Set Passsword for existing User

Hi All,

I know, this should work with "ALTER USER...", But when I set the
password this way, i´m still able to gain unrestricted access without a
password. When setting a Password by creating the user, there´s no such
problem. I´m working with PostgreSQL 7.1 on a SuSE 7.1 Linux. Hope
anyone knows this Problem or is able to tell me what i have done wrong.
I intend to use Postgresql in a commercial productive Environment, but
without ability to change user passwords, i must refuse. But i certainly
don´t want to use that fucking MySQL Shit..............

Greetings,

Andy