--- name: scanning-network-with-nmap-advanced-57b686209b29 description: 'Performs advanced network recon using Nmap''s Scripting Engine (NSE), timing controls, firewall/IDS evasion, and structured output parsing to discover hosts, enumerate service versions, detect vulnerabilities, and fingerprint OSes. Use during authorized penetration tests or enterprise asset-discovery assessments needing scan evasion, NSE vulnerability checks, or output fed into a vulnerability management pipeline. ' domain: cybersecurity subdomain: network-security tags: - network-security - nmap - port-scanning - service-enumeration - reconnaissance version: '1.0' author: mahipal license: Apache-2.0 nist_csf: - PR.IR-01 - DE.CM-01 - ID.AM-03 - PR.DS-02 mitre_attack: - T1046 - T1040 - T1557 - T1071 - T1595 --- # Scanning Network with Nmap Advanced Techniques ## When to Use - Performing comprehensive asset discovery across large enterprise networks during authorized assessments - Enumerating service versions and configurations to identify outdated or vulnerable software - Bypassing firewall rules and IDS during authorized penetration tests using scan evasion techniques - Scripting automated vulnerability checks using the Nmap Scripting Engine (NSE) - Generating structured scan output for integration into vulnerability management pipelines **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. ## Prerequisites - Nmap 7.90+ installed (`nmap --version` to verify) - Root/sudo privileges for SYN scans, OS detection, and raw packet techniques - Written authorization specifying in-scope IP ranges and any excluded hosts - Network access to target ranges (VPN, direct connection, or jump host) - Familiarity with TCP/IP protocols and common port assignments ## Workflow ### Step 1: Host Discovery with Multiple Probes Use layered discovery to find live hosts even when ICMP is blocked: ```bash # 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: ```bash grep "Host:" discovery_combined.gnmap | awk '{print $2}' | sort -t. -k1,1n -k2,2n -k3,3n -k4,4n > live_hosts.txt ``` ### Step 2: Port Scanning with Timing and Performance Tuning ```bash # 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 ``` ### Step 3: Service Version Detection and OS Fingerprinting ```bash # Aggressive service detection with version intensity nmap -sV --version-intensity 5 -sC -O --osscan-guess -p -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 -oN service_detail.txt ``` ### Step 4: NSE Vulnerability Scanning ```bash # Run vulnerability detection scripts nmap --script vuln -p -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 ``` ### Step 5: Firewall Evasion Techniques ```bash # Fragment packets to evade simple packet inspection nmap -sS -f --mtu 24 -p 80,443 -oN fragmented_scan.txt # Use decoy addresses to obscure scan origin nmap -sS -D RND:10 -p 80,443 -oN decoy_scan.txt # Spoof source port as DNS (53) to bypass poorly configured firewalls nmap -sS --source-port 53 -p 1-1024 -oN spoofed_port_scan.txt # Idle scan using a zombie host (completely stealthy) nmap -sI -p 80,443,445 -oN idle_scan.txt # Slow scan to evade IDS rate-based detection nmap -sS -T1 --max-rate 10 -p 1-1024 -oA stealth_scan ``` ### Step 6: Output Parsing and Reporting ```bash # 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 ``` ## Key Concepts | 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 | ## Tools & Systems - **Nmap 7.90+**: Core scanning engine with NSE scripting, OS detection, version probing, and multiple output formats - **nmap-parse-output**: Community tool for parsing Nmap XML output into structured formats (CSV, JSON, host lists) - **Ndiff**: Nmap utility for comparing two scan results to identify changes in network state over time - **Zenmap**: Official Nmap GUI providing visual network topology mapping and scan profile management - **Metasploit Framework**: Imports Nmap XML output for direct correlation of scan results with exploit modules ## Common Scenarios ### Scenario: Enterprise Network Asset Discovery and Vulnerability Baseline **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**: 1. Run layered host discovery using ARP (local subnets), TCP SYN (ports 22,80,443,445,3389), and ICMP echo probes across all /24 subnets 2. Perform a full TCP SYN scan on discovered hosts using `--min-rate 5000` and `-T4` to complete within the window 3. Run service version detection and default NSE scripts on all open ports 4. Execute targeted NSE vulnerability scripts for critical services (SMB, SSL/TLS, HTTP) 5. Parse XML output to generate per-subnet CSV reports and import into the vulnerability management platform 6. Schedule Ndiff comparisons against future scans to track remediation progress **Pitfalls**: - Setting `--min-rate` too high on congested network segments causing packet loss and false negatives - Running `-T5` (Insane) timing on production networks, potentially overwhelming older network devices - Forgetting to scan UDP ports, missing critical services like SNMP (161), DNS (53), and TFTP (69) - Not saving output in XML format (`-oX` or `-oA`), losing structured data for downstream tool integration ## Output Format ``` ## 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 ``` --- Source attribution: costrict-plugins-repo Original project: https://github.com/costrict-plugins-repo/mukul975-anthropic-cybersecurity-skills-cybersecurity-skills/blob/1b344d155f00bae5cf27d8eba9508e8f5050d904/skills/scanning-network-with-nmap-advanced/SKILL.md License: Apache-2.0 License information: https://www.apache.org/licenses/LICENSE-2.0 Original upstream instructions; downloaded from Mega AI Hub. ## Upstream license notice Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Definitions. "License" shall mean the terms and conditions for use, reproduction, and distribution as defined by Sections 1 through 9 of this document. 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See the License for the specific language governing permissions and limitations under the License. # Mega AI Hub resource metadata Creator / publisher: costrict-plugins-repo Original project: https://github.com/costrict-plugins-repo/mukul975-anthropic-cybersecurity-skills-cybersecurity-skills/blob/1b344d155f00bae5cf27d8eba9508e8f5050d904/skills/scanning-network-with-nmap-advanced/SKILL.md Attribution basis: Source repository record Fields of work: Development & Engineering Roles: Security Engineer Specialties: API Tools: Nmap Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: 8784d7efb36ac28e825fe499befcf57626b202fb6e60b8e56099b935321656a7