ssh-keygen with no passphrase

[Jonathan Baron <baron psych upenn edu>]

I control about 5 Linux computers, all running RedHat 9 or some
version of Fedora.

In several versions of RedHat and with Fedora Core 1, I've been
able to use ssh-keygen to make a public key without a passphrase,
which I then put into .ssh/authorized_keys or
.ssh/authorized_keys2, and I am able to log in, or transfer files
with scp, without typing a password, a great convenience, which I
use with many scripts, such as those in which I back up stuff
from one Linux box to another (or even to a Solaris server).

This has stopped working in Fedora Core 2 test 2 and test 3.  I
can't find anything about it in bugzilla or the archives of this
list.  I really don't see why it shouldn't work, since this is
all part of openssh, which hasn't changed.  Or has it?  The
problem is that I must type in a password all the time.

Advice?

Jon
-- 
Jonathan Baron, Professor of Psychology, University of Pennsylvania
Home page:            http://www.sas.upenn.edu/~baron