Port Checker
Free online port checker. Test if TCP ports are open on any server. Check common services — HTTP (80), HTTPS (443), SSH (22), FTP (21) and more. Useful for network diagnostics and security audits.
Enter a hostname and ports to check above.
How to Use Port Checker
Enter Host and Ports
Type a hostname or IP address, then enter one or more port numbers to check (separated by commas). Common ports like 80 (HTTP), 443 (HTTPS), and 22 (SSH) are pre-filled for convenience.
Run the Check
Click "Check Ports" to test each port. The tool attempts to establish a TCP connection to each port and reports whether it succeeded (open) or failed (closed/filtered).
Interpret Results
Open ports mean a service is listening and accepting connections. Closed ports mean no service is listening. Filtered ports mean a firewall is blocking the connection attempt — you can't tell if a service is behind it.
Common Port Numbers
| Port | Service | Should It Be Open? |
|---|---|---|
| 80 | HTTP | Yes for public web servers |
| 443 | HTTPS | Yes for secure web servers |
| 22 | SSH | Only for administrators |
| 21 | FTP | Use SFTP (port 22) instead |
| 3306 | MySQL | Never expose to public internet |
| 5432 | PostgreSQL | Never expose to public internet |
Frequently Asked Questions
What is a TCP port?
A port is a number (0-65535) that identifies a specific service or application on a server. Think of the IP address as the building address and the port number as the apartment number. Port 80 is standard for HTTP, 443 for HTTPS, 22 for SSH, 21 for FTP, 25 for SMTP, and 3306 for MySQL. Well-known ports (0-1023) are assigned by IANA to standard services.
What does "open" vs "closed" vs "filtered" mean?
Open: a service is actively listening on this port and accepted the connection. Closed: no service is listening — the server actively rejected the connection with a RST packet. Filtered: no response was received — a firewall is likely dropping packets to this port. Filtered is the most secure state for ports you don't want publicly accessible.
Can I check any port on any server?
Browser-based port checking is limited. Browsers can only attempt connections to certain ports via HTTP/HTTPS. For comprehensive port scanning, use command-line tools like nmap or netcat. Our tool checks the most common HTTP/HTTPS ports via fetch requests and reports results. For full TCP port scans, use "nmap -p 1-1000 target.com" from your terminal.
Why would I need to check ports?
Common reasons: verify your web server is actually listening on port 443 after deploying SSL, check if SSH port 22 is accessible before connecting remotely, confirm database port 3306 is NOT publicly accessible (a security check), troubleshoot "connection refused" errors by verifying the port is open, and audit your own server's exposed ports as part of a security review.
Port Checking for Security
Every open port is a potential entry point for attackers. A regular port audit — checking which services your servers expose to the internet — is one of the most effective security practices you can adopt. Close everything you don't need. Move administrative services (SSH, database ports, management consoles) to private networks or VPN access only.
Security Best Practices
- Run periodic port scans on your own infrastructure — know what's exposed before attackers do
- Close any port that doesn't need to be publicly accessible
- Use a firewall to restrict access to administrative ports by IP address
- Move databases to private subnets — never expose MySQL/PostgreSQL ports to the internet
- After deploying a new service, verify it's only listening on the intended ports