Open Port Scanner
Scan common ports on any server or domain to discover open, closed, and filtered ports.
What Port Scanner Detects
Quickly audit which network services are exposed on any server.
18 Common Ports
Scans the most critical ports including web (80/443), mail (25/587), database (3306/5432), and remote access (22/3389) services.
Response Timing
Measures the exact response time for each port in milliseconds, helping identify latency issues and network performance.
Filtered Detection
Distinguishes between closed ports (actively refused) and filtered ports (silently dropped by a firewall) for accurate analysis.
Security Audit
Identifies potentially dangerous open ports like database servers or SMB shares that should not be publicly accessible.
How It Works
Three simple steps to scan ports on any server.
Enter Host
Type a domain name or IP address. The tool resolves domains to their IP automatically before scanning.
Scan Ports
All 18 common ports are checked simultaneously using TCP connections with a 3-second timeout per port.
Review Results
View which ports are open, closed, or filtered along with service names and response times for each port.
Related Tools
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Frequently Asked Questions
Common questions about port scanning and network security.
What is port scanning and why is it useful?
Port scanning is the process of checking which network ports on a server are open and accepting connections. It is useful for security auditing, as open ports represent potential entry points for attackers. System administrators use port scans to verify that only intended services are exposed to the internet and that firewalls are configured correctly.
What is the difference between open, closed, and filtered ports?
An open port is actively accepting connections, meaning a service is running and listening on that port. A closed port responds with a TCP RST packet, meaning no service is running but the port is reachable. A filtered port does not respond at all, typically because a firewall is silently dropping packets. Filtered ports are the safest from a security perspective.
Which open ports are considered a security risk?
Database ports (MySQL 3306, PostgreSQL 5432, MongoDB 27017) should never be publicly accessible as they can expose sensitive data. SMB (445) is frequently targeted by malware. FTP (21) transmits credentials in plain text. SSH (22) should use key-based authentication. Ideally, only web ports (80, 443) should be open on public-facing servers.
Is port scanning legal?
Port scanning your own servers is perfectly legal and is a standard security practice. Scanning third-party servers exists in a legal gray area that varies by jurisdiction. Most security professionals consider it acceptable when done responsibly, but aggressive scanning can trigger intrusion detection systems. Always scan only systems you own or have permission to test.