samba - Dec 2002 - Public shares under user security level

Hello,
   I am wondering if under user security level, is this possible to offer a 
public share to anyone without username/password? I tried the following 
setting:

[global]
    security = user
    auto services = tmp
    default service = defaultshare
    null passwords = yes
....

[tmp]
   path = /tmp
   read only = no
   public = yes
   guest ok = yes
   browseable = yes

[defaultshare]
   copy = tmp



But it failed. Anything options I should modify?  Or should I modify the 
file for the option of username map? If so, how to do it?

Thanks.

Long-Sheng    Dec. 15, 02