I can't connect using an ed25519-sk or ecdsa-sk FIDO2 key

FIDO2-based authentication is available only in the Dekstop Termius app, starting from 7.41.0, and in the iOS Termius app, starting from 4.13.9. It is included in the Pro and Team plans and available during a trial period.

Termius supports only the FIDO 2.0 (CTAP 2) protocol.

Connecting using a key stored on the authenticator is possible only if no other methods except public key authentication is allowed on the server. Also, if you're trying to establish a connection using a key stored on an authenticator, make sure no key is attached to the host entry.

FIDO2-based authentication requires OpenSSH 8.2 or higher to be installed on the server.

Support for FIDO2 keys has been tested on a limited number of devices, so, if you're facing connection issues, please, send us an email including the name of your authenticator. Please attach a screen recording or a screenshot illustrating the issue.

You can read more about the support for FIDO2-based authentication in Termius here.

OS-specific requirements

Termius needs access to the hardware key to complete authentication using FIDO2 keys. Please, make sure you grant Termius permissions to USB devices.

This type of authentication requires your hardware key to be plugged into a USB port and recognized by the OS.

Linux requires adding a udev rule for you to be able to access FIDO devices, similar to this one:

#udev rule for allowing HID access to Yubico devices for FIDO support.
KERNEL=="hidraw*", SUBSYSTEM=="hidraw", \
  MODE="0664", GROUP="plugdev", ATTRS{idVendor}=="1050"