[thirdparty/systemd.git] / man / dnssec-trust-anchors.d.xml

<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<!--
  SPDX-License-Identifier: LGPL-2.1+
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<refentry id="dnssec-trust-anchors.d" conditional='ENABLE_RESOLVE'
    xmlns:xi="http://www.w3.org/2001/XInclude">
  <refentryinfo>
    <title>dnssec-trust-anchors.d</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>dnssec-trust-anchors.d</refentrytitle>
    <manvolnum>5</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>dnssec-trust-anchors.d</refname>
    <refname>systemd.positive</refname>
    <refname>systemd.negative</refname>
    <refpurpose>DNSSEC trust anchor configuration files</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <para><filename>/etc/dnssec-trust-anchors.d/*.positive</filename></para>
    <para><filename>/run/dnssec-trust-anchors.d/*.positive</filename></para>
    <para><filename>/usr/lib/dnssec-trust-anchors.d/*.positive</filename></para>
    <para><filename>/etc/dnssec-trust-anchors.d/*.negative</filename></para>
    <para><filename>/run/dnssec-trust-anchors.d/*.negative</filename></para>
    <para><filename>/usr/lib/dnssec-trust-anchors.d/*.negative</filename></para>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>The DNSSEC trust anchor configuration files define positive
    and negative trust anchors
    <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    bases DNSSEC integrity proofs on.</para>
  </refsect1>

  <refsect1>
    <title>Positive Trust Anchors</title>

    <para>Positive trust anchor configuration files contain DNSKEY and
    DS resource record definitions to use as base for DNSSEC integrity
    proofs. See <ulink
    url="https://tools.ietf.org/html/rfc4035#section-4.4">RFC 4035,
    Section 4.4</ulink> for more information about DNSSEC trust
    anchors.</para>

    <para>Positive trust anchors are read from files with the suffix
    <filename>.positive</filename> located in
    <filename>/etc/dnssec-trust-anchors.d/</filename>,
    <filename>/run/dnssec-trust-anchors.d/</filename> and
    <filename>/usr/lib/dnssec-trust-anchors.d/</filename>. These
    directories are searched in the specified order, and a trust
    anchor file of the same name in an earlier path overrides a trust
    anchor files in a later path. To disable a trust anchor file
    shipped in <filename>/usr/lib/dnssec-trust-anchors.d/</filename>
    it is sufficient to provide an identically-named file in
    <filename>/etc/dnssec-trust-anchors.d/</filename> or
    <filename>/run/dnssec-trust-anchors.d/</filename> that is either
    empty or a symlink to <filename>/dev/null</filename> ("masked").</para>

    <para>Positive trust anchor files are simple text files resembling
    DNS zone files, as documented in <ulink
    url="https://tools.ietf.org/html/rfc1035#section-5">RFC 1035, Section
    5</ulink>. One DS or DNSKEY resource record may be listed per
    line. Empty lines and lines starting with a semicolon
    (<literal>;</literal>) are ignored and considered comments. A DS
    resource record is specified like in the following example:</para>

    <programlisting>. IN DS 19036 8 2 49aac11d7b6f6446702e54a1607371607a1a41855200fd2ce1cdde32f24e8fb5</programlisting>

    <para>The first word specifies the domain, use
    <literal>.</literal> for the root domain. The domain may be
    specified with or without trailing dot, which is considered
    equivalent. The second word must be <literal>IN</literal> the
    third word <literal>DS</literal>. The following words specify the
    key tag, signature algorithm, digest algorithm, followed by the
    hex-encoded key fingerprint. See <ulink
    url="https://tools.ietf.org/html/rfc4034#section-5">RFC 4034,
    Section 5</ulink> for details about the precise syntax and meaning
    of these fields.</para>

    <para>Alternatively, DNSKEY resource records may be used to define
    trust anchors, like in the following example:</para>

    <programlisting>. IN DNSKEY 257 3 8 AwEAAagAIKlVZrpC6Ia7gEzahOR+9W29euxhJhVVLOyQbSEW0O8gcCjFFVQUTf6v58fLjwBd0YI0EzrAcQqBGCzh/RStIoO8g0NfnfL2MTJRkxoXbfDaUeVPQuYEhg37NZWAJQ9VnMVDxP/VHL496M/QZxkjf5/Efucp2gaDX6RS6CXpoY68LsvPVjR0ZSwzz1apAzvN9dlzEheX7ICJBBtuA6G3LQpzW5hOA2hzCTMjJPJ8LbqF6dsV6DoBQzgul0sGIcGOYl7OyQdXfZ57relSQageu+ipAdTTJ25AsRTAoub8ONGcLmqrAmRLKBP1dfwhYB4N7knNnulqQxA+Uk1ihz0=</programlisting>

