It would have to be a very old release indeed.
IIRC, Oracle 7 sent the password encrypted.
There were exceptions: the first logon attempt was encrypted. Subsequent attempts ( as in you typed the password incorrectly) would be sent in clear text.
A perusal of the docs would probably be in order.
The OP has not stated if his original question has been answered. It was rather vague.
Jared
Sorry I got confused I thought you was asking about the fact old database releases send through network the password as clear text, when you log. :( -- //www.freelists.org/webpage/oracle-l
-- Jared Still Certifiable Oracle DBA and Part Time Perl Evangelist