Theta42 Jump Host

An SSH jump host for the theta42 self-hosted stack. Users SSH into one public host and land on any downstream host they're entitled to — audited end to end.

Two backends, same SSH front door and audit trail: the default mode authenticates against the shared LDAP directory and authorizes from the SSO Manager's inventory graph; standalone mode (below) runs with no LDAP or SSO at all, storing users and hosts in a local SQL database instead.

Two ways to connect

Direct (WinSCP/SFTP-friendly):

ssh alice_-_web01@jump.example.com          # -> host slug 'web01' / 'host_web01'
sftp -P 2222 alice_-_web01@jump.example.com # SFTP passes through unchanged

The username grammar is {uid}_-_{target}. target is a directory host slug (with or without the host_ prefix), a bare hostname, or an IP.

Interactive picker:

ssh alice@jump.example.com

Plain login shows a TUI list of the hosts you can reach; pick one and you're bridged straight in.

How it works

1. Inbound auth — LDAP. Public key (matched against your sshPublicKey, the jump host's own injected key excluded) or password (LDAP bind; the ssh.passwordAuth policy can restrict passwords to local clients or disable them — keys-only is recommended for a public host).
2. Authorization — the hosts you may reach are the union of your LDAP groups × the SSO directory (/api/discovery/resources?group=<cn>). No directory entry, no access.
3. Key injection — on first use the jump host appends its own public key to your sshPublicKey in LDAP (comment-marked), then connects downstream as you using its private key. Downstream hosts already serve keys from LDAP via ldap-client's AuthorizedKeysCommand, so nothing downstream needs changing.
4. Bridge — shell, exec, and the SFTP subsystem are spliced to the downstream sshd. Every session is audited.

Standalone mode

Run without LDAP or the SSO Manager at all. Set standalone.enabled: true and the jump host stores users and hosts itself, via @simpleworkjs/orm (Sequelize under the hood — defaults to a local SQLite file, but any Sequelize-supported dialect works via conf.orm):

standalone: { enabled: true },
orm: { dialect: 'sqlite', storage: './data/standalone.sqlite', logging: false },

Everything else — the SSH front door, key injection, bridging, the web UI and audit trail — is unchanged; only where users/hosts live and how passwords are checked differs. There's no admin UI for standalone users/hosts yet — add them with the ORM models directly:

const StandaloneUser = require('./models/standalone_user');
const StandaloneHost = require('./models/standalone_host');
const bcrypt = require('bcrypt');

await StandaloneUser.create({
  uid: 'alice',
  passwordHash: await bcrypt.hash('a real password', 10),
  sshPublicKeys: ['ssh-ed25519 AAAA... alice@laptop'],
  groups: [],
});

await StandaloneHost.create({
  slug: 'host_web01',
  displayName: 'web01',
  kind: 'host',
  metadata: { ip: '10.0.0.5', sshPort: 22 },
});

In standalone mode every stored host is reachable by every stored user — there is no group-based authorization (the groups field on StandaloneUser is accepted for interface parity but not yet enforced).

Requirements

(default LDAP + SSO mode — see Standalone mode to skip all of this)

• The SSO Manager (OpenLDAP directory + /api/discovery).
• Downstream hosts joined via ldap-client (SSSD + AuthorizedKeysCommand).
• An LDAP bind account with write access to the sshPublicKey attribute on user entries (see the ACL note in secrets.js.example).
• An SSO API token (sso_…) for the directory queries.

Install

Unified theta-env stack (recommended)

Enable it in theta-env/setup.env (CFG_JUMP_HOST_ENABLED=true) and re-run ./setup.sh. The stack wires the LDAP bind account, the write-ACL, the API token, and a directory entry automatically.

Standalone Docker

cp secrets.js.example config/jump-secrets.js   # then edit it
docker compose up -d --build

Bare metal

curl -fsSL https://raw.githubusercontent.com/theta42/jump-host/master/ops/install.sh | sudo bash
sudo $EDITOR /etc/jump-host/secrets.js         # fill in LDAP + SSO
sudo systemctl restart jump-host

Installs to /opt/theta42/jump-host; idempotent (re-run to update).

Ports

Port	Purpose
2222	SSH front door (default; see below for :22)
3002	Web UI + HTTP API (audit, metrics)

The default SSH port is 2222 so the service needs no privilege. To listen on 22, set ssh.listenPort: 22 in your secrets and either uncomment AmbientCapabilities=CAP_NET_BIND_SERVICE in the systemd unit, or DNAT 22 → 2222 at the firewall.

Web UI / API

https://jump.example.com/ (behind the proxy) — built on the same Express + EJS + Bootstrap stack as the SSO Manager and Proxy, so it looks and behaves like the rest of the stack. Login is OIDC against the SSO (the "Log in with SSO" button) plus a local anti-lockout admin that works even if the SSO is unreachable. Admin access requires membership in auth.adminGroups (default app_sso_admin) or being the local auth.adminUsers account.

• GET /health — open; {status, activeSessions, version}
• GET /api/sessions — active sessions
• GET /api/audit?page=&uid=&target=&status= — paged audit log
• GET /api/metrics — counters (total, failures, top users/hosts)

Configuration

Config layers via @simpleworkjs/conf: conf/base.js < conf/<NODE_ENV>.js < the CONF_SECRETS file < app_* env. See secrets.js.example for every key.

Development

cd nodejs && npm install
npm test          # unit + integration (node --test)
NODE_ENV=development npm run dev

License

MIT