This help article is for Windows 10. If you use Linux/Ubuntu then read this article.
Make sure you have the Developer mode enabled on your Sailfish device. If not, see this article.
If you have not defined any SSH password yet (or you have forgotten it) in "Settings > Developer tools > Remote connection" then create one for yourself. You will need it soon.
Connect a USB cable between you PC and your Sailfish device. At the moment of connection, choose "Developer mode" at the device display.
Setting up SSH session
1. Launch Putty application on PC
If your phone has Sailfish OS 3.4.0 or later (*),
- enter firstname.lastname@example.org to the Host name (IP address) box
If your phone has Sailfish OS 3.3.0 or earlier,
- enter email@example.com to the Host name (IP address) box
(*) Some of these devices may still have "nemo" as the username.
Check that SSH is selected below the box.
2. Terminal window of Putty appears (black background)
- type your SSH password
You are now in the directory $HOME of the phone.
Check what is in the home directory:
Check the repositories required for over-the-air updates of Sailfish OS
If the connection attempt fails, disconnect the phone from the PC. Restart the phone (consider restarting the PC, too). Try again.