On 8/23/23 12:22, Grigory Shamov wrote:

Hi Stefan,

Thank you very much for your response! Yes, it looks like our SSH server "interactive" response for Yubikey/Duo is not being recognized by the current X2Go clients. The kind of response that looks like this:

==== (user@host) Duo two-factor login for user:

Enter a passcode or select one of the following options:

Passcode:

We are running an HPC machine here, with user authentication coming from a National-wide HPC organization, that chose Duo for MFA. We cannot easily just pick a random 2nd factor vendor.

The related common SSH/SFTP/SCP GUI clients like PuTTY and and MobaXterm and FileZilla do not seem to have this issue, at least in recent versions. (I just had a user that out of exasperation tried to run X2go over an SSH client created by Putty which is of course impossible) .

I think the main difference between x2goclient and at least putty is that x2goclient is managing the ssh interaction and feeding the prompts as needed. putty is simply presenting the prompts to the user and allowing them to interact with them. I'm not sure x2goclient has any other way to know that the connection is waiting for more authentication input.

x2go client has the following known prompts:

const QString SshMasterConnection::challenge_auth_code_prompts_[] = { "Verification code:", // GA (http://github.com/google/google-authenticator) "One-time password (OATH) for", // OATH (http://www.nongnu.org/oath-toolkit/pam_oath.html) "passcode:", // MOTP (http://motp.sourceforge.net) "Enter PASSCODE:", // SecurID "YubiKey for" // YubiKey (https://en.wikipedia.org/wiki/YubiKey) };

which is close. We could either add "Passcode:" for Duo, or make the comparison case insensitive.

-- Orion Poplawski he/him/his - surely the least important thing about me IT Systems Manager 720-772-5637 NWRA, Boulder/CoRA Office FAX: 303-415-9702 3380 Mitchell Lane orion@nwra.com Boulder, CO 80301 https://www.nwra.com/