Установил samba-2.2.0.
И обнаружил новый файл secrets.tdb(в одной директории с smb.conf).
Раньше стояла 2.0.7 и ничего подобного не встречал.
Решил поискать,нашел вот это:

"MACHINEPASSWORDTIMEOUT" machine password timeout
If a Samba server is a member of an Windows NT Domain (see the
security=domain parameter) then periodically a running smbd(8) process will try and change the MACHINE ACCOUNT PASSWORD stored in the TDB called
private/secrets.tdb.

    This parameter specifies how often this password will be changed, in
seconds. The default is one week (expressed in seconds), the same as a
Windows NT Domain member server.

This file is created and owned by root and is not  readable by any other
user. It is the key to the domain-level  security for your system, and should be treated as carefully  as a shadow
password file.

Now, before restarting the Samba daemons you must  edit your smb.conf file to tell Samba it should now use domain security.

Change (or add) your <parameter> security = domain line in the [global]
section  of your smb.conf

Стоит самба, не членом домена,а как обычная станция.
Почему создается, непонятно.
Это не критично, все работает, просто интересно.
OS - RH7.0

• RE: samba-2.2.0, PJ, 15:48 , 27-Авг-02, (1)