Check if Your TCP Port is Open
Check if a TCP port on your public IP address is reachable from the internet.
Your public IP address
216.73.216.122
Results may be affected by firewalls, NAT, ISP restrictions, and server configuration. A timed-out connection is not always definitively blocked.
What is a TCP Port?
A TCP port is a numbered endpoint (0–65535) used by the Transmission Control Protocol to route network traffic to the correct application on a host. When a server runs a web application on port 443, for example, any incoming TCP connection to that port number is delivered to that application.
Ports below 1024 are known as well-known ports and are typically reserved for standard services (HTTP, HTTPS, SSH, etc.). Ports 1024–49151 are registered ports used by many applications. Ports 49152–65535 are dynamic or ephemeral ports used for outgoing connections.
What is Port Checking?
Port checking is the process of testing whether a specific TCP port on a host is reachable from a remote location. This tool attempts to establish a TCP connection from our servers to your public IP address on the port you specify.
The attempt tells you whether the port is visible and accepting connections from the internet — which is essential when hosting a server, configuring a firewall, or troubleshooting connectivity problems.
Understanding the Results
✓ Reachable (Open)
Our server successfully established a TCP connection. An application is listening on this port and your network allows the connection.
✕ Connection Refused
Your host actively rejected the connection. Either no application is listening on the port, or a local firewall is sending back a refusal packet.
⏱ Timed Out
No response was received within the timeout period. A firewall is most likely silently dropping the connection attempt. This is not a definitive confirmation that the port is blocked.
! Check Failed
The check could not be completed due to a network or system error. Please try again. If the problem persists, your IP address may be temporarily unreachable from our servers.
Why Would a Port Appear Closed?
Many layers of your network can prevent a port from being reachable:
- ISP filtering: Some internet service providers block specific ports (e.g. port 25 SMTP).
- Router / NAT: Without port forwarding, inbound connections cannot reach your device.
- Router firewall: Many routers include built-in firewalls that block inbound traffic by default.
- OS firewall: Windows Defender, iptables, nftables, and similar tools may block the port.
- Cloud / VPS firewall: Cloud providers (AWS, GCP, Azure, Hetzner, etc.) have security group rules.
- Application not running: If nothing is listening on the port, the connection will be refused.
- Corporate firewall: Enterprise environments often restrict outbound and inbound connections.
- Security software: Antivirus or endpoint protection tools may interfere with connections.
Common TCP Ports Reference
The table below lists well-known ports and their typical applications. Whether a port is open on your system depends entirely on your configuration.
| Port | Common Use |
|---|---|
| 20 / 21 | FTP (File Transfer) |
| 22 | SSH (Secure Shell) |
| 23 | Telnet |
| 25 | SMTP (Email sending) |
| 53 | DNS (Domain resolution) |
| 80 | HTTP (Web traffic) |
| 110 | POP3 (Email retrieval) |
| 143 | IMAP (Email retrieval) |
| 443 | HTTPS (Secure web traffic) |
| 465 | SMTPS (Secure email sending) |
| 587 | SMTP Submission |
| 993 | IMAPS (Secure email retrieval) |
| 995 | POP3S (Secure email retrieval) |
| 3306 | MySQL / MariaDB |
| 3389 | RDP (Remote Desktop) |
| 5432 | PostgreSQL |
| 6379 | Redis |
| 8080 | HTTP (alternate / proxy) |
| 27017 | MongoDB |
Frequently Asked Questions
- Why does my port show as closed even though my server is running?
- Several things can prevent a port from being reachable: your router or firewall may not have a port-forwarding rule, your ISP may block certain ports, or a software firewall on your server may be filtering inbound connections. Check each layer individually.
- What is the difference between "connection refused" and "timed out"?
- "Connection refused" means the target host actively rejected the connection — something is listening but denying access, or nothing is listening at all. "Timed out" means no response was received within the timeout period, which typically indicates a firewall silently dropping packets rather than rejecting them.
- Can I check ports on another IP address?
- Not in Phase 1. This tool is intentionally limited to your own detected public IP to prevent abuse. Checking arbitrary IP addresses will be available after authentication is introduced.
- Why might the result be inaccurate?
- The check is a single TCP connection attempt from our server to your IP at a specific moment. Transient network issues, asymmetric routing, or connection throttling can produce misleading results. For important infrastructure, run the check multiple times and verify from multiple sources.
- Does this tool work with IPv6?
- IPv6 support depends on your network and the deployment environment. The tool uses your detected public IP, which may be an IPv4 or IPv6 address.
- Is there a limit to how many checks I can run?
- Yes. To prevent abuse, requests are rate-limited per IP address. If you exceed the limit, you will need to wait a short time before trying again.