{
  # this is a collection of tcp related sysctl commands that are floating around,
  # unsure who the original author is

  # see:
  # <https://madaidans-insecurities.github.io/guides/linux-hardening.html>
  # github:fort-nix/nix-bitcoin
  # github:hlissner/dotfiles
  # github:notashelf/nyx
  boot = {
    kernel.sysctl = {
      # TCP hardening
      # Prevent bogus ICMP errors from filling up logs.
      "net.ipv4.icmp_ignore_bogus_error_responses" = 1;
      # Reverse path filtering causes the kernel to do source validation of
      # packets received from all interfaces. This can mitigate IP spoofing.
      "net.ipv4.conf.default.rp_filter" = 1;
      "net.ipv4.conf.all.rp_filter" = 1;
      # Do not accept IP source route packets (we're not a router)
      "net.ipv4.conf.all.accept_source_route" = 0;
      "net.ipv6.conf.all.accept_source_route" = 0;
      # Don't send ICMP redirects (again, we're on a router)
      "net.ipv4.conf.all.send_redirects" = 0;
      "net.ipv4.conf.default.send_redirects" = 0;
      # Refuse ICMP redirects (MITM mitigations)
      "net.ipv4.conf.all.accept_redirects" = 0;
      "net.ipv4.conf.default.accept_redirects" = 0;
      "net.ipv4.conf.all.secure_redirects" = 0;
      "net.ipv4.conf.default.secure_redirects" = 0;
      "net.ipv6.conf.all.accept_redirects" = 0;
      "net.ipv6.conf.default.accept_redirects" = 0;
      # Protects against SYN flood attacks
      "net.ipv4.tcp_syncookies" = 1;
      # Incomplete protection again TIME-WAIT assassination
      "net.ipv4.tcp_rfc1337" = 1;
      # And other stuff
      "net.ipv4.conf.all.log_martians" = true;
      "net.ipv4.conf.default.log_martians" = true;
      "net.ipv4.icmp_echo_ignore_broadcasts" = true;
      "net.ipv6.conf.default.accept_ra" = 0;
      "net.ipv6.conf.all.accept_ra" = 0;
      "net.ipv4.tcp_timestamps" = 0;

      # TCP optimization
      # TCP Fast Open is a TCP extension that reduces network latency by packing
      # data in the sender’s initial TCP SYN. Setting 3 = enable TCP Fast Open for
      # both incoming and outgoing connections:
      "net.ipv4.tcp_fastopen" = 3;
      # Bufferbloat mitigations + slight improvement in throughput & latency
      "net.ipv4.tcp_congestion_control" = "bbr";
      "net.core.default_qdisc" = "cake";

      # Other stuff that I am too lazy to document
      "net.core.optmem_max" = 65536;
      "net.core.rmem_default" = 1048576;
      "net.core.rmem_max" = 16777216;
      "net.core.somaxconn" = 8192;
      "net.core.wmem_default" = 1048576;
      "net.core.wmem_max" = 16777216;
      "net.ipv4.ip_local_port_range" = "16384 65535";
      "net.ipv4.tcp_max_syn_backlog" = 8192;
      "net.ipv4.tcp_max_tw_buckets" = 2000000;
      "net.ipv4.tcp_mtu_probing" = 1;
      "net.ipv4.tcp_rmem" = "4096 1048576 2097152";
      "net.ipv4.tcp_slow_start_after_idle" = 0;
      "net.ipv4.tcp_tw_reuse" = 1;
      "net.ipv4.tcp_wmem" = "4096 65536 16777216";
      "net.ipv4.udp_rmem_min" = 8192;
      "net.ipv4.udp_wmem_min" = 8192;
      "net.netfilter.nf_conntrack_generic_timeout" = 60;
      "net.netfilter.nf_conntrack_max" = 1048576;
      "net.netfilter.nf_conntrack_tcp_timeout_established" = 600;
      "net.netfilter.nf_conntrack_tcp_timeout_time_wait" = 1;
    };
  };
}