diff --git a/include/applet/adguard.h b/include/applet/adguard.h
index b3ebb61..9d8af96 100644
--- a/include/applet/adguard.h
+++ b/include/applet/adguard.h
@@ -1,8 +1,7 @@
 #ifndef _ADGUARD_H_
 #define _ADGUARD_H_
 
-#include "common.h"
-#include "process.h"
+#include <stdint.h>
 
 typedef struct {
     uint8_t debug; // bool value
diff --git a/include/applet/dnsproxy.h b/include/applet/dnsproxy.h
index 56b8979..c8597de 100644
--- a/include/applet/dnsproxy.h
+++ b/include/applet/dnsproxy.h
@@ -1,7 +1,7 @@
 #ifndef _DNSPROXY_H_
 #define _DNSPROXY_H_
 
-#include "common.h"
+#include <stdint.h>
 #include "process.h"
 
 typedef struct {
diff --git a/include/applet/overture.h b/include/applet/overture.h
index 2cdd5d7..610e148 100644
--- a/include/applet/overture.h
+++ b/include/applet/overture.h
@@ -1,7 +1,7 @@
 #ifndef _OVERTURE_H_
 #define _OVERTURE_H_
 
-#include "common.h"
+#include <stdint.h>
 #include "process.h"
 
 typedef struct {
diff --git a/include/common.h b/include/common.h
index a513baa..aa12ca1 100644
--- a/include/common.h
+++ b/include/common.h
@@ -1,12 +1,14 @@
 #ifndef _COMMON_H_
 #define _COMMON_H_
 
-#include <stdlib.h>
+//#include <stdlib.h>
+//
+//typedef u_int8_t uint8_t;
+//typedef u_int16_t uint16_t;
+//typedef u_int32_t uint32_t;
+//typedef u_int64_t uint64_t;
 
-typedef u_int8_t uint8_t;
-typedef u_int16_t uint16_t;
-typedef u_int32_t uint32_t;
-typedef u_int64_t uint64_t;
+#include <stdint.h>
 
 #define VERSION "1.3.0-dev"
 
@@ -41,6 +43,8 @@ void save_file(const char *file, const char *content);
 void string_list_debug(char *describe, char **string_list);
 void uint32_list_debug(char *describe, uint32_t **uint32_list);
 
+uint8_t check_port(uint16_t port);
+
 char* string_init(const char *str);
 char* string_join(const char *base, const char *add);
 
diff --git a/include/utils/process.h b/include/utils/process.h
index ace4522..ce9d8c5 100644
--- a/include/utils/process.h
+++ b/include/utils/process.h
@@ -1,9 +1,6 @@
 #ifndef _PROCESS_H_
 #define _PROCESS_H_
 
-//void server_daemon();
-//void init_server(char *init_script, char *custom_script);
-
 typedef struct {
     char *name;
     char **cmd;
diff --git a/include/utils/structure.h b/include/utils/structure.h
index 43dfd1f..660171a 100644
--- a/include/utils/structure.h
+++ b/include/utils/structure.h
@@ -1,7 +1,7 @@
-#ifndef _STR_H_
-#define _STR_H_
+#ifndef _STRUCTURE_H_
+#define _STRUCTURE_H_
 
-#include "common.h"
+#include <stdint.h>
 
 uint32_t** uint32_list_init();
 char* uint32_list_dump(uint32_t **int_list);
diff --git a/src/applet/CMakeLists.txt b/src/applet/CMakeLists.txt
index afc98b7..3394051 100644
--- a/src/applet/CMakeLists.txt
+++ b/src/applet/CMakeLists.txt
@@ -1,3 +1,4 @@
 cmake_minimum_required(VERSION 2.8.12)
 
 add_library(applet adguard.c dnsproxy.c overture.c)
+target_link_libraries(applet utils)
diff --git a/src/applet/adguard.c b/src/applet/adguard.c
index df49112..ae1d237 100644
--- a/src/applet/adguard.c
+++ b/src/applet/adguard.c
@@ -1,3 +1,5 @@
+#include <stdlib.h>
+#include "common.h"
 #include "adguard.h"
 
