{...}: {
  # simple fail2ban config (not production ready or anything though)
  # refer to: https://nixos.wiki/wiki/Fail2Ban
  services.fail2ban = {
    enable = true;

    maxretry = 5;
    bantime = "10m"; # 10 minute ban
    bantime-increment = {
      enable = true;
      formula = "ban.Time * math.exp(float(ban.Count+1)*banFactor)/math.exp(1*banFactor)";
      multipliers = "1 2 4 8 16 32 64";
      maxtime = "168h"; # dont ban for more than 1 week
      overalljails = true;
    };
  };
}