Raspberry Pi SSH Without Logging In

I'm very annoyed that I can't just throw a Raspbian image onto an SD card and SSH into it without pulling out an HDMI monitor and keyboard. I finally have all the steps necessary to get it done. These steps were done on Raspbian Jessie 2017-07-05.

Image the SD card:

sudo dd if=imagefile.img of=/dev/yourdevice conv=notrunc,noerror ; sync

Now mount the "boot" partition of the SD card (you could just remove the SD card and insert it again).

In the boot partition, create an empty file called ssh (with no file extension).

(Optional) For WiFi, create a file in the boot partition called wpa_supplicant.conf and enter this content:

country=US
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
        ssid="YOUR_SSID"
        psk="YOUR_PASSWORD"
        key_mgmt=WPA-PSK
}

Then mount the primary partition of the SD card and run this in the terminal (assuming the SD card is mounted at /media/user/uuid):

cd /media/user/uuid/etc/ssh
sudo rm ssh_host_*

Now run these commands to set up dpkg-reconfigure to run on startup:

# Should create a line above "exit 0" like:
#   dpkg-reconfigure openssh-server
cd /media/user/uuid/etc
sudo sed -i 's/^exit\ 0/dpkg-reconfigure openssh-server\nexit\ 0/' rc.local

(Optional) You can remove that line later, or you can make it remove itself:

# Should create a line above "exit 0" like:
#   dpkg-reconfigure openssh-server && sed -i '/^dpkg.*/d' /etc/rc.local &
cd /media/user/uuid/etc
sed -i 's/^exit\ 0/dpkg-reconfigure openssh-server\ \&\&\ sed\ \-i\ '\''\/^dpkg\.\*\/d'\''\ \/etc\/rc\.local\ \&\nexit\ 0/' rc.local

Remove the SD card and put it into the Raspberry Pi. When you start up the Pi, you should be able to SSH into it immediately after everything runs (and once you figure out what the IP address is).

Remember, if you don't have a monitor it's easy to figure out the IP using:

sudo nmap -sn 192.168.0.0/24 | grep -B2 Raspberry

(Optional) If you didn't auto-remove the dpkg-reconfigure line, you can remove it:

sudo sed -i 's/dpkg.*//' /etc/rc.local