diff --git a/.gitignore b/.gitignore
index d119bc8..277cf8d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -54,4 +54,10 @@ dkms.conf
 
 #Bin
 bin/*
+client_test/*
+server_test/*
 
+p-client
+p-server
+server
+client
diff --git a/Makefile b/Makefile
index 767b38f..33a8a16 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,5 @@
 CC = gcc
 CFLAGS = -lm -Wall -O2
-
 Bin = server client p-server p-client
 
 all:
diff --git a/README.md b/README.md
index d76c8d7..8f08b4b 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,18 @@
 # HW12
 
-Homework
\ No newline at end of file
+Homework
+
+To build source, you should install `build-essential`. 
+
+Usage: 
+```bash
+./server [OPTION]...
+./client SERVERNAME PORT FILENAME
+```
+
+available macro:
+- DEFAULT_SERVER_PORT : 9091
+- DEFAULT_MAX_PATH_SIZE : 256(must be less than 1000)
+- TIMEOUT : 5(second unit)
+- USE_SENDFILE
+    - DEFAULT_SEND_FILE_CHUNK_SIZE : 0x100000(1MB)
\ No newline at end of file
diff --git a/client.c b/client.c
index 38c9fbf..08f02b9 100644
--- a/client.c
+++ b/client.c
@@ -16,7 +16,16 @@
 
 #ifdef USE_SENDFILE
 #include <sys/sendfile.h>
+#ifndef DEFAULT_SEND_FILE_CHUNK_SIZE
 const size_t SEND_FILE_CHUNK_SIZE = 0x100000; /*1MB*/
+#else
+const size_t SEND_FILE_CHUNK_SIZE = DEFAULT_SEND_FILE_CHUNK_SIZE; /*1MB*/
+#endif
+#endif
+#ifndef DEFAULT_TIMEOUT
+static const int TIMEOUT = 5;
+#else
+static const int TIMEOUT = DEFAULT_TIMEOUT;
 #endif
 
 /*========
diff --git a/p-client.c b/p-client.c
index f010eeb..17955d3 100644
--- a/p-client.c
+++ b/p-client.c
@@ -16,9 +16,17 @@
 
 #ifdef USE_SENDFILE
 #include <sys/sendfile.h>
+#ifndef DEFAULT_SEND_FILE_CHUNK_SIZE
 const size_t SEND_FILE_CHUNK_SIZE = 0x100000; /*1MB*/
+#else
+const size_t SEND_FILE_CHUNK_SIZE = DEFAULT_SEND_FILE_CHUNK_SIZE; /*1MB*/
+#endif
+#endif
+#ifndef DEFAULT_TIMEOUT
+static const int TIMEOUT = 5;
+#else
+static const int TIMEOUT = DEFAULT_TIMEOUT;
 #endif
-
 /*========
  *Operation
  *========*/
@@ -121,7 +129,7 @@ int main(int argc, const char *argv[]){
     struct sockaddr_in addr;
     const char * filename;
     const char * server_name;
-    in_port_t server_port = SERVER_PORT;
+    in_port_t server_port = 0;
     int sock, err;
     if (argc != 4){
         fprintf(stderr,"invaild arguments number.");
diff --git a/p-server.c b/p-server.c
index 44c2547..3f1731a 100644
--- a/p-server.c
+++ b/p-server.c
@@ -14,6 +14,33 @@
 #include <fcntl.h>
 #include "socket_wrapper.h"
 
+static const int MAX_LISTEN_SOCKET = 16;
+
+#ifdef USE_SENDFILE
+#include <sys/sendfile.h>
+#ifndef DEFAULT_SEND_FILE_CHUNK_SIZE
+const size_t SEND_FILE_CHUNK_SIZE = 0x100000; /*1MB*/
+#else
+const size_t SEND_FILE_CHUNK_SIZE = DEFAULT_SEND_FILE_CHUNK_SIZE; /*1MB*/
+#endif
+#endif
+#ifndef DEFAULT_SERVER_PORT
+static const in_port_t SERVER_PORT = 9091;
+#else
+static const in_port_t SERVER_PORT = DEFAULT_SERVER_PORT;
+#endif
+#ifndef DEFAULT_MAX_PATH_SIZE
+/*0 < x < MAX_PATH_SIZE*/
+static const uint16_t MAX_PATH_SIZE = 256;
+#else
+static const uint16_t MAX_PATH_SIZE = DEFAULT_MAX_PATH_SIZE;
+#endif
+#ifndef DEFAULT_TIMEOUT
+static const int TIMEOUT = 5;
+#else
+static const int TIMEOUT = DEFAULT_TIMEOUT;
+#endif
+
 /*========
  *Operation
  *========*/
@@ -190,7 +217,7 @@ int main(int argc, const char *argv[]){
         assert(msg != NULL);
         fprintf(stderr,"server bind on %s:%d\n",msg ,SERVER_PORT);
     }
-    if(listen(sock,1) < 0){
+    if(listen(sock,MAX_LISTEN_SOCKET) < 0){
         perror("listen failed");
         return 1;
     }
diff --git a/server.c b/server.c
index c654071..c0c6e0a 100644
--- a/server.c
+++ b/server.c
@@ -14,6 +14,31 @@
 #include <fcntl.h>
 #include "socket_wrapper.h"
 
+#ifdef USE_SENDFILE
+#include <sys/sendfile.h>
+#ifndef DEFAULT_SEND_FILE_CHUNK_SIZE
+const size_t SEND_FILE_CHUNK_SIZE = 0x100000; /*1MB*/
+#else
+const size_t SEND_FILE_CHUNK_SIZE = DEFAULT_SEND_FILE_CHUNK_SIZE; /*1MB*/
+#endif
+#endif
+#ifndef DEFAULT_SERVER_PORT
+static const in_port_t SERVER_PORT = 9091;
+#else
+static const in_port_t SERVER_PORT = DEFAULT_SERVER_PORT;
+#endif
+#ifndef DEFAULT_MAX_PATH_SIZE
+/*0 < x < MAX_PATH_SIZE*/
+static const uint16_t MAX_PATH_SIZE = 256;
+#else
+static const uint16_t MAX_PATH_SIZE = DEFAULT_MAX_PATH_SIZE;
+#endif
+#ifndef DEFAULT_TIMEOUT
+static const int TIMEOUT = 5;
+#else
+static const int TIMEOUT = DEFAULT_TIMEOUT;
+#endif
+
 /*========
  *Operation
  *========*/
@@ -146,6 +171,7 @@ int send_response(int sock,int fd, uint8_t * buf, size_t bufsize){
 #endif
     return 0;
 }
+
 static int sock;
 void safe_exit(){
     close(sock);
diff --git a/socket_wrapper.h b/socket_wrapper.h
index aae57ba..e8fa0bd 100644
--- a/socket_wrapper.h
+++ b/socket_wrapper.h
@@ -7,17 +7,9 @@
 #include <arpa/inet.h>
 #include <netdb.h>
 
-#ifdef USE_SENDFILE
-#include <sys/sendfile.h>
-const size_t SEND_FILE_CHUNK_SIZE = 0x100000; /*1MB*/
-#endif
 
-static const in_port_t SERVER_PORT = 9091;
 static const size_t DEFAULT_BUF_SIZE = 4096;
 static const size_t MINIMUM_BUF_SIZE = 1024;
-/*0 < x < MAX_PATH_SIZE*/
-static const uint16_t MAX_PATH_SIZE = 256;
-static const int TIMEOUT = 5;
 
 enum{
     RES_OK = 0,