diff --git a/Client/main.c b/Client/main.c
new file mode 100644
index 0000000..b9d0e0a
--- /dev/null
+++ b/Client/main.c
@@ -0,0 +1,72 @@
+//
+//  main.c
+//  presonal poster client
+//
+//  Created by Eric on 16-2-17.
+//  Copyright (c) 2016年 Bakantu Eric. All rights reserved.
+//
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <unistd.h>
+#include <string.h>
+
+#define PROT 8884
+#define N_MAX 256
+
+int main(int argc, const char * argv[]) {
+    int sockfd;
+    int len;
+    struct sockaddr_in addr;
+    int newsockfd;
+    char buf[N_MAX];
+    int len2;
+    char rebuf[N_MAX];
+    int i,key;
+    char ch;
+    
+    printf("Input key: (<= 6)");
+    scanf("%d",&key);
+    getchar();
+    
+    while (1){
+        sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        addr.sin_family = AF_INET;
+        addr.sin_addr.s_addr = htonl(INADDR_ANY);
+        addr.sin_port = PROT;
+        len = sizeof(addr);
+        newsockfd = connect(sockfd, (struct sockaddr *)&addr, len);
+        if (newsockfd == -1){
+            printf("Fail in connect the Server!");
+            return -1;
+        }
+        
+        printf("SEND: ");
+        i = 0;
+        while ((ch = getchar()) != '\n'){
+            buf[i] = ch;
+            i++;
+        }
+        buf[i] = '\0';
+        if (!strcmp(buf, "quit")) break;
+        for (i = 0; i < strlen(buf); i++){
+            if (buf[i] == ' ') buf[i] = '_';
+            buf[i] += key;
+        }
+        len2 = sizeof(buf);
+        send(sockfd, buf, len2, 0);
+        
+        
+        usleep(1000);
+        recv(sockfd, rebuf, N_MAX, 0);
+        rebuf[strlen(rebuf)+1] = '\0';
+        printf("Receive message: %s\n",rebuf);
+        close(sockfd);
+    }
+    return 0;
+}
diff --git a/Server/main.c b/Server/main.c
new file mode 100644
index 0000000..7ddb0c8
--- /dev/null
+++ b/Server/main.c
@@ -0,0 +1,63 @@
+//
+//  main.c
+//  personal poster
+//
+//  Created by Eric on 16-2-17.
+//  Copyright (c) 2016年 Bakantu Eric. All rights reserved.
+//
+
+#include <stdio.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <unistd.h>
+#include <string.h>
+
+#define PROT 8096
+
+int main(int argc, const char * argv[]) {
+    char string_send[255] = "Success";
+    char buf[256];
+    int s_fd, c_fd;
+    int s_len, c_len;
+    struct sockaddr_in s_addr;
+    struct sockaddr_in c_addr;
+    if ((s_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
+    {
+        printf("Socket failed");
+        return -1;
+    }
+    s_addr.sin_family = AF_INET;
+    s_addr.sin_addr.s_addr = htonl(INADDR_ANY);
+    s_addr.sin_port = PROT;
+    s_len = sizeof(s_addr);
+    if (bind(s_fd, (struct sockaddr *)&s_addr, s_len) == -1) { printf("Bind failed!"); return -1;}
+    listen(s_fd, 10);
+    int key;
+    pid_t pid;
+    
+    printf("Input key: (<= 6)");
+    scanf("%d",&key);
+    while(1){
+        c_len = sizeof(c_addr);
+        c_fd = accept(s_fd, (struct sockaddr *)&c_addr, (socklen_t*__restrict)&c_len);
+        printf("#+# %s Login\n",inet_ntoa(c_addr.sin_addr));
+        pid=fork();
+        if(pid==-1)
+        {
+            printf("Fork failed");
+        }
+        if (pid == 0){
+            recv(c_fd, buf, 256, 0);
+            buf[strlen(buf)+1] = '\0';
+            printf("#!#Receive message: %s From %s\n",buf,inet_ntoa(c_addr.sin_addr));
+            write(c_fd,buf,sizeof(buf));
+            send(c_fd, string_send, sizeof(string_send), 0);
+        }
+        if(pid>0){
+            close(c_fd);
+        }
+    }
+    return 0;
+}