mirror of
https://github.com/systemd/systemd
synced 2024-11-05 18:25:39 +00:00
856 lines
49 KiB
XML
856 lines
49 KiB
XML
<?xml version="1.0"?>
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<!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
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<!ENTITY % entities SYSTEM "custom-entities.ent" >
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%entities;
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]>
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="org.freedesktop.resolve1" conditional='ENABLE_RESOLVE'
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>org.freedesktop.resolve1</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>org.freedesktop.resolve1</refentrytitle>
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<manvolnum>5</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>org.freedesktop.resolve1</refname>
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<refpurpose>The D-Bus interface of systemd-resolved</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Introduction</title>
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<para>
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<citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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is a system service that provides hostname resolution and caching using DNS, LLMNR, and mDNS. It also
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does DNSSEC validation. This page describes the resolve semantics and the D-Bus interface.</para>
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<para>This page contains an API reference only. If you are looking for a longer explanation how to use
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this API, please consult
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<ulink url="https://wiki.freedesktop.org/www/Software/systemd/writing-network-configuration-managers">
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Writing Network Configuration Managers</ulink> and
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<ulink url="https://wiki.freedesktop.org/www/Software/systemd/writing-resolver-clients">Writing Resolver
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Clients</ulink>.
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</para>
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</refsect1>
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<refsect1>
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<title>The Manager Object</title>
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<para>The service exposes the following interfaces on the Manager object on the bus:</para>
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<programlisting executable="systemd-resolved" node="/org/freedesktop/resolve1" interface="org.freedesktop.resolve1.Manager">
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node /org/freedesktop/resolve1 {
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interface org.freedesktop.resolve1.Manager {
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methods:
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ResolveHostname(in i ifindex,
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in s name,
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in i family,
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in t flags,
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out a(iiay) addresses,
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out s canonical,
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out t flags);
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ResolveAddress(in i ifindex,
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in i family,
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in ay address,
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in t flags,
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out a(is) names,
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out t flags);
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ResolveRecord(in i ifindex,
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in s name,
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in q class,
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in q type,
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in t flags,
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out a(iqqay) records,
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out t flags);
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ResolveService(in i ifindex,
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in s name,
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in s type,
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in s domain,
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in i family,
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in t flags,
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out a(qqqsa(iiay)s) srv_data,
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out aay txt_data,
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out s canonical_name,
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out s canonical_type,
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out s canonical_domain,
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out t flags);
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GetLink(in i ifindex,
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out o path);
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SetLinkDNS(in i ifindex,
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in a(iay) addresses);
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SetLinkDNSEx(in i ifindex,
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in a(iayqs) addresses);
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SetLinkDomains(in i ifindex,
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in a(sb) domains);
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SetLinkDefaultRoute(in i ifindex,
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in b enable);
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SetLinkLLMNR(in i ifindex,
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in s mode);
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SetLinkMulticastDNS(in i ifindex,
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in s mode);
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SetLinkDNSOverTLS(in i ifindex,
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in s mode);
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SetLinkDNSSEC(in i ifindex,
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in s mode);
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SetLinkDNSSECNegativeTrustAnchors(in i ifindex,
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in as names);
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RevertLink(in i ifindex);
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RegisterService(in s name,
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in s name_template,
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in s type,
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in q service_port,
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in q service_priority,
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in q service_weight,
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in aa{say} txt_datas,
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out o service_path);
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UnregisterService(in o service_path);
