{ config, pkgs, lib, ... }: {
  # modified from https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/profiles/hardened.nix
  # but with some stuff not turned on

  boot.kernelPackages = pkgs.linuxPackages_hardened;

  environment.memoryAllocator.provider = "scudo";
  environment.variables.SCUDO_OPTIONS = "ZeroContents=1";

  # TODO: this breaks NetworkManager
  # security.lockKernelModules = true;

  security.protectKernelImage = true;

  security.forcePageTableIsolation = true;

  # This is required by podman to run containers in rootless mode.
  security.unprivilegedUsernsClone = lib.mkDefault config.virtualisation.containers.enable;

  security.virtualisation.flushL1DataCache = "always";

  boot.kernelParams = [
    # Slab/slub sanity checks, redzoning, and poisoning
    "slub_debug=FZP"

    # Overwrite free'd memory
    "page_poison=1"

    # Enable page allocator randomization
    "page_alloc.shuffle=1"

    # Disable slab merging
    "slab_nomerge"

    # Zero memory on alloc and init
    # Scudo should do this but make kernel do it as well
    "init_on_alloc=1"
    "init_on_free=1"

    # Make page allocations less predictable
    "page_alloc.shuffle=1"

    # Turn on page table isolation
    "pti=on"

    # Disable vsyscalls
    "vsyscall=none"

    # Disable debugfs
    "debugfs=off"
  ];

  boot.kernel.sysctl = {
    # Restrict ptrace() usage to processes with a pre-defined relationship
    # (e.g., parent/child)
    "kernel.yama.ptrace_scope" = 1;

    # Hide kptrs even for processes with CAP_SYSLOG
    "kernel.kptr_restrict" = 2;

    # Disable bpf() JIT (to eliminate spray attacks)
    "net.core.bpf_jit_enable" = false;

    # Disable unprivileged bpf
    "kernel.unprivileged_bpf_disabled" = 1;

    # Disable ftrace debugging
    "kernel.ftrace_enabled" = false;

    # Disable kexec
    "kernel.kexec_load_disabled" = 1;

    # Disable sysrq
    "kernel.sysrq" = 0;

    # Enable strict reverse path filtering (that is, do not attempt to route
    # packets that "obviously" do not belong to the iface's network; dropped
    # packets are logged as martians).
    "net.ipv4.conf.all.log_martians" = true;
    "net.ipv4.conf.all.rp_filter" = "1";
    "net.ipv4.conf.default.log_martians" = true;
    "net.ipv4.conf.default.rp_filter" = "1";

    # Ignore broadcast ICMP (mitigate SMURF)
    "net.ipv4.icmp_echo_ignore_broadcasts" = true;

    # Ignore incoming ICMP redirects (note: default is needed to ensure that the
    # setting is applied to interfaces added after the sysctls are set)
    "net.ipv4.conf.all.accept_redirects" = false;
    "net.ipv4.conf.all.secure_redirects" = false;
    "net.ipv4.conf.default.accept_redirects" = false;
    "net.ipv4.conf.default.secure_redirects" = false;
    "net.ipv6.conf.all.accept_redirects" = false;
    "net.ipv6.conf.default.accept_redirects" = false;

    # Ignore outgoing ICMP redirects (this is ipv4 only)
    "net.ipv4.conf.all.send_redirects" = false;
    "net.ipv4.conf.default.send_redirects" = false;
  };
}