Building a network port scanner

Code:
"#!/usr/bin/env python
from socket import *
import sys, getopt, time, os
#To-DO-LIST

#Version 1.1:
#1: Add more comments to code
#2: Make -l work with -s and -e
#3: Make script run more efficently(THREADS can be used)
#4: Add better error handling
#5: Make code more dry

#NEXT:
#Create Port-Knocking script for better service detection
#Try to get service version
#Basic OS detection
#better OS detection
#OS version detection
#Find dns server for target
#Add premade Port Lists for more efficent scanning(1000 most common ports)
#add -f to display only specified services
#Store Scaned hosts in a file
#Add support for UDP scanning

def Banner():
   print("\n"*50)
   author = "N30N_PH4NT0M"
   version = 1.0
   version_stage = "ALPHA"
   text = """ _______           _______  _______ _________   _______     ___    _______ 
(  ____ \|\     /|(  __   )(  ____ \\__   __/  (       )   /   )  (  ____ )
| (    \/| )   ( || (  )  || (    \/   ) (     | () () |  / /) |  | (    )|
| |      | (___) || | /   || (_____    | |     | || || | / (_) (_ | (____)|
| | ____ |  ___  || (/ /) |(_____  )   | |     | |(_)| |(____   _)|  _____)
| | \_  )| (   ) ||   / | |      ) |   | |     | |   | |     ) (  | (      
| (___) || )   ( ||  (__) |/\____) |   | |     | )   ( |     | |  | )      
(_______)|/     \|(_______)\_______)   )_(_____|/     \|     (_)  |/       
                                        (_____)                           """
   print("--------------------------------------------------------------------------------")
   print(text)
   print("Version "+str(version)+" "+version_stage+"\t\t\t\t Created by "+author)
   print("--------------------------------------------------------------------------------")
   print("")
   

def Space_Layout(DATA_LIST,STR_LENGTH):
   STR_LENGTH = len(str(DATA_LIST[STR_LENGTH]))
   LIST_LENGTHS = []
   MAX_LENGTH = 0
   for i in range (len(DATA_LIST)):
       LIST_LENGTHS.append(int(len(str(DATA_LIST[i]))))

   MAX_LENGTH = max(LIST_LENGTHS)
   SPACES = (" "*(int(MAX_LENGTH)-int(STR_LENGTH)+1))
   return SPACES 

def User_Error():
   print("Syntax invalid")
   print("---------------------------------------------------------------------------------------------------------")
   print("Usage: GH0ST_SC4NN3R.py -t <targets> -s <start_port> -e <end port> -l <list_of_ports> -v <veribosity level>")
   print("---------------------------------------------------------------------------------------------------------")
   print("Example: GH0ST_SC4NN3R.py -t 127.0.0.1 -s 80 -e 8080")
   print("---------------------------------------------------------------------------------------------------------")
   print("Example: GH0ST_SC4NN3R.py -t 127.0.0.1 -l 21,22,80,8080,443")
   print("---------------------------------------------------------------------------------------------------------")
   print("Example: GH0ST_SC4NN3R.py -t 127.0.0.1,192.168.1.1 -v 3")
   print("---------------------------------------------------------------------------------------------------------")
   print("Example: GH0ST_SC4NN3R.py -f ips.txt -l ")
   print("---------------------------------------------------------------------------------------------------------")
   print("Use -h for more info")
   print("")

def Command_Help():
   print("--------------------------------------------------------------------------------")
   print("'-h' Shows this help page")
   print("'-t <target_ip>' Specifiy the target you want to scan")
   print("'-s <start_port>' Specify the port that the scan starts from")
   print("'-e <end_port>' Specify the port that the scan end in")
   print("'-v <level>' The veribosity level of the script(1-4)")
   print("'-l <list...>' Allows you to specify a list of ports to scan")
   print("'-f <file>' Allows you to specify a file to read targets from(line seperated)")
   print("--------------------------------------------------------------------------------")

def Read_file(filename):
   try:
       ips = []
       F = open(filename,"r")
       for line in F:
           ips.append(line.strip())
       return ips
   except FileNotFoundError:
       print("[ERROR] IP file "+str(filename)+" not found")
       return []

def main(argv):
   skip_host = False
   targetIPs = []
   serv_name = []
   serv_state = []
   Target_Selected = 0
   Start_Port = 20
   End_Port = 1000
   Veribosity_Level = 1
   Port_List = []
   result = ""
   ARRAY_COUNTER = 0
   SERVICES_PRINTED = 0
   HELP_ENABLED = False
   dev_silent_on_error = False
   try:
       opts, args = getopt.getopt(sys.argv[1:],"t:s:e:v:l:f:h")
   except getopt.GetoptError:
       User_Error()
   try:
       for opt, arg in opts:
           if(opt == "-h"):
               HELP_ENABLED = True
           elif(opt == "-t"):  
               PL1 = arg.split(",")
               for i in range (len(PL1)):
                   targetIPs.append(gethostbyname(str(PL1[i])))
           elif(opt == "-s"):
               Start_Port = int(arg)
           elif(opt == "-e"):
               End_Port = int(arg)+1
           elif(opt == "-v"):
               Veribosity_Level = int(arg)
           elif(opt == "-l"):
               PL = arg.split(",")
               for i in range (0,(len(PL))):
                   Port_List.append(int(PL[i]))
           elif(opt == "-f"):
               try:
                   targetIPs = Read_file(arg)
               except:
                   HELP_ENABLED = True
                   exit(0)
           else:
               print("'",opt,"'"," is a invalid argument")
   except:
       raise Exception("Command Argument function failed")

