# Hetzner Codex Remote > Prepare a Hetzner Cloud VPS for secure Codex remote SSH access. Use when the user wants to create or configure a Hetzner server for Codex remote control, fix "No codex found in PATH" on a remote machine, install agent development tooling on a VPS, harden SSH access to a Hetzner server, or connect the server through Codex Settings, Connections, Add SSH. - Skill: `vltansky/hetzner-codex-remote` (Agent Skill, multi-file: 3 files) - Install (CLI): `npx skillmds@latest add vltansky/hetzner-codex-remote` - Raw SKILL.md: https://api.skillmd.com/api/skills/vltansky/hetzner-codex-remote/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: DevOps & Infra - Author: vltansky (https://skillmd.com/u/vltansky) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/vltansky/hetzner-codex-remote --- # Hetzner Codex Remote ## Overview Set up a Hetzner Cloud server so Codex can use it as a remote SSH connection. Keep the setup secure by default: key-only SSH, no root SSH, a dedicated `codex` user, firewall allowlisting where practical, optional Tailscale-only SSH for roaming clients, and a verified `codex` CLI in `PATH`. Do not copy personal data from examples or prior chats into commands, files, or documentation. Use placeholders for IPs, keys, project IDs, host aliases, and account details. ## Workflow 1. Determine whether the user already has a Hetzner VPS. 2. If no VPS exists, explain how to create one in Hetzner Cloud Console. 3. Confirm SSH access and the server IP. 4. Harden SSH and create the `codex` user. 5. Install coding-agent tooling and Codex CLI. 6. If the user will connect from changing networks, move SSH behind Tailscale. 7. Verify from a plain non-interactive SSH command. 8. Tell the user to add the host in Codex: Settings > Connections > Add SSH. ## If No VPS Exists Give concise creation instructions instead of guessing through the UI: 1. Open Hetzner Cloud Console and create or choose a project. 2. Create a server with Ubuntu LTS. 3. Choose a small general-purpose instance to start; CPX or CX instances are fine for agent work. Suggest more CPU/RAM only if the user expects heavy builds. 4. Add the user's SSH public key during server creation. Prefer Ed25519 keys. 5. Enable public IPv4 unless the user has a private-network-only plan. 6. Name the server clearly, for example `codex-remote`. 7. After creation, collect the public IPv4 and continue with SSH setup. If the user has no local SSH key, create one locally with: ```bash ssh-keygen -t ed25519 -C "codex-remote" ``` Do not ask the user to paste private keys. Only public keys may be copied to providers or servers. ## Initial Access Use the server IP from Hetzner: ```bash ssh -o StrictHostKeyChecking=accept-new root@ 'id && uname -a' ``` If root SSH does not work but another user does, adapt the commands to that user with `sudo`. If SSH key injection failed, use Hetzner's web console or rescue mode to add the public key; do not weaken the final SSH policy to password access. Find the user's current public IPv4 for firewall allowlisting: ```bash curl -4 -s https://ifconfig.me || curl -4 -s https://icanhazip.com ``` Warn that an IP allowlist can lock out SSH when the user's public IP changes. If the user uses the same client device from different networks, prefer Tailscale-only SSH over chasing public IP allowlists. ## Harden SSH Run from the local machine, replacing placeholders: ```bash PUBKEY="$(sed -n '1p' ~/.ssh/id_ed25519.pub)" MYIP="" SERVER="" ssh root@"$SERVER" "PUBKEY='$PUBKEY' MYIP='$MYIP' bash -s" <<'REMOTE' set -euo pipefail export DEBIAN_FRONTEND=noninteractive apt-get update -y apt-get install -y sudo ufw fail2ban unattended-upgrades curl ca-certificates git if ! id codex >/dev/null 2>&1; then adduser --disabled-password --gecos "Codex remote user" codex fi usermod -aG sudo codex install -d -m 700 -o codex -g codex /home/codex/.ssh printf '%s\n' "$PUBKEY" > /home/codex/.ssh/authorized_keys chown codex:codex /home/codex/.ssh/authorized_keys chmod 600 /home/codex/.ssh/authorized_keys printf 'codex ALL=(ALL) NOPASSWD:ALL\n' > /etc/sudoers.d/90-codex chmod 