SSH Key-Based Authentication: Passwordless Login

Learn how to set up SSH key-based authentication for passwordless login and secure server access. This step-by-step tutorial covers generating SSH keys, configuring authorized_keys, and enabling password-free connections on Linux, Unix, macOS, and Windows systems. Discover why SSH keys improve security, reduce brute-force attacks, and streamline workflows for sysadmins and developers. Say goodbye to passwords and hello to efficient, secure automation with SSH!

#SSH #SSHKeys #PasswordlessLogin #Linux #Windows #SysAdmin #ITPro #Automation #CyberSecurity #DarienTips

Applies to:

✅ Red Hat, SUSE, Debian, Ubuntu, Unix, macOS
✅ Windows 10, Windows 11
✅ Windows Server 2016–2025


Chapters

0:00 Introduction
0:50 Generate SSH Key Pair
2:46 Copy Public Key to “Remote” System; SSH without Password
3:07 Copy Public Key — Linux to Linux
3:37 Copy Public Key — Linux to Windows
4:56 Copy Public Key — Windows to Windows
5:36 Copy Public Key — Windows Remote Management and Trusted Hosts
6:11 ssh -i (identity file) using the private key
7:28 OpenSSH Server Installation
7:40 OpenSSH Server Installation — Windows Server 2025
9:07 OpenSSH Server Installation — Windows Server 2022 and earlier
11:01 OpenSSH Server Installation — Windows 11
11:24 OpenSSH Server Installation — Ubuntu Linux 24.04 and Debian distros
12:04 OpenSSH Server Installation — SUSE Linux
12:55 OpenSSH Server Installation — Red Hat Linux and clones
13:14 Windows Server 2025 caveat
13:39 Thank you for watching


Glossary:

APT = Advanced Package Tool
DNF = Dandified YUM
DPKG = Debian Package (package manager for Debian-based distributions)
DSA = Digital Signature Algorithm
ECDSA = Elliptic Curve Digital Signature Algorithm
Ed25519 = Edwards-curve Digital Signature Algorithm
PKI = Public Key Infrastructure
RSA = Rivest–Shamir–Adleman
SCP = Secure Copy Protocol
SSH = Secure Shell
WinRM = Windows Remote Management
WS-Man = Web Services-Management
YaST = Yet another Setup Tool


Commands:

systemctl status ssh*
apt list openssh*
sudo apt install openssh-server
sudo systemctl enable --now sshd
ssh-keygen -t ed25519 -C "[comment]"
ssh-copy-id [user]@[host]
scp ~/.ssh/id_[algorithm].pub [user]@wsvr2025:"C:\Users\[user]"
Get-Content .\id_rsa.pub | Out-File -Encoding ascii -Append .\.ssh\authorized_keys


Links:

https://askubuntu.com/questions/13044...
https://docs.fedoraproject.org/en-US/...
https://linux.die.net/man/1/ssh
https://unix.stackexchange.com/questi...
https://www.pragmaticlinux.com/2021/0...
https://www.ssh.com/academy/ssh/keygen


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