{
  config,
  lib,
  service_configs,
  ...
}:
{
  services.coturn = {
    enable = true;
    realm = service_configs.https.domain;
    use-auth-secret = true;
    static-auth-secret = lib.strings.trim (builtins.readFile ../secrets/coturn_static_auth_secret);
    listening-port = service_configs.ports.coturn;
    tls-listening-port = service_configs.ports.coturn_tls;
    no-cli = true;

    # recommended security settings from Synapse's coturn docs
    extraConfig = ''
      denied-peer-ip=10.0.0.0-10.255.255.255
      denied-peer-ip=192.168.0.0-192.168.255.255
      denied-peer-ip=172.16.0.0-172.31.255.255
      denied-peer-ip=0.0.0.0-0.255.255.255
      denied-peer-ip=100.64.0.0-100.127.255.255
      denied-peer-ip=169.254.0.0-169.254.255.255
      denied-peer-ip=192.0.0.0-192.0.0.255
      denied-peer-ip=198.18.0.0-198.19.255.255
      denied-peer-ip=198.51.100.0-198.51.100.255
      denied-peer-ip=203.0.113.0-203.0.113.255
      denied-peer-ip=240.0.0.0-255.255.255.255
      denied-peer-ip=::1
      denied-peer-ip=64:ff9b::-64:ff9b::ffff:ffff
      denied-peer-ip=::ffff:0.0.0.0-::ffff:255.255.255.255
      denied-peer-ip=100::-100::ffff:ffff:ffff:ffff
      denied-peer-ip=2001::-2001:1ff:ffff:ffff:ffff:ffff:ffff:ffff
      denied-peer-ip=2002::-2002:ffff:ffff:ffff:ffff:ffff:ffff:ffff
      denied-peer-ip=fc00::-fdff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
      denied-peer-ip=fe80::-febf:ffff:ffff:ffff:ffff:ffff:ffff:ffff
    '';
  };

  # coturn needs these ports open
  networking.firewall = {
    allowedTCPPorts = [
      service_configs.ports.coturn
      service_configs.ports.coturn_tls
    ];
    allowedUDPPorts = [
      service_configs.ports.coturn
      service_configs.ports.coturn_tls
    ];
    # relay port range
    allowedUDPPortRanges = [
      {
        from = config.services.coturn.min-port;
        to = config.services.coturn.max-port;
      }
    ];
  };
}