Sniffer: Probe Request Sniffer

Code:
#!/usr/bin/env python
#RUN WITH python probreqsniff.py

import os
from scapy.all import *

def check_wireless_interfaces():
        chk_wl_int=os.popen("ifconfig | sed 's/[ \t].*//;/^\(lo\|\)$/d;/eth/d' | grep wlan").read() #Check if wlan interfaces are activated
        if not chk_wl_int:
                print ("[+] No wireless interface available. You must turn on a wireless interface.")
                print ("[+] Closing")
                exit()
        else:
                print ("[+] Wireless interface detected")

def check_monitor():
        chk_mon=os.popen("ifconfig | sed 's/[ \t].*//;/^\(lo\|\)$/d;/eth/d' | grep mon").read() #Check if monitor mode has been enabled
        if not chk_mon:
                print ("[+] No monitoring interface detected")
                print ("[+] Available wireless interface(s)\n")
                wl_int_list=os.popen("ifconfig | sed 's/[ \t].*//;/^\(lo\|\)$/d;/eth/d' | grep wlan").read() #Listing wlan interfaces
                print wl_int_list
                int_mon=raw_input("[+] Which interface do you want to monitor?: ")
                while (int_mon != "wlan0") and (int_mon != "wlan1") and (int_mon != "wlan2") and (int_mon != "wlan3"):
                        int_mon=raw_input("[+] Choose an interface from the list: ")
                print ("[+] Trying to enable monitoring on interface "+int_mon)
                os.system("airmon-ng start "+int_mon+" > /dev/null 2>&1") #Activate monitoring on choosen interface
                chk_mon=os.popen("ifconfig | sed 's/[ \t].*//;/^\(lo\|\)$/d;/eth/d' | grep mon").read() #Checking again if monitor mode is enabled
                if not chk_mon:
                        print ("[+] Monitoring couldn't be enabled on interface "+int_mon)
                        print ("[+] Closing")
                else:
                        print ("[+] Monitoring enabled on interface "+int_mon)
        else:
                print ("[+] Monitoring interface detected")

def sniff_probe(p):
        if (p.haslayer(Dot11ProbeReq)): #Checking if Dot11ProbeReq is present
                mac_address=(p.addr2) #Grabbing source mac address
                ssid=p[Dot11Elt].info #Grabbing ssid
                ssid=ssid.decode('utf-8','ignore') #Translating ssid
                if ssid == "":
                        ssid="null"
                else:
                        print "[>] Probe Request from %s for SSID '%s'" %(mac_address,ssid)

print ("[+] Checking wireless interface")
check_wireless_interfaces()
print ("[+] Checking monitoring mode")
check_monitor()
print ("[+] Starting capture - CTRL + C to stop")
sniff(iface="mon0",prn=sniff_probe)