ARP Watcher

With Address Resolution Protocol (ARP), we can find live internal hosts. We can write a script to scan for hosts in a given network with Scapy.

How to do it...

We can write a ARP Watcher with the following steps:

1. Create an arp-scanner.py file and open it in your editor.
2. We then have to import the required modules:

from scapy.all import *

3. Now declare the variables for the script:

interface = "en0"
ip_rage = "192.168.1.1/24"
broadcastMac = "ff:ff:ff:ff:ff:ff"

4. Now we can send ARP packets to all the IPs in the IP range, and get answered and unanswered packets.
5. Create the ARP packet as follows:

pkt = Ether(dst=broadcastMac)/ARP(pdst = ip_rage) 

The structure of the packet will be as follows:

6. Then, send the packet with srp() and receive the response:

answered, unanswered = srp(pkt, timeout =2, iface=interface, inter=0.1)

7. Next, iterate through all the answered packets and print their MAC and IPs:

for send,recive in ans:
print (recive.sprintf(r"%Ether.src% - %ARP.psrc%"))  

8. Now, run the script with...