PYTHON -Chapter 5 NETWORK - MAULIK BORSANIYA
- 1. Chapter - 5 Network – 5.2 Maulik Borsaniya Gardividyapith
- 2. What is network ? • A computer network, or data network, is a digital telecommunications network which allows nodes to share resources. In computer networks, computing devices exchange data with each other using connections between nodes
- 3. What is protocol ? • A network protocol defines rules and conventions for communication between network devices. • Network protocols include mechanisms for devices to identify and make connections with each other, as well as formatting rules that specify how data is packaged into messages sent and received • FTP: File Transfer Protocol. ... • SSL: Secure Sockets Layer. ... • TELNET (telnet) ... • SMTP: Simple Mail Transfer Protocol. ... • POP3: Post Office Protocol.
- 4. Starting With the Socket Programming • Socket programming is a way of connecting two nodes on a network to communicate with each other. One socket(node) listens on a particular port at an IP, while other socket reaches out to the other to form a connection. • Server forms the listener socket while client reaches out to the server. • They are the real backbones behind web browsing. In simpler terms there is a server and a client. • Socket programming is started by importing the socket library and making a simple socket
- 5. • import socket s =socket.socket(socket.AF_INET, socket.SOCK_STREAM) • Here we made a socket instance and passed it two parameters. • The first parameter is AF_INET and the • second one is SOCK_STREAM. • AF_INET refers to the address family ipv4. • The SOCK_STREAM means connection oriented TCP protocol.
- 6. Here is an example of a script for connecting to Google An example script to connect to Google using socket # programming in Python import socket # for socket import sys try: s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) print ("Socket successfully created") except socket.error as err: print ("socket creation failed with error") # default port for socket port = 80 try: host_ip = socket.gethostbyname('www.google.com') except socket.gaierror: # this means could not resolve the host print ("there was an error resolving the host") sys.exit() # connecting to the server s.connect((host_ip, port)) print ("the socket has successfully connected to google on port == %s" %(host_ip))
- 7. Http Request Reponses • HTTP is based on the client-server architecture model and a stateless request/response protocol that operates by exchanging messages across a reliable TCP/IP connection. • An HTTP "client" is a program (Web browser or any other client) that establishes a connection to a server for the purpose of sending one or more HTTP request messages. An HTTP "server" is a program ( generally a web server like Apache Web Server or Internet Information Services IIS, etc. ) • that accepts connections in order to serve HTTP requests by sending HTTP response messages.
- 8. Installation of http requests Navigate Python34/script Pip install requests
- 9. Download images from web – with request response import requests image_url = "https://www.python.org/static/community_logos/python-logo-master-v3- TM.png" # URL of the image to be downloaded is defined as image_url r = requests.get(image_url) # create HTTP response object # send a HTTP request to the server and save # the HTTP response in a response object called r with open("python_logo.png",'wb') as f: # Saving received content as a png file in # binary format # write the contents of the response (r.content) # to a new file in binary mode. f.write(r.content)
- 10. Client Server Connection Establishment #Server # first of all import the socket library import socket # next create a socket object s = socket.socket() print ("Socket successfully created") # reserve a port on your computer in our # case it is 12345 but it can be anything port = 12345 # Next bind to the port # we have not typed any ip in the ip field # instead we have inputted an empty string # this makes the server listen to requests # coming from other computers on the network s.bind(('', port)) print ("socket binded to %s" %(port)) # put the socket into listening mode s.listen(5) print ("socket is listening") # a forever loop until we interrupt it or # an error occurs while True: # Establish connection with client. c, addr = s.accept() print ('Got connection from', addr) # send a thank you message to the client. c.send('Thank you for connecting') # Close the connection with the client Python server.py telnet localhost 12345
- 11. A server has a bind() method which binds it to a specific ip and port so that it can listen to incoming requests on that ip and port. A server has a listen() method which puts the server into listen mode. This allows the server to listen to incoming connections. And last a server has an accept() and close() method. The accept method initiates a connection with the client and the close method closes the connection with the client.
- 12. • First of all we import socket which is necessary. • Then we made a socket object and reserved a port on our pc. • After that we binded our server to the specified port. Passing an empty string means that the server can listen to incoming connections from other computers as well. If we would have passed 127.0.0.1 then it would have listened to only those calls made within the local computer. • After that we put the server into listen mode.5 here means that 5 connections are kept waiting if the server is busy and if a 6th socket try's to connect then the connection is refused. • At last we make a while loop and start to accept all incoming connections and close those connections after a thank you message to all connected sockets.
- 13. #Client # Import socket module import socket # Create a socket object s = socket.socket() # Define the port on which you want to connect port = 12345 # connect to the server on local computer s.connect(('127.0.0.1', port)) # receive data from the server s.recv(1024) # close the connection s.close()
- 14. TCP & UDP • The user datagram protocol (UDP) works differently from TCP/IP. • Where TCP is a stream oriented protocol, ensuring that all of the data is transmitted in the right order, • UDP is a message oriented protocol. • UDP does not require a long-lived connection, so setting up a UDP socket is a little simpler. • On the other hand, UDP messages must fit within a single packet (for IPv4, that means they can only hold 65,507 bytes because the 65,535 byte packet also includes header information) and delivery is not guaranteed as it is with TCP.
- 15. Sending mail # Python code to illustrate Sending mail from #error # your Gmail account import smtplib # creates SMTP session s = smtplib.SMTP('smtp.gmail.com', 587) # start TLS for security s.starttls() # Authentication s.login("patelmaulik752@gmail.com", “password") # message to be sent message = "Test Message" # sending the mail s.sendmail("borsaniyamaulik@gmail.com", "inspirationalstory1@gmail.com", message) # terminating the session s.quit()
- 16. success import smtplib gmailaddress = input("what is your gmail address? n ") gmailpassword = input("what is the password for that email address? n ") mailto = input("what email address do you want to send your message to? n ") msg = input("What is your message? n ") mailServer = smtplib.SMTP('smtp.gmail.com' , 587) mailServer.starttls() mailServer.login(gmailaddress , gmailpassword) mailServer.sendmail(gmailaddress, mailto , msg) print(" n Sent!") mailServer.quit()