diff --git a/code/reference/ch_socket/SMTPClient.py b/code/reference/ch_socket/SMTPClient.py
index bfec76a..accfa03 100644
--- a/code/reference/ch_socket/SMTPClient.py
+++ b/code/reference/ch_socket/SMTPClient.py
@@ -1,66 +1,71 @@
 from socket import *
 from base64 import *
-
 mailfrom = "mail from:2@test.com\r\n"
 rcptto = "rcpt to:1@test.com\r\n"
 data = "data\r\n"
 quitmsg = "quit\r\n"
 
-msg = "\r\n I love computer networks!"
+# 填写代码使程序发送的邮件中包含内容为 "Hello World!"。
+msg = "Hello World!"
+
 endmsg = "\r\n.\r\n"
-#此处使用易邮邮件服务器软件搭建了一个内网邮件服务器
-mailserver = '10.130.82.62'
+
+#本地搭建的邮件服务器IP地址。
+mailserver = 'localhost'
+# 在端口25上启动邮件服务器。
 mailport = 25
 connectaddress = (mailserver, mailport)
-# Create socket called clientSocket and establish a TCP connection with mailserver
+# 创建 socket 和邮件服务器建立 TCP 连接。
 clientSocket = socket(AF_INET, SOCK_STREAM)
 clientSocket.connect(connectaddress)
-
 recv = clientSocket.recv(1024)
-print (recv)
-if recv[:3] != '220':
+  
+if recv.decode()[:3] != '220':
     print ('220 reply not received from server.')
-# Send HELO command and print server response.
+    
+# 发送 HELO 命令，打印服务器响应。
 heloCommand = 'HELO Alice\r\n'
 clientSocket.send(bytes(heloCommand.encode()))
 recv1 = clientSocket.recv(1024)
-print (recv1.decode())
-if recv1[:3] != '250':
+ 
+if recv1.decode()[:3] != '250':
     print ('250 reply not received from server.')
-
-#print('000000000000000')
-#从命令和打印服务器响应发送邮件。
+    
+#发送登陆认证信息
 login = b'auth login\r\n'
 clientSocket.send(login)
 recv2 = clientSocket.recv(1024).decode('utf-8')
-print ('222+',recv2)
-
+print ('登陆认证',recv2)
+#发送用户名
 userCommand = b64encode('2@test.com'.encode('utf-8'))
 clientSocket.send((str(userCommand,encoding='utf-8')+'\r\n').encode())
 recv3 = clientSocket.recv(1024).decode('utf-8')
-print ('333+',recv3)
-
+print ('用户名',recv3)
+#发送密码
 password = b64encode('2'.encode('utf-8'))
 clientSocket.send((str(password,encoding='utf-8')+'\r\n').encode())
 recv4 = clientSocket.recv(1024).decode('utf-8')
-print ('444+',recv4)
-
-#print('0000000000000000')
+print ('密码',recv4)  
 
