I have an Ubuntu 14.04 instance running on AWS.
I was browsing the auth logs (
/var/log/auth.log*), and noticed the following line appearing:
Could not load host key: /etc/ssh/ssh_host_ed25519_key
This line appears between 1k-10k times a day, presumably due to failed hack attempts.
In researching this problem, I came up with a number of questions.
What is the effect of the absence of this key? I can still log in fine with the key provided by AWS. Is it forcing the security of my SSH connections to be downgraded? Has it been disabled on purpose because of security concerns?
I've seen some people suggest that the key wasn't generated correctly during installation, and that I need to regenerate the key with
Alternatively, I've also seen people recommend just commenting out the line:
HostKey /etc/ssh/ssh_host_ed25519_key in