Janus

Janus is the god of doorways and passages.

Setup

Step-CA Getting Started

step ca init --ssh --acme

Running step-ca as a Daemon

Renewal using systemd timers

SSH Certificates

Server

Use step-ca to sign an existing public key to produce a signed certificate with some principals on it.

step ssh certificate --host --sign \
--principal janus --principal janus.john-stream.com \
--provisioner admin \
janus /etc/ssh/ssh_host_ed25519_key.pub

Get the (public) cert for the CA that signs the user SSH certs from step-ca.

step ssh config --roots > /etc/ssh/ssh_user_ca.pub

Configure sshd to point to the key/cert combo.

cat << EOF > /etc/ssh/sshd_config.d/certs.conf
TrustedUserCAKeys /etc/ssh/ssh_user_ca.pub
HostKey /etc/ssh/ssh_host_ed25519_key
HostCertificate /etc/ssh/ssh_host_ed25519_key-cert.pub
EOF

systemctl reload sshd

Client

step ssh certificate --sign \
--principal root --principal john \
--provisioner admin \
john@john-pc-ubuntu ~/.ssh/id_ed25519.pub