How to Set Up Password‑Free SSH Between Linux Machines

Introduction

Linux users can control computers remotely using the Secure Shell (SSH) protocol. This guide explains how to configure SSH on two machines and achieve password‑less login.

Related Terms

Service : background software such as a web server.

Host : any computer that can run services for other machines.

Local : the computer you are currently using (e.g., localhost).

Remote : a computer you access over the network.

Activate SSH on Each Host

Both the client and server parts of SSH must be installed. Verify installation by checking configuration files:

$ file /etc/ssh/ssh_config

/etc/ssh/ssh_config: ASCII text

If the command returns “No such file or directory”, the client is missing. Check the server side similarly:

$ file /etc/ssh/sshd_config

/etc/ssh/sshd_config: ASCII text

Install missing components (example for Fedora/RHEL):

$ sudo dnf install openssh-clients openssh-server

Enable the SSH service on the remote machine: $ sudo systemctl enable --now sshd On GNOME, enable SSH via Settings → Sharing (see screenshot).

Test Password Login

After enabling SSH, test a password login using a known user account. Remote users can differ from local users; you only need the correct username and password.

Find the remote machine’s IP address (example shows 10.1.1.5): $ ip addr show | grep "inet " If ip is unavailable, try ifconfig (or ipconfig on Windows).

Ping the remote host to confirm reachability: $ ping -c1 10.1.1.5 Then log in: $ ssh [email protected] Successful login confirms the basic SSH setup.

Create SSH Keys

To log in without a password, generate an SSH key pair. The private key stays on the local machine; the public key is copied to the remote host. $ ssh-keygen -t ed25519 -f ~/.ssh/lan This creates lan (private) and lan.pub (public) files.

Copy the public key to the remote host (you must have password access first):

$ ssh-copy-id -i ~/.ssh/lan.pub [email protected]

After copying, use the private key for future logins: $ ssh -i ~/.ssh/lan [email protected] Repeat the key‑copy process for every machine in the LAN to achieve password‑less access across the network.

Disable Password Authentication (Optional)

To enforce key‑only authentication, edit /etc/ssh/sshd_config on each host and set: PasswordAuthentication no Restart the SSH service to apply the change:

$ sudo systemctl restart sshd && echo "OK"

Everyday Use of SSH

OpenSSH lets you work on any computer from anywhere, breaking the need to sit in front of the machine. Use SSH to manage servers, develop on remote systems, or access IoT devices securely.