Don't get password prompt when ssh-ing from fedora
It turns out that this is due to a bug in the implementation of openssh in OSX Yosemite (too small message buffers to accommodate the modern range of available cyphers - please see Redhat Bugzilla bug 1373835 for details). The workaround given there, to limit the cypher list by specifying it explicitly, as for instance

ssh -o HostKeyAlgorithms=ssh-rsa,ssh-dss -o KexAlgorithms=diffie-hellman-group1-sha1 -o Ciphers=aes128-cbc,3des-cbc -o MACs=hmac-md5,hmac-sha1 user@host


works for me.