Forwarding of smartcard authentication to GNOME desktop doesn't work properly, e.g. users still need to authenticate when using 'sudo'.

This behaviour seems to be triggered by GNOME3,  which resets the forwarded smartcard key.

As a workaround, user can readd the smartcard key to SSH:

ssh-add -s <martcard_module_path_on_client>

Provide the PIN when requested.

For centOS/RedHat clients, command is:
ssh-add -s /usr/lib64/opensc-pkcs11.so

For Debian/Ubuntu clients it is:
ssh-add -s /usr/lib/x86_64-linux-gnu/opensc-pkcs11.so

After that,  sudo command will work without asking for password.

This requires that the pam_ssh_agent is configured properly on the remote host.

Path to the smartcard module specified in the NoMachine client UI must be valid and 'Forward authentication' must be selected.