security mask = 000
force security mode = 660
directory security mask = 000
force directory security mode = 770
force user = nobody
force group = Domain Users

[global]
    workgroup = WORKGROUP
    server string = %h server (Samba, Ubuntu)
    interfaces = 127.0.0.0/8, eth0
    map to guest = Bad User
    obey pam restrictions = Yes
    passdb backend = ldapsam:ldap://ldap
    pam password change = Yes
    passwd program = /usr/bin/passwd %u
    passwd chat = *Entersnews*spassword:* %nn *Retypesnews*spassword:* %nn *passwordsupdatedssuccessfully* .
    syslog = 0
    log file = /var/log/samba/log.%m
    max log size = 1000
    load printers = No
    domain master = Yes
    dns proxy = No
    ldap admin dn = cn=root,dc=example,dc=com
    ldap group suffix = ou=Groups
    ldap idmap suffix = ou=Idmap
    ldap machine suffix = ou=Computers
    ldap passwd sync = yes
    ldap suffix = dc=example,dc=com
    ldap ssl = no
    ldap user suffix = ou=People
    usershare allow guests = Yes
    panic action = /usr/share/samba/panic-action %d
    idmap config * : backend = tdb

[CommonShare]
    comment = Common share
    path = /srv/samba/common
    valid users = @myusers
    read only = No
    create mask = 0660
    force create mode = 0770
    directory mask = 0770
    force directory mode = 0770
    inherit permissions = Yes
    inherit owner = Yes

[Myshare]
...
valid users = @bureau
...

[Myshare]
...
valid users = nobody @bureau
...