Add extra admin users - FreshTomato

Hi,

I am using and loving FreshTomato on a Netgear R6250 router. I was hoping to add extra admin users, but I cannot find a way to do it. I've tried adding user information to /tmp/etc/passwd, shadow, group, but this does not seem to work.

I have a reverse proxy tool that wants to pass basic authentication credentials and the extra users would be used for this.

Any suggestions?

thanks

David