The following issues are known changes in behavior between Samba-2.2 and
Samba-3 that may affect certain installations of Samba.
When operating as a member of a Windows domain, Samba-2.2 would map any users authenticated by the remote DC
to the “guest account” if a UID could not be obtained via the getpwnam() call. Samba-3 rejects
the connection with the error message “NT_STATUS_LOGON_FAILURE.” There is no current workaround
to re-establish the Samba-2.2 behavior.
When adding machines to a Samba-2.2 controlled domain, the
“add user script” was used to create the UNIX identity of the
machine trust account. Samba-3 introduces a new “add machine
script” that must be specified for this purpose. Samba-3 will
not fall back to using the “add user script” in the absence of
an “add machine script”.