440 /etc/sudoers.d/90-codex visudo -cf /etc/sudoers.d/90-codex >/dev/null install -d -m 755 /etc/ssh/sshd_config.d cat > /etc/ssh/sshd_config.d/99-codex-secure.conf <<'EOF' PasswordAuthentication no KbdInteractiveAuthentication no PubkeyAuthentication yes PermitRootLogin no X11Forwarding no AllowUsers codex EOF sshd -t systemctl reload ssh ufw --force reset ufw default deny incoming ufw default allow outgoing if [ -n "${MYIP:-}" ] && [ "$MYIP" != "skip" ]; then ufw allow from "$MYIP" to any port 22 proto tcp comment 'SSH from user public IP' else ufw allow 22/tcp comment 'SSH key-only' fi ufw --force enable systemctl enable --now fail2ban systemctl enable --now unattended-upgrades || true REMOTE ``` Verify before closing any working session: ```bash ssh -o BatchMode=yes codex@ 'id && sudo -n true && echo sudo-ok' ssh -o BatchMode=yes root@ 'echo root-should-not-work' ``` The root command should fail. ## Local SSH Alias Add a memorable alias to the user's local SSH config: ```sshconfig Host HostName User codex IdentityFile ~/.ssh/id_ed25519 IdentitiesOnly yes ServerAliveInterval 30 ServerAliveCountMax 3 ``` Verify: ```bash ssh 'whoami && hostname' ``` ## Optional: Tailscale-Only SSH Use this when the same client device needs SSH from different networks, or when the user wants SSH reachable only through their tailnet. Keep the existing public SSH path open until SSH over Tailscale is verified. Install Tailscale on the remote server: ```bash ssh 'set -euo pipefail curl -fsSL https://tailscale.com/install.sh | sh sudo -n systemctl enable --now tailscaled tailscale version sudo -n tailscale up --hostname= --accept-dns=false || true sudo -n tailscale status --json | python3 -c "import json,sys; d=json.load(sys.stdin); print({\"BackendState\": d.get(\"BackendState\"), \"AuthURL\": d.get(\"AuthURL\"), \"TailscaleIPs\": (d.get(\"Self\") or {}).get(\"TailscaleIPs\"), \"DNSName\": (d.get(\"Self\") or {}).get(\"DNSName\"), \"HostName\": (d.get(\"Self\") or {}).get(\"HostName\")})"' ``` If `BackendState` is `NeedsLogin`, open the `AuthURL` in the user's browser and connect the device to the intended tailnet. If browser automation is available and the user asked you to handle it, use the browser to authorize the device. Select the correct tailnet when more than one is offered. After authorization, collect the Tailscale IP: ```bash TAILSCALE_IP="$(ssh 'sudo -n tailscale ip -4 | sed -n "1p"')" printf '%s\n' "$TAILSCALE_IP" ``` Verify SSH over Tailscale before changing the firewall: ```bash ssh -o BatchMode=yes -o ConnectTimeout=8 codex@"$TAILSCALE_IP" 'hostname; whoami; codex --version' ``` If SSH reports a host-key mismatch, compare the public and Tailscale host keys before accepting the new host entry: ```bash ssh-keyscan -T 5 -t ed25519 "$TAILSCALE_IP" ssh -o StrictHostKeyChecking=accept-new codex@"$TAILSCALE_IP" 'hostname; whoami' ``` Then update the local SSH alias to use the Tailscale IP: ```sshconfig Host HostName User codex IdentityFile ~/.ssh/id_ed25519 IdentitiesOnly yes ServerAliveInterval 30 ServerAliveCountMax 3 ``` Finally, close public SSH and allow SSH only over `tailscale0`: ```bash ssh 'set -euo pipefail sudo -n ufw allow in on tailscale0 to any port 22 proto tcp comment "SSH over Tailscale" sudo -n ufw --force delete allow from to any port 22 proto tcp || true sudo -n ufw status numbered' ``` Verify that the alias still works and public SSH is blocked: ```bash ssh -o BatchMode=yes -o ConnectTimeout=8 'hostname; whoami; sudo -n tailscale status --self; sudo -n ufw status numbered' nc -vz -G 5 22 ``` The `nc` check should fail or time out. If it succeeds, public SSH is still exposed and the firewall rules need another pass. Disable Tailscale key expiry for long-lived remotes: 1. Open Tailscale admin console > Machines. 2. Find ``. 3. Open the device actions menu. 4. Choose Disable key expiry. 