I came across a new machine that needed to connect to many SSH hosts via ansible. I had a problem where ansible was prompting me for each post if I wanted to accept the RSA key. As I had dozens of hosts I didn’t want to type yes for every single one; furthermore the yes command didn’t appear to work. I needed a way to automatically accept all SSH RSA keys from a list of server names. I know you can disable RSA key checking but I didn’t want to do that.

I eventually found this site which suggested a small for loop, which did the trick beautifully. I modified it to suit my needs.

This little two-liner takes a file (in my case, my ansible hosts file) and then runs ssh-keyscan against it and adds the results to the .ssh/known_hosts file. The end result is an automated way to accept many SSH keys.

SERVER_LIST=$(cat /etc/ansible/hosts)
for host in $SERVER_LIST; do ssh-keyscan -H $host >> ~/.ssh/known_hosts; done