Headscale

Headscale est un logiciel libre imitant l'API de Tailscale. Il permet de lier via un "hub" commun de multiples appareils, formant un réseau local interne. Certains nœuds de ce réseau sont des sorties, qui peuvent être utiliser par tous les nœuds du réseau pour le trafic sortant (accès internet) ce qui permet de les considérer comme des VPN, en plus de nœuds internes.

Configuration actuelle

Sur l'architecture actuelle, il tourne sur le serveur computing et est accessible ici ici. En plus des appareils utilisant le VPN, chaque serveur est un nœud (même les serveurs DNS). Les serveurs sont des nœuds de sortie, ce qui permet aux appareil de choisir le lieu de connexion pour les services web accédé par l'utilisateur de celui-ci.

Procédures

Ajout un nœud de sortie (exit node)

Créer le nœud avec la commande suivante: tailscale up --login-server=https://headscale.linarphy.net --advertise-exit-node --accept-dns=false ou, s'il existe déjà, la commande tailscale set --advertise-exit-node.

Sur le serveur computing (exécutant headscale), lancer la commande headscale routes list ce qui permet d'afficher un tableau trié par ID. Cibler les deux ID correspondant au nœud de sortie (IPv4 et IPv6) et exécuter la commande headscale routes enable -r {ID} pour ces deux nombres.

Sur le noeud lancer la commande:

echo 'net.ipv4.ip_forward = 1' | tee -a /etc/sysctl.d/99-tailscale.conf
echo 'net.ipv6.conf.all.forwarding = 1' | tee -a /etc/sysctl.d/99-tailscale.conf
sysctl -p /etc/sysctl.d/99-tailscale.conf

Si firewalld est installé, il est nécessaire d'effectuer les commandes suivantes:

firewall-cmd --add-masquerade --zone=public --permanent 
firewall-cmd --add-interface=tailscale0 --zone=trusted --permanent
firewall-cmd --reload

Dans ce cas, il est aussi possible d'avoir besoin d’exécuter la commande firewall-cmd --add-service wireguard --permanent puis firewall-cmd --reload.

Installation

Si non indiqué, l'utilisateur effectuant les commandes dans la suite des opérations et le root (ou superutilisateur).

Prérequis

• Nginx
• Certbot
• Freeipa-client
• Keycloak

Téléchargement et installation

Le service s'installe sur les systèmes debian à l'aide de package .deb disponible ici. Si l'architecture du serveur n'est pas connu, utiliser le paquet pour l'architecture amd64. Une fois l'archive téléchargé avec curl: curl -L {url} -o headscale.tar.gz, puis l'avoir extrait avec tar -xf headscale.tar.gz et supprimer l'archive avec rm headscale.tar.gz, il suffit alors de l'installer avec aptitude: apt install ./headscale.deb.

Reverse proxy

Comme pour la plupart des services, Headscale sera disponible via un nom de domaine spécial.

Ajouter le nom de domaine sur la zone DNS de l'interface d'administration de FreeIPA (procédure ici).

Créer le fichier /etc/nginx/sites-available/headscale.linarphy.net contenant la configuration Nginx suivante:

server {
  server_name headscale.linarphy.net;

  listen 80;
  listen [::]:80;
}

Puis créer un lien symbolique avec la commande ln -s /etc/nginx/sites-available/headscale.linarphy.net /etc/nginx/sites-enabled/headscale.linarphy.net et tester la configuration via nginx -t. Si la configuration est valide, il est nécessaire de recharger le service systemd avec systemctl reload nginx et mettre en place le chiffrement ssl avec certbot --nginx --domain auth.linarphy.net --deploy-hook=/usr/share/keycloak/certs/hook.sh.

Vérifier ensuite sur un navigateur l'accès au service sur le protocole https.

