LuabifyQuick device diagnostics

Free Open Port Check Online (Port Forwarding & Firewall Test)

Click Check your ports Instantly test whether a TCP port is open on your public IP for self-hosting, remote access, game servers, cameras, NAS, SSH, RDP, and web services.

Port reachability

Open Ports Test

Check if common ports are reachable on your public IP or another host.

Ready
Your public IP--

Results will appear here after a scan.

This test uses a server-side TCP check to see if a port is reachable.

Common ports

Why run an open port check online

An open port check helps you verify whether a TCP service on your public IP is reachable from the internet. Use it after configuring port forwarding, changing router or firewall rules, exposing a NAS, SSH, RDP, a game server, a camera system, or any service that must answer from outside your network. A good test should tell you whether the port is actually open from the public side, not just whether the service works on your local network.

How the test runs

The tool sends an external TCP connection attempt to the public IPv4 address and port you provide. If the target responds, the port is reported as open. If it does not respond, the result is usually closed or filtered, which often means the service is down, forwarding is missing, the firewall is blocking the path, or the ISP is interfering.

How to interpret results

Open means the TCP port answered from the outside path. Closed or filtered means the port could not be reached, but that does not always mean the router alone is wrong. Check the service first, then the device IP on your LAN, the forwarding rule, local firewall rules, ISP restrictions, CGNAT, and whether you are testing the correct public IP.

  • Open: the port is reachable from the internet and a TCP service answered.
  • Closed: the port did not answer, often because forwarding is missing, the service is down, or the wrong IP was tested.
  • Filtered: a firewall, ISP rule, CGNAT, or security layer may be blocking the connection path.
  • Different results at different times: the service may start late, the IP may have changed, or the network path may vary.
  • Only some ports open: the host may be reachable, but only selected services are correctly exposed.

When to use this open port test

Run it after changing router settings, exposing a new service, moving to a different ISP, troubleshooting game server access, setting up remote desktop or SSH, or checking whether a used router or firewall configuration is actually working from outside. It is especially useful when something works inside your home network but fails from a phone on mobile data or from another location.

What this tool can and cannot confirm

This tool checks external TCP reachability only. It does not test UDP, does not validate application-level responses, does not scan private LAN addresses, and does not guarantee that an open service is secure. It does not store personal data and should be used as a first network-path check, not as a full security audit.

Related tools

Frequently Asked Questions

What does this open port check online test?

It tests whether a TCP port on your public IPv4 address is reachable from the internet. This is useful for checking port forwarding, firewall rules, and whether a service is actually exposed externally.

How does the open port test work?

The tool attempts an external TCP connection to the IP and port you provide. If the target answers, the port is reported as open. If not, it is usually closed or filtered.

Does this test check whether my port is open on the internet?

Yes. That is the core purpose of the page. It checks whether the port can be reached from outside your local network, not just from another device on the same router.

Why is my port showing closed?

Common causes are missing port forwarding, a stopped service, the wrong local device IP, host firewall rules, ISP blocking, or CGNAT. Start by checking that the service is running and that the forwarding rule points to the correct machine.

Why is my port still closed after port forwarding?

Port forwarding alone is not enough if the service is down, the target device changed IP, a local firewall blocks the port, or your ISP uses CGNAT. You may also be testing the wrong public IP or a port that the ISP blocks.

Can I test any host or domain name here?

This checker is designed for public IPv4 reachability and accepts public IPv4 targets. Private, local, and internal LAN addresses cannot be reached from the internet path used by this tool.

Does this test work for SSH, RDP, web servers, NAS, and game servers?

Yes, as long as the service uses TCP and is meant to answer on a public IPv4 path. It is useful for checking ports commonly used by SSH, RDP, HTTP, HTTPS, NAS dashboards, and many game servers.

Can a VPN or ISP block an open port?

Yes. VPNs, cloud firewalls, consumer router protections, CGNAT, and ISP rules can all interfere with reachability. If results look wrong, compare from another network or disable the VPN path for testing.

Does an open port mean the service is secure?

No. Open only means reachable from the internet. Security depends on authentication, patching, service configuration, rate limiting, and whether the service should be exposed at all.

Why do open port results differ between tools?

Different tools use different source locations, timeouts, retry behavior, and network paths. Small differences happen, but repeated closed results across tools usually point to a real reachability problem.

Can this test check UDP ports?

No. This page checks TCP reachability only. UDP needs different probing logic and should be tested with a dedicated UDP-focused tool.

Can this test scan my local network or private IP?

No. It checks public internet reachability and cannot scan RFC1918 private LAN addresses like 192.168.x.x or 10.x.x.x. For local network discovery, you need a LAN-specific tool.

Is the open port test safe and private?

Yes. It only tests reachability for the public IP and port values you provide. It does not access files, does not log into services, and does not store personal data.

What can this open port checker not do?

It cannot confirm whether the application behind the port works correctly, cannot test UDP, cannot find vulnerabilities, and cannot prove that an open service is safe. Treat it as a reachability check, not a complete security assessment.

When should I use this open port check online?

Use it after changing router or firewall rules, exposing a new service, setting up SSH or RDP, opening a game server, or troubleshooting why something works locally but not from the internet. It is often the fastest first check before deeper network debugging.