What is a NIC?

NIC stands for Network Interface Card. It's a hardware component that allows your computer to connect to a network. Think of it as the physical port that connects your computer to the outside world.

A computer network is a collection of interconnected computers and devices that can share resources and communicate with each other.

What is a MAC Address?

A MAC address (Media Access Control address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment.

Key points about MAC addresses:

• Unique: Each device with a network interface has a unique MAC address.
• Hardware-based: It's embedded into the network card during manufacturing, making it difficult to change.
• Format: Typically represented as six groups of two hexadecimal digits separated by colons (e.g., 01:23:45:67:89:AB).
• Local network: MAC addresses are used for communication within a local network.
• Not routable: Unlike IP addresses, MAC addresses cannot be used to identify devices across different networks.

Think of a MAC address as a physical address for your network device. It helps devices on the same network to recognize and communicate with each other.

What is Address Resolution Protocol

ARP is a network protocol used to find the MAC address of a device based on its IP address. It's essential for communication within a local network (LAN).

How ARP Works?

• Need for MAC address: When a device wants to send data to another device on the same network, it needs the recipient's MAC address.
• ARP request: The sending device broadcasts an ARP request asking for the MAC address associated with a specific IP address.
• ARP reply: The device with the matching IP address responds with an ARP reply, providing its MAC address.
• Communication: The sending device now has the MAC address and can send data directly to the recipient.
• Local network: ARP works within a single network segment.
• Dynamic: ARP mappings are dynamic, meaning they can change as devices join or leave the network.
• ARP cache: Devices maintain an ARP cache to store recently discovered MAC address-IP address mappings for efficiency.

ARP Broadcast and Reply packets captured by Wireshark

ARP Poisoning

ARP poisoning, also known as ARP spoofing or ARP cache poisoning, is a type of cyberattack that exploits a vulnerability in the Address Resolution Protocol (ARP) to disrupt or intercept network traffic.

How it Works?

• ARP Basics: ARP is used to map IP addresses to MAC addresses on a local network.
• The Attack: An attacker sends forged ARP messages to devices on the network, falsely associating their own MAC address with the IP address of another device (often the default gateway).
• Man-in-the-Middle: This allows the attacker to intercept and potentially modify network traffic between the targeted devices.

Using arpspoof in Kali Linux to spoof Target 1

Using arpspoof in Kali Linux to spoof Target 2

Target 1 arp cache updated with the mac address of Hacker

Target 2 arp cache updated with the mac address of Hacker

Intercepting data from Target 1 to Target 2 using Wireshark

Consequences

• Data interception: The attacker can eavesdrop on network traffic to steal sensitive information.
• Man-in-the-middle attacks: The attacker can modify or inject data into the network traffic.
• Denial of service: The attacker can disrupt network communication by flooding the network with forged ARP messages.

How to Mitigate Arp Spoofing

• Static ARP Entries: Manually configure ARP entries for critical devices, preventing the ARP cache from being poisoned.
• DHCP Snooping: Enable DHCP snooping on your router to verify the authenticity of DHCP messages.
• Port Security: Configure port security on network switches to restrict the number of devices that can connect to a port.
• Firewall: Implement packet filtering firewalls to detect and block suspicious ARP traffic.
• Intrusion Detection Systems (IDS): Deploy IDS solutions to monitor network traffic for signs of ARP spoofing.
• Network Segmentation: Divide the network into smaller segments to limit the impact of a successful attack.

Disclaimer

The content provided on this page is for educational purposes only. It is intended to demonstrate the vulnerabilities of computer systems and networks and to promote ethical hacking practices. Any unauthorized use of the information or tools presented here is strictly prohibited and may violate applicable laws.

By accessing and using this information, you agree to the following:

• No Malicious Use: You will not use the information or tools to harm others, damage property, or violate any laws.
• Ethical Use: You will use the information and tools responsibly and ethically, respecting the privacy and security of others.
• Legal Compliance: You will comply with all applicable laws and regulations regarding hacking and cybersecurity.

It is important to note that hacking systems without proper authorization is illegal and unethical. If you have concerns about the security of your own systems, please consult with a qualified security professional.