I examined a friend's system today, to help him configure it.  He just
"installed" from scratch the samba package, it appears that you have
provided a default smb.conf file for redhat 6.1 that puts samba private
configuration files in /etc.  The suggested options, for example show
"smbpasswd file = /etc/smbpasswd".

This is REALLY bad.

1) You CANNOT put smbpasswd in /etc.

2) You CANNOT put private files DOMAIN.TRUST_ACCOUNT.mac in /etc.

I know that these require root access, however if your users start to
assume that just because these files are in /etc, they are equivalent to
/etc/passwd, they may decide to make these world-readable, and as a result
they will compromise the security of the box, and potentially the security
of remote nt-compatible boxes too (including other samba servers) because
these files contain CLEAR_TEXT EQUIVALENT PASSWORDS.

For example, private .mac files can contain information sufficient to
compromise a remote server by obtaining all remote clear-text equivalent
passwords: the .mac file is used to store the "Backup Domain Controller"
trust account password.

I know that there are people out there who are using samba configured in
the way your installation suggests, because I have received debug log
files from people on the samba lists showing that trust accounts are being
read from /etc/DOMAIN.SERVER_NAME.mac.

Thank you.

luke (samba team, iss x-force research).