## 7.2.2 Example

Here are two minimal example programs using the TCP/IP protocol: a server that echoes all data that it receives back (servicing only one client), and a client using it. Note that a server must perform the sequence `socket`, `bind`, `listen`, `accept` (possibly repeating the `accept` to service more than one client), while a client only needs the sequence `socket`, `connect`. Also note that the server does not `send`/`receive` on the socket it is listening on but on the new socket returned by `accept`.

    # Echo server program
    from socket import *
    HOST = ''                 # Symbolic name meaning the local host
    PORT = 50007              # Arbitrary non-privileged server
    s = socket(AF_INET, SOCK_STREAM)
    s.bind(HOST, PORT)
    s.listen(1)
    conn, addr = s.accept()
    print 'Connected by', addr
    while 1:
        data = conn.recv(1024)
        if not data: break
        conn.send(data)
    conn.close()

    # Echo client program
    from socket import *
    HOST = 'daring.cwi.nl'    # The remote host
    PORT = 50007              # The same port as used by the server
    s = socket(AF_INET, SOCK_STREAM)
    s.connect(HOST, PORT)
    s.send('Hello, world')
    data = s.recv(1024)
    s.close()
    print 'Received', `data`

See Also:

`SocketServer` (classes that simplify writing network servers)