Finalement, modifier le fichier /etc/nginx/sites-available/headscale.linarphy.ent pour y insérer la configuration suivante:

map $http_upgrade $connection_upgrade {
        default   upgrade;
        ''        close;
}

server {
        server_name headscale.linarphy.net;

        listen [::]:443 ssl; # managed by Certbot
        listen 443 ssl; # managed by Certbot

        location /web {
                alias /var/www/headscale.linarphy.net;
                index index.html;
        }

        location / {
                proxy_pass http://localhost:8082;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection $connection_upgrade;
                proxy_set_header Host $server_name;
                proxy_redirect http:// https://;
                proxy_buffering off;
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header X-Forwarded-Proto $scheme;
                add_header Strict-Transport-Security "max-age=15552000; includeSubDomains" always;
        }

        ssl_certificate /etc/letsencrypt/live/headscale.linarphy.net/fullchain.pem; # managed by Certbot
        ssl_certificate_key /etc/letsencrypt/live/headscale.linarphy.net/privkey.pem; # managed by Certbot
        include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
        ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
}
server {
        server_name headscale.linarphy.net;

        location / {
                return 301 https://$host$request_uri;
        }

        listen 80;
        listen [::]:80;

        return 404; # managed by Certbot
}

Préparation à l'authentification

Dans Keycloak, ajouter un nouveau client sur le realm gérant l'authentification des services du site.

Configuration

La configuration peut ensuite être modifiée via le fichier /etc/headscale/config.yaml et modifier le pour correspondre au fichier suivant:

---
# headscale will look for a configuration file named `config.yaml` (or `config.json`) in the following order:
#
# - `/etc/headscale`
# - `~/.headscale`
# - current working directory

# The url clients will connect to.
# Typically this will be a domain like:
#
# https://myheadscale.example.com:443
#
server_url: https://headscale.linarphy.net:443

# Address to listen to / bind to on the server
#
# For production:
# listen_addr: 0.0.0.0:8080
listen_addr: 127.0.0.1:8082

# Address to listen to /metrics, you may want
# to keep this endpoint private to your internal
# network
#
metrics_listen_addr: 127.0.0.1:9092

# Address to listen for gRPC.
# gRPC is used for controlling a headscale server
# remotely with the CLI
# Note: Remote access _only_ works if you have
# valid certificates.
#
# For production:
# grpc_listen_addr: 0.0.0.0:50443
grpc_listen_addr: 127.0.0.1:50443

# Allow the gRPC admin interface to run in INSECURE
# mode. This is not recommended as the traffic will
# be unencrypted. Only enable if you know what you
# are doing.
grpc_allow_insecure: false

# The Noise section includes specific configuration for the
# TS2021 Noise protocol
noise:
  # The Noise private key is used to encrypt the
  # traffic between headscale and Tailscale clients when
  # using the new Noise-based protocol.
  private_key_path: /var/lib/headscale/noise_private.key

# List of IP prefixes to allocate tailaddresses from.
# Each prefix consists of either an IPv4 or IPv6 address,
# and the associated prefix length, delimited by a slash.
# It must be within IP ranges supported by the Tailscale
# client - i.e., subnets of 100.64.0.0/10 and fd7a:115c:a1e0::/48.
# See below:
# IPv6: https://github.com/tailscale/tailscale/blob/22ebb25e833264f58d7c3f534a8b166894a89536/net/tsaddr/tsaddr.go#LL81C52-L81C71
# IPv4: https://github.com/tailscale/tailscale/blob/22ebb25e833264f58d7c3f534a8b166894a89536/net/tsaddr/tsaddr.go#L33
# Any other range is NOT supported, and it will cause unexpected issues.
prefixes:
  v6: fd7a:115c:a1e0::/48
  v4: 100.64.0.0/10

  # Strategy used for allocation of IPs to nodes, available options:
  # - sequential (default): assigns the next free IP from the previous given IP.
  # - random: assigns the next free IP from a pseudo-random IP generator (crypto/rand).
  allocation: sequential

