Securing Root

In addition to the default user, pi, there is another default user on the Pi. This is the root user. The root user is, essentially, an administrative user that is used by the machine to execute low-level commands. This user has access to everything and can do anything because, well, it’s the machine. Unlike the default pi user, however, root does not have a default password. It has no password.

Your root user is now secured, which is good because you’ll need it for the next step in the configuration.

Change the Default Username

At this point, you have changed the default user credentials for both the default user and the root user. You have also changed the hostname. This is the minimum needed to secure your Pi and your robot.

Your Raspberry Pi is now set up, configured, and ready for use. There is one more thing we’re going to want to do before we move on to the next chapter, and that is setting up your Pi to be headless.

Making a machine “headless” simply means configuring it so you no longer need to connect a monitor, a keyboard, and a mouse to it to operate it. This is generally done in two ways: with a KVM switch or by setting up remote access. On a mobile robot, connecting a KVM is not really an option. In fact, it would be a little different from simply having everything connected to it. What we want to do is set up the Pi so that we can access it remotely over the network. But first, let’s make sure that you’re connected to your network.

Remote Desktop with xrdp

Let’s start with accessing the desktop remotely from another computer. The following instructions are for Windows users. Most modern Windows installations come with Remote Desktop Connection already installed, which is what we’ll use to connect to the Pi once it’s set up.

To get connected, do the following:

1. 4.

   On the Pi, type sudo ifconfig.

    
2. 5.

   Note the Internet address (inet addr) in the eth0 block if you are using an Ethernet cable or the wlan0 block for Wi-Fi.

    
3. 6.

   On your laptop, open Remote Desktop Connection. This displays the connection dialog box, as shown in Figure 2-7.

    

You should see the remote desktop screen with the xrdp login form (see Figure 2-8).

1. 9.

   Enter your username and password.

    
2. 10.

   Click OK. This opens the desktop from your Pi (see Figure 2-9).

    

As long as the IP address of your Pi doesn’t change, you no longer need the keyboard, mouse, or monitor to use your Pi.

SSH with PuTTY

The most common SSH client is probably PuTTY. It’s free to use and can be downloaded from www.chiark.greenend.org.uk/~sgtatham/putty/download.html.

The file you downloaded for PuTTY is an executable, which won’t need to be installed. Put it on your desktop or somewhere easy to find. To get connected, do the following:

1. 1.

   Open the PuTTY interface (see Figure 2-10).

    

1. 2.

   Enter your Raspberry Pi’s IP address.

    
2. 3.

   Click Open.

    
3. 4.

   You will likely get a security warning, as shown in Figure 2-11, but we know that this is the proper connection, so click Yes.

    

A terminal window opens, asking for your username and password.

1. 5.

   Enter your username and password. You should now see the terminal prompt, as shown in Figure 2-12.

    

That’s it. You are now connected via SSH to your Raspberry Pi. You can have multiple connections going at once, but don’t have more than you need to. Multiple connections are handy when you’re working with something like the Robot Operating System (ROS). (Don’t worry; that’s a ways away.) ROS runs multiple programs via the terminal. Each one requires its own terminal window. With PuTTY, you’re able to have as many remote terminal connections as you need.

Finding Your Device on a Network

To access your Pi remotely, you need to know its IP address on the network. Generally, a network switch retains a device’s IP from session to session; however, this isn’t guaranteed.

Finding your device’s IP address on the network can be tricky. If you are at home and have access to your router’s admin panel, this is probably the most straightforward way to find your device. Simply log on to your router, find the list of connected devices, and scroll down until you find the hostname of your Raspberry Pi.

If you need to find the IP address but are away from home, there are a few ways to do it. The easiest is to use an Nmap app on your phone. I use an app called Fing on my Android phone. Once the phone is connected to the local Wi-Fi network, the app scans the network and lists all the other devices on that network. You can just scroll down the list until you find your hostname.

If the network is new to you, your Raspberry Pi will not automatically connect to it. This situation makes it a little tricky. To make things easier, be prepared before you go out. I am a Windows user; if you are not, you need to look up the proper procedure for your OS. I do this operation with the laptop I have when traveling. It allows me to remote into the Pi long enough to connect to the local Wi-Fi and get the wlan0 IP address.

Keep in mind that the IP is assigned by the laptop. The IP you get at the end of this operation will likely not work from any other machine.

On a Windows 7 or later machine, you can perform the following steps to remote into your Pi directly to get its IP address. Make note of the IP address should you ever need to connect directly to the Pi to set up a new Wi-Fi connection. You will need a short Ethernet cable, which should be added to your kit or toolbox.

You should now have a remote connection from your laptop directly to the Raspberry Pi. Make sure that you save this IP address where you can find it later. Remote Desktop Connection should remember it, but it’s a good idea to also save it somewhere else.

Now whenever you are trying to connect to a new Wi-Fi network, you can use the Ethernet cable to remote into your Pi directly from your laptop. Once remoted in, simply select the network from the list of available networks and enter the passcode, if there is one.