How to check the IP address and port of your computer

When troubleshooting network issues, ensuring network security, configuring remote access, or debugging applications, confirming your device's IP address and port status is a frequent necessity.

This guide will leverage two practical online features provided by the ToDetect browser fingerprint detection tool—IP Address Lookup and Port Scanning—to help you quickly grasp the methods.

1. Distinguish Between "Public IP" and "Private IP" First

Public IP is the address seen by internet servers or the external network, typically provided by your ISP or virtual network service.

Private IP (LAN IP) is the address you use within your router, corporate network, or home network. Common private IP ranges include:

• 192.168.x.x

• 10.x.x.x

• 172.16.x.x – 172.31.x.x

It's important to note that if your ISP uses CGNAT, the WAN address you see in your router might not be a true public IP address. In this case, directly opening ports to the public internet is usually not feasible.

2. How to Quickly Check Your Public IP

1. Using the ToDetect Online IP Address Lookup Tool

The page will directly display your public IP, geographic location, ISP, and other information. The process is simple, ideal for quickly confirming your current exit address.

Besides ToDetect, you can also use other online tools for cross-validation, and combine them with your router's admin panel and local machine commands for more reliable judgment.

2. Check Router WAN

Log into your home or office router's admin panel. You can see the external IP address assigned to the router in the "Wide Area Network (WAN)" information section. If it shows a private address range, it indicates the presence of CGNAT.

3. Command Line Method (Suitable for Scripting)

You can also obtain your public IP by calling an external service from the terminal (e.g., using curl on an API that returns your IP). This method is suitable for automated detection or for use on servers without a graphical interface.

3. How to Find Your Private IP (Local Machine Address)

The steps vary slightly across different operating systems, but the principle is the same—check your network interface information.

● Windows

In the Command Prompt, enter: ipconfig 

Find the IPv4 address corresponding to the currently active network adapter; this is your local private IP.

● macOS / Linux

In the terminal, enter: ifconfig or ip addr

(Modern Linux recommends `ip addr`)

Find the `inet` entry under the corresponding interface (e.g., en0, eth0, or wlan0).

4. How to Perform Port Queries and Scanning

Port information consists of two parts:

1. Whether a port is listening on the local machine (i.e., whether the service is running).

2. Whether that port is externally reachable (affected by NAT, firewalls, etc.).

1. Check Local Listening Status

● Windows

Lists all listening ports and their corresponding Process IDs (PID).

Continuing with the example above, enter:

You can then see exactly which program is using that port.

● macOS / Linux

Can be used to view TCP listening ports and processes.

These commands confirm whether an application is indeed occupying a port. If it's not listening, it cannot be connected to from the external network.

2. External Reachability Detection

● Online Port Scanning

To determine if a port is open from the public internet's perspective, use the ToDetect online port scanner to detect open ports on your device. Go to the port scanning page, wait a moment, and you will see the results of the open port scan.

● Verification from Local to Public Network

First, ensure your router has proper port forwarding configured. Then, turn off Wi-Fi on your phone and switch to mobile data. Attempt to connect from the external network; successful connection confirms the port is open to the public.

5. Summary

Understanding and managing your IP addresses and port status is fundamental to ensuring normal network operation and security. Using the online IP info lookup and port scanning features provided by ToDetect, you can quickly and accurately confirm your public and private IPs, check whether local ports are listening and open to the outside world. This enables effective troubleshooting of network issues, configuration of remote access, or enhancement of security measures.

Simultaneously, properly managing open ports to avoid unnecessary risks is a crucial responsibility for every network user and administrator. Mastering these skills will make your network usage safer and more efficient.

Frequently Asked Questions (FAQ) on IP Address and Port Queries

1. Port shows as listening locally but is inaccessible from the internet?

This is usually due to the router not having port forwarding configured, firewall blocking, or the ISP using CGNAT.

2. Public IP doesn't match the router's WAN IP?

Check if you are behind a double NAT, or if you are connected to the ISP's modem/router without it being in bridge mode.