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ResetStatistics();
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FlushCaches();
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ResetServerFeatures();
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properties:
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readonly s LLMNRHostname = '...';
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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readonly s LLMNR = '...';
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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readonly s MulticastDNS = '...';
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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readonly s DNSOverTLS = '...';
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readonly a(iiay) DNS = [...];
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readonly a(iiayqs) DNSEx = [...];
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@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
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readonly a(iiay) FallbackDNS = [...];
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@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
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readonly a(iiayqs) FallbackDNSEx = [...];
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readonly (iiay) CurrentDNSServer = ...;
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readonly (iiayqs) CurrentDNSServerEx = ...;
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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readonly a(isb) Domains = [...];
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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readonly (tt) TransactionStatistics = ...;
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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readonly (ttt) CacheStatistics = ...;
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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readonly s DNSSEC = '...';
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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readonly (tttt) DNSSECStatistics = ...;
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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readonly b DNSSECSupported = ...;
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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readonly as DNSSECNegativeTrustAnchors = ['...', ...];
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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readonly s DNSStubListener = '...';
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@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
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readonly s ResolvConfMode = '...';
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};
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interface org.freedesktop.DBus.Peer { ... };
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interface org.freedesktop.DBus.Introspectable { ... };
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interface org.freedesktop.DBus.Properties { ... };
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};
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</programlisting>
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<!--method RegisterService is not documented!-->
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<!--method UnregisterService is not documented!-->
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<!--method FlushCaches is not documented!-->
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<!--method ResetServerFeatures is not documented!-->
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<!--property DNSSECNegativeTrustAnchors is not documented!-->
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<!--Autogenerated cross-references for systemd.directives, do not edit-->
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<variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.resolve1.Manager"/>
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<variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.resolve1.Manager"/>
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<variablelist class="dbus-method" generated="True" extra-ref="ResolveHostname()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="ResolveAddress()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="ResolveRecord()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="ResolveService()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="GetLink()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="SetLinkDNS()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="SetLinkDNSEx()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="SetLinkDomains()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="SetLinkDefaultRoute()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="SetLinkLLMNR()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="SetLinkMulticastDNS()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="SetLinkDNSOverTLS()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="SetLinkDNSSEC()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="SetLinkDNSSECNegativeTrustAnchors()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="RevertLink()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="RegisterService()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="UnregisterService()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="ResetStatistics()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="FlushCaches()"/>
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<variablelist class="dbus-method" generated="True" extra-ref="ResetServerFeatures()"/>
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<variablelist class="dbus-property" generated="True" extra-ref="LLMNRHostname"/>
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<variablelist class="dbus-property" generated="True" extra-ref="LLMNR"/>
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<variablelist class="dbus-property" generated="True" extra-ref="MulticastDNS"/>
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<variablelist class="dbus-property" generated="True" extra-ref="DNSOverTLS"/>
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<variablelist class="dbus-property" generated="True" extra-ref="DNS"/>
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<variablelist class="dbus-property" generated="True" extra-ref="DNSEx"/>
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<variablelist class="dbus-property" generated="True" extra-ref="FallbackDNS"/>
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<variablelist class="dbus-property" generated="True" extra-ref="FallbackDNSEx"/>
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<variablelist class="dbus-property" generated="True" extra-ref="CurrentDNSServer"/>
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<variablelist class="dbus-property" generated="True" extra-ref="CurrentDNSServerEx"/>
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<variablelist class="dbus-property" generated="True" extra-ref="Domains"/>
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<variablelist class="dbus-property" generated="True" extra-ref="TransactionStatistics"/>
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<variablelist class="dbus-property" generated="True" extra-ref="CacheStatistics"/>
