Hands-On Penetration Testing with Kali NetHunter

Idle scans

An older but still usable method of scanning is using the idle scan technique. Within an idle scan, the attacker machines (device A) send a SYN/ACK packet to a zombie machine (device B) to obtain its fragmentation identification number.

IPID is sometimes referred to as IP fragmentation ID. Within the TCP/IP stack, before a device sends a datagram (message) onto a network, it is broken up into smaller pieces and then each is sent on its way to the destination. An IPID is assigned to each of these smaller pieces of the message (bits) to indicate they are of the same datagram or message.

Since the attacker machine did not initiate ...