I checked my router's open ports and what I found was terrifying

Setting up your home network seems like a reasonably simple task. Your ISP already does all the heavy lifting for you, and all you have to do is enter a Wi-Fi password to get going. This sure is all you need to do to connect to the internet, but your router isn't as secure as you think.

I thought my Wi-Fi was secure until I checked my router's settings, but scanning open ports revealed far bigger dangers. From the outside, everything looked fine, but behind the scenes, my router was quietly answering knocks from the open internet on ports I'd never consciously exposed.

What an open port actually means for your network

It’s not just a number—it’s an open door

Think of your home network as a building and the router as the main gate. Each port is like a numbered door into that building. Most of the time, the router only lets traffic in when something inside your network starts the conversation, like your browser loading a website.

An open port that's exposed to the internet means anyone out there can knock on that door directly. That's not automatically bad or insecure, because some services genuinely need it, like game servers, remote access, or media servers. But every open port is a potential attack path if whatever sits behind it is weak, outdated, or misconfigured. A couple of careless checkboxes or default settings can quietly turn that abstract risk into something very real.

How to scan your router for open ports

The simple tools anyone can use

To see what the outside world can reach, you have to scan your public IP from the internet's side, not from inside your network or Wi-Fi. The easiest way is through browser-based tools such as YouGetSignal's Open Port Check Tool, PortChecker, or similar sites. They usually auto-detect your public IP and scan for a common range of open ports.

For a deeper, more technical insight, you can use Nmap. Once installed on Linux or macOS, a quick scan can be run with the following command:

nmap -Pn -F YOUR_PUBLIC_IP

For a more thorough scan, run:

nmap -Pn --top-ports 1000 YOUR_PUBLIC_IP

And to identify services and versions:

nmap -Pn -sV --top-ports 1000 YOUR_PUBLIC_IP

On Windows, after installing Nmap, the same commands work in PowerShell or Windows Terminal. If you prefer a GUI, use Zenmap, type your external IP, and run an intense scan. To match those results to actual apps on your machines, use netstat -ano | findstr LISTENING on Windows, ss -tulpn on Linux, or lsof -i -P | grep LISTEN on macOS.

What I discovered on my “normal” home router

Default settings weren’t as safe as I assumed

When I scanned my own average home router, I expected a clean bill of health. Instead, I got a neat little list of open doors. There was a web port open for a remote management feature my ISP had quietly enabled so they could administer the router from outside. There was a random high port that turned out to be a NAS cloud backup feature port I never closed after testing. Another high port mapped to a Minecraft server I'd shut down months earlier but never removed from my router's port forwarding rules.

Individually, none of these looked dramatic. Together, they meant my router login page was reachable from the internet, and two unpatched, rarely-checked devices were sitting there waiting for whoever scanned the right range on the right day. If you scan an average set-up router, you'll probably see something familiar. It all feels harmless until you remember that attackers automate these scans and can go through entire port ranges in minutes, over hundreds, if not thousands of IP addresses.

Why exposed ports are a serious security risk

One open port is sometimes all it takes

Attackers don't guess your IP and poke at it manually; they run massive automated sweeps across the internet, looking for anything that answers on interesting ports. Once they get a response, they fingerprint the service, check its version, and start throwing known exploits, default logins, or credential-stuffing attempts at it.

Weak or default passwords make routers and services trivial to brute force, especially considering your router's default password is likely sitting in a public database. Unpatched firmware and server software often have public, copy-and-paste exploits available. Accidentally exposed admin interfaces effectively hand over your network keys if someone manages to log in. Services like open FTP (Port 21), SMB (Port 445), or RDP (Port 3389) can leak files or provide a perfect beachhead to move deeper into your home network. Meanwhile, everything inside still seems fine: Wi-Fi works, streaming works, and you have no obvious signs that your router is quietly answering knocks from the outside world.

How I closed those ports and hardened my router

A few settings and you'll be relatively secure

Once you know which ports are open, your job is to close anything you don't explicitly need and harden the rest. Log in to your router's admin page from inside your network by typing the default gateway IP (usually 192.168.0.1 or 192.168.1.1) into a browser. If the admin password is still the default printed on the sticker, change it immediately to a strong, unique password.

Next, find and disable any remote management from the internet. These options are usually found under administration, system, or management settings. Then hunt down UPnP and NAT-PMP under Advanced, Network, or NAT/Forwarding and disable them, so devices can't silently punch holes in your firewall.

On the port forwarding or virtual servers page, delete rules you don't recognize or no longer use, especially ones pointing at cameras, NAS boxes, or PCs. Update your router's firmware if possible to ensure any known bugs are patched.

For anything you intentionally keep open, use strong passwords, enable two-factor authentication if possible, prefer secure protocols like SSH or a VPN over Telnet, FTP, or exposed RDP, and restrict access by IP where the software allows it.

If you do one thing today, close these ports

A 10-minute security win

I started this exercise thinking it would be a boring confirmation that everything was locked down. Instead, forgotten devices, leftover forwards, and ISP-enabled remote access had quietly turned my normal home network into something a random bot could stumble across and decimate.

If you haven't scanned your network for open ports yet, take an afternoon out to do so. Run a scan, clean up forwards, disable remote management, and please change the default password on your router. The goal isn't to be perfectly secure, but you practically can't, but it is to be boring enough, so attackers move on to the next, easier target.