How do I enable SSH on raspbian stretch (2018-04-18) by default on boot without a monitor

Question

Background: I setup my wireless without a screen by mounting my distribution image(2018-04-18-raspbian-stretch-lite.img) according to the instructions on these links.

mounting distribution image

changing files to connect to wireless

and then using the linux dd command to put the modified image on my SD card

with Arch linux I use $ip addr to view my public ip address and $sudo nmap -sn XXX.XXX.X.XXX/XX to view connected devices on my wireless network. The raspberry pi shows up with its ip address and I have included the ssh file in the boot folder of the raspberry pi to enable ssh, but when I try to ssh into it using $ssh [email protected] I get ssh: connect to host XXX.XXX.X.XXX port 22: Connection refused. I believe the problem in this latest distribution is that placing ssh into boot doesn't enable ssh anymore. A commenter called Decades references that it does not work for him either in a recent post located here. What is an alternative to placing a file named ssh into the raspberry pi boot directory that would work for enabling ssh on boot?

Note: XXX.XXX.X.XXX/XX or XXX.XXX.X.XXX represents an ip address.

edit: the issue was that I placed ssh in the boot directory not the boot partition. ssh now works fine.

Answer 1

I have just tested with a fresh flashed Raspbian Stretch Lite 2018-04-18 on a Raspberry Pi 3B+. Adding an empty file /boot/ssh will persistent enable the ssh server on the Raspberry Pi. Even after several boots I get (have a serial tty-usb console cable):

pi@raspberrypi:~$ systemctl status ssh.service
● ssh.service - OpenBSD Secure Shell server
   Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2018-04-18 01:08:39 UTC; 1 months 0 days ago
  Process: 524 ExecStartPre=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS)
 Main PID: 527 (sshd)
   CGroup: /system.slice/ssh.service
           └─527 /usr/sbin/sshd -D

Apr 18 01:08:39 raspberrypi systemd[1]: Starting OpenBSD Secure Shell server...
Apr 18 01:08:39 raspberrypi sshd[527]: Server listening on 0.0.0.0 port 22.
Apr 18 01:08:39 raspberrypi sshd[527]: Server listening on :: port 22.
Apr 18 01:08:39 raspberrypi systemd[1]: Started OpenBSD Secure Shell server.
pi@raspberrypi:~$

To enable wifi you have to add /boot/wpa_supplicant.conf on your raspi with something like:

country=DE
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
    ssid="[email protected]"
    psk="verySecretPassword"
}

You don't use a pi-3b+ but for the completeness for other readers: Adding the country=XX line is essential for Pi 3 B+ because without it wifi will not start. Look at release notes:

018-03-13: * Raspberry Pi 3 B+ support
* WiFi is disabled until wireless regulatory domain is set (Pi 3 B+ only) - The domain can be done through 'Raspberry Pi Configuration' (rc_gui), 'raspi-config' or by setting 'country=' to an appropriate ISO 3166 alpha2 country code in /etc/wpa_supplicant/wpa_supplicant.conf.
* Default wireless regulatory domain is now unset

Putting it all together I have done this:

pc ~$ # on a pc with debian and mounted SD card to /dev/sdb
pc ~$ sudo -Es
pc ~# unzip -p 2018-04-18-raspbian-stretch-lite.zip | dd of=/dev/sdb bs=4M conv=fsync
pc ~# mount /dev/sdb1 /mnt/
pc ~# touch /mnt/ssh
pc ~# cat >/mnt/wpa_supplicant.conf <<EOF   # use your settings
country=DE
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
    ssid="[email protected]"
    psk="verySecretPassword"
}
EOF

pc ~# umount /mnt/
pc ~# exit
pc ~$

Put the SD card into your raspi and boot. If you do exactly the same as above you should be able to ssh into your raspi through wifi. If not the raspi isn't the reason (or it's broken). Look at your environment. Or you have done wrong settings.