134 lines
3.2 KiB
Nix
134 lines
3.2 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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let
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inherit (pkgs) ntp;
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cfg = config.services.ntp;
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stateDir = "/var/lib/ntp";
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ntpUser = "ntp";
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configFile = pkgs.writeText "ntp.conf" ''
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driftfile ${stateDir}/ntp.drift
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restrict default ${toString cfg.restrictDefault}
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restrict -6 default ${toString cfg.restrictDefault}
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restrict source ${toString cfg.restrictSource}
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restrict 127.0.0.1
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restrict -6 ::1
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${toString (map (server: "server " + server + " iburst\n") cfg.servers)}
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'';
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ntpFlags = "-c ${configFile} -u ${ntpUser}:nogroup ${toString cfg.extraFlags}";
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in
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{
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###### interface
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options = {
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services.ntp = {
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enable = mkOption {
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default = false;
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description = ''
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Whether to synchronise your machine's time using ntpd, as a peer in
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the NTP network.
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</para>
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<para>
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Disables <literal>systemd.timesyncd</literal> if enabled.
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'';
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};
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restrictDefault = mkOption {
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type = types.listOf types.str;
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description = ''
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The restriction flags to be set by default.
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</para>
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<para>
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The default flags prevent external hosts from using ntpd as a DDoS
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reflector, setting system time, and querying OS/ntpd version. As
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recommended in section 6.5.1.1.3, answer "No" of
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http://support.ntp.org/bin/view/Support/AccessRestrictions
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'';
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default = [ "limited" "kod" "nomodify" "notrap" "noquery" "nopeer" ];
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};
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restrictSource = mkOption {
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type = types.listOf types.str;
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description = ''
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The restriction flags to be set on source.
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</para>
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<para>
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The default flags allow peers to be added by ntpd from configured
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pool(s), but not by other means.
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'';
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default = [ "limited" "kod" "nomodify" "notrap" "noquery" ];
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};
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servers = mkOption {
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default = config.networking.timeServers;
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description = ''
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The set of NTP servers from which to synchronise.
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'';
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};
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extraFlags = mkOption {
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type = types.listOf types.str;
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description = "Extra flags passed to the ntpd command.";
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example = literalExample ''[ "--interface=eth0" ]'';
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default = [];
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};
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};
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};
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###### implementation
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config = mkIf config.services.ntp.enable {
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# Make tools such as ntpq available in the system path.
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environment.systemPackages = [ pkgs.ntp ];
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services.timesyncd.enable = mkForce false;
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systemd.services.systemd-timedated.environment = { SYSTEMD_TIMEDATED_NTP_SERVICES = "ntpd.service"; };
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users.users = singleton
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{ name = ntpUser;
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uid = config.ids.uids.ntp;
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description = "NTP daemon user";
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home = stateDir;
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};
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systemd.services.ntpd =
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{ description = "NTP Daemon";
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wantedBy = [ "multi-user.target" ];
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wants = [ "time-sync.target" ];
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before = [ "time-sync.target" ];
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preStart =
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''
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mkdir -m 0755 -p ${stateDir}
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chown ${ntpUser} ${stateDir}
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'';
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serviceConfig = {
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ExecStart = "@${ntp}/bin/ntpd ntpd -g ${ntpFlags}";
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Type = "forking";
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};
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};
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};
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}
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