+# 发送 MAIL FROM 命令，打印服务器响应。
 clientSocket.send(bytes(mailfrom.encode()))
 check = clientSocket.recv(1024)
 print(check)
+# 发送 RCPT TO 命令，打印服务器响应。
 clientSocket.send(bytes(rcptto.encode()))#将RCPT发送到命令和打印服务器响应。
 check1 = clientSocket.recv(1024)
 print(check1)
+# 发送 DATA 命令，打印服务器响应。
 clientSocket.send(bytes(data.encode()))#发送数据命令和打印服务器响应。
 check2 = clientSocket.recv(1024)
 print(check2)
+# 发送邮件内容。消息以单个"." 结束。
 clientSocket.send(bytes((mailfrom+msg+endmsg).encode()))#发送消息数据。
 check3 = clientSocket.recv(1024)
 print(check3)
-#发送退出命令并获得服务器响应。
+# 发送 QUIT 命令，获取服务器响应。
 clientSocket.send(bytes(quitmsg.encode()))
 check4 = clientSocket.recv(1024)
 print(check4)
-clientSocket.close()
+
+clientSocket.close()
\ No newline at end of file
diff --git a/code/reference/ch_socket/Webserver.py b/code/reference/ch_socket/Webserver.py
new file mode 100644
index 0000000..fee4e57
--- /dev/null
+++ b/code/reference/ch_socket/Webserver.py
@@ -0,0 +1,50 @@
+from socket import * 
+import sys
+
+# 准备服务器端 socket
+serverSocket = socket(AF_INET, SOCK_STREAM)
+# 设定端口号
+serverPort = 80
+# 绑定地址（host,port）到套接字
+serverSocket.bind(("localhost", serverPort))
+# 开始 TCP 监听，该值至少为 1
+serverSocket.listen(1)
+while True: 
+    # 建立连接 
+    print('Ready to serve...') 
+
+    # 收到客户端请求时建立一个新连接
+    connectionSocket, addr = serverSocket.accept()
+
+    try: 
+
+        # 按需补充，接受来自客户端的请求
+        message = connectionSocket.recv(1024).decode()
+
+        # 从消息中提取所请求对象的路径
+        # 路径是HTTP标头的第二部分，由[1]标识
+        filename = message.split()[1] 
+        # 因为HTTP请求的提取路径包括一个字符“ \”，我们从第二个字符读取路径
+        f = open(filename[1:]) 
+
+        # 将请求文件的全部内容存储在临时缓冲区中
+        outputdata = f.read() 
+        # 将HTTP响应标头行发送到连接套接字
+        connectionSocket.send("HTTP/1.1 200 OK\r\n\r\n".encode()) 
+        # 将请求文件的内容发送到客户端
+        for i in range(0, len(outputdata)):
+            connectionSocket.send(outputdata[i].encode())
+        connectionSocket.send("\r\n".encode()) 
+        connectionSocket.close()
+    except IOError: 
+
+        # 按需补充代码：发送未找到文件的响应消息 
+        connectionSocket.send("HTTP/1.1 404 Not Found\r\n\r\n".encode())
+        connectionSocket.send("<html><head></head><body><h1>404 Not Found</h1></body></html>\r\n".encode())
+        # 按需补充代码：关闭客户端 socket 
+        connectionSocket.close()
+serverSocket.close()
+sys.exit()
+
+
+
diff --git a/code/reference/ch_socket/Websever.py b/code/reference/ch_socket/Websever.py
deleted file mode 100644
index d901408..0000000
--- a/code/reference/ch_socket/Websever.py
+++ /dev/null
@@ -1,62 +0,0 @@
-# Import socket module
-from socket import * 
-import sys # In order to terminate the program
-
-# Create a TCP server socket
-#(AF_INET is used for IPv4 protocols)
-#(SOCK_STREAM is used for TCP)
-
-serverSocket = socket(AF_INET, SOCK_STREAM)
-
-# Assign a port number
-serverPort = 80
-
-# Bind the socket to server address and server port
-serverSocket.bind(("", serverPort))
-
-# Listen to at most 1 connection at a time
-serverSocket.listen(1)
-
-# Server should be up and running and listening to the incoming connections
-
-while True:
-	print('The server is ready to receive')
-
-	# Set up a new connection from the client
