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Epithet makes SSH certificates easy

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Epithet is an SSH certificate authority that replaces static authorized_keys with short-lived certificates (2-10 minutes). It creates on-demand SSH agents for each outbound connection, enabling real-time policy enforcement without touching your target hosts.

Quick start

1. Build epithet:

git clone https://github.com/epithet-ssh/epithet.git
cd epithet
make build

2. Start the agent:

epithet agent \
  --ca-url https://your-ca.example.com \
  --auth "epithet auth oidc --issuer https://accounts.google.com --client-id YOUR_CLIENT_ID"

3. Add to your SSH config (~/.ssh/config):

Include ~/.epithet/run/*/ssh-config.conf

4. SSH as normal:

ssh server.example.com

First connection opens your browser for authentication (~2-5 seconds). Subsequent connections use cached tokens (~100-200ms).

How it works

When you run ssh server.example.com, OpenSSH's Match exec triggers epithet match, which asks the broker for a certificate. The broker handles authentication (via browser-based OIDC or a custom auth plugin), requests a signed certificate from the CA (which checks policy in real-time), and spins up a per-connection SSH agent with the short-lived certificate. See architecture for detailed sequence diagrams.

Components:

  • Broker (epithet agent): Daemon managing authentication state and certificate lifecycle. Creates per-connection SSH agents.
  • CA Server (epithet ca): Signs SSH certificates after validating tokens against a policy server.
  • Policy Server (epithet policy): Makes authorization decisions - who can access what hosts as which users.
  • Per-connection Agents: In-process SSH agents, one per unique connection, serving short-lived certificates.

Commands

Command Description
epithet agent Start the broker daemon that manages certificates and agents
epithet agent inspect Query a running broker's state
epithet server Run the CA and policy server together
epithet match Called by SSH Match exec to trigger certificate flow
epithet ca Run the certificate authority server
epithet policy Run the policy server with OIDC authorization
epithet auth oidc Built-in OIDC/OAuth2 authentication plugin

Documentation

Development

make build    # Build all binaries
make test     # Run tests
make clean    # Clean build artifacts

Requirements: Go 1.25+

License

Apache 2.0

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Secure and easy ssh certs via an ssh-agent and CA

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