Cloud-init user not created: how to log in
Locked out because cloud-init never made your login user? Find the real username, read cloud-init status and the logs, and get back in from the console.
#ssh
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The history of SSH, from telnet to OpenSSH
A 1995 password sniffing attack in Helsinki produced SSH. Here is the verified timeline from telnet and rlogin to OpenSSH and post-quantum defaults.
Keep a command running after SSH disconnect
When SSH drops, the kernel sends SIGHUP and your job dies. Use nohup, disown, tmux or systemd-run to keep it alive, and know which one fits the job.
Fix SSH Too Many Authentication Failures
Too many authentication failures means your SSH agent offered every key it holds and the server cut you off. Diagnose it with ssh -v and fix it for good.
Ansible inventory files explained
Your Ansible inventory decides which host gets which variable: INI and YAML forms, groups, group_vars, host_vars, connection settings and precedence.
Central Linux logins: LDAP or SSH CA
Centralize Linux logins so one change reaches every server. Compare a directory with SSSD, an SSH certificate authority, and Ansible-managed keys.
Change the SSH port with SELinux and firewalld
Moving sshd to a new port on Rocky Linux or AlmaLinux needs firewalld, an SELinux port label and sshd_config. Do it in the order that keeps you logged in.
File transfer protocols, from Kermit to rsync
Kermit turns 45 and just shipped a new release. The story of file transfer, from noisy phone lines to FTP behind NAT, and why rsync and SFTP won.
Post-Quantum SSH: What Changed on Ubuntu
OpenSSH already negotiates a post-quantum key exchange by default. Check what your Ubuntu box really uses, and learn why host keys are still classical.
Fix 'unknown terminal type' over SSH
Your terminal sets a TERM name the server has never heard of, so curses programs fail. Fix it with a terminfo entry in your home directory, no root.
SSH: Connection Refused vs Connection Timed Out
Two SSH errors, opposite causes. Refused means the server answered. Timed out means nothing answered at all. Learn which test to run, and from where.
SSH over a Tor onion service, no open ports
Put sshd behind a Tor onion service so the VPS answers on no inbound port. Setup, v3 client authorisation, and the exact order that avoids a lockout.
What is SSH, and how does it work?
SSH is an encrypted channel to a remote server. Learn the client and server model, port 22, host key fingerprints, and key versus password login.
Fix SSH Permission denied (publickey)
Permission denied (publickey) is five different faults. Read the ssh -v output, find which one you have, and fix it without locking yourself out.
Self-hosted Git server: Forgejo, Gitea or cgit
Four ways to run a self-hosted Git server, ranked by RAM: bare repos over SSH, cgit, Forgejo or Gitea, and GitLab. See what a 1 GB VPS can host.
Change your VPS root password on Ubuntu
Change a VPS root or user password on Ubuntu with passwd, chpasswd and chage, verify it works, and get back in when SSH or the root password is lost.
tty7: a terminal workbench for agents
tty7 is a Rust terminal workbench with a session daemon, native SSH and agent-aware panes. Install it, then see where tmux on the VPS still wins.
Use Claude Code from your phone
Claude Code runs in tmux on a VPS and your phone is only the window. SSH keys, mosh for flaky mobile data, tmux attach, and the keyboard fixes that matter.
SSH key management basics
How SSH keys work and how to manage them: one ed25519 key per device, the permissions sshd demands, config Host blocks, and revoking a lost key.
Manage multiple Linux servers: tools that work
SSH config, tmux, Ansible, Uptime Kuma, Zabbix and Webmin, ranked by how many servers you have: what each replaces, setup cost in minutes, the one gotcha.
First 10 minutes on a new VPS
A new VPS is a target from its first minute. This ten-minute runbook creates a user, sets SSH keys, disables root, and turns on the firewall.
SSH hardening on a VPS
Lock down SSH on your VPS: switch to key-only login, disable root and passwords with a drop-in config, and layer Fail2ban and a VPN on top.
Install Fail2ban on Ubuntu 24.04: stop SSH bots
On Ubuntu 24.04 a plain apt install already bans SSH brute force. The fail2ban-client status sshd output proves it, plus the fix when Total failed stays at 0.
Run Claude Code on a remote VPS with tmux
Run Claude Code on an always-on Linux VPS inside tmux so agent sessions survive a dropped SSH connection. Install, harden, and the failure modes to expect.