    <para>The first word specifies the domain again, the second word
    must be <literal>IN</literal>, followed by
    <literal>DNSKEY</literal>. The subsequent words encode the DNSKEY
    flags, protocol and algorithm fields, followed by the key data
    encoded in Base64. See <ulink
    url="https://tools.ietf.org/html/rfc4034#section-2">RFC 4034,
    Section 2</ulink> for details about the precise syntax and meaning
    of these fields.</para>

    <para>If multiple DS or DNSKEY records are defined for the same
    domain (possibly even in different trust anchor files), all keys
    are used and are considered equivalent as base for DNSSEC
    proofs.</para>

    <para>Note that <filename>systemd-resolved</filename> will
    automatically use a built-in trust anchor key for the Internet
    root domain if no positive trust anchors are defined for the root
    domain. In most cases it is hence unnecessary to define an
    explicit key with trust anchor files. The built-in key is disabled
    as soon as at least one trust anchor key for the root domain is
    defined in trust anchor files.</para>

    <para>It is generally recommended to encode trust anchors in DS
    resource records, rather than DNSKEY resource records.</para>

    <para>If a trust anchor specified via a DS record is found revoked
    it is automatically removed from the trust anchor database for the
    runtime. See <ulink url="https://tools.ietf.org/html/rfc5011">RFC
    5011</ulink> for details about revoked trust anchors. Note that
    <filename>systemd-resolved</filename> will not update its trust
    anchor database from DNS servers automatically. Instead, it is
    recommended to update the resolver software or update the new
    trust anchor via adding in new trust anchor files.</para>

    <para>The current DNSSEC trust anchor for the Internet's root
    domain is available at the <ulink
    url="https://data.iana.org/root-anchors/root-anchors.xml">IANA
    Trust Anchor and Keys</ulink> page.</para>
  </refsect1>

  <refsect1>
    <title>Negative Trust Anchors</title>

    <para>Negative trust anchors define domains where DNSSEC validation shall be turned
    off. Negative trust anchor files are found at the same location as positive trust anchor files,
    and follow the same overriding rules. They are text files with the
    <filename>.negative</filename> suffix. Empty lines and lines whose first character is
    <literal>;</literal> are ignored. Each line specifies one domain name which is the root of a DNS
    subtree where validation shall be disabled.</para>

    <para>Negative trust anchors are useful to support private DNS
    subtrees that are not referenced from the Internet DNS hierarchy,
    and not signed.</para>

    <para><ulink url="https://tools.ietf.org/html/rfc7646">RFC
    7646</ulink> for details on negative trust anchors.</para>

    <para>If no negative trust anchor files are configured a built-in
    set of well-known private DNS zone domains is used as negative
    trust anchors.</para>

    <para>It is also possibly to define per-interface negative trust
    anchors using the <varname>DNSSECNegativeTrustAnchors=</varname>
    setting in
    <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
    files.</para>
  </refsect1>

  <refsect1>
      <title>See Also</title>
      <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>resolved.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
      </para>
  </refsect1>

