An operating system is the fundamental software that operates the hardware and enables the execution of other programs on the device. The operating system is the “bridge” between the physical hardware (circuits, chips, memory, etc.) and everything else you do with the device. In the case of the router, there is an operating system installed on the device by the manufacturer. This operating system is used to route the information on the device, connect information, and communicate with other devices. Without the operating system, the hardware is useless.

When one purchases a commercial router, it comes with the manufacturer's own firmware, which is essentially the embedded OS. It is this firmware that runs the show, including the security features. It is the brain behind the entire operation. Unfortunately, it is closed-source, which means one is unable to view the code, alter it, or even use it for something other than what the manufacturer intended. It is essentially the user being stuck with what the manufacturer intended the product to do. It is relevant to your thesis because it is the same logic behind privatized infrastructure.

OpenWrt is a customizable operating system based on Linux, designed for embedded devices. Unlike other firmware, which is a fixed operating system, OpenWrt is a Linux-based operating system that enables applications to be added or removed as needed without having to rebuild the firmware. OpenWrt was originally developed as a solution to allow users and developers to control router firmware. Essentially, what happens when you install OpenWrt on your device is that you "flash" it, which means replacing its original software with an alternative open-source software. This gives one the freedom to bypass the application and configuration options offered by the manufacturer and customize the device to a community's needs. So it is no longer seen as something which can only be used for the purposes intended by the manufacturer, but as something which can be completely reprogrammed.

What follows is the documentation of my first attempt at flashing a routing device with OpenWrt, an open-source firmware. The device I used is a TP-Link TL-WDR3600 (I’m working on a MacOS).

To choose which device to start with, I consulted the Table of Hardware, a list of compatible devices provided by the OpenWrt platform. I looked for something affordable and with multiple compatible versions, and found the TP-Link TL-WDR3600 available at a low price on Vinted.

Once I selected the device on the Table of Hardware, a dedicated page on the OpenWrt website opened. Once on the pop-up opened, I clicked on "Download Installation Firmware", and a download started.

 

If you want to quickly check whether your device is compatible with OpenWrt, this tool lets you type in your device model and version to find the most suitable firmware for it here. Your device model and version number can usually be found on the box or on a sticker on the device itself. Alternatively, here is the full list of available firmware files the full list of available firmware files, where you can look up your model and download directly.

I connected my device to my laptop using an ethernet cable, making sure it was connected to one of the router's yellow ports.

To access the router, I opened the preinstalled web browser on my computer. (If you are on macOS, use Safari; if you are on Windows, use Internet Explorer or Edge, as this tends to cause fewer issues). In the address bar, I typed 192.168.1.1 and pressed enter. (This should connect you to the router through the ethernet cable, and a TP-Link login page should appear).

 

In my case, this did not work on the first try. What I did to fix this issue was: I went to my computer's system settings and navigated to reach the “Network” section, here, looked for USB 10/100 LAN (if the router is connected it should be on the top under the wifi and highlighted with a green dot on its left), and opened the voice “Details…” on its right.

 

Settings → Network → USB 10/100 LAN (or Ethernet)

 

In this pop-up window I went to “TCP/IP”. Here there should be a button with written “Using DHCP by default. If you click it a selection menu should pop up, here I clicked “manually”. Now came the tricky part. I had to manually update three fields in the network settings:

 

IP Address 192.168.0.2 This is the identity of your Mac on the local network — like a house number. You're manually telling your Mac "your address is .0.2" instead of letting the router assign one automatically (DHCP).

 

Subnet Mask 255.255.255.0 This defines the "neighbourhood" — which devices can talk to each other directly. 255.255.255.0 means all devices starting with 192.168.0. are in the same neighbourhood and can communicate.

 

Router 192.168.0.1 This tells your Mac where the "exit" of the network is — the device that forwards traffic to the internet. You're pointing it to the TP-Link's address.

 

Then I clicked “ok” on the bottom right of the window. Once I entered these values, my computer was able to communicate with the router.

After making these changes, I was able to access the router by typing 192.168.0.1 into Safari on my Mac. A login page appeared. If the router is new, you may be able to get in simply by pressing Enter without typing anything. Otherwise, try typing admin in the username field and password in the password field.

Once logged in, the original TP-Link firmware interface offers plenty of options, though it is clearly an older operating system. The interface may look different depending on the device you are using. In my case, it had a very dated feel, reminiscent of early 2000s web design. To install the new operating system, I navigated to System Tools in the left-hand menu of the TP-Link interface, then selected Firmware Upgrade.

 

System Tools → Firmware Upgrade

 

This section was originally designed to let users install newer official versions of TP-Link's own firmware. However, we can use the same Choose File button to upload the OpenWrt factory image we downloaded earlier, effectively replacing the manufacturer's software with our own. Once I selected the file and clicked Upgrade, the router began the installation. The file you need to select is the one downloaded from the OpenWrt website. In my case it was called: openwrt-25.12.1-ath79-generic-tplink_tl-wdr3600-v1-squashfs-factory.bin.

 

However, when I first tried to upload it through the Choose File window, I received an error message. The fix turned out to be very simple: the filename was too long for the router to accept. I found this solution on the OpenWrt device page, which recommended renaming the file to something shorter before uploading. I renamed it to factory.bin and the upload worked without any issues.

 

I then waited a couple of minutes while a progress bar filled during the installation. In these moments I’ve been very careful not to unplug the router or close the browser while it was working. At a certain point, the connection dropped entirely, which was briefly alarming. After checking the guide again, I found out this was completely normal: once OpenWrt is installed, the router switches to a different default address.

I went back to my system's network settings by navigating to System Settings, then Network, then USB 10/100 LAN or Ethernet.

 

System Settings → Network → USB 10/100 LAN (or Ethernet)

 

I clicked the Details button again and opened the TCP/IP section in the pop-up window. Under Configure IPv4, I made sure the setting was still on Manually, and updated the values to the following:

 

IP address: 192.168.1.2

Subnet mask: 255.255.255.0

Router: 192.168.1.1

 

Then I clicked OK in the bottom right corner of the window.

Back in Safari, I typed http://192.168.1.1 into the address bar to reach the newly flashed router. A new interface appeared, and the browser asked whether I wanted to save a password. I ignored this and simply pressed Enter. I had finally made it inside my newly flashed device.