ED25519 vs RSA SSH keys: a practical choice
Prefer Ed25519 for new general-purpose keys; retain RSA only where compatibility requirements are real and documented.
Speed up repeated SSH connections with ControlMaster
Multiplexing makes repeated Git, rsync, and shell sessions fast, but stale sockets need bounded lifetimes and predictable paths.
Fix SSH Permission denied (publickey) without random changes
Follow the key from client selection to server authorization and permissions; do not weaken sshd globally to fix one account.
SSH port forwarding: local, remote, and dynamic tunnels
Name the listening side and destination before typing; most tunnel mistakes are direction mistakes.
SSH timeout debugging from laptop to server
Compare client-side reachability with server-side packet capture to distinguish cloud firewall, host firewall, and routing issues.
Why is my systemd service failing? A deterministic checklist
A deterministic checklist is easier when you treat it as an evidence problem instead of a command-memory test.
From bare VPS to production in one sitting (without locking yourself out)
The canonical Ubuntu server setup — users, SSH keys, UFW, fail2ban, swap, Node, nginx, TLS — in the right order, with the classic footguns labeled.