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|
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.services.resolved;
dnsmasqResolve = config.services.dnsmasq.enable &&
config.services.dnsmasq.resolveLocalQueries;
in
{
options = {
services.resolved.enable = mkOption {
default = false;
type = types.bool;
description = lib.mdDoc ''
Whether to enable the systemd DNS resolver daemon.
'';
};
services.resolved.fallbackDns = mkOption {
default = [ ];
example = [ "8.8.8.8" "2001:4860:4860::8844" ];
type = types.listOf types.str;
description = lib.mdDoc ''
A list of IPv4 and IPv6 addresses to use as the fallback DNS servers.
If this option is empty, a compiled-in list of DNS servers is used instead.
'';
};
services.resolved.domains = mkOption {
default = config.networking.search;
defaultText = literalExpression "config.networking.search";
example = [ "example.com" ];
type = types.listOf types.str;
description = lib.mdDoc ''
A list of domains. These domains are used as search suffixes
when resolving single-label host names (domain names which
contain no dot), in order to qualify them into fully-qualified
domain names (FQDNs).
For compatibility reasons, if this setting is not specified,
the search domains listed in
{file}`/etc/resolv.conf` are used instead, if
that file exists and any domains are configured in it.
'';
};
services.resolved.llmnr = mkOption {
default = "true";
example = "false";
type = types.enum [ "true" "resolve" "false" ];
description = lib.mdDoc ''
Controls Link-Local Multicast Name Resolution support
(RFC 4795) on the local host.
If set to
- `"true"`: Enables full LLMNR responder and resolver support.
- `"false"`: Disables both.
- `"resolve"`: Only resolution support is enabled, but responding is disabled.
'';
};
services.resolved.dnssec = mkOption {
default = "allow-downgrade";
example = "true";
type = types.enum [ "true" "allow-downgrade" "false" ];
description = lib.mdDoc ''
If set to
- `"true"`:
all DNS lookups are DNSSEC-validated locally (excluding
LLMNR and Multicast DNS). Note that this mode requires a
DNS server that supports DNSSEC. If the DNS server does
not properly support DNSSEC all validations will fail.
- `"allow-downgrade"`:
DNSSEC validation is attempted, but if the server does not
support DNSSEC properly, DNSSEC mode is automatically
disabled. Note that this mode makes DNSSEC validation
vulnerable to "downgrade" attacks, where an attacker might
be able to trigger a downgrade to non-DNSSEC mode by
synthesizing a DNS response that suggests DNSSEC was not
supported.
- `"false"`: DNS lookups are not DNSSEC validated.
'';
};
services.resolved.extraConfig = mkOption {
default = "";
type = types.lines;
description = lib.mdDoc ''
Extra config to append to resolved.conf.
'';
};
};
config = mkIf cfg.enable {
assertions = [
{ assertion = !config.networking.useHostResolvConf;
message = "Using host resolv.conf is not supported with systemd-resolved";
}
];
users.users.systemd-resolve.group = "systemd-resolve";
# add resolve to nss hosts database if enabled and nscd enabled
# system.nssModules is configured in nixos/modules/system/boot/systemd.nix
# added with order 501 to allow modules to go before with mkBefore
system.nssDatabases.hosts = (mkOrder 501 ["resolve [!UNAVAIL=return]"]);
systemd.additionalUpstreamSystemUnits = [
"systemd-resolved.service"
];
systemd.services.systemd-resolved = {
wantedBy = [ "multi-user.target" ];
aliases = [ "dbus-org.freedesktop.resolve1.service" ];
restartTriggers = [ config.environment.etc."systemd/resolved.conf".source ];
};
environment.etc = {
"systemd/resolved.conf".text = ''
[Resolve]
${optionalString (config.networking.nameservers != [])
"DNS=${concatStringsSep " " config.networking.nameservers}"}
${optionalString (cfg.fallbackDns != [])
"FallbackDNS=${concatStringsSep " " cfg.fallbackDns}"}
${optionalString (cfg.domains != [])
"Domains=${concatStringsSep " " cfg.domains}"}
LLMNR=${cfg.llmnr}
DNSSEC=${cfg.dnssec}
${config.services.resolved.extraConfig}
'';
# symlink the dynamic stub resolver of resolv.conf as recommended by upstream:
# https://www.freedesktop.org/software/systemd/man/systemd-resolved.html#/etc/resolv.conf
"resolv.conf".source = "/run/systemd/resolve/stub-resolv.conf";
} // optionalAttrs dnsmasqResolve {
"dnsmasq-resolv.conf".source = "/run/systemd/resolve/resolv.conf";
};
# If networkmanager is enabled, ask it to interface with resolved.
networking.networkmanager.dns = "systemd-resolved";
networking.resolvconf.package = pkgs.systemd;
};
}
|
