.ssh config file/IdentityFile issue, which key to copy?

Question

I'm a little confused on why this is not working and think it may have something to do with me using the wrong key, but I'm not sure what other one to use. Maybe I am missing a step? We have a "jumpbox" (we'll call it server1) that allows us to get in to some vendor's servers. There is a config files in .ssh for each of the different servers we connect to. Everyone here copies an ssh key to different systems to get access and no one uses the password to the final server (server2).

I created a config file in .ssh and it looks like this:

Host server2
    Hostname IPADDRESS
    ProxyCommand ssh -W %h:%p root@jumpbox.company.com
    IdentityFile ~/.ssh/server2
    User root

I copied the keys from another users system but fear that I may have the wrong ones or I'm missing a step. When I try to ssh to server2, it prompts me for the jumpbox root PW, but then after that it prompts me for the server2 password and doesn't let me in with the key.

I feel like I copied the wrong key, but I don't see how. I copied 2 keys for server2 from a coworker's system. One that was just server2 and one that was server2.pub. As you can see in the IdentityFile it only references server2. The error that I get before being prompted for server2's PW is:

sign_and_send_pubkey: signing failed: agent refused operation

I've been trying to research the answer but feel like I'm missing a step or something. Don't have anyone else here that can assist as I am the one that does this stuff :) Can any of yall point me in the right direction?

Answer 1

sign_and_send_pubkey: signing failed: agent refused operation

This points to the case where your ssh-agent is in use. To exclude it from the use case, try to connect without it:

SSH_AUTH_SOCK="" ssh server2

If it will work, it is problem in ssh-agent. It might be problem that it is some different tool talking this protocol (gnome-keyring) which does not know that key type (ed25519) or many different reasons.

What key type is that? Show us the public key to investigate further if none from above works.