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Authelia Cheat Sheet

Overview

Authelia is an open-source authentication and authorization server that provides single sign-on (SSO) and two-factor authentication (2FA) for applications behind a reverse proxy. It acts as a companion to reverse proxies like Nginx, Traefik, HAProxy, and Caddy, intercepting requests and enforcing authentication policies before allowing access to protected services.

Authelia supports multiple second-factor methods including TOTP (time-based one-time passwords), WebAuthn/FIDO2 security keys, and Duo push notifications. It features password reset flows, access control rules based on domain, path, user, and group, and supports LDAP and file-based user backends with OpenID Connect identity provider capabilities.

Installation

# Docker (recommended)
docker pull authelia/authelia

# Docker Compose
mkdir authelia && cd authelia
curl -O https://raw.githubusercontent.com/authelia/authelia/master/examples/compose/lite/docker-compose.yml
curl -O https://raw.githubusercontent.com/authelia/authelia/master/examples/compose/lite/authelia/configuration.yml

# Linux binary
wget https://github.com/authelia/authelia/releases/latest/download/authelia-linux-amd64.tar.gz
tar xzf authelia-linux-amd64.tar.gz
sudo mv authelia /usr/local/bin/

# Kubernetes Helm
helm repo add authelia https://charts.authelia.com
helm install authelia authelia/authelia

# Verify
authelia --version

Core Configuration

# configuration.yml
server:
  address: "tcp://0.0.0.0:9091/"

log:
  level: info

theme: dark

default_redirection_url: "https://home.example.com"

totp:
  issuer: example.com
  period: 30
  skew: 1

authentication_backend:
  file:
    path: /config/users_database.yml
    password:
      algorithm: argon2id
      iterations: 3
      memory: 65536
      parallelism: 4
      key_length: 32
      salt_length: 16

access_control:
  default_policy: deny
  rules:
    - domain: "public.example.com"
      policy: bypass

    - domain: "*.example.com"
      policy: one_factor

    - domain: "secure.example.com"
      policy: two_factor

    - domain: "admin.example.com"
      policy: two_factor
      subject:
        - "group:admins"

session:
  name: authelia_session
  secret: insecure_session_secret
  expiration: 1h
  inactivity: 5m
  remember_me: 1M
  cookies:
    - domain: example.com
      authelia_url: https://auth.example.com

storage:
  local:
    path: /config/db.sqlite3

notifier:
  filesystem:
    filename: /config/notification.txt

User Database

# users_database.yml
users:
  john:
    displayname: "John Doe"
    password: "$argon2id$v=19$m=65536,t=3,p=4$hash..."
    email: john@example.com
    groups:
      - admins
      - devops

  jane:
    displayname: "Jane Smith"
    password: "$argon2id$v=19$m=65536,t=3,p=4$hash..."
    email: jane@example.com
    groups:
      - developers
# Generate password hash
authelia crypto hash generate argon2 --password "YourSecurePassword"

# Generate random password and hash it
authelia crypto hash generate argon2 --random --random.length 72

LDAP Backend

authentication_backend:
  ldap:
    implementation: custom
    address: "ldap://ldap.example.com:389"
    timeout: 5s
    start_tls: false
    base_dn: "dc=example,dc=com"
    additional_users_dn: "ou=users"
    users_filter: "(&(|({username_attribute}={input})({mail_attribute}={input}))(objectClass=inetOrgPerson))"
    additional_groups_dn: "ou=groups"
    groups_filter: "(member={dn})"
    user: "cn=admin,dc=example,dc=com"
    password: "ldap-admin-password"
    attributes:
      username: uid
      display_name: displayName
      mail: mail
      group_name: cn

Access Control Rules

access_control:
  default_policy: deny

  rules:
    # Public endpoints (no auth)
    - domain: "public.example.com"
      policy: bypass

    - domain: "*.example.com"
      resources:
        - "^/api/health$"
      policy: bypass

    # Single factor for general access
    - domain:
        - "app.example.com"
        - "wiki.example.com"
      policy: one_factor

    # Two factor for sensitive services
    - domain: "vault.example.com"
      policy: two_factor

    # Group-based access
    - domain: "admin.example.com"
      policy: two_factor
      subject:
        - "group:admins"

    # Network-based rules
    - domain: "internal.example.com"
      policy: bypass
      networks:
        - "10.0.0.0/8"
        - "172.16.0.0/12"

    # Method-based rules
    - domain: "api.example.com"
      policy: one_factor
      methods:
        - GET
        - HEAD

