SSH Access From Multiple Devices

Got a Linux box set up with SSH key auth from one PC, want to SSH in from others too?

If you set up passwordless SSH the normal way, you generated a keypair on one PC and dropped the public half into ~/.ssh/authorized_keys on the remote machine. That means only that one PC can get in. Don’t fix this by copying the private key onto every other device — private keys shouldn’t travel. Instead, give each device its own identity.

1. Generate a keypair on each additional PC

ssh-keygen -t ed25519 -C "some-name-for-this-device"

Leave the passphrase blank if you want fully passwordless, or set one if the device isn’t fully trusted (laptop that leaves the house, etc).

2. Add each new public key to the remote machine’s authorized_keys

Get the Key

Get-Content C:\Users\Rick\.ssh\id_ed25519.pub

Easiest way, from a PC that already has access:

ssh user@remote-host "echo '<paste-new-pubkey-here>' >> ~/.ssh/authorized_keys"

Or from the new PC itself, if password auth is still enabled on the remote host:

ssh-copy-id user@remote-host

Each key gets its own line in authorized_keys — they stack, they don’t overwrite each other, and you can remove one device’s access later by deleting its line without touching the rest.

3. Reachability

This only gets you SSH access from devices on the same LAN/subnet as the remote box. If you want access from off-network (laptop out and about, phone, etc), key auth alone doesn’t solve that — you also need one of:

• Tailscale / WireGuard on the remote box — simplest, no port forwarding, devices join a private mesh network
• Port forward + reverse proxy or bastion — more exposure, only do this if you know what you’re locking down

Notes

• If you disable password auth entirely (PasswordAuthentication no in /etc/ssh/sshd_config), ssh-copy-id needs an existing authorized key or physical/console access to seed the first one.
• Rotate or remove a device’s key any time by deleting its line from authorized_keys — no need to touch anyone else’s.