If 'Anyone' doesn't have User rights on a project, you can't perform an analysis without providing sonar.login and sonar.password.
However, the error message you get doesn't differentiate between the issues of:
- secured server
- secured project
So you spend time banging your head against the fact that sonar.forceAuthentication is set to false.
Please differentiate the error messages between 'Anonymous doesn't have rights to this project, please supply sonar.login and sonar.password' and 'Anonymous can't access this Sonar server, please supply sonar.login and sonar.password'