I have this same problem since updating to 6.10.2. I have two unraid servers both on 6.10.2 If I SSH in from one to the other I get the error "hostfile_replace_entries: link /root/.ssh/known_hosts to /root/.ssh/known_hosts.old: Operation not permitted
update_known_hosts: hostfile_replace_entries failed for /root/.ssh/known_hosts: Operation not permitted". It does proceed to log me in though. I tried clearing the known host file and it did then update the file despite the message. The other oddity is it only does it in one direction. If I SSH in form the other server it works fine. I can see no difference between the file permissions. The only other difference I can think of is that on one server I updated regularly through the 6.10 beta releases and on the other I went from 6.9 straigh to the stable release of 6,10. I see that this was reported with OpenSSH but it was patched some while ago
