1

I'm trying to understand the difference bw these two files:

  1. /etc/ssh/ssh_host_rsa_key
  2. ~/.ssh/id_rsa_key

Which one's on the server side? which one on the client, connecting via ssh to a remote host?

I ask this, following this question that popped up in a quiz for the LPIC1 exam 102:

Wade’s OpenSSH private key was compromised, so he needs to create himself a new public/ private key pair. Using super user privileges, what command should he use?

  1. ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key
  2. ssh-keygen -t rsa -f /etc/ssh/ssh_host_ecdsa_key
  3. ssh-keygen -t rsa -f ~/.ssh/id_rsa_key
  4. ssh-keygen -t rsa -f ~/.ssh/id_ecdsa_key
  5. ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key.pub

The correct answer seems to be 1. but I'd opted for 3. Why is 1. correct? how is it different than 3.?

2
  • 1
    Weird question, generating a new pair of keys for your user does not require "super user privileges".
    – Panki
    Apr 16 '21 at 12:56
  • 1
    To understand which key is what, read the section "AUTHENTICATION" of man ssh
    – Panki
    Apr 16 '21 at 13:00
0

You can already infer from the file names that a key in /etc belongs to the system, while a key in ~ (or $HOME) belongs to a user.

If a person's user is compromised, that user creates a new key. Super user privileges are not necessary.

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