Port Scanner Tool
Check which ports are open on a server
Responsible Use Notice
This port scanner is provided for educational purposes and network diagnostics. Only scan systems you own or have permission to scan. Unauthorized port scanning may be against the terms of service of your ISP or illegal in some jurisdictions.
Results may vary based on network conditions and firewalls
Learn more about port scanningWhat is a Port Scanner?
A port scanner is a software tool designed to probe a server or host for open ports. This information can help identify which services are running on a target machine, potential security vulnerabilities, and network configuration issues.
How Port Scanning Works
Port scanning works by sending packets to specific ports on a target system and analyzing the responses. Different scanning techniques (like TCP SYN, TCP connect, UDP) can reveal whether ports are open, closed, or filtered by a firewall.
Port States
- Open: The port is accepting connections
- Closed: The port is not accepting connections
- Filtered: A firewall or other network device is blocking the port
Common Ports
- HTTP (80) - Web servers
- HTTPS (443) - Secure web servers
- SSH (22) - Secure Shell
- FTP (21) - File Transfer Protocol
- SMTP (25) - Email transmission
- DNS (53) - Domain name resolution
Ethical Considerations
Port scanning should only be performed on systems you own or have explicit permission to scan. Unauthorized port scanning may violate terms of service, privacy policies, or even laws in some jurisdictions.