diff --git a/.travis.yml b/.travis.yml
index 1824f0cdf..6c43eadf9 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,10 +1,15 @@
 language: c
+compiler: gcc
+
+cache:
+  directories:
+    - thirdparty
 
 install:
   - make dependencies
 script:
   - make build
+after_success:
   - make test
-deploy:
   - make doc
-  - make deploy
\ No newline at end of file
+  - make deploy
diff --git a/Makefile b/Makefile
index 604c7a4de..36b054d80 100644
--- a/Makefile
+++ b/Makefile
@@ -31,7 +31,10 @@ libnl3: dirs
 
 # Compile S2SS server
 build:
-	make -C server CFLAGS=-I$(PREFIX)/usr/include/ LDFLAGS=-Wl,-L$(PREFIX)/usr/lib/
+	CFLAGS=-I$(PREFIX)/usr/include/ \
+	LDFLAGS=-Wl,-L$(PREFIX)/usr/lib/ \
+	NLDIR=$(PREFIX)/usr/include/libnl3/ \
+	make -C server
 
 # Test S2SS server by running it for 3 secs
 test:
diff --git a/server/include/msg_format.h b/server/include/msg_format.h
index 86f68d68a..efbdc7af9 100644
--- a/server/include/msg_format.h
+++ b/server/include/msg_format.h
@@ -31,6 +31,7 @@
 #define MSG_TYPE_DATA		0 /**< Message contains float values */
 #define MSG_TYPE_START		1 /**< Message marks the beginning of a new simulation case */
 #define MSG_TYPE_STOP		2 /**< Message marks the end of a simulation case */
+#define MSG_TYPE_EMPTY		3 /**< Message does not carry useful data */
 
 #define MSG_ENDIAN_LITTLE	0 /**< Message values are in little endian format (float too!) */
 #define MSG_ENDIAN_BIG		1 /**< Message values are in bit endian format */
diff --git a/server/src/cfg.c b/server/src/cfg.c
index aed896637..c274ef34c 100644
--- a/server/src/cfg.c
+++ b/server/src/cfg.c
@@ -12,14 +12,15 @@
 #include "utils.h"
 #include "list.h"
 #include "if.h"
-#include "tc.h"
 #include "cfg.h"
 #include "node.h"
 #include "path.h"
 #include "hooks.h"
 
-#include "socket.h"
 #include "file.h"
+#ifdef ENABLE_SOCKET
+ #include "socket.h"
+#endif
 #ifdef ENABLE_GTFPGA
   #include "gtfpga.h"
 #endif
diff --git a/server/src/node.c b/server/src/node.c
index 7a2435c6d..7ca13d463 100644
--- a/server/src/node.c
+++ b/server/src/node.c
@@ -125,9 +125,11 @@ int node_stop(struct node *n)
 void node_reverse(struct node *n)
 {
 	switch (n->vt->type) {
+#ifdef ENABLE_SOCKET
 		case BSD_SOCKET:
 			SWAP(n->socket->remote, n->socket->local);
 			break;
+#endif
 		case LOG_FILE:
 			SWAP(n->file->path_in, n->file->path_out);
 			break;