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<variablelist class="dbus-property" generated="True" extra-ref="DNSSEC"/>
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<variablelist class="dbus-property" generated="True" extra-ref="DNSSECStatistics"/>
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<variablelist class="dbus-property" generated="True" extra-ref="DNSSECSupported"/>
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<variablelist class="dbus-property" generated="True" extra-ref="DNSSECNegativeTrustAnchors"/>
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<variablelist class="dbus-property" generated="True" extra-ref="DNSStubListener"/>
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<variablelist class="dbus-property" generated="True" extra-ref="ResolvConfMode"/>
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<!--End of Autogenerated section-->
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<refsect2>
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<title>Methods</title>
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<para><function>ResolveHostname()</function> takes a hostname and resolves it to one or more IP
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addresses. As parameters it takes the Linux network interface index to execute the query on, or 0 if
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it may be done on any suitable interface. The <varname>name</varname> parameter specifies the hostname
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to resolve. Note that if required, IDNA conversion is applied to this name unless it is resolved via
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LLMNR or MulticastDNS. The <varname>family</varname> parameter limits the results to a specific address
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family. It may be <constant>AF_INET</constant>, <constant>AF_INET6</constant> or
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<constant>AF_UNSPEC</constant>. If <constant>AF_UNSPEC</constant> is specified (recommended), both
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kinds are retrieved, subject to local network configuration (i.e. if no local, routable IPv6 address is
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found, no IPv6 address is retrieved; and similarly for IPv4). A 64-bit <varname>flags</varname> field
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may be used to alter the behaviour of the resolver operation (see below). The method returns an array
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of address records. Each address record consists of the interface index the address belongs to, an
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address family as well as a byte array with the actual IP address data (which either has 4 or 16
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elements, depending on the address family). The returned address family will be one of
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<constant>AF_INET</constant> or <constant>AF_INET6</constant>. For IPv6, the returned address interface
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index should be used to initialize the .sin6_scope_id field of a
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<structname>struct sockaddr_in6</structname> instance to permit support for resolution to link-local IP
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addresses. The address array is followed by the canonical name of the host, which may or may not be
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identical to the resolved hostname. Finally, a 64-bit <varname>flags</varname> field is returned that
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is defined similarly to the <varname>flags</varname> field that was passed in, but contains information
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about the resolved data (see below). If the hostname passed in is an IPv4 or IPv6 address formatted as
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string, it is parsed, and the result is returned. In this case, no network communication is
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done.</para>
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<para><function>ResolveAddress()</function> executes the reverse operation: it takes an IP address and
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acquires one or more hostnames for it. As parameters it takes the interface index to execute the query
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on, or <constant>0</constant> if all suitable interfaces are OK. The <varname>family</varname>
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parameter indicates the address family of the IP address to resolve. It may be either
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<constant>AF_INET</constant> or <constant>AF_INET6</constant>. The <varname>address</varname> parameter
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takes the raw IP address data (as either a 4 or 16 byte array). The <varname>flags</varname> input
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parameter may be used to alter the resolver operation (see below). The method returns an array of name
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records, each consisting of an interface index and a hostname. The <varname>flags</varname> output
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field contains additional information about the resolver operation (see below).</para>
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<para><function>ResolveRecord()</function> takes a DNS resource record (RR) type, class and name, and
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retrieves the full resource record set (RRset), including the RDATA, for it. As parameter it takes the
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Linux network interface index to execute the query on, or <constant>0</constant> if it may be done on
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any suitable interface. The <varname>name</varname> parameter specifies the RR domain name to look up
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(no IDNA conversion is applied), followed by the 16-bit class and type fields (which may be
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ANY). Finally, a <varname>flags</varname> field may be passed in to alter behaviour of the look-up (see
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below). On completion, an array of RR items is returned. Each array entry consists of the network interface
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index the RR was discovered on, the type and class field of the RR found, and a byte array of the raw
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RR discovered. The raw RR data starts with the RR's domain name, in the original casing, followed
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by the RR type, class, TTL and RDATA, in the binary format documented in
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<ulink url="https://www.ietf.org/rfc/rfc1035.txt">RFC 1035</ulink>. For RRs that support name
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compression in the payload (such as MX or PTR), the compression is expanded in the returned
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data.</para>
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<para>Note that currently, the class field has to be specified as IN or ANY. Specifying a different
