IP and MAC Spoofing Using Nmap

Getting detected by firewalls and intrusion detection systems (IDSs) is a primary concern while using Nmap. We can minimize detection by spoofing IPs with Nmap. It allows us to alter the source IP address of a packet, making it appear as if it came from a different IP address.

Let’s explore this concept in detail.

What is IP spoofing?

Nmap allows us to specify the source IP address for the packets it sends, which can be used for masking the origin of the scan or bypassing firewall rules. This is known as IP spoofing. Using this approach, even if an IDS picks up an attacker’s IP, it can’t be easily traced back to the attacker.

Before we start looking at IP spoofing, there are two things to keep in mind:

• IP spoofing doesn’t give us a response back. The response goes to the spoofed IP address. This spoofing is usually done when the attacker and the target are on the same network. This helps an attacker monitor the traffic using a tool like Wireshark to analyze the responses from the target.

• IP spoofing is often used by malicious attackers. This will rarely be requested during a pen testing audit. Therefore, understand the legal and ethical concerns in IP spoofing before attempting it. Make sure you have permission to spoof the target.

There are two flags used for spoofing in Nmap: –S and –spoof-mac. The first flag takes an IP address, and the second flag takes a MAC address. A MAC address is a unique system ID that comes with every computer. The MAC address is used primarily within internal networks and isn’t transmitted over the internet.

Here’s the syntax for IP and MAC spoofing: