Connect to Server Using SFTP and Public SSH Key with FileZilla on Windows

The only correct way is to ask the server administrator to provide you the host key.

If you retrieve the host key remotely yourself, you cannot really trust the key, as you can be under a Man-in-the-middle attack already.

Anyway, the easiest way is to use ssh-keyscan tool:

> ssh-keyscan example.com
# example.com:22 SSH-2.0-OpenSSH_5.3
example.com ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEA0hVqZOvZ7yWgie9OHdTORJVI5fJJoH1yEGamAd5G3werH0z7e9ybtq1mGUeRkJtea7bzru0ISR0EZ9HIONoGYrDmI7S+BiwpDBUKjva4mAsvzzvsy6Ogy/apkxm6Kbcml8u4wjxaOw3NKzKqeBvR3pc+nQVA+SJUZq8D2XBRd4EDUFXeLzwqwen9G7gSLGB1hJkSuRtGRfOHbLUuCKNR8RV82i3JvlSnAwb3MwN0m3WGdlJA8J+5YAg4e6JgSKrsCObZK7W1R6iuyuH1zA+dtAHyDyYVHB4FnYZPL0hgz2PSb9c+iDEiFcT/lT4/dQ+kRW6DYn66lS8peS8zCJ9CSQ==

If you are on Windows, you can get a Windows build of ssh-keyscan from Win32-OpenSSH project or Git for Windows. It's built-in in recent versions of Windows 10.

For more options and background information, see my article Where do I get SSH host key fingerprint to authorize the server?

You can save the text that was sent to you as a file and use the built in "Choose..." feature on Cyberduck. I am on a Windows machine so I used the Notepad app. I assume TextEdit on a Mac would have similar results. Here are the steps:

1. Open Notepad
2. Paste the text that was provided for your SSH key
3. Save the file (I named mine key.txt)
4. Open Cyberduck
5. Select Open Connection
6. Select SFTP (SSH File Transfer Protocol) for the connection type
7. Enter server, port (22), username
8. You can skip password - it will use the SSH key
9. For SSH Private Key, select Choose... and find the save location of your file
10. Click Connect
11. The Unknown Fingerprint prompt will appear, click Allow (and you can select Always if this is a connection you trust and will often use)
12. You should see your files and/or your assigned folder location!