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class will return an error indicating that look-ups of this kind are unsupported. Similarly, some
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special types are not supported either (AXFR, OPT, …). While <filename>systemd-resolved</filename> parses and validates resource
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records of many types, it is crucial that clients using this API understand that the RR data originates
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from the network and should be thoroughly validated before use.</para>
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<para><function>ResolveService()</function> may be used to resolve a DNS SRV service record, as well as the
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hostnames referenced in it, and possibly an accompanying DNS-SD TXT record containing additional
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service metadata. The primary benefit of using this method over <function>ResolveRecord()</function>
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specifying the SRV type is that it will resolve the SRV and TXT RRs as well as the hostnames referenced
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in the SRV in a single operation. As parameters it takes a Linux network interface index, a service
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name, a service type and a service domain. This method may be invoked in three different modes:</para>
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<orderedlist>
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<listitem><para>To resolve a DNS-SD service, specify the service name (e.g. <literal>Lennart's
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Files</literal>), the service type (e.g. <literal>_webdav._tcp</literal>) and the domain to search in
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(e.g. <literal>local</literal>) as the three service parameters. The service name must be in UTF-8
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format, and no IDNA conversion is applied to it in this mode (as mandated by the DNS-SD
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specifications). However, if necessary, IDNA conversion is applied to the domain parameter.</para>
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</listitem>
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<listitem><para>To resolve a plain SRV record, set the service name parameter to the empty string
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and set the service type and domain properly. (IDNA conversion is applied to the domain, if
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necessary.)</para></listitem>
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<listitem><para>Alternatively, leave both the service name and type empty and specify the full
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domain name of the SRV record (i.e. prefixed with the service type) in the domain parameter. (No IDNA
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conversion is applied in this mode.)</para></listitem>
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</orderedlist>
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<para>The <varname>family</varname> parameter of the <function>ResolveService()</function> method encodes
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the desired family of the addresses to resolve (use <constant>AF_INET</constant>,
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<constant>AF_INET6</constant>, or <constant>AF_UNSPEC</constant>). If this is enabled (Use the
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<constant>NO_ADDRESS</constant> flag to turn address resolution off, see below). The
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<varname>flags</varname> parameter takes a couple of flags that may be used to alter the resolver
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operation.</para>
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<para>On completion, <function>ResolveService()</function> returns an array of SRV record structures. Each
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items consisting of the priority, weight and port fields as well as the hostname to contact, as encoded in the SRV
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record. Immediately following is an array of the addresses of this hostname, with each item consisting
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of the interface index, the address family and the address data in a byte array. This address array is
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followed by the canonicalized hostname. After this array of SRV record structures an array of byte
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arrays follows that encodes the TXT RR strings, in case DNS-SD look-ups are enabled. The next parameters
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are the canonical service name, type and domain. This may or may not be identical to the parameters
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passed in. Finally, a <varname>flags</varname> field is returned that contains information about the
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resolver operation performed.</para>
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<para>The <function>ResetStatistics()</function> method resets the various statistics counters that
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<filename>systemd-resolved</filename> maintains to zero. (For details, see the statistics properties below.)</para>
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<para>The <function>GetLink()</function> method takes a network interface index and returns the object
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path to the <interfacename>org.freedesktop.resolve1.Link</interfacename> object corresponding to it.
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</para>
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<para>The <function>SetLinkDNS()</function> method sets the DNS servers to use on a specific
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interface. This method (and the following ones) may be used by network management software to configure
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per-interface DNS settings. It takes a network interface index as well as an array of DNS server IP
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address records. Each array item consists of an address family (either <constant>AF_INET</constant> or
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<constant>AF_INET6</constant>), followed by a 4-byte or 16-byte array with the raw address data. This
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method is a one-step shortcut for retrieving the Link object for a network interface using
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<function>GetLink()</function> (see above) and then invoking the <function>SetDNS()</function> method
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(see below) on it.</para>
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<para><function>SetLinkDNSEx()</function> is similar to <function>SetLinkDNS()</function>, but allows
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an IP port (instead of the default 53) and DNS name to be specified for each DNS server. The server
