I had a need to get a host to ssh into a ESXi host without password. Obviously this is done with a public key, but everything changed on your ESXi gets lost on reboot, so here’s how to do it.
On your remote host:
ssh-keygen -t rsa
(Choose default location, and do not enter a password)
On your ssh-enabled ESXi:
mkdir /.ssh
Back on the remote host:
scp ~/.ssh/id_rsa.pub :/.ssh/authorized_keys
Check that you can now log in without password requirements.
Now the fun part – persisting the /.ssh/authorized_keys file. On the ESXi host:
busybox tar c - /.emptytgz /.ssh | gzip > /bootbank/oem.tgz
This will obviously destroy the contents of you oem.tgz file, so if you’ve installed with a custom ESXi image these changes get lost (but hey, if you did that, you already know about oem.tgz).