Using Same Pub Key on 2 VM

You do not need to copy the private key (the file on your computer) to the new VM. You only need to copy the Public Key (the "Lock").

Since Computer 1 and Computer 2 already hold the same Private Key, you only need to perform this setup once (from Computer 1). Once the new VM has the Public Key, both computers will automatically be able to log in.

Step 1: Use Computer 1 to install the key

Since Computer 1 has the original .pub file, use it to set up the new VM.

Run this command on Computer 1:

Bash

ssh-copy-id -i ~/.ssh/id_ed25519.pub user@NEW_VM_IP

(Replace user and NEW_VM_IP with your new VM's details.)

Step 2: Test from both computers

1. From Computer 1: Try ssh user@NEW_VM_IP. It should work without a password.

2. From Computer 2: Try ssh user@NEW_VM_IP.

   • It will work instantly. You do not need to do anything on Computer 2.

   • Why? Because Computer 2 has the same "Key" in its pocket. You just installed the matching "Lock" on the new VM.

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Alternative: What if I am currently on Computer 2?

If you are sitting at Computer 2 and want to set up the new VM from there, you might be missing the .pub file (since we only copied the private key earlier).

You can regenerate the Public Key from your Private Key using this command on Computer 2:

1. Generate the missing Public Key file:

   Bash

    ssh-keygen -y -f ~/.ssh/id_ed25519 > ~/.ssh/id_ed25519.pub
   

2. Now copy it to the new VM:

   Bash

    ssh-copy-id -i ~/.ssh/id_ed25519.pub user@NEW_VM_IP
   

Summary of the Setup

• Computer 1 & 2: Both hold the Private Key (Identity).

• All VMs: All hold the Public Key (Authorized List).

Would you like to know how to set up an "SSH Alias" so you can just type ssh vm2 instead of the IP address?