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name is used for Server Name Indication (SNI), which is useful when DNS-over-TLS is
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used. C.f. <varname>DNS=</varname> in
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<citerefentry><refentrytitle>resolved.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
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</para>
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<para><function>SetLinkDefaultRoute()</function> specifies whether the link shall be used as the
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default route for name queries. See the description of name routing in
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<citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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for details.</para>
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<para>The <function>SetLinkDomains()</function> method sets the search and routing domains to use on a
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specific network interface for DNS look-ups. It takes a network interface index and an array of domains,
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each with a boolean parameter indicating whether the specified domain shall be used as a search domain
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(false), or just as a routing domain (true). Search domains are used for qualifying single-label names into
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FQDN when looking up hostnames, as well as for making routing decisions on which interface to send
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queries ending in the domain to. Routing domains are only used for routing decisions and not used for single-label
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name qualification. Pass the search domains in the order they should be used.</para>
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<para>The <function>SetLinkLLMNR()</function> method enables or disables LLMNR support on a specific
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network interface. It takes a network interface index as well as a string that may either be empty or one of
|
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<literal>yes</literal>, <literal>no</literal> or <literal>resolve</literal>. If empty, the systemd-wide
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default LLMNR setting is used. If <literal>yes</literal>, LLMNR is used for resolution of single-label
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||
names and the local hostname is registered on all local LANs for LLMNR resolution by peers. If
|
||
<literal>no</literal>, LLMNR is turned off fully on this interface. If <literal>resolve</literal>, LLMNR
|
||
is only enabled for resolving names, but the local hostname is not registered for other peers to
|
||
use.</para>
|
||
|
||
<para>Similarly, the <function>SetLinkMulticastDNS()</function> method enables or disables MulticastDNS
|
||
support on a specific interface. It takes the same parameters as <function>SetLinkLLMNR()</function>
|
||
described above.</para>
|
||
|
||
<para>The <function>SetLinkDNSSEC()</function> method enables or disables DNSSEC validation on a
|
||
specific network interface. It takes a network interface index as well as a string that may either be
|
||
empty or one of <literal>yes</literal>, <literal>no</literal>, or <literal>allow-downgrade</literal>. When
|
||
empty, the system-wide default DNSSEC setting is used. If <literal>yes</literal>, full DNSSEC validation
|
||
is done for all look-ups. If the selected DNS server does not support DNSSEC, look-ups will fail if this
|
||
mode is used. If <literal>no</literal>, DNSSEC validation is fully disabled. If
|
||
<literal>allow-downgrade</literal>, DNSSEC validation is enabled, but is turned off automatically if the
|
||
selected server does not support it (thus opening up behaviour to downgrade attacks). Note that DNSSEC
|
||
only applies to traditional DNS, not to LLMNR or MulticastDNS.</para>
|
||
|
||
<para>The <function>SetLinkDNSSECNegativeTrustAnchors()</function> method may be used to configure DNSSEC
|
||
Negative Trust Anchors (NTAs) for a specific network interface. It takes a network interface index and a
|
||
list of domains as arguments.</para>
|
||
|
||
<para>The <function>SetLinkDNSOverTLS()</function> method enables or disables DNS-over-TLS.
|
||
C.f. <varname>DNSOverTLS=</varname> in
|
||
<citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
|
||
for details.</para>
|
||
|
||
<para>Network management software integrating with <filename>systemd-resolved</filename> should call
|
||
<function>SetLinkDNS()</function> or <function>SetLinkDNSEx()</function>,
|
||
<function>SetLinkDefaultRoute()</function>, <function>SetLinkDomains()</function> and others after the
|
||
interface appeared in the kernel (and thus after a network interface index has been assigned), but
|
||
before the network interfaces is activated (<constant>IFF_UP</constant> set) so that all settings take
|
||
effect during the full time the network interface is up. It is safe to alter settings while the
|
||
interface is up, however. Use <function>RevertLink()</function> (described below) to reset all
|
||
per-interface settings.</para>
|
||
|
||
<para>The <function>RevertLink()</function> method may be used to revert all per-link settings
|
||
described above to the defaults.</para>
|
||
|
||
<refsect3>
|
||
<title>The Flags Parameter</title>
|
||
|
||
<para>The four methods above accept and return a 64-bit flags value. In most cases passing 0 is sufficient
|
||
and recommended. However, the following flags are defined to alter the look-up:</para>
|
||
|
||
<programlisting>
|
||
#define SD_RESOLVED_DNS (UINT64_C(1) << 0)
|
||
#define SD_RESOLVED_LLMNR_IPV4 (UINT64_C(1) << 1)
|
||
#define SD_RESOLVED_LLMNR_IPV6 (UINT64_C(1) << 2)
|
||
#define SD_RESOLVED_MDNS_IPV4 (UINT64_C(1) << 3)
|
||
#define SD_RESOLVED_MDNS_IPV6 (UINT64_C(1) << 4)
|
||
#define SD_RESOLVED_NO_CNAME (UINT64_C(1) << 5)
|
||
#define SD_RESOLVED_NO_TXT (UINT64_C(1) << 6)
|
||
#define SD_RESOLVED_NO_ADDRESS (UINT64_C(1) << 7)
|
||
#define SD_RESOLVED_NO_SEARCH (UINT64_C(1) << 8)
|
||
#define SD_RESOLVED_AUTHENTICATED (UINT64_C(1) << 9)
|
||
</programlisting>
|
||
|
||
<para>On input, the first five flags control the protocols to use for the look-up. They refer to
|
||
classic unicast DNS, LLMNR via IPv4/UDP and IPv6/UDP respectively, as well as MulticastDNS via
|
||
IPv4/UDP and IPv6/UDP. If all of these five bits are off on input (which is strongly recommended) the
|
||
look-up will be done via all suitable protocols for the specific look-up. Note that these flags
|
||
operate as filter only, but cannot force a look-up to be done via a protocol. Specifically,
|
||
<filename>systemd-resolved</filename> will only route look-ups within the .local TLD to MulticastDNS
|
||
(plus some reverse look-up address domains), and single-label names to LLMNR (plus some reverse
|
||
address lookup domains). It will route neither of these to Unicast DNS servers. Also, it will do
|
||
LLMNR and Multicast DNS only on interfaces suitable for multicast.</para>
|
||
|
||
<para>On output, these five flags indicate which protocol was used to execute the operation, and hence
|
||
where the data was found.</para>
|
||
|
||
<para>The primary use cases for these five flags are follow-up look-ups based on DNS data retrieved
|
||
