Hellobot IRC python

#!/usr/bin/env python
#Greets whoever joins the channel.

import sys, socket, string

if len(sys.argv) != 5:
    print "Usage: ./hellobot.py <host> <port> <nick> <channel>"
    sys.exit(1)

HOST = sys.argv[1]
PORT = int(sys.argv[2])
NICK = sys.argv[3]
CHAN = sys.argv[4]
readbuffer = ""

s=socket.socket( )
s.connect((HOST, PORT))
s.send("NICK %s\r\n" % NICK)
s.send("USER %s %s bla :%s\r\n" % (NICK, NICK, NICK))
s.send("JOIN :%s\r\n" % CHAN)

while 1:
    readbuffer=readbuffer+s.recv(1024)
        temp=string.split(readbuffer, "\n")
        readbuffer=temp.pop( )

        for line in temp:
            line=string.rstrip(line)
            line=string.split(line)

        try:
            if line[1] == "JOIN":
                name = str(line[0].split("!")[0])
                s.send("PRIVMSG %s :%s%s\r\n" % (CHAN, "Welcome, ", name.replace(":","")))
        except(IndexError):
            pass

            if(line[0]=="PING"):
                s.send("PONG %s\r\n" % line[1])