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-sI Idlescan. Greatest stealth of any nmap scan - Completely “blind” scanning - no packets are sent to target from machine running nmap Investigate IP-based trust relationships of target network. Idlescan technique.
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-sI Idlescan • Greatest stealth of any nmap scan - Completely “blind” scanning - no packets are sent to target from machine running nmap • Investigate IP-based trust relationships of target network
Idlescan technique • Exploits OS’s that predictably increment their fragmentation ID numbers (IPID) whenever they send a packet • Zombie used to mask the original source of the scan must have this property - excludes OpenBSD, Solaris, recent Linux • A Zombie candidate must also be “idle” - no network traffic during scan other than communication with nmap machine - nmap will rely on IPID number of zombie to determine how the target has responded to the zombie with respect to the forged portscan • Zombie must be susceptible to responding to SYN/ACK packet with a RST packet which nmap derives the IPID from • Nmap automatically tests reliability of zombie