How to Connect to WiFi from a Root Shell in Ubuntu

Introduction

Sometimes, you may find yourself needing to connect to a WiFi network from a root shell, especially when troubleshooting or working in a minimal environment without a graphical interface. This guide provides step-by-step instructions on how to connect to WiFi from a root shell using the nmcli and wpa_supplicant commands in Ubuntu.

Step 1: Identify Available WiFi Networks

Before connecting to a WiFi network, you need to identify the available networks:

• Use nmcli to list available WiFi networks:

nmcli dev wifi list
   

This command lists all available WiFi networks, showing details such as SSID (network name), signal strength, and security type.

• Note the SSID of the network you want to connect to.

Step 2: Connect to the WiFi Network Using nmcli

nmcli is a command-line tool for managing NetworkManager, which controls network connections in Ubuntu.

• Connect to the WiFi network:

nmcli dev wifi connect "SSID" password "your_password"
   

Replace "SSID" with the name of your WiFi network and "your_password" with the network’s password.

• Verify the connection:

After running the command, you should see a message indicating that the device has successfully connected to the network. To verify:

nmcli dev status
   

This command shows the status of your network interfaces, confirming if the WiFi connection is active.

Step 3: Manually Connecting Using wpa_supplicant

If nmcli is not available, or you prefer a more manual approach, you can use wpa_supplicant to connect to WiFi.

• Create a configuration file for wpa_supplicant:

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf
   

Add the following configuration, replacing your_ssid and your_password with your network’s SSID and password:

network={
       ssid="your_ssid"
       psk="your_password"
   }
   

• Start wpa_supplicant:

Use the following command to connect to the WiFi network:

sudo wpa_supplicant -B -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf
   

Replace wlan0 with the name of your wireless interface, which can be found using the ip link command.

• Obtain an IP address:

Once connected, obtain an IP address using dhclient:

sudo dhclient wlan0
   

This command configures the network interface with an IP address, allowing you to access the internet.

Step 4: Troubleshooting Connection Issues

If you encounter issues connecting to WiFi, here are some troubleshooting steps:

• Check the interface status:

ip link show wlan0
   

Ensure that your wireless interface is up and running.

• Check the logs:

If the connection fails, check the logs for wpa_supplicant:

sudo journalctl -u wpa_supplicant
   

This command provides detailed logs that can help diagnose the issue.

• Restart the network interface:

If the connection is unstable, try restarting the network interface:

sudo ip link set wlan0 down
   sudo ip link set wlan0 up
   

Conclusion

Connecting to WiFi from a root shell is a useful skill, especially when working in a non-GUI environment or troubleshooting network issues. By following this guide, you can easily connect to a WiFi network using either nmcli for simplicity or wpa_supplicant for a more manual approach. These methods ensure that you can maintain network connectivity even when operating at the root level.