infrastructure/nixos-modules/system/security.nix
2025-03-25 14:10:54 +02:00

35 lines
1.7 KiB
Nix

{
lib,
...
}:
with lib;
{
# ###########################################################################
# Options taken from hardened kernel profile, see
# https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/profiles/hardened.nix
# ###########################################################################
# 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).
boot.kernel.sysctl."net.ipv4.conf.all.log_martians" = mkDefault true;
boot.kernel.sysctl."net.ipv4.conf.all.rp_filter" = mkDefault "1";
boot.kernel.sysctl."net.ipv4.conf.default.log_martians" = mkDefault true;
boot.kernel.sysctl."net.ipv4.conf.default.rp_filter" = mkDefault "1";
# Ignore broadcast ICMP (mitigate SMURF)
boot.kernel.sysctl."net.ipv4.icmp_echo_ignore_broadcasts" = mkDefault true;
# Ignore incoming ICMP redirects (note: default is needed to ensure that the
# setting is applied to interfaces added after the sysctls are set)
boot.kernel.sysctl."net.ipv4.conf.all.accept_redirects" = mkDefault false;
boot.kernel.sysctl."net.ipv4.conf.all.secure_redirects" = mkDefault false;
boot.kernel.sysctl."net.ipv4.conf.default.accept_redirects" = mkDefault false;
boot.kernel.sysctl."net.ipv4.conf.default.secure_redirects" = mkDefault false;
boot.kernel.sysctl."net.ipv6.conf.all.accept_redirects" = mkDefault false;
boot.kernel.sysctl."net.ipv6.conf.default.accept_redirects" = mkDefault false;
# Ignore outgoing ICMP redirects (this is ipv4 only)
boot.kernel.sysctl."net.ipv4.conf.all.send_redirects" = mkDefault false;
boot.kernel.sysctl."net.ipv4.conf.default.send_redirects" = mkDefault false;
}