Port Checker
Check open ports
Frequently Asked Questions
How do I check if a port is open?
Enter the IP address or hostname and port number. The tool attempts a TCP connection. Open: connection accepted (service is running). Closed: connection refused (no service). Filtered: no response (firewall blocking). Results show status and response time.
What are common port numbers and their services?
21: FTP. 22: SSH. 25: SMTP. 53: DNS. 80: HTTP. 110: POP3. 143: IMAP. 443: HTTPS. 993: IMAPS. 3306: MySQL. 3389: RDP. 5432: PostgreSQL. 8080: HTTP alternate. 8443: HTTPS alternate. The tool identifies the service for known ports.
Why would I need to check if a port is open?
Troubleshooting connection issues (can't reach a server). Verifying firewall rules are correct. Checking if a service is running. Security auditing (finding unexpected open ports). Confirming port forwarding is working on your router.
How do I check multiple ports at once?
Enter a comma-separated list (80, 443, 8080) or a range (1-1024). The tool scans all specified ports and shows the status of each. Common presets: web ports, email ports, database ports, or full scan of well-known ports (1-1024).
What does it mean if a port is filtered?
Filtered means a firewall is silently dropping packets (no response). Unlike "closed" (which sends a rejection), filtered ports give no indication of whether a service exists. This is a security measure to hide services from port scanners.