   Banner()
   if(len(targetIPs) == 1):
       print("Starting scan on host "+str(targetIPs[Target_Selected]))
   elif(len(targetIPs) >= 1):
       hosts = ""
       for i in range (len(targetIPs)):
           if(i < (len(targetIPs)-1)):
               hosts += targetIPs[i]+"-"
           else:
               hosts += targetIPs[i]
       print("Starting scan on hosts "+hosts)
   else:
       if(HELP_ENABLED == False):
           print("No Hosts Found")
       else:
           Command_Help()
   if(Port_List != []):
       Start_Port = 0
       End_Port = len(Port_List)
   for i2 in range(len(targetIPs)):
       print("")
       try:
           if(dev_silent_on_error == False):
               print("Services for "+(str(gethostbyaddr(targetIPs[Target_Selected])[0]))+" ["+targetIPs[Target_Selected]+"] ["+str(len(targetIPs)-(i2))+" hosts left]:")
       except:
           print("[ERROR]: "+targetIPs[i2]+" is unreachable")
           skip_host = True
       print("----------------------------------------") if SERVICES_PRINTED == 0 else ...
       
       for i in range(Start_Port, End_Port):
           if skip_host == False:
               s = socket(AF_INET, SOCK_STREAM)
               result = s.connect_ex((targetIPs[Target_Selected], (int(Port_List[i])) if Port_List!= [] else i))
               
               if(result == 0):
                   serv_state.append("OPEN")
               elif(result == 10061 or Veribosity_Level <= 2):
                   serv_state.append("CLOSED")
               elif(Veribosity_Level >= 2):
                   serv_state.append("UNKNOWN")
               else:
                   serv_state.append("ERROR")
               try:
                   if(serv_state[ARRAY_COUNTER] == "OPEN"):
                       serv_name.append(str(getservbyport(Port_List[i])) if Port_List != [] else str(getservbyport(i)))
                   else:
                       serv_name.append("")   
               except:
                   serv_name.append("Unknown")
               
               SERVICES_PRINTED+=1
               if(Veribosity_Level == 1 and serv_state[ARRAY_COUNTER] != "UNKNOWN" and serv_state[ARRAY_COUNTER] != "CLOSED"):
                   print((str(Port_List[i])+Space_Layout(Port_List,i)+(str(serv_state[ARRAY_COUNTER]))+Space_Layout(serv_state,ARRAY_COUNTER)+str(serv_name[ARRAY_COUNTER]) if Port_List != [] else str(i)+" "+str(serv_state[ARRAY_COUNTER])+Space_Layout(serv_state,ARRAY_COUNTER)+str(serv_name[ARRAY_COUNTER])))
               elif(Veribosity_Level == 2 and serv_state[ARRAY_COUNTER] != "UNKNOWN"):
                   print((str(Port_List[i])+Space_Layout(Port_List,i)+(str(serv_state[ARRAY_COUNTER]))+Space_Layout(serv_state,ARRAY_COUNTER)+str(serv_name[ARRAY_COUNTER]) if Port_List != [] else str(i)+" "+str(serv_state[ARRAY_COUNTER])+Space_Layout(serv_state,ARRAY_COUNTER)+str(serv_name[ARRAY_COUNTER])))
               elif(Veribosity_Level == 3):
                   print((str(Port_List[i])+Space_Layout(Port_List,i)+(str(serv_state[ARRAY_COUNTER]))+Space_Layout(serv_state,ARRAY_COUNTER)+str(serv_name[ARRAY_COUNTER]) if Port_List != [] else str(i)+" "+str(serv_state[ARRAY_COUNTER])+Space_Layout(serv_state,ARRAY_COUNTER)+str(serv_name[ARRAY_COUNTER])))
               elif(Veribosity_Level == 4):
                   print((str(Port_List[i])+Space_Layout(Port_List,i)+(str(serv_state[ARRAY_COUNTER]))+Space_Layout(serv_state,ARRAY_COUNTER)+str(serv_name[ARRAY_COUNTER]) if Port_List != [] else str(i)+" "+str(serv_state[ARRAY_COUNTER])+Space_Layout(serv_state,ARRAY_COUNTER)+str(serv_name[ARRAY_COUNTER])))
               elif(Veribosity_Level < 1 or Veribosity_Level > 4 ):
                   raise Exception("Invalid Veribosity level: "+str(Veribosity_Level)+" only levels between 1 and 4 are valid")
                   os.kill()
               else:
                   SERVICES_PRINTED-=1
               s.close()
               ARRAY_COUNTER+=1
       print("----------------------------------------") if SERVICES_PRINTED != 0 else ...
       if(dev_silent_on_error == False and SERVICES_PRINTED == 0):
           print("No Open Ports were found")
           print("----------------------------------------")
       SERVICES_PRINTED=0
       Target_Selected+=1
       skip_host = False
       
if __name__ == "__main__":
  main(sys.argv[1:])