banner grabber python

import socket  
 import sys  
 import os  
 #grab the banner  
 def grab_banner(ip_address,port):  
      try:  
           s=socket.socket()  
           s.connect((ip_address,port))  
           banner = s.recv(1024)  
           print (ip_address + ':' + banner )
      except:  
           return  
 def checkVulns(banner):  
      if len(sys.argv) >=2:  
           filename = sys.argv[1]  
           for line in filename.readlines():  
                line = line.strip('\n')  
                if banner in line:  
                     print ("%s is vulnerable" %banner) 
                else:  
                     print ("%s is not vulnerable")  
 def main():  
      portList = [21,22,25,80,110]  
      for x in range(0,255):  
           for port in portList:  
                ip_address = '192.168.0.' + str(x)  
                grab_banner(ip_address,port)  
 if __name__ == '__main__':  
      main()