Connecting To Raspberry Pi Over WiFi

Raspberry Pi is great. It is a small and cheap computer that can be used for a variety of projects. Sometimes you may wish to remotely control a Rasperry Pi that is in your local WiFi network. This is possible and even quite easy.

We will use a Secure Shell aka SSH to establish a remote connection. I assume that you have previously connected your Raspberry Pi board to a WiFi network. I also assume that you are connecting from a Linux or OS X machine.

Step 1: Enable SSH On Raspberry Pi

There are several methods to enable SSH access, including graphical user interface (GUI). However, I find the easiest method is without even turning on your Raspi board. This also does not require any GUI to be installed. We enable SSH simply by creating a blank file named ssh on the Raspbian OS boot partition. That is on the memory card where Raspbian OS is intalled.

So insert the Raspi SD card in your computer. Assuming that the SD card maps to two devices¹, /dev/mmcblk0p1 and /dev/mmcblk0p2, the first of them usually corresponds to the /boot partition. Below, we mount the partition to an existing directory /mnt/usbstick. Finally, we create ("touch") a blank file ssh within the directory.

sudo mount /dev/mmcblk0p1 /mnt/usbstick
cd /mnt/usbstick
sudo touch ssh

Afterwards, before inserting the memory card back into Raspberry Pi, we unmount the partition:

cd
sudo umount /dev/mmcblk0p1

Done. Now, during its boot, Raspbian will find the ssh file and will allow SSH access.

Step 2: Discover IP Address of Raspberry Pi

One way is to boot your Raspi, open terminal and type:

$ hostname -I
192.168.0.13

If this works for you, note the address and skip directly to Step 3. However, if there is no monitor connected to your Raspi board this is not a problem at all. You can discover connected devices on your WiFi network. First, learn your network address range and then scan it for connected devices.

Network Information

ip addr

Note that on some machines ip addr command is called ifconfig.

This will provide the information about network interfaces.

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: wlp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 9c:b6:d0:8e:ad:19 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.11/24 brd 192.168.0.255 scope global dynamic noprefixroute wlp2s0
       valid_lft 85985sec preferred_lft 85985sec
    inet6 fe80::42f4:2e5a:a6b2:9232/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
...

Our computer has local IP address 192.168.0.11. Therefore, our WiFi network has IPs starting with 192.168.0..

Scan Your WiFi Network

Install nmap using your system's package manager. For example, on Arch Linux:

sudo pacman -S nmap

Scan with

$ nmap -sn 192.168.0.0/24
...
Nmap done: 256 IP addresses (3 hosts up) scanned in 2.52 seconds

If your Raspi board was off, boot it now, wait until it connects and scan the network again.

$ nmap -sn 192.168.0.0/24
Starting Nmap 7.80 ( https://nmap.org ) at 2020-04-25 16:03 CEST
Nmap scan report for 192.168.0.1
Host is up (0.044s latency).
Nmap scan report for 192.168.0.5
Host is up (0.019s latency).
Nmap scan report for 192.168.0.11
Host is up (0.000066s latency).
Nmap scan report for 192.168.0.13
Host is up (0.016s latency).
Nmap done: 256 IP addresses (4 hosts up) scanned in 2.37 seconds

The newly appeared host is your board.

Step 3: Connect To Raspi

$ ssh pi@192.168.0.13
pi@192.168.0.13's password: 
Linux raspberrypi 4.19.75-v7+ #1270 SMP Tue Sep 24 18:45:11 BST 2019 armv7l

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Sat Apr 25 16:03:26 2020

Now, we can control the board or even exchange files with scp.

$ pi@raspberrypi:~ $ whoami
pi

Hint: do not forget to change the default user password:

sudo passwd pi