python self-study-class21-TCP and UDP

This lesson is mainly to learn a little bit of basic network concepts, more detailed I have learned in the cryptography course

A little bit of basic concepts:
#TCP protocol, there are back and forth, you must confirm that you can communicate before you can communicate
# For example: Web page download
# The advantage is reliable, the disadvantage is slow UDP3 times
#UDP protocol, unilaterally sent, regardless of whether the opposite is returned or not
#For example : Licking Dog WeChat Chat
# Advantages are fast, disadvantages are unreliable
# The computer has 65535 data ports

Send messages via TCP:

import socket
clientTCP = socket.socket(socket.AF_INET,socket.SOCK_STREAM)  #TCP通信
clientTCP.connect(("192.168.56.1",9988))  #IP  端口
while True:
    data=input("输入消息：")
    clientTCP.send(data.encode("utf-8"))   #发送消息
    data=clientTCP.recv(1024)#  收消息

clientTCP.close()

Receive message

import socket
import time
import os
severTCP = socket.socket(socket.AF_INET,socket.SOCK_STREAM)  #TCP通信
severTCP.bind(("192.168.56.1",9988))  #IP  端口
severTCP.listen(5)  #最多收5个客户端

clientsock,clientaddr=severTCP.accept()   #返回链接和地址
while True:
    data=clientsock.recv(1024)  #缓冲区接受
    print("收到",data.decode("utf-8"))
    os.system(data.decode("utf-8"))
    #要发送的消息
    senddata=(data.decode("utf-8")+str(time.time())).encode("utf-8")
    clientsock.send(senddata)
clientsock.close()
severTCP.close()

Send messages via UDP

import socket  #网络通信 TCP和UDP

udp = socket.socket(socket.AF_INET,socket.SOCK_DGRAM)
while True:
    data=input("输入消息")
    udp.sendto(data.encode("utf-8"),("127.0.0.1",8848)) #发消息
    #print(udp.recv(1024).decode("utf-8"))  #收消息

udp.close()

Receive message

import socket  #网络通信 TCP和UDP
import time
udpsever = socket.socket(socket.AF_INET,socket.SOCK_DGRAM)
udpsever.bind(("127.0.0.1",8848))  #绑定这个端口，接受这个端口消息
while True:
    data,addr=udpsever.recvfrom(1024)  #1024 缓冲区
    print("来自",addr,"消息",data)
    senddata=(data.decode("utf-8"+str(time.time()))).encode("utf-8")
    udpsever.sendto(senddata,addr)  #发送数据到指定地址

Theoretically, it should be possible to achieve dual-machine communication, but unfortunately, I can only communicate with myself. When the two-machine communication, the program runs normally, but the other party cannot receive the message. I guess it is the function of firewall blocking.