SSH List-dwellers: I'm using OpenSSH in an environment with lots of clusters. These clusters have IP addresses which are associated with a particular application rather than with a particular host. Oftentimes (especially for file transfers) it's helpful to ssh/scp to the IP address associated with the application rather than the one associated with the host. However, given that each host has its own host key, we frequently get: WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! Which of course panics the user the first time they see it, and causes them to ignore it the second time onward-- neither of which are desired behaviors... I've thought about several solutions to this including: 1) Make all the host keys the same (hundreds of hosts, kind of diminishes the value of a host key...) 2) Configure ssh to ignore host key changes (harder than you might think since often new ssh clients are brought in) 3) Give each application its own dedicated ssh and host key (tricky to set up and monitor, fairly high effort) 4) Tweak OpenSSH so that it will accept any host key from a list (requires some programming effort, might not be a good idea) 5) Other? What do you all think of option 4? In particular, I was thinking that there might be a way to allow hosts on the same subnet to simply prompt to add the additional key for the same DNS name rather than popping up the man-in-the-middle warning. If there were multiple keys present in known_hosts for a given hostname, any of them would be accepted. Could this be done without weakening the host security of OpenSSH? Should I instead just hold The Great Re-Keying and go with option 1? I appreciate any advice. Thanks, -- Steve Bonds
