SSH on Linux: Disabling host key checking for hosts on local subnet (known_hosts)

This is the configuration I use for our ever-changing EC2 hosts:

maxim@maxim-desktop:~$ cat ~/.ssh/config 
Host *amazonaws.com
        IdentityFile ~/.ssh/keypair1-openssh
        IdentityFile ~/.ssh/keypair2-openssh
        User ubuntu
        StrictHostKeyChecking no
        UserKnownHostsFile /dev/null

This disables host confirmation StrictHostKeyChecking no and also uses a nice hack to prevent ssh from saving the host identify to a persistent file UserKnownHostsFile /dev/null note that as an added value I’ve added the default user with which to connect to the host and the option to try several different identify private keys.