错误 - 未定义全局名称'SOL_SOCKET

我正在尝试创建一个使用p2p(点对点)连接的基本即时消息程序,因此它不需要服务器.我很确定没有错,但每次运行我创建的客户端程序时,都会收到此错误:s.setsockopt(SOL_SOCKET,SO_REUSEADDR,1)NameError:全局名称'SOL_SOCKET'未定义以下是程序:

import socket

def Receiver():

    # Create socket that supports IPv4, TCP Protocol
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    print "Socket created."
    # Requests for IP of host (DNS)
    dns = "localhost"
    HOST = ''
    PORT = 25395
    try:

        s.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
    except socket.error as serror:
        print "socket error"
    s.bind((HOST, PORT)) # Listens on all interfaces...
    print 'Listening on port 25565'
    s.listen(True) # Listen on the newly created socket... 
    conn, addr = s.accept()
    print 'Connected in port 25565'
    data = conn.recv(1024)
    print data
    s.close()
def Sender():

    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    dns = "localhost"
    HOST = socket.gethostbyname(dns)
    port = 25565    
    # Connect to server
    s.connect((host,port))

    print "Socket connected to " + dns + " on IP " + host

    # Assign message to be sent to server to a variable
    message = raw_input("Message to be sent to server: ")

    #Send the actual message to server
    s.sendall(message)
    print "Message sent successfully"
    s.close()


input = raw_input('S is send, R is receive: ')
if input == 's':
    Sender()
if input == 'r':
    Receiver()

我已经尝试删除s.setsockopt(SOL_SOCKET,SO_REUSEADDR,1)但它告诉我,当没有2个套接字使用相同的端口时,我不能在同一端口上使用2个套接字.