add dhcp listener tutorial

x4nth055 · x4nth055 · commit be6e68bbbca4 · 2022-04-05T18:03:12.000+01:00
diff --git a/README.md b/README.md
@@ -7,7 +7,7 @@ This is a repository of all the tutorials of [The Python Code](https://www.thepy
         - [Getting Started With Scapy: Python Network Manipulation Tool](https://www.thepythoncode.com/article/getting-started-with-scapy)
         - [Building an ARP Spoofer](https://www.thepythoncode.com/article/building-arp-spoofer-using-scapy). ([code](scapy/arp-spoofer))
         - [Detecting ARP Spoof attacks](https://www.thepythoncode.com/article/detecting-arp-spoof-attacks-using-scapy). ([code](scapy/arp-spoof-detector))
-        - DHCP Listener script. ([code](scapy/dhcp_listener))
+        - [How to Make a DHCP Listener using Scapy in Python](https://www.thepythoncode.com/article/dhcp-listener-using-scapy-in-python). ([code](scapy/dhcp_listener))
         - [Fake Access Point Generator](https://www.thepythoncode.com/article/create-fake-access-points-scapy). ([code](scapy/fake-access-point))
         - [Forcing a device to disconnect using scapy in Python](https://www.thepythoncode.com/article/force-a-device-to-disconnect-scapy). ([code](scapy/network-kicker))
         - [Simple Network Scanner](https://www.thepythoncode.com/article/building-network-scanner-using-scapy). ([code](scapy/network-scanner))
diff --git a/scapy/dhcp_listener/README.md b/scapy/dhcp_listener/README.md
@@ -1,7 +1,7 @@
-# Listening for new Connected Devices in the Network using DHCP
+# [How to Make a DHCP Listener using Scapy in Python](https://www.thepythoncode.com/article/dhcp-listener-using-scapy-in-python)
 to run this:
 - `pip3 install -r requirements.txt`
 -   
     ```
-    python3 dhcp_listener.py
+    $ python3 dhcp_listener.py
     ```
diff --git a/scapy/dhcp_listener/dhcp_listener.py b/scapy/dhcp_listener/dhcp_listener.py
@@ -1,16 +1,16 @@
 from scapy.all import *
 import time
 
-hosts = []
-Ether = 1
-
 
 def listen_dhcp():
     # Make sure it is DHCP with the filter options
-    k = sniff(prn=print_packet, filter='udp and (port 67 or port 68)')
+    sniff(prn=print_packet, filter='udp and (port 67 or port 68)')
+
 
 def print_packet(packet):
+    # initialize these variables to None at first
     target_mac, requested_ip, hostname, vendor_id = [None] * 4
+    # get the MAC address of the requester
     if packet.haslayer(Ether):
         target_mac = packet.getlayer(Ether).src
     # get the DHCP options
@@ -21,15 +21,18 @@ def print_packet(packet):
         except ValueError:
             continue
         if label == 'requested_addr':
+            # get the requested IP
             requested_ip = value
         elif label == 'hostname':
+            # get the hostname of the device
             hostname = value.decode()
         elif label == 'vendor_class_id':
+            # get the vendor ID
             vendor_id = value.decode()
-        if target_mac and vendor_id and hostname and requested_ip and target_mac not in hosts:
-            hosts.append(target_mac)
-            time_now = time.strftime("[%Y-%m-%d - %H:%M:%S] ")
-            print("{}: {}  -  {} / {} requested {}".format(time_now, target_mac, hostname, vendor_id, requested_ip))
+    if target_mac and vendor_id and hostname and requested_ip:
+        # if all variables are not None, print the device details
+        time_now = time.strftime("[%Y-%m-%d - %H:%M:%S]")
+        print(f"{time_now} : {target_mac}  -  {hostname} / {vendor_id} requested {requested_ip}")
 
 
 if __name__ == "__main__":
