Python Simple socket emulation SSH

OSI seven-layer model (open System interconnection, open systems interconnect)

Application    -Layer network processes access the application layer:        provides network services for application processes such as e-mail, file transfer, and terminal emulation, and        provides user authentication presentation layer    Data representation:        ensures that the receiving system can read the data;        Format data,        construct data,        negotiate data transfer syntax for application tiers,        provide encrypted session-level    inter-host communication:        establish, manage, and terminate conversation transport-layer         transfer issues between applications:        Ensure the reliability of data transmission        , establish, maintain and terminate the virtual circuit,        Pass error detection and recovery,        information flow control to ensure the reliability of network layer data         transmission:        route packet;        Select the best path to pass the data;        supports logical addressing and path selection Data link layer      Access media:        defines how data is formatted for transmission and how to control access to the network;        support for error detection physical layer         binary transmission: Unit bit        

　　

Socket instantiation of a socket

Bind binding to address and port

Listen started listening.

Accept waits for wait incoming data

Recv Accept Data

Send data (default send size is 32768 (32k) size)

Sendall Send all data

Close socket

　　

A simple communication process

Service side:

Import socket# instantiation, binding, listening, waiting, deconstructing (identity, Ip-port), receiving, responding, shutting down server = Socket.socket () server.bind ((' localhost ', 6969)) Server.listen () print (' Start listening ... ') conn,addr = Server.accept () print (conn,addr) data = CONN.RECV (1024x768) print (' Server-side received: ', Data.decode ()) conn.send (' Hi, I am the server. ') Encode ()) Server.close ()

　　

Client:

Import socket# instantiation, connection, send, receive response, close client = Socket.socket () client.connect ((' localhost ', 6969)) client.send (' Hi,i am the Client. '. Encode ()) print (' Send data ... ') data = CLIENT.RECV Print (' Client received data: ', Data.decode ()) Client.close ()

　

Output Result:

1. Run the server first, listen to the port, and start waiting for incoming data:

Start listening ...

2. Start the client, send the data, receive the response:

Send data ... The client receives the data: Hi, I am the server.

　　

3. Go back to the server to view the received data:

Start listening ... <socket.socket fd=6, family=addressfamily.af_inet, Type=socketkind.sock_stream, proto=0, Laddr= (' 127.0.0.1 ', 6969), raddr= (' 127.0.0.1 ', 55149) > (' 127.0.0.1 ', 55149) received data: Hi,i am the client.

　　

Second, analog SSH remote command execution

Server-side:

Import Socketimport timeimport os# instantiation, binding, listening, waiting, deconstructing (identity, Ip-port), receiving, responding, shutting down server = Socket.socket () server.bind (' localhost ', 6969)) Server.listen (3) #表示当正在处理一个连接时, you can suspend up to the next 3 connections in order (which can be understood as queues), and if a 4th is connected, a timeout exception will be thrown after a certain amount of time: Timeouterror : [Errno] Operation timed Outprint (' Start listening ... ') Try:    while True:        conn,addr = server.accept ()        # PRINT (conn, Addr)        Peerip,peerport = Conn.getpeername ()        localip,localport = Conn.getsockname ()        print (' {}:{}--and {} : {} '. Format (peerip,peerport,localip,localport)) while        True:            data = CONN.RECV (1024x768)            if not data:                Break            print (Data.decode ())            ret = Os.popen (Data.decode ()). Read ()            conn.send (Ret.encode ())    Server.close () except Keyboardinterrupt as E:    print (' connection interrupted ... ')

　　

　　

Client

Import socket# instantiation, connection, send, receive response, close client = Socket.socket () client.connect ((' localhost ', 6969)) print (' Connecting server ... ') while True:    msg = input (' >>> '). Strip ()    # print (' sending data ... ')    if not msg:        continue    Client.send (Msg.encode ())    # print (' Sent ... ')    data = Client.recv (1024x768)    if not data: Break    Print (Data.decode ()) Client.close ()

　　

　　

Operation Result:

1. Service side:

Start listening ...

2. The client (you can enter the executed command to receive the execution result returned by the server):

Connecting to service side ... >>>ls-ltotal 48-rw-r--r--  1 Zhangsan staff   222 Nov 10:37 1.0.py-rw-r--r--  1 Zhangsan  Staff   433-16:49 2.0.py-rw-r--r--  1 Zhangsan staff   158 Nov 10 23:18 error.log-rw-r--r--  1 Zhangsan  staff   437 Nov 14:10 socket_client1.py-rw-r--r--  1 Zhangsan  staff  1010-14:21 socket_server1.py-rw-r--r--  1 Zhangsan staff   608 Nov 10 23:31 exception handling. py >>>ls-l. /total 0drwxr-xr-x   7 Zhangsan  staff  224 Nov  8 12:51 1106drwxr-xr-x one  zhangsan  staff  352  9 11:33 1108drwxr-xr-x 8 Zhangsan Staff--  14:21 1110>>>

　　

　　

3. Service side:

Start listening ... 127.0.0.1:56380--127.0.0.1:6969ls-lls-l. /    #记录执行的命令

　　

Protocol cluster:

Af_inet IPV4

Af_inet6 IPV6

Af_unix Local Address

Protocol: Protocol

Sock_stream TCP

Sock_dgram UDP

Sock_raw raw sockets, can forge data such as source IP

Python Simple socket emulation SSH