Rotating host keys and updating known_hosts

One thing we've not mentioned yet are host keys, and the known_hosts file.

This is something that is often overlooked, so I'd like to take a few minutes to go over these otherwise-ignored treasures.

In this section, we will inspect what happens when you first SSH to a new machine, and then we will change the keys of that machine to see what problems this causes us.

Getting ready

Connect to centos1 and centos2 in different sessions:

$ vagrant ssh centos1
$ vagrant ssh centos2

If you're working on a fresh setup, SSH to centos2 from centos1 and accept the host key when you're presented with it.

Log back out of centos2:

[vagrant@centos1 ~]$ ssh 192.168.33.11
The authenticity...