Free Nmap Online Port Scanner – Advanced Network Security Tool
🔒 Free Nmap Online Port Scanner
Free Nmap online port scanner. Scan networks, detect services, identify OS & vulnerabilities. Professional security testing tool. No installation required.
✨ Free · No Registration Required · Enterprise-Grade SecurityScan port with Nmap
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What is Nmap Online Port Scan?
Nmap (Network Mapper) Online Port Scanner is a powerful web-based network security tool that allows you to perform comprehensive port scanning, service detection, OS fingerprinting, and vulnerability assessment directly from your browser. Our advanced implementation provides enterprise-grade network analysis capabilities without requiring software installation.
Key Features
Advanced Port Scanning
Perform multiple scan types including SYN Stealth Scan, TCP Connect, UDP scanning, and full network sweeps. Scan single hosts, IP ranges, or entire subnets with support for all 65,535 TCP and UDP ports.
Service Version Detection
Automatically identify and fingerprint services running on open ports with precise version information. Interrogates network services using 6,500+ signatures across 650+ different services.
OS Fingerprinting
Identify operating systems and device types through advanced TCP/IP stack analysis. Database of 2,600+ OS fingerprints for accurate system identification.
NSE Script Scanning
Leverage the Nmap Scripting Engine for advanced security auditing, vulnerability detection, and network discovery with 600+ specialized scripts.
Vulnerability Detection
Identify potential security vulnerabilities by correlating service versions with known CVE databases. Detect outdated software and security misconfigurations.
Professional Reporting
Generate comprehensive scan reports with multiple export formats including JSON, CSV, and PDF for documentation and compliance requirements.
Common Use Cases
- Network Security Auditing: Identify unauthorized services, verify firewall rules, and detect security misconfigurations
- Penetration Testing: Map attack surfaces, discover vulnerable services, and test network defenses
- Compliance Verification: Ensure systems meet ISO 27001, SOC 2, PCI DSS, and other security standards
- Network Inventory: Document all devices, services, and applications running on your network
- Troubleshooting: Diagnose connectivity issues, verify service availability, and test firewall configurations
- Security Monitoring: Track changes in network topology, detect rogue devices, and monitor exposed services
Port States Explained
Open: An application is actively accepting TCP connections, UDP datagrams, or SCTP associations on this port. This is typically the primary goal of port scanning as open ports represent potential attack vectors.
Closed: The port is accessible and responds to probe packets, but no application is listening. Closed ports can still provide valuable information about the target system.
Filtered: Packet filtering prevents probes from reaching the port. This typically indicates a firewall, router rule, or host-based filtering is blocking access.
Unfiltered: The port is accessible but Nmap cannot determine if it’s open or closed. Only the ACK scan classifies ports this way.
Open|Filtered: Nmap cannot determine if the port is open or filtered. This occurs when open ports give no response.
Closed|Filtered: Nmap cannot determine if the port is closed or filtered. Only used for IP ID idle scan.
Best Practices
- Always obtain explicit permission before scanning networks you don’t own
- Start with less aggressive scan types (T2-T3) to avoid triggering IDS/IPS systems
- Use targeted port ranges instead of full scans when possible to reduce scan time
- Enable service detection to get accurate information beyond simple port states
- Document all scan results and maintain audit logs for compliance purposes
- Schedule regular scans to detect changes in your network topology
- Combine port scanning with vulnerability assessments for comprehensive security audits
Technical Specifications
Supported Protocols: TCP, UDP, SCTP
Port Range: 1-65535 (all TCP/UDP ports)
Scan Types: SYN, TCP Connect, UDP, FIN, NULL, Xmas, ACK, Window, Maimon
OS Detection: 2,600+ OS fingerprints
Service Detection: 6,500+ service signatures for 650+ protocols
NSE Scripts: 600+ security and discovery scripts
Timing Templates: T0 to T5 for speed/stealth tradeoffs
Output Formats: JSON, CSV, PDF, XML, plain text
Security & Privacy
All scans are performed from our secure cloud infrastructure. We do not store scan results or target information. Your scanning activity remains private and confidential. This tool is designed for authorized security testing only and should never be used for malicious purposes.
⚠️ Legal Disclaimer
Port scanning without authorization may violate computer misuse laws in your jurisdiction. Always obtain explicit written permission before scanning networks or systems you do not own. Unauthorized scanning may be considered an attempted computer intrusion and could result in criminal prosecution. Use this tool responsibly and ethically for legitimate security auditing, network administration, and authorized penetration testing only.
Frequently Asked Questions
What is the difference between SYN and TCP Connect scans?
SYN scan (half-open scan) sends SYN packets and doesn’t complete the TCP three-way handshake, making it stealthier and faster. TCP Connect scan completes the full connection, making it more reliable but more detectable. SYN scans require raw packet privileges while TCP Connect works without special permissions.
How long does a scan take?
Scan duration depends on several factors: number of ports, scan type, timing template, and network conditions. A quick scan of 100 common ports typically takes 1-2 minutes, while scanning all 65,535 ports can take 10-30 minutes. Aggressive timing (T4-T5) significantly reduces scan time but may trigger security systems.
Why do some ports show as filtered?
Filtered ports indicate that a firewall, router ACL, or packet filtering device is blocking probe packets from reaching the target port. This is common for internet-facing systems with properly configured firewalls. Filtered status doesn’t necessarily mean the port is closed, just that it’s protected.
Can I scan IPv6 addresses?
Yes, our scanner fully supports IPv6 address scanning. Simply enter an IPv6 address in standard notation (e.g., 2001:0db8:85a3::8a2e:0370:7334). IPv6 scanning uses the same techniques as IPv4 but accounts for the larger address space and different packet structures.
What is OS fingerprinting accuracy?
OS detection accuracy depends on several factors: number of open and closed ports found, network distance, and target cooperation. With at least one open and one closed port, accuracy typically exceeds 90%. The scanner uses TCP/IP stack analysis, comparing responses against a database of 2,600+ OS fingerprints.
Is UDP scanning slower than TCP?
Yes, UDP scanning is significantly slower because UDP is connectionless and doesn’t provide acknowledgments. The scanner must wait for timeout periods to determine if ports are open or filtered. UDP scans can take 10-20 times longer than equivalent TCP scans.