# DERP is a relay system that Tailscale uses when a direct
# connection cannot be established.
# https://tailscale.com/blog/how-tailscale-works/#encrypted-tcp-relays-derp
#
# headscale needs a list of DERP servers that can be presented
# to the clients.
derp:
  server:
    # If enabled, runs the embedded DERP server and merges it into the rest of the DERP config
    # The Headscale server_url defined above MUST be using https, DERP requires TLS to be in place
    enabled: false

    # Region ID to use for the embedded DERP server.
    # The local DERP prevails if the region ID collides with other region ID coming from
    # the regular DERP config.
    region_id: 999

    # Region code and name are displayed in the Tailscale UI to identify a DERP region
    region_code: "headscale"
    region_name: "Headscale Embedded DERP"

    # Listens over UDP at the configured address for STUN connections - to help with NAT traversal.
    # When the embedded DERP server is enabled stun_listen_addr MUST be defined.
    #
    # For more details on how this works, check this great article: https://tailscale.com/blog/how-tailscale-works/
    stun_listen_addr: "0.0.0.0:3478"

    # Private key used to encrypt the traffic between headscale DERP
    # and Tailscale clients.
    # The private key file will be autogenerated if it's missing.
    #
    private_key_path: /var/lib/headscale/derp_server_private.key

    # This flag can be used, so the DERP map entry for the embedded DERP server is not written automatically,
    # it enables the creation of your very own DERP map entry using a locally available file with the parameter DERP.paths
    # If you enable the DERP server and set this to false, it is required to add the DERP server to the DERP map using DERP.paths
    automatically_add_embedded_derp_region: true

    # For better connection stability (especially when using an Exit-Node and DNS is not working),
    # it is possible to optionally add the public IPv4 and IPv6 address to the Derp-Map using:
    ipv4: 1.2.3.4
    ipv6: 2001:db8::1

  # List of externally available DERP maps encoded in JSON
  urls:
    - https://controlplane.tailscale.com/derpmap/default

  # Locally available DERP map files encoded in YAML
  #
  # This option is mostly interesting for people hosting
  # their own DERP servers:
  # https://tailscale.com/kb/1118/custom-derp-servers/
  #
  # paths:
  #   - /etc/headscale/derp-example.yaml
  paths: []

  # If enabled, a worker will be set up to periodically
  # refresh the given sources and update the derpmap
  # will be set up.
  auto_update_enabled: true

  # How often should we check for DERP updates?
  update_frequency: 24h

# Disables the automatic check for headscale updates on startup
disable_check_updates: false

# Time before an inactive ephemeral node is deleted?
ephemeral_node_inactivity_timeout: 30m

database:
  # Database type. Available options: sqlite, postgres
  # Please note that using Postgres is highly discouraged as it is only supported for legacy reasons.
  # All new development, testing and optimisations are done with SQLite in mind.
  type: sqlite

  # Enable debug mode. This setting requires the log.level to be set to "debug" or "trace".
  debug: false

  # GORM configuration settings.
  gorm:
    # Enable prepared statements.
    prepare_stmt: true

    # Enable parameterized queries.
    parameterized_queries: true

    # Skip logging "record not found" errors.
    skip_err_record_not_found: true

    # Threshold for slow queries in milliseconds.
    slow_threshold: 1000

  # SQLite config
  sqlite:
    path: /var/lib/headscale/db.sqlite

    # Enable WAL mode for SQLite. This is recommended for production environments.
    # https://www.sqlite.org/wal.html
    write_ahead_log: true

  # # Postgres config
  # Please note that using Postgres is highly discouraged as it is only supported for legacy reasons.
  # See database.type for more information.
  # postgres:
  #   # If using a Unix socket to connect to Postgres, set the socket path in the 'host' field and leave 'port' blank.
  #   host: localhost
  #   port: 5432
  #   name: headscale
  #   user: foo
  #   pass: bar
  #   max_open_conns: 10
  #   max_idle_conns: 10
  #   conn_max_idle_time_secs: 3600

