Setting Up Passwordless SSH Login between a Client and Two Servers

Setting up passwordless SSH login with key pairs makes connecting to your servers both quicker and more secure, since you’re no longer typing a password every time or relying on one to keep people out. This guide covers generating a key on your client machine and configuring passwordless logins to two separate servers.

Step 1: Generate a Key Pair on the Client

On the client machine, open a terminal and generate a key. We’re using ed25519 here, which is the modern, secure default:

ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519_client -C "[email protected]"

Step 2: Copy the Public Key to Each Server

Use ssh-copy-id to install your public key on each server, replacing <username> and the hostname with your own. Run it once for each server:

ssh-copy-id -i ~/.ssh/id_ed25519_client.pub <username>@<server1_hostname>
ssh-copy-id -i ~/.ssh/id_ed25519_client.pub <username>@<server2_hostname>

If ssh-copy-id isn’t available on your system, you can achieve the same thing by manually appending the contents of the .pub file to ~/.ssh/authorized_keys on each server.

Step 3: Configure SSH on the Client

To avoid typing out the full hostname, user, and key path every time, set up a config file on the client that gives each server a short alias:

nano ~/.ssh/config

Add a block for each server, filling in your own hostnames and usernames:

Host server1
    HostName <server1_hostname>
    User <server1_username>
    IdentityFile ~/.ssh/id_ed25519_client

Host server2
    HostName <server2_hostname>
    User <server2_username>
    IdentityFile ~/.ssh/id_ed25519_client

Save and exit.

Step 4: Test the Connection

Thanks to the aliases in your config file, you can now connect to either server by name, with no password prompt:

ssh server1
ssh server2

If both connect straight through without asking for a password, you’re done. From here you’ve got quick, key-based access to both servers, and you can extend the same config with more hosts as your setup grows.

Related guides

• How to Fix “Host Key Verification Failed” Error in Proxmox
• A Guide to Adding Groups and Users in Linux
• A Guide to Crontabs: Scheduling Tasks