Redmine

Hi:
I was reading the LDAP Authentication in the Redmine Guide and I'm trying to get this work. Now when I logging using my LDAP account all is fine but I need to setup this in the administration and I don't want this because I have at least 1000 workers and If I need do this for every one of them then this will take a lot of time.

So I have a doubt about the "On the fly user creation". As I understood when I check this it means when a user register in the Redmine SW and the same user have a LDAP domain account then the user will be able to login with both passwords? I mean the password that it used to register and the LDAP account password? I'm wrong? Any way to link automatically without the admin intervention the new created user with the LDAP Domain?

Regards