This article describes the steps to configure public key authentication for admin account.
Download and install both PuTTY and PuTTYGen from www.putty.org.
Open PuTTYGen and select SSH-2 RSA (or RSA in newer version of PuTTYGen) and click Generate.
Note: PuTTYGen will generate a warning if your keylife isn’t protected by a password. Password protected is recommended as an additional security meansure, but not required for SSH to work.
If you’d like to set a password, enter it in the Key Passphrase and repeat it in the Confirm Passphrase fields prior to clicking Save private key.
Copy the public key from PuTTYGen or from it’s saved location and go to Administrator -> Device Access. Add this public key under Public Key Authentication section.
Start PuTTY and go to Connection -> SSH -> Auth.
Click Browse to select the .ppk keyfile generated earlier.
Navigate to Session and enter the Sophos Firewall’s IP address or hostname.
Make sure Connection type is set to SSH and click Open to connect to Sophos Firewall.
Enter the name admin to authenticate to Sophos firewall.