix/time.c
index d4a1a2cd..f7951fde 100644
--- a/hal/time/unix/time.c
+++ b/hal/time/unix/time.c
@@ -21,10 +21,7 @@
  *  See COPYING file for the complete license text.
  */
 
-
-#include "libiec61850_platform_includes.h"
-
-#include "stack_config.h"
+#include "hal_time.h"
 
 #include <time.h>
 
diff --git a/hal/time/win32/time.c b/hal/time/win32/time.c
index 1af39b5f..af58793f 100644
--- a/hal/time/win32/time.c
+++ b/hal/time/win32/time.c
@@ -21,10 +21,7 @@
  *  See COPYING file for the complete license text.
  */
 
-
-#include "libiec61850_platform_includes.h"
-
-#include "stack_config.h"
+#include "hal_time.h"
 
 #include <time.h>
 
diff --git a/src/common/inc/libiec61850_platform_includes.h b/src/common/inc/libiec61850_platform_includes.h
index 41e12b39..f2770139 100644
--- a/src/common/inc/libiec61850_platform_includes.h
+++ b/src/common/inc/libiec61850_platform_includes.h
@@ -5,6 +5,8 @@
 #ifndef LIBIEC61850_PLATFORM_INCLUDES_H_
 #define LIBIEC61850_PLATFORM_INCLUDES_H_
 
+#include "stack_config.h"
+
 #include "libiec61850_common_api.h"
 
 #include "string_utilities.h"
diff --git a/src/iec61850/client/ied_connection.c b/src/iec61850/client/ied_connection.c
index 269474ad..f271dadc 100644
--- a/src/iec61850/client/ied_connection.c
+++ b/src/iec61850/client/ied_connection.c
@@ -21,12 +21,11 @@
  *  See COPYING file for the complete license text.
  */
 
+#include "stack_config.h"
 #include "libiec61850_platform_includes.h"
 
 #include "iec61850_client.h"
 
-#include "stack_config.h"
-
 #include "mms_client_connection.h"
 
 #include "ied_connection_private.h"
diff --git a/src/iec61850/server/model/model.c b/src/iec61850/server/model/model.c
index 0b5f84b7..c6d06c6d 100644
--- a/src/iec61850/server/model/model.c
+++ b/src/iec61850/server/model/model.c
@@ -23,6 +23,7 @@
 
 #include "iec61850_model.h"
 
+#include "stack_config.h"
 #include "libiec61850_platform_includes.h"
 
 static void
diff --git a/src/mms/iso_client/iso_client_connection.c b/src/mms/iso_client/iso_client_connection.c
index 3b2e8060..4e5a315a 100644
--- a/src/mms/iso_client/iso_client_connection.c
+++ b/src/mms/iso_client/iso_client_connection.c
@@ -289,6 +289,13 @@ IsoClientConnection_associate(IsoClientConnection self, IsoConnectionParameters
 
     Socket_setConnectTimeout(self->socket, connectTimeoutInMs);
 
+#if (CONFIG_ACTIVATE_TCP_KEEPALIVE == 1)
+    Socket_activateTcpKeepAlive(self->socket,
+            CONFIG_TCP_KEEPALIVE_IDLE,
+            CONFIG_TCP_KEEPALIVE_INTERVAL,
+            CONFIG_TCP_KEEPALIVE_CNT);
+#endif
+
     if (!Socket_connect(self->socket, params->hostname, params->tcpPort))
         goto returnError;
 
diff --git a/src/mms/iso_server/iso_server.c b/src/mms/iso_server/iso_server.c
index 1b5628b9..f36af1dd 100644
--- a/src/mms/iso_server/iso_server.c
+++ b/src/mms/iso_server/iso_server.c
@@ -342,6 +342,13 @@ setupIsoServer(IsoServer self)
         goto exit_function;
     }
 
+#if (CONFIG_ACTIVATE_TCP_KEEPALIVE == 1)
+    Socket_activateTcpKeepAlive(self->serverSocket,
+            CONFIG_TCP_KEEPALIVE_IDLE,
+            CONFIG_TCP_KEEPALIVE_INTERVAL,
+            CONFIG_TCP_KEEPALIVE_CNT);
+#endif
+
     ServerSocket_setBacklog((ServerSocket) self->serverSocket, BACKLOG);
 
     ServerSocket_listen((ServerSocket) self->serverSocket);