Performs advanced network reconnaissance using Nmap's scripting engine, timing controls, evasion techniques, and output parsing to discover hosts, enumerate services, detect vulnerabilities, and fingerprint operating systems across authorized target networks.
Do not use against networks without explicit written authorization, on production systems during peak hours without approval, or to perform denial-of-service through aggressive scan timing.
nmap --version to verify)Use layered discovery to find live hosts even when ICMP is blocked:
# ARP discovery for local subnet (most reliable on LAN)
nmap -sn -PR 192.168.1.0/24 -oA discovery_arp
# Combined ICMP + TCP + UDP probes for remote networks
nmap -sn -PE -PP -PS21,22,25,80,443,445,3389,8080 -PU53,161,500 10.0.0.0/16 -oA discovery_combined
# List scan to resolve DNS names without sending packets to targets
nmap -sL 10.0.0.0/24 -oN dns_resolution.txt
Consolidate results into a live hosts file:
grep "Host:" discovery_combined.gnmap | awk '{print $2}' | sort -t. -k1,1n -k2,2n -k3,3n -k4,4n > live_hosts.txt
# Full TCP SYN scan with optimized timing
nmap -sS -p- --min-rate 5000 --max-retries 2 -T4 -iL live_hosts.txt -oA full_tcp_scan
# Top 1000 UDP ports with version detection
nmap -sU --top-ports 1000 --version-intensity 0 -T4 -iL live_hosts.txt -oA udp_scan
# Specific port ranges for targeted assessment
nmap -sS -p 1-1024,3306,5432,6379,8080-8090,9200,27017 -iL live_hosts.txt -oA targeted_ports
# Aggressive service detection with version intensity
nmap -sV --version-intensity 5 -sC -O --osscan-guess -p <open_ports> -iL live_hosts.txt -oA service_enum
# Specific service probing for ambiguous ports
nmap -sV --version-all -p 8443 --script ssl-cert,http-title,http-server-header <target> -oN service_detail.txt
# Run vulnerability detection scripts
nmap --script vuln -p <open_ports> -iL live_hosts.txt -oA vuln_scan
# Target specific vulnerabilities
nmap --script smb-vuln-ms17-010,smb-vuln-ms08-067 -p 445 -iL live_hosts.txt -oA smb_vulns
nmap --script ssl-heartbleed,ssl-poodle,ssl-ccs-injection -p 443,8443 -iL live_hosts.txt -oA ssl_vulns
# Brute force default credentials on discovered services
nmap --script http-default-accounts,ftp-anon,ssh-auth-methods -p 21,22,80,8080 -iL live_hosts.txt -oA default_creds
# Fragment packets to evade simple packet inspection
nmap -sS -f --mtu 24 -p 80,443 <target> -oN fragmented_scan.txt
# Use decoy addresses to obscure scan origin
nmap -sS -D RND:10 -p 80,443 <target> -oN decoy_scan.txt
# Spoof source port as DNS (53) to bypass poorly configured firewalls
nmap -sS --source-port 53 -p 1-1024 <target> -oN spoofed_port_scan.txt
# Idle scan using a zombie host (completely stealthy)
nmap -sI <zombie_host> -p 80,443,445 <target> -oN idle_scan.txt
# Slow scan to evade IDS rate-based detection
nmap -sS -T1 --max-rate 10 -p 1-1024 <target> -oA stealth_scan
# Convert XML output to HTML report
xsltproc full_tcp_scan.xml -o scan_report.html
# Extract open ports per host from grepable output
grep "Ports:" full_tcp_scan.gnmap | awk -F'Ports: ' '{print $1 $2}' > open_ports_summary.txt
# Parse XML with nmap-parse-output for structured data
nmap-parse-output full_tcp_scan.xml hosts-to-port 445
# Import into Metasploit database
msfconsole -q -x "db_import full_tcp_scan.xml; hosts; services; exit"
# Generate CSV for vulnerability management tools
nmap-parse-output full_tcp_scan.xml csv > scan_results.csv
| Term | Definition |
|---|---|
| SYN Scan (-sS) | Half-open TCP scan that sends SYN packets and analyzes responses without completing the three-way handshake, making it faster and stealthier than connect scans |
| NSE (Nmap Scripting Engine) | Lua-based scripting framework built into Nmap that enables vulnerability detection, brute forcing, service discovery, and custom automation |
| Timing Templates (-T0 to -T5) | Predefined scan speed profiles ranging from Paranoid (T0) to Insane (T5), controlling probe parallelism, timeout values, and inter-probe delays |
| Idle Scan (-sI) | Advanced scan technique that uses a zombie host's IP ID sequence to port scan a target without sending packets from the scanner's own IP address |
| Version Intensity | Controls how many probes Nmap sends to determine service versions, ranging from 0 (light) to 9 (all probes), trading speed for accuracy |
| Grepable Output (-oG) | Legacy Nmap output format designed for easy parsing with grep, awk, and sed for scripted analysis of scan results |
Context: A security team needs to establish a vulnerability baseline for a corporate network spanning 10.0.0.0/8 with approximately 5,000 active hosts. Scanning must complete within a weekend maintenance window with minimal network disruption.
Approach:
--min-rate 5000 and -T4 to complete within the windowPitfalls:
--min-rate too high on congested network segments causing packet loss and false negatives-T5 (Insane) timing on production networks, potentially overwhelming older network devices-oX or -oA), losing structured data for downstream tool integration## Nmap Scan Summary
**Scan Profile**: Full TCP + Top 200 UDP + Service Enumeration
**Target Range**: 10.10.0.0/16
**Hosts Discovered**: 347 live hosts
**Scan Duration**: 2h 14m
### Critical Findings
| Host | Port | Service | Version | Vulnerability |
|------|------|---------|---------|---------------|
| 10.10.5.23 | 445/tcp | SMB | Windows Server 2012 R2 | MS17-010 (EternalBlue) |
| 10.10.8.100 | 443/tcp | Apache httpd | 2.4.29 | CVE-2021-41773 (Path Traversal) |
| 10.10.12.5 | 3306/tcp | MySQL | 5.6.24 | CVE-2016-6662 (RCE) |
| 10.10.3.77 | 161/udp | SNMP | v2c | Public community string |
### Recommendations
1. Patch MS17-010 on 10.10.5.23 immediately -- Critical RCE vulnerability
2. Upgrade Apache httpd to 2.4.58+ on 10.10.8.100
3. Upgrade MySQL to 8.0.x on 10.10.12.5 and restrict bind address
4. Change SNMP community strings from "public" on 10.10.3.77