  #   # If other 'sslmode' is required instead of 'require(true)' and 'disabled(false)', set the 'sslmode' you need
  #   # in the 'ssl' field. Refers to https://www.postgresql.org/docs/current/libpq-ssl.html Table 34.1.
  #   ssl: false

### TLS configuration
#
## Let's encrypt / ACME
#
# headscale supports automatically requesting and setting up
# TLS for a domain with Let's Encrypt.
#
# URL to ACME directory
acme_url: https://acme-v02.api.letsencrypt.org/directory

# Email to register with ACME provider
acme_email: ""

# Domain name to request a TLS certificate for:
tls_letsencrypt_hostname: ""

# Path to store certificates and metadata needed by
# letsencrypt
# For production:
tls_letsencrypt_cache_dir: /var/lib/headscale/cache

# Type of ACME challenge to use, currently supported types:
# HTTP-01 or TLS-ALPN-01
# See [docs/tls.md](docs/tls.md) for more information
tls_letsencrypt_challenge_type: HTTP-01
# When HTTP-01 challenge is chosen, letsencrypt must set up a
# verification endpoint, and it will be listening on:
# :http = port 80
tls_letsencrypt_listen: ":http"

## Use already defined certificates:
tls_cert_path: ""
tls_key_path: ""

log:
  # Output formatting for logs: text or json
  format: text
  level: info

## Policy
# headscale supports Tailscale's ACL policies.
# Please have a look to their KB to better
# understand the concepts: https://tailscale.com/kb/1018/acls/
policy:
  # The mode can be "file" or "database" that defines
  # where the ACL policies are stored and read from.
  mode: file
  # If the mode is set to "file", the path to a
  # HuJSON file containing ACL policies.
  path: ""

## DNS
#
# headscale supports Tailscale's DNS configuration and MagicDNS.
# Please have a look to their KB to better understand the concepts:
#
# - https://tailscale.com/kb/1054/dns/
# - https://tailscale.com/kb/1081/magicdns/
# - https://tailscale.com/blog/2021-09-private-dns-with-magicdns/
#
# Please note that for the DNS configuration to have any effect,
# clients must have the `--accept-dns=true` option enabled. This is the
# default for the Tailscale client. This option is enabled by default
# in the Tailscale client.
#
# Setting _any_ of the configuration and `--accept-dns=true` on the
# clients will integrate with the DNS manager on the client or
# overwrite /etc/resolv.conf.
# https://tailscale.com/kb/1235/resolv-conf
#
# If you want stop Headscale from managing the DNS configuration
# all the fields under `dns` should be set to empty values.
dns:
  # Whether to use [MagicDNS](https://tailscale.com/kb/1081/magicdns/).
  # Only works if there is at least a nameserver defined.
  #magic_dns: false
  magic_dns: ''

  # Defines the base domain to create the hostnames for MagicDNS.
  # This domain _must_ be different from the server_url domain.
  # `base_domain` must be a FQDN, without the trailing dot.
  # The FQDN of the hosts will be
  # `hostname.base_domain` (e.g., _myhost.example.com_).
  base_domain:

  # List of DNS servers to expose to clients.
  nameservers:
    global:
      #- 1.1.1.1
      #- 1.0.0.1
      #- 2606:4700:4700::1111
      #- 2606:4700:4700::1001

      # NextDNS (see https://tailscale.com/kb/1218/nextdns/).
      # "abc123" is example NextDNS ID, replace with yours.
      # - https://dns.nextdns.io/abc123

    # Split DNS (see https://tailscale.com/kb/1054/dns/),
    # a map of domains and which DNS server to use for each.
    split:
      {}
      # foo.bar.com:
      #   - 1.1.1.1
      # darp.headscale.net:
      #   - 1.1.1.1
      #   - 8.8.8.8

  # Set custom DNS search domains. With MagicDNS enabled,
  # your tailnet base_domain is always the first search domain.
  search_domains: []