</refentry>
Commit	Line	Data
514094f9	1	<?xml version='1.0'?>
b5a8703f LP	2	<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
	3	"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
	4
	5	<!--
572eb058	6	SPDX-License-Identifier: LGPL-2.1+
b5a8703f LP	7	-->
b5a8703f LP	8
1ec57f33	9	<refentry id="dnssec-trust-anchors.d" conditional='ENABLE_RESOLVE'
b5a8703f LP	10	xmlns:xi="http://www.w3.org/2001/XInclude">
	11	<refentryinfo>
	12	<title>dnssec-trust-anchors.d</title>
	13	<productname>systemd</productname>
b5a8703f LP	14	</refentryinfo>
	15
	16	<refmeta>
	17	<refentrytitle>dnssec-trust-anchors.d</refentrytitle>
	18	<manvolnum>5</manvolnum>
	19	</refmeta>
	20
	21	<refnamediv>
	22	<refname>dnssec-trust-anchors.d</refname>
	23	<refname>systemd.positive</refname>
	24	<refname>systemd.negative</refname>
	25	<refpurpose>DNSSEC trust anchor configuration files</refpurpose>
	26	</refnamediv>
	27
	28	<refsynopsisdiv>
	29	<para><filename>/etc/dnssec-trust-anchors.d/*.positive</filename></para>
	30	<para><filename>/run/dnssec-trust-anchors.d/*.positive</filename></para>
	31	<para><filename>/usr/lib/dnssec-trust-anchors.d/*.positive</filename></para>
	32	<para><filename>/etc/dnssec-trust-anchors.d/*.negative</filename></para>
	33	<para><filename>/run/dnssec-trust-anchors.d/*.negative</filename></para>
	34	<para><filename>/usr/lib/dnssec-trust-anchors.d/*.negative</filename></para>
	35	</refsynopsisdiv>
	36
	37	<refsect1>
	38	<title>Description</title>
	39
	40	<para>The DNSSEC trust anchor configuration files define positive
	41	and negative trust anchors
	42	<citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
	43	bases DNSSEC integrity proofs on.</para>
	44	</refsect1>
	45
	46	<refsect1>
	47	<title>Positive Trust Anchors</title>
	48
	49	<para>Positive trust anchor configuration files contain DNSKEY and
	50	DS resource record definitions to use as base for DNSSEC integrity
	51	proofs. See <ulink
	52	url="https://tools.ietf.org/html/rfc4035#section-4.4">RFC 4035,
	53	Section 4.4</ulink> for more information about DNSSEC trust
	54	anchors.</para>
	55
	56	<para>Positive trust anchors are read from files with the suffix
	57	<filename>.positive</filename> located in
	58	<filename>/etc/dnssec-trust-anchors.d/</filename>,
	59	<filename>/run/dnssec-trust-anchors.d/</filename> and
	60	<filename>/usr/lib/dnssec-trust-anchors.d/</filename>. These
	61	directories are searched in the specified order, and a trust
	62	anchor file of the same name in an earlier path overrides a trust
	63	anchor files in a later path. To disable a trust anchor file
	64	shipped in <filename>/usr/lib/dnssec-trust-anchors.d/</filename>
	65	it is sufficient to provide an identically-named file in
	66	<filename>/etc/dnssec-trust-anchors.d/</filename> or
	67	<filename>/run/dnssec-trust-anchors.d/</filename> that is either
	68	empty or a symlink to <filename>/dev/null</filename> ("masked").</para>
	69
	70	<para>Positive trust anchor files are simple text files resembling
	71	DNS zone files, as documented in <ulink
	72	url="https://tools.ietf.org/html/rfc1035#section-5">RFC 1035, Section
	73	5</ulink>. One DS or DNSKEY resource record may be listed per
	74	line. Empty lines and lines starting with a semicolon
	75	(<literal>;</literal>) are ignored and considered comments. A DS
	76	resource record is specified like in the following example:</para>
	77
78	<programlisting>. IN DS 19036 8 2 49aac11d7b6f6446702e54a1607371607a1a41855200fd2ce1cdde32f24e8fb5</programlisting>
79
80	<para>The first word specifies the domain, use
81	<literal>.</literal> for the root domain. The domain may be
82	specified with or without trailing dot, which is considered
83	equivalent. The second word must be <literal>IN</literal> the
84	third word <literal>DS</literal>. The following words specify the
85	key tag, signature algorithm, digest algorithm, followed by the
86	hex-encoded key fingerprint. See <ulink
87	url="https://tools.ietf.org/html/rfc4034#section-5">RFC 4034,
88	Section 5</ulink> for details about the precise syntax and meaning
89	of these fields.</para>
90
91	<para>Alternatively, DNSKEY resource records may be used to define
92	trust anchors, like in the following example:</para>
93
