Target Specification
1. -iL (Input from list)
This option allows you to scan targets listed in a file. The file can contain IPs, hostnames, CIDR ranges, or octet ranges.
Example:
Where target_list.txt contains:
2. -iR (Choose random targets)
Randomly generates a specified number of IP addresses to scan.
Example:
This command scans 1000 randomly chosen IPs on port 80.
3. --exclude [,[,...]] (Exclude hosts/networks)
Excludes certain hosts or networks from the scan.
Example:
This command will scan the entire 192.168.1.0/24 network except for 192.168.1.1 and 192.168.1.50.
4. --excludefile <exclude_file> (Exclude list from file)
Similar to --exclude, but the excluded targets come from a file.
Example:
Where exclude_list.txt contains:
5. -n (No DNS resolution)
Disables reverse DNS resolution during the scan.
Example:
This scans the 192.168.1.0/24 network without attempting DNS resolution.
6. -R (DNS resolution for all targets)
Forces Nmap to perform reverse DNS resolution on all targets, even if they aren't active.
Example:
This command resolves the hostnames of all targets, even if they are down.
7. --resolve-all (Scan each resolved address)
Scans all resolved addresses when a hostname resolves to multiple IPs.
Example:
This scans all IPs associated with example.com.
8. --unique (Scan each address only once)
Ensures that each IP address is scanned only once, even if it appears multiple times in the target list.
Example:
This ensures that 192.168.1.1 is scanned only once, despite being listed twice.
9. --system-dns (Use system DNS resolver)
Forces Nmap to use the system's DNS resolver rather than Nmap's parallel resolver.
Example:
This forces the system's DNS resolver to resolve the target instead of Nmap's default.
10. --dns-servers [,[,...]] (Servers to use for reverse DNS queries)
Specifies custom DNS servers for reverse DNS queries.
Example:
This uses Google’s DNS servers (8.8.8.8 and 8.8.4.4) for reverse DNS resolution.
These examples demonstrate how to fine-tune Nmap's target selection and DNS options for different scanning needs, from basic network sweeps to customized DNS lookups and exclusions.
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