 adguard* adguard_init() {
diff --git a/src/applet/dnsproxy.c b/src/applet/dnsproxy.c
index 15bf5d3..e13149a 100644
--- a/src/applet/dnsproxy.c
+++ b/src/applet/dnsproxy.c
@@ -1,10 +1,9 @@
 #include <stdlib.h>
+#include "cJSON.h"
+#include "common.h"
+#include "logger.h"
 #include "dnsproxy.h"
 #include "structure.h"
-#include "process.h"
-#include "logger.h"
-#include "common.h"
-#include "cJSON.h"
 
 char* dnsproxy_config(dnsproxy *info);
 void dnsproxy_dump(const char *caption, dnsproxy *info);
@@ -58,11 +57,14 @@ void dnsproxy_dump(const char *caption, dnsproxy *info) { // show dnsproxy info
 }
 
 process* dnsproxy_load(const char *caption, dnsproxy *info, const char *file) {
-
-    // TODO: check primary server number (non-zero)
-    // TODO: check port (1 ~ 65535)
-
     dnsproxy_dump(caption, info);
+    if (!check_port(info->port)) { // invalid server port
+        log_fatal("Invalid port `%u`", info->port);
+    }
+    if (string_list_len(info->primary) == 0) { // without primary dns server
+        log_fatal("%s without primary dns server", caption);
+    }
+
     char *config = dnsproxy_config(info); // string config (JSON format)
     char *config_file = string_join(WORK_DIR, file);
     save_file(config_file, config);
diff --git a/src/applet/overture.c b/src/applet/overture.c
index 2405c5f..0e71f4d 100644
--- a/src/applet/overture.c
+++ b/src/applet/overture.c
@@ -1,12 +1,12 @@
-#include <stdio.h>
+#include <stdio.h> // TODO: use int to string instead of sprintf
 #include <stdlib.h>
-#include "overture.h"
-#include "process.h"
+#include "cJSON.h"
 #include "common.h"
 #include "logger.h"
-#include "cJSON.h"
+#include "overture.h"
 #include "structure.h"
 
+
 void overture_dump(overture *info);
 char* overture_config(overture *info);
 
diff --git a/src/cleardns.c b/src/cleardns.c
index 7123644..56294e1 100644
--- a/src/cleardns.c
+++ b/src/cleardns.c
@@ -36,10 +36,10 @@ int main(int argc, char *argv[]) { // ClearDNS server
     LOG_LEVEL = LOG_DEBUG;
     log_info("ClearDNS server start (%s)", VERSION);
 
-    load_config("test.json");
-
-    dnsproxy_load("Domestic", loader.domestic, "domestic.json");
-    dnsproxy_load("Foreign", loader.foreign, "foreign.json");
+//    load_config("test.json");
+//
+//    dnsproxy_load("Domestic", loader.domestic, "domestic.json");
+//    dnsproxy_load("Foreign", loader.foreign, "foreign.json");
 
 //    char **temp = string_list_init();
 //    temp = string_list_append(temp, "123");
@@ -62,27 +62,27 @@ int main(int argc, char *argv[]) { // ClearDNS server
 //    uint32_list_free(temp);
 