earlier. In this case it is often a good idea to limit the follow-up look-up to the protocol that was
|
||
used to discover the first DNS result.</para>
|
||
|
||
<para>The NO_CNAME flag controls whether CNAME/DNAME resource records shall be followed during the
|
||
look-up. This flag is only available at input, none of the functions will return it on output. If a
|
||
CNAME/DNAME RR is discovered while resolving a hostname, an error is returned instead. By default,
|
||
when the flag is off, CNAME/DNAME RRs are followed.</para>
|
||
|
||
<para>The NO_TXT and NO_ADDRESS flags only influence operation of the
|
||
<function>ResolveService()</function> method. They are only defined for input, not output. If
|
||
NO_TXT set, the DNS-SD TXT RR look-up is not done in the same operation. If NO_ADDRESS is specified,
|
||
the hostnames discovered are not implicitly translated to their addresses.</para>
|
||
|
||
<para>The NO_SEARCH flag turns off the search domain logic. It is only defined for input in
|
||
<function>ResolveHostname()</function>. When specified, single-label hostnames are not qualified
|
||
using defined search domains, if any are configured. Note that <function>ResolveRecord()</function>
|
||
will never qualify single-label domain names using search domains. Also note that
|
||
multi-label hostnames are never subject to search list expansion.</para>
|
||
|
||
<para>The AUTHENTICATED bit is defined only in the output flags of the four functions. If set, the
|
||
returned data has been fully authenticated. Specifically, this bit is set for all DNSSEC-protected data
|
||
for which a full trust chain may be established to a trusted domain anchor. It is also set for locally
|
||
synthesized data, such as <literal>localhost</literal> or data from
|
||
<filename>/etc/hosts</filename>. Moreover, it is set for all LLMNR or mDNS RRs which originate from the
|
||
local host. Applications that require authenticated RR data for operation should check this flag before
|
||
trusting the data. Note that <filename>systemd-resolved</filename> will never return invalidated data, hence this flag
|
||
simply allows to discern the cases where data is known to be trustable, or where there is proof that
|
||
the data is "rightfully" unauthenticated (which includes cases where the underlying protocol or server
|
||
does not support authenticating data).</para>
|
||
</refsect3>
|
||
</refsect2>
|
||
|
||
<refsect2>
|
||
<title>Properties</title>
|
||
|
||
<para>The <varname>LLMNR</varname> and <varname>MulticastDNS</varname> properties report whether LLMNR
|
||
and MulticastDNS are (globally) enabled. Each may be one of <literal>yes</literal>,
|
||
<literal>no</literal>, and <literal>resolve</literal>. See <function>SetLinkLLMNR()</function>
|
||
and <function>SetLinkMulticastDNS()</function> above.</para>
|
||
|
||
<para><varname>LLMNRHostname</varname> contains the hostname currently exposed on the network via
|
||
LLMNR. It usually follows the system hostname as may be queried via
|
||
<citerefentry project="man-pages"><refentrytitle>gethostname</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||
but may differ if a conflict is detected on the network.</para>
|
||
|
||
<para><varname>DNS</varname> and <varname>DNSEx</varname> contain arrays of all DNS servers currently
|
||
used by <filename>systemd-resolved</filename>. <varname>DNS</varname> contains information similar to
|
||
the DNS server data in <filename>/run/systemd/resolve/resolv.conf</filename>. Each structure in the
|
||
array consists of a numeric network interface index, an address family, and a byte array containing the
|
||
DNS server address (either 4 bytes in length for IPv4 or 16 bytes in lengths for IPv6).
|
||
<varname>DNSEx</varname> is similar, but additionally contains the IP port and server name (used for
|
||
Server Name Indication, SNI). Both arrays contain DNS servers configured system-wide, including those
|
||
possibly read from a foreign <filename>/etc/resolv.conf</filename> or the <varname>DNS=</varname>
|
||
setting in <filename>/etc/systemd/resolved.conf</filename>, as well as per-interface DNS server
|
||
information either retrieved from
|
||
<citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
|
||
or configured by external software via <function>SetLinkDNS()</function> or
|
||
<function>SetLinkDNSEx()</function> (see above). The network interface index will be 0 for the
|
||
system-wide configured services and non-zero for the per-link servers.</para>
|
||
|
||
<para><varname>FallbackDNS</varname> and <varname>FallbackDNSEx</varname> contain arrays of all DNS
|
||
servers configured as fallback servers, if any, using the same format as <varname>DNS</varname> and
|
||
<varname>DNSEx</varname> described above. See the description of <varname>FallbackDNS=</varname> in
|
||
<citerefentry><refentrytitle>resolved.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
|
||
the description of when those servers are used.</para>
|
||
|
||
<para><varname>CurrentDNSServer</varname> and <varname>CurrentDNSServerEx</varname> specify the server
|
||
that is currently used for query resolution, in the same format as a single entry in the
|
||
<varname>DNS</varname> and <varname>DNSEx</varname> arrays described above.</para>
|
||
|
||
<para>Similarly, the <varname>Domains</varname> property contains an array of all search and routing
|
||
domains currently used by <filename>systemd-resolved</filename>. Each entry consists of a network
|
||
interface index (again, 0 encodes system-wide entries), the actual domain name, and whether the entry
|
||
is used only for routing (true) or for both routing and searching (false).</para>
|
||
|
||
<para>The <varname>TransactionStatistics</varname> property contains information about the number of
|
||
transactions <filename>systemd-resolved</filename> has processed. It contains a pair of unsigned 64-bit counters, the first
|
||
containing the number of currently ongoing transactions, the second the number of total transactions
|
||
<filename>systemd-resolved</filename> is processing or has processed. The latter value may be reset using the
|
||
<function>ResetStatistics()</function> method described above. Note that the number of transactions does
|
||
not directly map to the number of issued resolver bus method calls. While simple look-ups usually require a
|
||
single transaction only, more complex look-ups might result in more, for example when CNAMEs or DNSSEC
|
||
are in use.</para>
|
||
|
||
<para>The <varname>CacheStatistics</varname> property contains information about the executed cache
|
||
operations so far. It exposes three 64-bit counters: the first being the total number of current cache
|
||
entries (both positive and negative), the second the number of cache hits, and the third the number of
|
||
cache misses. The latter counters may be reset using <function>ResetStatistics()</function> (see
|
||
above).</para>
|
||
|
||
<para>The <varname>DNSSEC</varname> property specifies current status of DNSSEC validation. It is one
|
||
of <literal>yes</literal> (validation is enforced), <literal>no</literal> (no validation is done),
|
||
<literal>allow-downgrade</literal> (validation is done if the current DNS server supports it). See the
|
||
description of <varname>DNSSEC=</varname> in
|
||
<citerefentry><refentrytitle>resolved.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
|
||
</para>
|
||
|
||
<para>The <varname>DNSSECStatistics</varname> property contains information about the DNSSEC
|
||
validations executed so far. It contains four 64-bit counters: the number of secure, insecure, bogus,
|