94	<programlisting>. IN DNSKEY 257 3 8 AwEAAagAIKlVZrpC6Ia7gEzahOR+9W29euxhJhVVLOyQbSEW0O8gcCjFFVQUTf6v58fLjwBd0YI0EzrAcQqBGCzh/RStIoO8g0NfnfL2MTJRkxoXbfDaUeVPQuYEhg37NZWAJQ9VnMVDxP/VHL496M/QZxkjf5/Efucp2gaDX6RS6CXpoY68LsvPVjR0ZSwzz1apAzvN9dlzEheX7ICJBBtuA6G3LQpzW5hOA2hzCTMjJPJ8LbqF6dsV6DoBQzgul0sGIcGOYl7OyQdXfZ57relSQageu+ipAdTTJ25AsRTAoub8ONGcLmqrAmRLKBP1dfwhYB4N7knNnulqQxA+Uk1ihz0=</programlisting>
95
96	<para>The first word specifies the domain again, the second word
97	must be <literal>IN</literal>, followed by
98	<literal>DNSKEY</literal>. The subsequent words encode the DNSKEY
99	flags, protocol and algorithm fields, followed by the key data
b8e1d4d1	100	encoded in Base64. See <ulink
b5a8703f LP	101	url="https://tools.ietf.org/html/rfc4034#section-2">RFC 4034,
	102	Section 2</ulink> for details about the precise syntax and meaning
	103	of these fields.</para>
	104
	105	<para>If multiple DS or DNSKEY records are defined for the same
	106	domain (possibly even in different trust anchor files), all keys
	107	are used and are considered equivalent as base for DNSSEC
	108	proofs.</para>
	109
	110	<para>Note that <filename>systemd-resolved</filename> will
	111	automatically use a built-in trust anchor key for the Internet
	112	root domain if no positive trust anchors are defined for the root
	113	domain. In most cases it is hence unnecessary to define an
	114	explicit key with trust anchor files. The built-in key is disabled
	115	as soon as at least one trust anchor key for the root domain is
	116	defined in trust anchor files.</para>
	117
	118	<para>It is generally recommended to encode trust anchors in DS
	119	resource records, rather than DNSKEY resource records.</para>
	120
	121	<para>If a trust anchor specified via a DS record is found revoked
	122	it is automatically removed from the trust anchor database for the
	123	runtime. See <ulink url="https://tools.ietf.org/html/rfc5011">RFC
	124	5011</ulink> for details about revoked trust anchors. Note that
	125	<filename>systemd-resolved</filename> will not update its trust
	126	anchor database from DNS servers automatically. Instead, it is
	127	recommended to update the resolver software or update the new
	128	trust anchor via adding in new trust anchor files.</para>
	129
	130	<para>The current DNSSEC trust anchor for the Internet's root
b8e1d4d1	131	domain is available at the <ulink
b5a8703f LP	132	url="https://data.iana.org/root-anchors/root-anchors.xml">IANA
	133	Trust Anchor and Keys</ulink> page.</para>
	134	</refsect1>
	135
	136	<refsect1>
	137	<title>Negative Trust Anchors</title>
	138
e788ef48 ZJS	139	<para>Negative trust anchors define domains where DNSSEC validation shall be turned
	140	off. Negative trust anchor files are found at the same location as positive trust anchor files,
	141	and follow the same overriding rules. They are text files with the
	142	<filename>.negative</filename> suffix. Empty lines and lines whose first character is
	143	<literal>;</literal> are ignored. Each line specifies one domain name which is the root of a DNS
	144	subtree where validation shall be disabled.</para>
b5a8703f LP	145
	146	<para>Negative trust anchors are useful to support private DNS
	147	subtrees that are not referenced from the Internet DNS hierarchy,
	148	and not signed.</para>
	149
	150	<para><ulink url="https://tools.ietf.org/html/rfc7646">RFC
	151	7646</ulink> for details on negative trust anchors.</para>
30c77809 LP	152
	153	<para>If no negative trust anchor files are configured a built-in
	154	set of well-known private DNS zone domains is used as negative
	155	trust anchors.</para>
8a516214 LP	156
	157	<para>It is also possibly to define per-interface negative trust
	158	anchors using the <varname>DNSSECNegativeTrustAnchors=</varname>
	159	setting in
	160	<citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
	161	files.</para>
b5a8703f LP	162	</refsect1>
	163
	164	<refsect1>
	165	<title>See Also</title>
	166	<para>
	167	<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
	168	<citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
8a516214 LP	169	<citerefentry><refentrytitle>resolved.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
8a516214 LP	170	<citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
b5a8703f LP	171	</para>
	172	</refsect1>
	173
	174	</refentry>