5. Confirm the machine row shows `Expiry disabled`. ## Install Agent Tooling Install common build and coding-agent dependencies: ```bash ssh 'sudo -n DEBIAN_FRONTEND=noninteractive apt-get update -y && sudo -n DEBIAN_FRONTEND=noninteractive apt-get install -y git gh python3 python-is-python3 python3-pip python3-venv python3-dev pipx build-essential curl ca-certificates unzip jq ripgrep fd-find' ``` Install `nvm`, Node LTS, npm, Corepack-managed pnpm/yarn, and Codex CLI as the `codex` user: ```bash ssh 'bash -s' <<'REMOTE' set -euo pipefail NVM_DIR="$HOME/.nvm" latest_tag=$(git ls-remote --tags https://github.com/nvm-sh/nvm.git 'v*' | awk '{print $2}' | sed 's#refs/tags/##; s#\^{}##' | sort -V | tail -1) if [ ! -d "$NVM_DIR/.git" ]; then git clone https://github.com/nvm-sh/nvm.git "$NVM_DIR" fi git -C "$NVM_DIR" fetch --tags --quiet git -C "$NVM_DIR" checkout --quiet "$latest_tag" for f in "$HOME/.bashrc" "$HOME/.profile"; do touch "$f" if ! grep -q 'NVM_DIR' "$f"; then cat >> "$f" <<'EOF' export NVM_DIR="$HOME/.nvm" [ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh" [ -s "$NVM_DIR/bash_completion" ] && . "$NVM_DIR/bash_completion" EOF fi done . "$NVM_DIR/nvm.sh" nvm install --lts nvm alias default 'lts/*' nvm use default corepack enable corepack prepare pnpm@latest --activate corepack prepare yarn@stable --activate npm config set fund false npm config set audit false npm install -g @openai/codex@latest NODE_BIN_DIR=$(dirname "$(command -v node)") for bin in node npm npx corepack pnpm yarn codex; do sudo -n ln -sfn "$NODE_BIN_DIR/$bin" "/usr/local/bin/$bin" done sudo -n ln -sfn /usr/bin/fdfind /usr/local/bin/fd REMOTE ``` Use `/usr/local/bin` shims because remote-control checks often run non-interactive shells that do not source `.bashrc`. ## Final Verification Run the verification from a plain SSH command: ```bash ssh 'set -e command -v codex codex --version node --version npm --version pnpm --version yarn --version git --version gh --version | sed -n "1p" python --version python3 --version sudo -n sshd -T | egrep "^(permitrootlogin|passwordauthentication|allowusers|kbdinteractiveauthentication|pubkeyauthentication) " sudo -n ufw status verbose sudo -n fail2ban-client status sshd || true sudo -n tailscale status --self 2>/dev/null || true test -f /var/run/reboot-required && echo reboot-required || echo reboot-not-required' ``` Expected properties: - `command -v codex` resolves, preferably under `/usr/local/bin/codex`. - `codex --version` prints a version. - SSH config reports `permitrootlogin no`, `passwordauthentication no`, and `allowusers codex`. - UFW is active. - `ssh root@` fails. - If Tailscale-only SSH was configured, `` resolves to the Tailscale IP and public `:22` times out. - `apt-get -s upgrade` shows no urgent pending upgrades, or the remaining work is reported clearly. If the user sees `No codex found in PATH`, install `@openai/codex` and recreate the `/usr/local/bin/codex` shim. ## GitHub CLI Install `gh`, but do not invent credentials. If the local machine already has an authenticated GitHub CLI session and the user asks to use GitHub from the remote, prefer transferring that auth through `gh auth token` over a device-code flow. Do not print the token, write it to a file, or ask the user to paste it in chat. Generic local-to-remote `gh` auth: ```bash gh auth status -h github.com gh auth token -h github.com | ssh 'gh auth login --hostname github.com --with-token' ssh 'gh auth setup-git --hostname github.com && gh config set git_protocol https --host github.com && gh auth status -h github.com' ``` Then clone the requested repository into a predictable remote workspace: ```bash ssh 'set -euo pipefail mkdir -p ~/Projects cd ~/Projects gh repo clone / cd printf "repo=%s\nbranch=%s\nhead=%s\n" "$PWD" "$(git branch --show-current)" "$(git rev-parse --short HEAD)" git status --short --branch' ``` If local `gh` is not authenticated or token transfer is not appropriate, use the user's normal secure token flow or GitHub's device login: ```bash ssh gh auth login ``` Do not ask for tokens in chat unless there is no safer route and the user explicitly chooses it. ## Finish In Codex End by instructing the user: 1. Open Codex Settings. 2. Go to Connections. 3. Choose Add SSH. 4. Enter the SSH host alias, for example ``, or the full `codex@` target. 5. Save and test the connection.