How to Use the Command 'netdiscover' (with Examples)

Netdiscover is an open-source network reconnaissance tool that is used for scanning and identifying live hosts on a network. This command is particularly useful for network administrators and cybersecurity professionals who need to understand which devices are currently active on their networks. It operates by sending ARP requests to a specified range of IP addresses or on a particular network interface, and it listens for ARP replies to identify live hosts.

Use Case 1: Scan the IP range on the network interface for active hosts

Code:

netdiscover -r 172.16.6.0/23 -i ens244

Motivation:

This use case is particularly valuable for network administrators or IT professionals who need to manage and monitor network resources actively. By scanning a specific range of IP addresses, administrators can quickly identify all active devices within the specified subnet. This can be crucial for network auditing, inventorying networked devices, identifying unauthorized devices, or simply understanding the network’s structure and its varying load. It helps in ensuring that network resources are optimally utilized and offers a security perspective by identifying devices that may not have been accounted for.

Explanation:

• netdiscover: This is the command that invokes the network scanning tool, netdiscover.

• -r 172.16.6.0/23: The -r option specifies the IP range to scan. Here, 172.16.6.0/23 indicates the subnet that will be scanned. This CIDR notation implies a range that spans 512 IP addresses from 172.16.6.0 to 172.16.7.255.

• -i ens244: The -i flag specifies the network interface to use for the scan. In this context, ens244 is the name of the network interface on which netdiscover will listen and send ARP requests. It’s crucial to select the correct network interface that is connected to the network you intend to scan to ensure that the scan results are accurate.

Example Output:

Currently scanning: 172.16.6.0/23   |   Screen View: Unique Hosts
192.168.6.1     00:1A:2B:3C:4D:5E  (Unknown Vendor)
192.168.6.5     00:1A:2B:3C:4D:6F  (Dell Inc)
192.168.7.10    00:1A:2B:AA:BB:CC  (HP)

This output illustrates the active devices detected within the specified IP range. It displays the IP addresses along with the corresponding MAC addresses and vendor information if available. This provides an accessible overview of who or what is active on the network, aiding in both network management and security auditing.

Conclusion:

Netdiscover proves to be a powerful yet straightforward tool for network scanning, particularly useful for tasks such as network monitoring, device auditing, and security assessments. By simply specifying the IP range and network interface, users can swiftly determine which hosts are live on their network. Its ease of use and ability to provide instant insights into network activity make it an essential tool for administrators and security experts alike.