-	connectionSocket, addr = serverSocket.accept()
-
-	# If an exception occurs during the execution of try clause
-	# the rest of the clause is skipped
-	# If the exception type matches the word after except
-	# the except clause is executed
-	try:
-		# Receives the request message from the client
-		message = connectionSocket.recv(1024).decode()
-		# Extract the path of the requested object from the message
-		# The path is the second part of HTTP header, identified by [1]
-		filename = message.split()[1]
-		# Because the extracted path of the HTTP request includes 
-		# a character '\', we read the path from the second character 
-		f = open(filename[1:])
-		# Store the entire contenet of the requested file in a temporary buffer
-		outputdata = f.read()
-		# Send the HTTP response header line to the connection socket
-		connectionSocket.send("HTTP/1.1 200 OK\r\n\r\n".encode()) 
- 
-		# Send the content of the requested file to the connection socket
-		for i in range(0, len(outputdata)):  
-			connectionSocket.send(outputdata[i].encode())
-		connectionSocket.send("\r\n".encode()) 
-		
-		# Close the client connection socket
-		connectionSocket.close()
-
-	except IOError:
-			# Send HTTP response message for file not found
-			connectionSocket.send("HTTP/1.1 404 Not Found\r\n\r\n".encode())
-			connectionSocket.send("<html><head></head><body><h1>404 Not Found</h1></body></html>\r\n".encode())
-			# Close the client connection socket
-			connectionSocket.close()
-
-serverSocket.close()  
-sys.exit()#Terminate the program after sending the corresponding data
diff --git a/data/copyright.tex b/data/copyright.tex
index 8f42736..96c10ce 100644
--- a/data/copyright.tex
+++ b/data/copyright.tex
@@ -15,10 +15,17 @@
   \begin{tabular*}{0.85\textwidth}{rm{0.8\textwidth}}
     \large $\copyright$ & \sffamily{\color{darkgray} 2021 计算机网络教案社区}
     \hspace{0.3em}\includegraphics[width=0.6cm]{figure/logo} \\
-    & \footnotesize 本教案中所有原创内容，包括但不限于文字、图片、图表、版面设计、标题等的版权归计算机网络教案社区所有，并受著作权法保护。 \\
-    & \footnotesize 读者可以将本教案的全部或部分内容{\color{purple}免费用于非商业用途}，但在使用本教案内容时请注明来源和版权声明，即“内容来自：计算机网络教案社区，版权归原作者所有”。 \\
-    & \footnotesize 对于不遵守此声明或者其他违法使用本教案内容者，我们将保留依法追究其侵权责任的权利。 \\
-    & \footnotesize 本教案如涉及特定版权内容，请版权方在社区提供相关信息以便及时删除该内容。 \\
+    & \footnotesize 本教案中所有原创内容，
+    包括但不限于文字、图片、图表、版面设计、
+    标题等的版权归计算机网络教案社区所有，并受著作权法保护。 \\
+    & \footnotesize 读者可以将本教案的全部或部分内容{\color{purple}免费用于非商业用途}，
+    但在使用本教案内容时请注明来源和版权声明，
+    即“内容来自：计算机网络教案社区，版权归原作者所有”。 \\
+    & \footnotesize 对于不遵守此声明或者其他违法使用本教案内容者，
+    我们将保留依法追究其侵权责任的权利。 \\
+    & \footnotesize 本教案如涉及特定版权内容，
+    请版权方在社区提供相关信息以便及时删除该内容。 \\
+    & \footnotesize 清华大学出版社参与了版式、字体设计等工作。
   \end{tabular*}
 \renewcommand{\arraystretch}{1}
 \end{center}
diff --git a/data/preface.tex b/data/preface.tex
index 6cb717c..d031321 100644
--- a/data/preface.tex
+++ b/data/preface.tex
@@ -18,12 +18,15 @@
 在附录\ref{app:cheatsheet}中做了汇总，方便老师快速查询。
 在实际使用中，任课老师可以根据具体授课需要在本指导书的基础上通过
 增删、组合、修改等方法设计适合自身课程的实验方案。
+本指导书基于Latex编写，
+源代码可以从 \href{https://gitee.com/xphi1980/nap_instructions}{Gitee} 获取。
 
 由于时间仓促，加之编者水平有限，
 本指导书中缺点和疏漏在所难免。
 作为社区项目，恳请广大读者和同行专家批评指正，
 同时欢迎更多读者和专家参与本项目的编纂和开发。
 
+
 \vspace{1em}
 
 本实验指导书各章节主要编纂人员如下：