 
-//    dnsproxy *domestic = dnsproxy_init(DOMESTIC_PORT);
-//
-//    dnsproxy_add_bootstrap(domestic, "1.1.1.1");
-//    dnsproxy_add_bootstrap(domestic, "8.8.8.8");
-//
-//    dnsproxy_add_primary(domestic, "223.5.5.5");
-//    dnsproxy_add_primary(domestic, "tls://dns.pub");
-//
-//    dnsproxy_add_fallback(domestic, "tls://223.6.6.6");
-//    dnsproxy_add_fallback(domestic, "tls://120.53.53.53");
-//
-//    domestic->verify = FALSE;
-//    domestic->parallel = FALSE;
-//    domestic->optimistic = TRUE;
-//    domestic->debug = TRUE;
-//    domestic->cache = 4194304; // 4MiB
-//
-//    process *p = dnsproxy_load("Domestic", domestic, "domestic.json");
-//    log_info("cmd -> %s", string_list_dump(p->cmd));
-//    log_info("env -> %s", string_list_dump(p->env));
-//    log_info("cwd -> %s", p->cwd);
+    dnsproxy *domestic = dnsproxy_init(DOMESTIC_PORT);
+
+    dnsproxy_add_bootstrap(domestic, "1.1.1.1");
+    dnsproxy_add_bootstrap(domestic, "8.8.8.8");
+
+    dnsproxy_add_primary(domestic, "223.5.5.5");
+    dnsproxy_add_primary(domestic, "tls://dns.pub");
+
+    dnsproxy_add_fallback(domestic, "tls://223.6.6.6");
+    dnsproxy_add_fallback(domestic, "tls://120.53.53.53");
+
+    domestic->verify = FALSE;
+    domestic->parallel = FALSE;
+    domestic->optimistic = TRUE;
+    domestic->debug = TRUE;
+    domestic->cache = 4194304; // 4MiB
+
+    process *p = dnsproxy_load("Domestic", domestic, "domestic.json");
+    log_info("cmd -> %s", string_list_dump(p->cmd));
+    log_info("env -> %s", string_list_dump(p->env));
+    log_info("cwd -> %s", p->cwd);
 
 
 //    overture *diverter = overture_init(DIVERTER_PORT);
diff --git a/src/common.c b/src/common.c
index d4c5466..bff9288 100644
--- a/src/common.c
+++ b/src/common.c
@@ -34,6 +34,13 @@ void uint32_list_debug(char *describe, uint32_t **uint32_list) {
     free(string_ret);
 }
 
+uint8_t check_port(uint16_t port) {
+    if (port > 0 && port <= 65535) { // 1 ~ 65535
+        return TRUE;
+    }
+    return FALSE;
+}
+
 void save_file(const char *file, const char *content) { // save into file
     log_debug("Write into `%s` -> \n%s", file, content);
     FILE* fp = fopen(file , "w");
diff --git a/src/loader/config.c b/src/loader/config.c
index 5f69079..d47c2b6 100644
--- a/src/loader/config.c
+++ b/src/loader/config.c
@@ -1,3 +1,4 @@
+#include <stdlib.h>
 #include "common.h"
 #include "config.h"
 #include "logger.h"
diff --git a/src/loader/loader.c b/src/loader/loader.c
index aa5730e..0019858 100644
--- a/src/loader/loader.c
+++ b/src/loader/loader.c
@@ -1,3 +1,4 @@
+#include <stdlib.h>
 #include "loader.h"
 #include "config.h"
 #include "parser.h"
diff --git a/src/utils/process.c b/src/utils/process.c
index f4ad4a1..d63aa90 100644
--- a/src/utils/process.c
+++ b/src/utils/process.c
@@ -1,6 +1,7 @@
-#include "common.h"
+#include <stdlib.h>
 #include "process.h"
 #include "structure.h"
+#include "common.h"
 
 process* process_init(const char *caption, const char *bin) { // init process struct
     process *proc = (process *)malloc(sizeof(process));
diff --git a/src/utils/structure.c b/src/utils/structure.c
index 08f4281..95f081d 100644
--- a/src/utils/structure.c
+++ b/src/utils/structure.c
@@ -1,7 +1,9 @@
 #include <stdio.h>
-#include <stdlib.h>
+
 #include <string.h>
+#include <stdlib.h>
 #include "structure.h"
+#include "common.h"
 
 uint32_t* uint32_init(uint32_t number) { // new uint32 (by malloc)
     uint32_t *data = (uint32_t *)malloc(sizeof(uint32_t));