||
and indeterminate DNSSEC validations so far. The counters are increased for each validated RRset, and
|
||
each non-existance proof. The secure counter is increased for each operation that successfully verified
|
||
a signed reply, the insecure counter is increased for each operation that successfully verified that an
|
||
unsigned reply is rightfully unsigned. The bogus counter is increased for each operation where the
|
||
validation did not check out and the data is likely to have been tempered with. Finally the
|
||
indeterminate counter is increased for each operation which did not complete because the necessary keys
|
||
could not be acquired or the cryptographic algorithms were unknown.</para>
|
||
|
||
<para>The <varname>DNSSECSupported</varname> boolean property reports whether DNSSEC is enabled and
|
||
the selected DNS servers support it. It combines information about system-wide and per-link DNS
|
||
settings (see below), and only reports true if DNSSEC is enabled and supported on every interface for
|
||
which DNS is configured and for the system-wide settings if there are any. Note that <filename>systemd-resolved</filename> assumes
|
||
DNSSEC is supported by DNS servers until it verifies that this is not the case. Thus, the reported
|
||
value may initially be true, until the first transactions are executed.</para>
|
||
|
||
<para>The <varname>DNSOverTLS</varname> boolean property reports whether DNS-over-TLS is enabled.
|
||
</para>
|
||
|
||
<para>The <varname>ResolvConfMode</varname> property exposes how <filename>/etc/resolv.conf</filename>
|
||
is managed on the host. Currently, the values <literal>uplink</literal>, <literal>stub</literal>,
|
||
<literal>static</literal> (these three correspond to the three different files
|
||
<filename>systemd-resolved.service</filename> provides), <literal>foreign</literal> (the file is
|
||
managed by admin or another service, <filename>systemd-resolved.service</filename> just consumes it),
|
||
<literal>missing</literal> (<filename>/etc/resolv.conf</filename> is missing).</para>
|
||
|
||
<para>The <varname>DNSStubListener</varname> property reports whether the stub listener on port 53 is
|
||
enabled. Possible values are <literal>yes</literal> (enabled), <literal>no</literal> (disabled),
|
||
<literal>udp</literal> (only the UDP listener is enabled), and <literal>tcp</literal> (only the TCP
|
||
listener is enabled).</para>
|
||
</refsect2>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Link Object</title>
|
||
|
||
<programlisting executable="systemd-resolved" node="/org/freedesktop/resolve1/link/_1" interface="org.freedesktop.resolve1.Link">
|
||
node /org/freedesktop/resolve1/link/_1 {
|
||
interface org.freedesktop.resolve1.Link {
|
||
methods:
|
||
SetDNS(in a(iay) addresses);
|
||
SetDNSEx(in a(iayqs) addresses);
|
||
SetDomains(in a(sb) domains);
|
||
SetDefaultRoute(in b enable);
|
||
SetLLMNR(in s mode);
|
||
SetMulticastDNS(in s mode);
|
||
SetDNSOverTLS(in s mode);
|
||
SetDNSSEC(in s mode);
|
||
SetDNSSECNegativeTrustAnchors(in as names);
|
||
Revert();
|
||
properties:
|
||
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
|
||
readonly t ScopesMask = ...;
|
||
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
|
||
readonly a(iay) DNS = [...];
|
||
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
|
||
readonly a(iayqs) DNSEx = [...];
|
||
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
|
||
readonly (iay) CurrentDNSServer = ...;
|
||
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
|
||
readonly (iayqs) CurrentDNSServerEx = ...;
|
||
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
|
||
readonly a(sb) Domains = [...];
|
||
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
|
||
readonly b DefaultRoute = ...;
|
||
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
|
||
readonly s LLMNR = '...';
|
||
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
|
||
readonly s MulticastDNS = '...';
|
||
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
|
||
readonly s DNSOverTLS = '...';
|
||
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
|
||
readonly s DNSSEC = '...';
|
||
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
|
||
readonly as DNSSECNegativeTrustAnchors = ['...', ...];
|
||
@org.freedesktop.DBus.Property.EmitsChangedSignal("false")
|
||
readonly b DNSSECSupported = ...;
|
||
};
|
||
interface org.freedesktop.DBus.Peer { ... };
|
||
interface org.freedesktop.DBus.Introspectable { ... };
|
||
interface org.freedesktop.DBus.Properties { ... };
|
||
};
|
||
</programlisting>
|
||
|
||
<!--property DNSSECNegativeTrustAnchors is not documented!-->
|
||
|
||
<!--Autogenerated cross-references for systemd.directives, do not edit-->
|
||
|
||
<variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.resolve1.Link"/>
|
||
|
||
<variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.resolve1.Link"/>
|
||
|
||
<variablelist class="dbus-method" generated="True" extra-ref="SetDNS()"/>
|
||
|
||
<variablelist class="dbus-method" generated="True" extra-ref="SetDNSEx()"/>
|
||
|
||
<variablelist class="dbus-method" generated="True" extra-ref="SetDomains()"/>
|
||
|
||
<variablelist class="dbus-method" generated="True" extra-ref="SetDefaultRoute()"/>
|
||
|
||
<variablelist class="dbus-method" generated="True" extra-ref="SetLLMNR()"/>
|
||
|
||
<variablelist class="dbus-method" generated="True" extra-ref="SetMulticastDNS()"/>
|
||
|
||
<variablelist class="dbus-method" generated="True" extra-ref="SetDNSOverTLS()"/>
|
||
|
||
<variablelist class="dbus-method" generated="True" extra-ref="SetDNSSEC()"/>
|
||
|
||
<variablelist class="dbus-method" generated="True" extra-ref="SetDNSSECNegativeTrustAnchors()"/>
|
||
|
||
<variablelist class="dbus-method" generated="True" extra-ref="Revert()"/>
|
||
|
||
<variablelist class="dbus-property" generated="True" extra-ref="ScopesMask"/>
|
||
|
||
<variablelist class="dbus-property" generated="True" extra-ref="DNS"/>
|
||
|
||
<variablelist class="dbus-property" generated="True" extra-ref="DNSEx"/>
|
||
|
||
<variablelist class="dbus-property" generated="True" extra-ref="CurrentDNSServer"/>
|
||
|
||
<variablelist class="dbus-property" generated="True" extra-ref="CurrentDNSServerEx"/>
|
||
|
||
<variablelist class="dbus-property" generated="True" extra-ref="Domains"/>
|
||
|
||
<variablelist class="dbus-property" generated="True" extra-ref="DefaultRoute"/>
|
||
|
||
<variablelist class="dbus-property" generated="True" extra-ref="LLMNR"/>
|
||
|
||
<variablelist class="dbus-property" generated="True" extra-ref="MulticastDNS"/>
|
||
|
||
<variablelist class="dbus-property" generated="True" extra-ref="DNSOverTLS"/>
|
||
|
||
<variablelist class="dbus-property" generated="True" extra-ref="DNSSEC"/>
|
||
|
||
<variablelist class="dbus-property" generated="True" extra-ref="DNSSECNegativeTrustAnchors"/>
|
||
|
||
<variablelist class="dbus-property" generated="True" extra-ref="DNSSECSupported"/>
|
||
|
||
<!--End of Autogenerated section-->
|
||
|
||
<para>For each Linux network interface a "Link" object is created which exposes per-link DNS
|
||
configuration and state. Use <function>GetLink()</function> on the Manager interface to retrieve the
|
||
object path for a link object given the network interface index (see above).</para>
|
||
|
||
<refsect2>
|
||
<title>Methods</title>
|
||
|
||
<para>The various methods exposed by the Link interface are equivalent to their similarly named
|
||
counterparts on the Manager interface. e.g. <function>SetDNS()</function> on the Link object maps to
|
||
