82 lines
3.3 KiB
Nix
82 lines
3.3 KiB
Nix
{ config, lib, ... }:
|
||
|
||
{
|
||
## System security tweaks
|
||
# sets hidepid=2 on /proc (make process info visible only to owning user)
|
||
# NOTE Was removed on nixpkgs-unstable because it doesn't do anything
|
||
# security.hideProcessInformation = true;
|
||
# Prevent replacing the running kernel w/o reboot
|
||
security.protectKernelImage = true;
|
||
|
||
# tmpfs = /tmp is mounted in ram. Doing so makes temp file management speedy
|
||
# on ssd systems, and volatile! Because it's wiped on reboot.
|
||
boot.tmpOnTmpfs = lib.mkDefault true;
|
||
# If not using tmpfs, which is naturally purged on reboot, we must clean it
|
||
# /tmp ourselves. /tmp should be volatile storage!
|
||
boot.cleanTmpDir = lib.mkDefault (!config.boot.tmpOnTmpfs);
|
||
|
||
# Fix a security hole in place for backwards compatibility. See desc in
|
||
# nixpkgs/nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix
|
||
boot.loader.systemd-boot.editor = false;
|
||
|
||
boot.kernel.sysctl = {
|
||
# The Magic SysRq key is a key combo that allows users connected to the
|
||
# system console of a Linux kernel to perform some low-level commands.
|
||
# Disable it, since we don't need it, and is a potential security concern.
|
||
"kernel.sysrq" = 0;
|
||
|
||
## 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;
|
||
|
||
## 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";
|
||
};
|
||
boot.kernelModules = [ "tcp_bbr" ];
|
||
|
||
# So we don't have to do this later...
|
||
security.acme.acceptTerms = true;
|
||
|
||
# Enable doas as an alternative to sudo
|
||
security.doas = {
|
||
enable = lib.mkDefault true;
|
||
extraRules = [
|
||
# Do not ask for a password again for some time after the user successfully authenticates.
|
||
{
|
||
groups = [ "wheel" "doas" ];
|
||
persist = true;
|
||
}
|
||
];
|
||
};
|
||
security.sudo.enable = !config.security.doas.enable;
|
||
|
||
# Disable ssh password login
|
||
services.openssh.passwordAuthentication = lib.mkDefault false;
|
||
}
|