Python : socket module

Reference

http://www.giantflyingsaucer.com/blog/?p=4684

Here is how to use socket module

This script listens TCP 8080 port.

I am using SO_REUSEPORT options which has been implemented in kernel 3.9, so multiple processes can bind 8080 port at the same time.

# cat server.py #!/usr/bin/env python import os import socket import sys # after TCP three way handshake, the server send data to clients def send_data():    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)    s.bind(('0.0.0.0', 8080))    s.listen(1)    conn, addr = s.accept()    data = str(os.getpid()) + '\n' #    data = 'hello'    conn.send(data)    conn.close() # aftere TCP three way handhsake, the server recieve data from clients and then send clients that data def recieve_send_data():    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)    s.bind(('0.0.0.0', 8080))    s.listen(1)    conn, addr = s.accept()    data = conn.recv(1024)    conn.send(data)    conn.close() if __name__ == '__main__':    argvs = sys.argv    argc = len(argvs)    if argc != 2:        print "python server.py send or python server.py recv_send"    elif argvs[1] == 'send':        while True:            send_data()    elif argvs[1] == 'recv_send':        while True:            recieve_send_data()

After TCP 3 way handshake, the server send data to clients

# ./server.py send

After TCP 3 way handshake, the server receive data from clients and then send clients that data.

# ./server.py recv_send

you can run multiple scripts, because this script supports SO_REUSEPORT.

You need to use kernels which support SO_REUSEPORT.

# ./server.py send & [1] 14053 # ./server.py send & [2] 14054 # ./server.py send & [3] 14055 # nc 127.0.0.1 8080 14053 # nc 127.0.0.1 8080 14055 # nc 127.0.0.1 8080 14054