  # Extra DNS records
  # so far only A-records are supported (on the tailscale side)
  # See https://github.com/juanfont/headscale/blob/main/docs/dns-records.md#Limitations
  extra_records: []
  #   - name: "grafana.myvpn.example.com"
  #     type: "A"
  #     value: "100.64.0.3"
  #
  #   # you can also put it in one line
  #   - { name: "prometheus.myvpn.example.com", type: "A", value: "100.64.0.3" }

  # DEPRECATED
  # Use the username as part of the DNS name for nodes, with this option enabled:
  # node1.username.example.com
  # while when this is disabled:
  # node1.example.com
  # This is a legacy option as Headscale has have this wrongly implemented
  # while in upstream Tailscale, the username is not included.
  #use_username_in_magic_dns: false
  use_username_in_magic_dns:

# Unix socket used for the CLI to connect without authentication
# Note: for production you will want to set this to something like:
unix_socket: /var/run/headscale/headscale.sock
unix_socket_permission: "0770"
#
# headscale supports experimental OpenID connect support,
# it is still being tested and might have some bugs, please
# help us test it.
# OpenID Connect
oidc:
#   only_start_if_oidc_is_available: true
#   issuer: "https://your-oidc.issuer.com/path"
    issuer: "https://auth.linarphy.net/realms/linarphy.net"
#   client_id: "your-oidc-client-id"
    client_id: "headscale"
#   client_secret: "your-oidc-client-secret"
    client_secret: "{secret}"
#   # Alternatively, set `client_secret_path` to read the secret from the file.
#   # It resolves environment variables, making integration to systemd's
#   # `LoadCredential` straightforward:
#   client_secret_path: "${CREDENTIALS_DIRECTORY}/oidc_client_secret"
#   # client_secret and client_secret_path are mutually exclusive.
#
#   # The amount of time from a node is authenticated with OpenID until it
#   # expires and needs to reauthenticate.
#   # Setting the value to "0" will mean no expiry.
#   expiry: 180d
#
#   # Use the expiry from the token received from OpenID when the user logged
#   # in, this will typically lead to frequent need to reauthenticate and should
#   # only been enabled if you know what you are doing.
#   # Note: enabling this will cause `oidc.expiry` to be ignored.
#   use_expiry_from_token: false
#
#   # Customize the scopes used in the OIDC flow, defaults to "openid", "profile" and "email" and add custom query
#   # parameters to the Authorize Endpoint request. Scopes default to "openid", "profile" and "email".
#
#   scope: ["openid", "profile", "email", "custom"]
#   extra_params:
#     domain_hint: example.com
#
#   # List allowed principal domains and/or users. If an authenticated user's domain is not in this list, the
#   # authentication request will be rejected.
#
#   allowed_domains:
#     - example.com
#   # Note: Groups from keycloak have a leading '/'
#   allowed_groups:
#     - /headscale
#   allowed_users:
#     - alice@example.com
#
#   # If `strip_email_domain` is set to `true`, the domain part of the username email address will be removed.
#   # This will transform `first-name.last-name@example.com` to the user `first-name.last-name`
#   # If `strip_email_domain` is set to `false` the domain part will NOT be removed resulting to the following
#   user: `first-name.last-name.example.com`
#
#   strip_email_domain: true

# Logtail configuration
# Logtail is Tailscales logging and auditing infrastructure, it allows the control panel
# to instruct tailscale nodes to log their activity to a remote server.
logtail:
  # Enable logtail for this headscales clients.
  # As there is currently no support for overriding the log server in headscale, this is
  # disabled by default. Enabling this will make your clients send logs to Tailscale Inc.
  enabled: false

# Enabling this option makes devices prefer a random port for WireGuard traffic over the
# default static port 41641. This option is intended as a workaround for some buggy
# firewall devices. See https://tailscale.com/kb/1181/firewalls/ for more information.
randomize_client_port: false

Le lancement du service s'effectue ensuite via systemd: systemctl enable headscale puis systemctl start headscale.