<function>SetLinkDNS()</function> on the Manager object, the main difference being that the later
|
||
expects an interface index to be specified. Invoking the methods on the Manager interface has the
|
||
benefit of reducing roundtrips, as it is not necessary to first request the Link object path via
|
||
<function>GetLink()</function> before invoking the methods. The same relationship holds for
|
||
<function>SetDNSEx()</function>, <function>SetDomains()</function>,
|
||
<function>SetDefaultRoute()</function>, <function>SetLLMNR()</function>,
|
||
<function>SetMulticastDNS()</function>, <function>SetDNSOverTLS()</function>,
|
||
<function>SetDNSSEC()</function>, <function>SetDNSSECNegativeTrustAnchors()</function>, and
|
||
<function>Revert()</function>. For further details on these methods see the
|
||
<interfacename>Manager</interfacename> documentation above.</para>
|
||
</refsect2>
|
||
|
||
<refsect2>
|
||
<title>Properties</title>
|
||
|
||
<para><varname>ScopesMask</varname> defines which resolver scopes are currently active on this
|
||
interface. This 64-bit unsigned integer field is a bit mask consisting of a subset of the bits of the
|
||
flags parameter describe above. Specifically, it may have the DNS, LLMNR and MDNS bits (the latter in
|
||
IPv4 and IPv6 flavours) set. Each individual bit is set when the protocol applies to a specific
|
||
interface and is enabled for it. It is unset otherwise. Specifically, a multicast-capable interface in
|
||
the "UP" state with an IP address is suitable for LLMNR or MulticastDNS, and any interface that is UP and
|
||
has an IP address is suitable for DNS. Note the relationship of the bits exposed here with the LLMNR
|
||
and MulticastDNS properties also exposed on the Link interface. The latter expose what is *configured*
|
||
to be used on the interface, the former expose what is actually used on the interface, taking into
|
||
account the abilities of the interface.</para>
|
||
|
||
<para><varname>DNSSECSupported</varname> exposes a boolean field that indicates whether DNSSEC is
|
||
currently configured and in use on the interface. Note that if DNSSEC is enabled on an interface, it is
|
||
assumed available until it is detected that the configured server does not actually support it. Thus,
|
||
this property may initially report that DNSSEC is supported on an interface.</para>
|
||
|
||
<para><varname>DefaultRoute</varname> exposes a boolean field that indicates whether the interface will
|
||
be used as default route for name queries. See <function>SetLinkDefaultRoute()</function> above.</para>
|
||
|
||
<para>The other properties reflect the state of the various configuration settings for the link which
|
||
may be set with the various methods calls such as <function>SetDNS()</function> or
|
||
<function>SetLLMNR()</function>.</para>
|
||
</refsect2>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Common Errors</title>
|
||
|
||
<para>Many bus methods <filename>systemd-resolved</filename> exposes (in particular the resolver methods such
|
||
as <function>ResolveHostname()</function> on the <interfacename>Manager</interfacename> interface) may return
|
||
some of the following errors:</para>
|
||
|
||
<variablelist>
|
||
<varlistentry><term><constant>org.freedesktop.resolve1.NoNameServers</constant></term>
|
||
<listitem><para>No suitable DNS servers were found to resolve a request.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><constant>org.freedesktop.resolve1.InvalidReply</constant></term>
|
||
<listitem><para>A response from the selected DNS server was not understood.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><constant>org.freedesktop.resolve1.NoSuchRR</constant></term>
|
||
<listitem><para>The requested name exists, but there is no resource record of the requested type for
|
||
it. (This is the DNS NODATA case).</para></listitem></varlistentry>
|
||
|
||
<varlistentry><term><constant>org.freedesktop.resolve1.CNameLoop</constant></term>
|
||
<listitem><para>The look-up failed because a CNAME or DNAME loop was detected.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><constant>org.freedesktop.resolve1.Aborted</constant></term>
|
||
<listitem><para>The look-up was aborted because the selected protocol became unavailable while the
|
||
operation was ongoing.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><constant>org.freedesktop.resolve1.NoSuchService</constant></term>
|
||
<listitem><para>A service look-up was successful, but the SRV record reported that the service is not
|
||
available.</para></listitem></varlistentry>
|
||
|
||
<varlistentry><term><constant>org.freedesktop.resolve1.DnssecFailed</constant></term>
|
||
<listitem><para>The acquired response did not pass DNSSEC validation.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><constant>org.freedesktop.resolve1.NoTrustAnchor</constant></term>
|
||
<listitem><para>No chain of trust could be established for the response to a configured DNSSEC trust
|
||
anchor.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><constant>org.freedesktop.resolve1.ResourceRecordTypeUnsupported</constant></term>
|
||
<listitem><para>The requested resource record type is not supported on the selected DNS servers. This
|
||
error is generated for example when an RRSIG record is requested from a DNS server that does not
|
||
support DNSSEC.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><constant>org.freedesktop.resolve1.NoSuchLink</constant></term>
|
||
<listitem><para>No network interface with the specified network interface index exists.
|
||
</para></listitem></varlistentry>
|
||
|
||
<varlistentry><term><constant>org.freedesktop.resolve1.LinkBusy</constant></term>
|
||
<listitem><para>The requested configuration change could not be made because
|
||
<citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
|
||
already took possession of the interface and supplied configuration data for it.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><constant>org.freedesktop.resolve1.NetworkDown</constant></term>
|
||
<listitem><para>The requested look-up failed because the system is currently not connected to any
|
||
suitable network.</para></listitem></varlistentry>
|
||
|
||
<varlistentry><term><constant>org.freedesktop.resolve1.DnsError.NXDOMAIN</constant></term>
|
||
<term><constant>org.freedesktop.resolve1.DnsError.REFUSED</constant></term>
|
||
<term>...</term>
|
||
<listitem><para>The look-up failed with a DNS return code reporting a failure. The error names used as
|
||
suffixes here are defined in by IANA in
|
||
<ulink url="https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-6">DNS RCODEs</ulink>.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Examples</title>
|
||
|
||
<example>
|
||
<title>Introspect <interfacename>org.freedesktop.resolve1.Manager</interfacename> on the bus</title>
|
||
|
||
<programlisting>
|
||
$ gdbus introspect --system \
|
||
--dest org.freedesktop.resolve1 \
|
||
--object-path /org/freedesktop/resolve1
|
||
</programlisting>
|
||
</example>
|
||
|
||
<example>
|
||
<title>Introspect <interfacename>org.freedesktop.resolve1.Link</interfacename> on the bus</title>
|
||
|
||
<programlisting>
|
||
$ gdbus introspect --system \
|
||
--dest org.freedesktop.resolve1 \
|
||
--object-path /org/freedesktop/resolve1/link/_11
|
||
</programlisting>
|
||
</example>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Versioning</title>
|
||
|
||
<para>These D-Bus interfaces follow <ulink url="http://0pointer.de/blog/projects/versioning-dbus.html">
|
||
the usual interface versioning guidelines</ulink>.</para>
|
||
</refsect1>
|
||
</refentry>
|