Hi People I am setting up some systems with ssh public keys and as part of this I am using the from directive inside .ssh/authorized_keys. Currently I am using the IP address to control the source. eg from="10.0.0.1" but on one CentOS 4 System that is up to date this will only work if I replace the IP with the DNS name of the server. I have verified that DNS is resolving the DNS Name to the correct IP address on the server in question and all seems to be fine. Aside from this CentOS Box have only been able to test this out on some old FC6 Machines and they behave as I expected. Anyone got any ideas why this might be happening ? I have compared the sshd config between the FC6 Machines and the CentOS Box and can't spot anything that would explain the issue. Thanks for any ideas, and have a nice day :)