Not really
@Michael M. It will be somewhere in ~ /opt/psa ~ (we think) but that will depend on your own server & plesk setups / access arrangements with your hosting company etc so you'd need to source that yourself. No idea of your Nginx usage, as you haven't mentioned it so far, but assuming that it's only setup in proxy mode, your .htaccess limitations should still be valid.
Meantime, as a temporary workaround (whilst sourcing the correct folder in your setup etc) you could maybe try this:
# Create /etc/sw-cp-server/conf.d/protect-plesk.inc with content:
location / {
auth_basic "Restricted";
auth_basic_user_file /etc/sw-cp-server/conf.d/passwd;
}
# Generate passwd file
htpasswd -cm /etc/sw-cp-server/conf.d/passwd
username
Check the permissions are correct:
/etc/sw-cp-server/conf.d/passwd should be 640
# Restart plesk panel
/etc/init.d/sw-cp-server stop
/etc/init.d/sw-cp-server start
We think that shoud work and it's close to what you are looking for.
Just delete /etc/sw-cp-server/conf.d/protect-plesk.inc and /etc/sw-cp-server/conf.d/passwd and the Restart plesk panel again if it doesn't