Online firewall testing with roots going back to 2002

Online Firewall Test and Open Port Checker

Check open ports, test your firewall, and verify port forwarding from anywhere on the internet. Built for practical troubleshooting, not vague security jargon.

Check Open Ports Test Port Forwarding Your Connection Only No Installation
Testing your public IP: detecting…
TCP only. UDP and port 25 cannot be tested from here.
On a VPN? The test checks the VPN's exit rather than your own connection.
On mobile or CGNAT? Carrier-grade NAT shares one public address among many customers, so a result can reflect their equipment as well as yours.
This test only checks your own connection. It opens a normal TCP connection back to your public IP from an outside server, then closes it. A short request log is kept for a few days for abuse handling. See the Terms for exactly what it records.

What your result means

A finished test reports one of three things. Here is what open, closed, and filtered actually mean for your connection.

Open

Something on your network accepted the connection from the internet. That is exactly right if you set up port forwarding on purpose — and worth a look at your router if you did not.

Closed

Your network answered and refused the connection — your address is reachable, but nothing is listening on that port.

Did not respond (filtered)

Nothing answered within three seconds. Something between the internet and your device dropped the connection without replying — usually a firewall or router, sometimes the ISP. Silence rather than refusal is why this state is also called “filtered” or “stealth.”

A closed or filtered result on one port does not by itself prove your firewall is configured correctly or that your system is secure. A test shows what happened on that port, from the outside, right now — nothing more.

Why use TestMyFirewall.com

The goal is simple - show whether your connection is actually reachable from outside your network, and help you understand what to do next.

Check Open Ports

Scan common or custom ports to see what is accessible from the public internet.

Test Port Forwarding

Verify that your router forwarding rules are working the way you intended.

Firewall Test

See whether your firewall is exposing, blocking, or filtering the services you care about.

Real-World Results

External checks are more useful than just looking at settings inside your own network.

Common use cases

Firewall and port tests matter most when something needs to work from outside your local network.

  • Remote Desktop, VNC, and remote support tools
  • Game servers and peer-to-peer connections
  • Web servers, HTTPS apps, and self-hosted services
  • NAS systems, Plex, security cameras, and smart home devices
  • Small business firewalls, routers, and branch office connectivity

What an online firewall test tells you

It helps separate configuration assumptions from what the internet can actually see.

  • Whether a port appears open, closed, or filtered
  • Whether a forwarded service is reachable from outside
  • Whether your firewall or router is blocking traffic you expected to allow
  • Whether a service is listening at all, versus a pure firewall problem
  • Where to focus next when remote access is not working

About TestMyFirewall.com

TestMyFirewall.com has roots going back to 2002. The focus is still the same - practical firewall testing, open port checks, and clear results that help people solve real connectivity problems.

How it works

1

We detect your IP

The test runs against your own public IP address, detected automatically. There is nothing to type in.

2

Choose common or custom ports

Test web, remote access, media, gaming, or other service ports that matter to your setup.

3

Review the result

See whether the service appears reachable and use that result to guide firewall or router troubleshooting.

Frequently asked questions

These answers cover the most common questions about online firewall tests, open ports, and router forwarding checks.

An online firewall test checks whether ports and services on your internet connection are reachable from outside your network. It shows what a remote system may actually be able to access.

They are closely related. A firewall test often includes checking whether a specific port appears open, closed, or filtered from the public internet.

Yes. If you forward a port on your router, an external check can help confirm whether that port is reachable from outside your network.

Home users, self-hosters, gamers, IT support staff, and small businesses can all benefit from external firewall testing when they need to troubleshoot reachability.

TestMyFirewall.com has roots going back to 2002, with a long-standing focus on firewall testing and internet-facing security checks.

Contact Us

Have a question about firewall testing, open ports, or port forwarding? Send a message.

  • General questions
  • Testing questions
  • Service feedback
or email help@testmyfirewall.com