Port Scanner
Check which ports are open on any server, host, or network device with our free online Port Scanner. Open ports reveal what services and applications are running on a target system, making this tool essential for network administrators, security professionals, and developers who need to audit their infrastructure. Whether you are verifying firewall rules, checking if a service is responding, hardening server security, or troubleshooting connectivity issues, this tool gives you instant visibility into a host's attack surface. Simply enter a hostname or IP address, choose a port range, and receive clear results showing each port's status. Scan common ports like HTTP (80), HTTPS (443), SSH (22), FTP (21), and SMTP (25), or define custom ranges for specialized needs.
What Is
A port scanner is a network analysis tool that probes a target host's ports to determine which ones are open, closed, or filtered. Every networked service listens on a specific port number — web servers use port 80 or 443, SSH uses port 22, FTP uses port 21, DNS uses port 53, and so on. By systematically checking each port on a target, a port scanner reveals what services are actively accepting connections. This information is critical for security auditing because open ports represent potential entry points for attackers. Network administrators use port scanners to verify firewall configurations, detect unauthorized services, and ensure only intended ports are exposed to the internet. Our free online Port Scanner supports both predefined common port lists and custom port ranges, making it suitable for quick checks and thorough audits alike. Results are displayed in an easy-to-read format showing port number, service name, and status. The tool is designed for legitimate security testing and network administration purposes only.
How to Use
- Enter the hostname or IP address of the target server you want to scan in the input field.
- Select a predefined common port list or enter a custom port range to scan.
- Click the scan button to begin checking each port on the target host.
- Review the results table showing each port number, its associated service name, and current status.
- Export or save the scan results for your security audit records or share them with your team.
Examples
Input: Target: scanme.nmap.org, Ports: 22,80,443
Process: TCP connect scan → Send SYN → Wait for SYN-ACK or timeout
Result: 22:OPEN, 80:OPEN, 443:OPEN, Scan time: 0.3s
Input: Range: 192.168.1.1 ports 1-1024
Process: Scan well-known ports → Identify service banners → Report
Result: Ports found: 22(SSH), 80(HTTP), 443(HTTPS)
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Frequently Asked Questions
Is port scanning legal?
Port scanning is legal when performed on servers you own or have explicit written permission to test. Scanning servers without authorization may violate computer fraud laws in many jurisdictions, including the Computer Fraud and Abuse Act in the United States and similar legislation worldwide. Always obtain proper authorization before scanning any network you do not own. Unauthorized port scanning can result in legal consequences, service termination by your ISP, and being blocked by the target's firewall.
What ports does this tool scan?
The tool includes predefined lists of the most commonly used ports, covering essential services like HTTP (80), HTTPS (443), SSH (22), FTP (21), SMTP (25), DNS (53), MySQL (3306), PostgreSQL (5432), and many more. You can also define a custom port range if you need to check specific ports not included in the predefined lists. This flexibility makes the tool suitable for both quick general scans and targeted security checks.
How long does a scan take?
Scan duration depends on the number of ports being checked and the responsiveness of the target host. A common port scan typically completes within a few seconds to a minute. Scanning all 65535 ports on a host will take significantly longer and may trigger intrusion detection systems. For most use cases, scanning the most common 100 to 1000 ports provides a good balance between speed and coverage. The tool shows real-time progress so you can monitor the scan as it runs.
Can port scanning damage the target server?
Standard TCP connect scanning is a non-intrusive technique that simply checks whether a port is open, similar to what a normal client would do when connecting to a service. It does not exploit vulnerabilities or cause damage to the target system. However, aggressive scanning techniques or scanning ports very rapidly may trigger security alerts on the target host. Always scan at a reasonable rate and respect any rate limits or security policies in place.
Why are some ports showing as filtered?
A port shows as filtered when the scanner receives no response, typically because a firewall or network security device is blocking the probe packets. This differs from a closed port, which actively refuses the connection. Filtered ports indicate that the target is protected by a firewall that silently drops unauthorized traffic, which is generally a good security posture. If you are scanning your own server and see unexpected filtered ports, review your firewall rules to ensure the correct ports are open.