63 lines
2.2 KiB
Nix
Executable file
63 lines
2.2 KiB
Nix
Executable file
{ config, lib, options, pkgs, ... }:
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with lib;
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let
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cfg = config.modules.security;
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in {
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options.modules.security = {
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useDoas = mkEnableOption "use doas instead of sudo";
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};
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config = mkIf cfg.enable {
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boot = {
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tmp.useTmpfs = lib.mkDefault true;
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tmp.cleanOnBoot = lib.mkDefault (!config.boot.tmp.useTmpfs);
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kernel.sysctl = {
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# magic sysrq key, allows low-level commands through keyboard input
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"kernel.sysrq" = 0;
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## TCP hardening
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# prevent bogus ICMP errors from filling up logs
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"net.ipv4.icmp_ignore_bogus_error_responses" = 1;
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# do not accept IP source packets (we are not a router)
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"net.ipv4.conf.all.accept_source_route" = 0;
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"net.ipv6.conf.all.accept_source_route" = 0;
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# Don't send ICMP redirects (again, we're not a router)
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"net.ipv4.conf.all.send_redirects" = 0;
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"net.ipv4.conf.default.send_redirects" = 0;
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# refuse ICMP redirects (MITM mitigations)
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"net.ipv4.conf.all.accept_redirects" = 0;
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"net.ipv4.conf.default.accept_redirects" = 0;
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"net.ipv4.conf.all.secure_redirects" = 0;
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"net.ipv4.conf.default.secure_redirects" = 0;
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"net.ipv6.conf.all.accept_redirects" = 0;
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"net.ipv6.conf.default.accept_redirects" = 0;
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# protects against SYN flood attacks
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"net.ipv4.tcp_syncookies" = 1;
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# incomplete protection against TIME-WAIT assassination
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"net.ipv4.tcp_rfc1337" = 1;
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## TCP optimization
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# TCP fastopen
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"net.ipv4.tcp_fastopen" = 3;
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# bufferbloat mitigations + improvement in throughput and latency
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"net.ipv4.tcp_conjestion_control" = "bbr";
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"net.core.default_qdisc" = "cake";
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};
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kernelModules = [ "tcp_bbr" ];
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};
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security = {
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# prevents replacing the kernel without a reboot
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protectKernelImage = true;
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# allows unprivileged processes to speak to privileged processes (ex. nmtui, reboot)
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polkit.enable = true;
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rtkit.enable = true;
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};
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} // (mkIf cfg.useDoas {
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security.sudo.enable = false;
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security.doas.enable = true;
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environment.systemPackages = with pkgs; [ doas-sudo-shim ];
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});
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}
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