I get the following output if I run the following command:-bash-3.2$ ssh -o StrictHostKeyChecking no 192.168.1.77Warning: Permanently added '192.168.1.77' (RSA) to the list of known hosts.Last login: Fri Jul  4 10:49:11 2014 from chlorine.example.comSun Microsystems Inc.   SunOS 5.10      Generic January 2005-bash-3.2$I would like to run this command, without 192.168.1.77 being added to the list of known hosts, but still permitting a successful login.Is there an SSH option that allows this? I have gone through the man page for ssh_config and I've tried all the likely options such as setting CheckHostIP no with no success.Both the local and remote systems are running Solaris 10.If necessary, I could back up my $HOME/.ssh/known_hosts file prior to making a connection, and restore it after making the connection, but if there is an SSH option that allows me to avoid doing this, then I would prefer to use that.
Using SSH to connect to a new server without storing the host keys in the $HOME/.ssh/known_host file
ssh;solaris;ssh config
I see couple of more options from the answer here.Option 1:-o UserKnownHostsFile /dev/nullOption 2:If you want this behavior because you're working with cloud servers (AWS EC2, Rackspace CloudServers etc.) or you're constantly provisioning new images in Vagrant you may want to update your SSH config instead of adding bash aliases or more options on the command line.Consider adding something like:  Host *.mydomain.com   StrictHostKeyChecking no  UserKnownHostsFile /dev/null  User foo  LogLevel QUIETUse as strict as regex for host as possible to be secure.Setting the LogLevel to QUIET will keep the Warning which Guillaume mentioned from showing up.