Port Checker

TCP

$ Your public IP address and network information:

> Your public IP

Detecting...

ISP

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City/Region

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Country

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ASN

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Check Port

[ TCP Scan ]

Host or IP (optional)

Leave empty to use your IP

Port *

> Common ports:

Understanding the Results

✓

Open

A service is listening on this port and accepting connections from the internet. Expected for web servers, games, and services you want to expose.

✗

Closed

The host responded, but no service is listening on this port. Check whether the application is running on the destination server.

⏱

Filtered (Timeout)

No response received. Usually indicates a firewall, a router without port forwarding, or blocking by your internet service provider (ISP).

Frequently Asked Questions

> Why does my port show as filtered? ▾

The most common causes are: (1) the router has no port forwarding configured, (2) the server firewall blocks the port, (3) your internet provider blocks common server ports (25, 80, 443) on residential plans, or (4) the service is not running. Check each layer, from the outermost (ISP) to the innermost (local firewall).

> Is using this tool safe? ▾

Yes. The tool only attempts to establish a standard TCP connection — exactly like any browser would. No data is read, sent, or stored beyond the host and port you enter. Only test the ports of systems you own or are authorized to test.

> What is the difference between TCP and UDP? ▾

TCP is connection-oriented (3-way handshake) and guarantees delivery — used by web, SSH, and email. UDP has no connection or acknowledgment — used by DNS, online gaming, and streaming, where speed matters more than reliability. UDP checks are less accurate because closed ports often do not respond.

> My IP changes frequently. What should I do? ▾

Most residential providers use dynamic IPs. Solutions: use a dynamic DNS (DDNS) service like No-IP or DuckDNS to have a fixed hostname, or get a static IP from your provider. If you are behind CGNAT (common in Brazil), traditional port forwarding will not work — consider VPNs with port forwarding or tunnels like Cloudflare Tunnel.