Python

Python_NAT

sockMiddle_server.py

 1 import sys
 2 import socket
 3 import threading
 4 
 5 #回复消息，原样返回
 6 def replyMessage(conn):
 7     while True:
 8         data = conn.recv(1024)
 9         conn.send(data)
10         if data.decode().lower() == 'bye':
11             break
12     conn.close()
13 
14 def main():
15     sockScr = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
16     sockScr.bind(('', port))
17     sockScr.listen(200)
18     while True:
19         try:
20             conn, addr = sockScr.accept()
21             #只允许特定主机访问本服务器
22             if addr[0] != onlyYou:
23                 conn.close()
24                 continue
25             #创建并启动线程
26             t = threading.Thread(target=replyMessage, args=(conn,))
27             t.start()        
28         except:
29             print('error')
30 
31 if __name__ == '__main__':
32     try:
33         #获取命令行参数
34         port = int(sys.argv[1])
35         onlyYou = sys.argv[2]
36         main()
37     except:
38         print('Must give me a number as port')
39

sockMiddle.py

 1 import sys
 2 import socket
 3 import threading
 4 
 5 def middle(conn, addr):
 6     #面向服务器的Socket
 7     sockDst = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 8     sockDst.connect((ipServer,portServer))
 9     while True:
10         data = conn.recv(1024).decode()
11         print('收到客户端消息：'+data)
12         if data == '不要发给服务器':
13             conn.send('该消息已被代理服务器过滤'.encode())
14             print('该消息已过滤')
15         elif data.lower() == 'bye':
16             print(str(addr)+'客户端关闭连接')
17             break
18         else:
19             sockDst.send(data.encode())
20             print('已转发服务器')
21             data_fromServer = sockDst.recv(1024).decode()
22             print('收到服务器回复的消息：'+data_fromServer)
23             if data_fromServer == '不要发给客户端':
24                 conn.send('该消息已被代理服务器修改'.encode())
25                 print('消息已被篡改')
26             else:
27                 conn.send(b'Server reply:'+data_fromServer.encode())
28                 print('已转发服务器消息给客户端')
29         
30     conn.close()
31     sockDst.close()
32 
33 def main():
34     sockScr = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
35     sockScr.bind(('', portScr))
36     sockScr.listen(200)
37     print('代理已启动')
38     while True:
39         try:
40             conn, addr = sockScr.accept()
41             t = threading.Thread(target=middle, args=(conn, addr))
42             t.start()
43             print('新客户：'+str(addr))
44         except:
45             pass
46         
47 if __name__ == '__main__':
48     try:
49         #(本机IP地址,portScr)<==>(ipServer,portServer)
50         #代理服务器监听端口
51         portScr = int(sys.argv[1])
52         #服务器IP地址与端口号
53         ipServer = sys.argv[2]
54         portServer = int(sys.argv[3])
55         main()
56     except:
57         print('Sth error')

sockMiddle_client.py

 1 import sys
 2 import socket
 3 import threading
 4 
 5 def middle(conn, addr):
 6     #面向服务器的Socket
 7     sockDst = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 8     sockDst.connect((ipServer,portServer))
 9     while True:
10         data = conn.recv(1024).decode()
11         print('收到客户端消息：'+data)
12         if data == '不要发给服务器':
13             conn.send('该消息已被代理服务器过滤'.encode())
14             print('该消息已过滤')
15         elif data.lower() == 'bye':
16             print(str(addr)+'客户端关闭连接')
17             break
18         else:
19             sockDst.send(data.encode())
20             print('已转发服务器')
21             data_fromServer = sockDst.recv(1024).decode()
22             print('收到服务器回复的消息：'+data_fromServer)
23             if data_fromServer == '不要发给客户端':
24                 conn.send('该消息已被代理服务器修改'.encode())
25                 print('消息已被篡改')
26             else:
27                 conn.send(b'Server reply:'+data_fromServer.encode())
28                 print('已转发服务器消息给客户端')
29         
30     conn.close()
31     sockDst.close()
32 
33 def main():
34     sockScr = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
35     sockScr.bind(('', portScr))
36     sockScr.listen(200)
37     print('代理已启动')
38     while True:
39         try:
40             conn, addr = sockScr.accept()
41             t = threading.Thread(target=middle, args=(conn, addr))
42             t.start()
43             print('新客户：'+str(addr))
44         except:
45             pass
46         
47 if __name__ == '__main__':
48     try:
49         #(本机IP地址,portScr)<==>(ipServer,portServer)
50         #代理服务器监听端口
51         portScr = int(sys.argv[1])
52         #服务器IP地址与端口号
53         ipServer = sys.argv[2]
54         portServer = int(sys.argv[3])
55         main()
56     except:
57         print('Sth error')

'''
启动3个终端cd到文件目录后:各终端执行一条语句
python sockMiddle_server.py 10000 10.2.1.2
python sockMiddle.py 30800 10.2.1.2 10000
python sockMiddle_client.py 10.2.1.2 30800
'''