    - domain: "api.example.com"
      policy: two_factor
      methods:
        - POST
        - PUT
        - DELETE

Reverse Proxy Integration

Nginx

server {
    listen 443 ssl;
    server_name app.example.com;

    location /authelia {
        internal;
        proxy_pass http://authelia:9091/api/authz/auth-request;
        proxy_set_header X-Original-URL $scheme://$http_host$request_uri;
        proxy_set_header X-Forwarded-Method $request_method;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header X-Forwarded-Host $http_host;
        proxy_set_header X-Forwarded-URI $request_uri;
        proxy_set_header Content-Length "";
        proxy_pass_request_body off;
    }

    location / {
        auth_request /authelia;
        auth_request_set $user $upstream_http_remote_user;
        auth_request_set $groups $upstream_http_remote_groups;
        auth_request_set $email $upstream_http_remote_email;
        proxy_set_header Remote-User $user;
        proxy_set_header Remote-Groups $groups;
        proxy_set_header Remote-Email $email;
        proxy_pass http://backend:8080;
    }
}

Traefik

# docker-compose.yml with Traefik
services:
  traefik:
    image: traefik:v3
    command:
      - "--providers.docker=true"
      - "--entrypoints.websecure.address=:443"
    labels:
      - "traefik.http.middlewares.authelia.forwardAuth.address=http://authelia:9091/api/authz/forward-auth"
      - "traefik.http.middlewares.authelia.forwardAuth.trustForwardHeader=true"
      - "traefik.http.middlewares.authelia.forwardAuth.authResponseHeaders=Remote-User,Remote-Groups,Remote-Email"

  my-app:
    image: my-app:latest
    labels:
      - "traefik.http.routers.my-app.rule=Host(`app.example.com`)"
      - "traefik.http.routers.my-app.middlewares=authelia@docker"

OpenID Connect Provider

identity_providers:
  oidc:
    hmac_secret: "your-hmac-secret"
    jwks:
      - key_id: "main"
        algorithm: RS256
        use: sig
        key: |
          -----BEGIN RSA PRIVATE KEY-----
          ...
          -----END RSA PRIVATE KEY-----
    clients:
      - client_id: grafana
        client_name: Grafana
        client_secret: "$pbkdf2-sha512$310000$hash..."
        public: false
        authorization_policy: two_factor
        redirect_uris:
          - "https://grafana.example.com/login/generic_oauth"
        scopes:
          - openid
          - profile
          - groups
          - email

      - client_id: portainer
        client_name: Portainer
        client_secret: "$pbkdf2-sha512$310000$hash..."
        redirect_uris:
          - "https://portainer.example.com"
        scopes:
          - openid
          - profile
          - email

Advanced Usage

Production Storage (PostgreSQL)

storage:
  postgres:
    address: "tcp://postgres:5432"
    database: authelia
    schema: public
    username: authelia
    password: "database-password"
    tls:
      skip_verify: false

Email Notifications

notifier:
  smtp:
    address: "submissions://smtp.gmail.com:465"
    username: "noreply@example.com"
    password: "app-password"
    sender: "Authelia <noreply@example.com>"
    subject: "[Authelia] {title}"
    tls:
      skip_verify: false

Redis Session Storage

session:
  redis:
    host: redis
    port: 6379
    password: "redis-password"
    database_index: 0
    maximum_active_connections: 8

Configuration

# Generate secrets
authelia crypto hash generate pbkdf2 --password "client-secret"
authelia crypto rand --length 64 --charset alphanumeric

# Validate configuration
authelia validate-configuration --config /config/configuration.yml

# Environment variable overrides
AUTHELIA_SESSION_SECRET=your-secret
AUTHELIA_STORAGE_POSTGRES_PASSWORD=db-password
AUTHELIA_NOTIFIER_SMTP_PASSWORD=smtp-password
AUTHELIA_IDENTITY_PROVIDERS_OIDC_HMAC_SECRET=hmac-secret

Troubleshooting

IssueSolution
Redirect loopCheck default_redirection_url and cookie domain settings
401 on all requestsVerify reverse proxy forwards correct headers to Authelia
2FA not workingCheck TOTP time sync; verify totp.period and totp.skew
LDAP bind failsTest LDAP credentials directly; check base DN and filters
Session not persistingEnsure cookie domain matches; check Redis connection
OIDC client unauthorizedVerify client secret hash; check authorization_policy
Emails not sendingTest SMTP settings; check spam filters and app passwords
Access denied despite rulesRules are evaluated top-to-bottom; first match wins