define a default username for logging in

[takCoder]

Hi All :)

i'm trying to find a way to enable a required feature : to set *default
username *in my Freebsd 8.2 server..

i mean, i wanna be able to login with just entering My Master Password(no
usernames needed.. also prefer it to be per tty), which is *not related to
my root account,  *but is the password of a user which i have defined as my
default user..

is it possible for, e.g. pam_login module (i couldn't find any manuals on
such feature yet..), to have such a config or is there any other ways to
set such default username for login?

i've googled most of the keywords i thought might be related, but haven't
find any related answers except for maybe working on nsswitch.conf or
master.passwd or login.conf options (which are, as you see, really *different
ways,  *and also none seems to be behaved per tty..)
and now, i'm not quite sure whether i'm taking the correct steps or not..
and i've got a bit confused..

would anyone please helps me find the way?
thanks a lot for your helps :)

Best Regards,
takCoder