1DNSSEC-TRUST-ANCHORS.D(5)   dnssec-trust-anchors.d   DNSSEC-TRUST-ANCHORS.D(5)
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NAME

6       dnssec-trust-anchors.d, systemd.positive, systemd.negative - DNSSEC
7       trust anchor configuration files
8

SYNOPSIS

10       /etc/dnssec-trust-anchors.d/*.positive
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12       /run/dnssec-trust-anchors.d/*.positive
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14       /usr/lib/dnssec-trust-anchors.d/*.positive
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16       /etc/dnssec-trust-anchors.d/*.negative
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18       /run/dnssec-trust-anchors.d/*.negative
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20       /usr/lib/dnssec-trust-anchors.d/*.negative
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DESCRIPTION

23       The DNSSEC trust anchor configuration files define positive and
24       negative trust anchors systemd-resolved.service(8) bases DNSSEC
25       integrity proofs on.
26

POSITIVE TRUST ANCHORS

28       Positive trust anchor configuration files contain DNSKEY and DS
29       resource record definitions to use as base for DNSSEC integrity proofs.
30       See RFC 4035, Section 4.4[1] for more information about DNSSEC trust
31       anchors.
32
33       Positive trust anchors are read from files with the suffix .positive
34       located in /etc/dnssec-trust-anchors.d/, /run/dnssec-trust-anchors.d/
35       and /usr/lib/dnssec-trust-anchors.d/. These directories are searched in
36       the specified order, and a trust anchor file of the same name in an
37       earlier path overrides a trust anchor files in a later path. To disable
38       a trust anchor file shipped in /usr/lib/dnssec-trust-anchors.d/ it is
39       sufficient to provide an identically-named file in
40       /etc/dnssec-trust-anchors.d/ or /run/dnssec-trust-anchors.d/ that is
41       either empty or a symlink to /dev/null ("masked").
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43       Positive trust anchor files are simple text files resembling DNS zone
44       files, as documented in RFC 1035, Section 5[2]. One DS or DNSKEY
45       resource record may be listed per line. Empty lines and lines starting
46       with "#" or ";" are ignored, which may be used for commenting. A DS
47       resource record is specified like in the following example:
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49           . IN DS 19036 8 2 49aac11d7b6f6446702e54a1607371607a1a41855200fd2ce1cdde32f24e8fb5
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51       The first word specifies the domain, use "."  for the root domain. The
52       domain may be specified with or without trailing dot, which is
53       considered equivalent. The second word must be "IN" the third word
54       "DS". The following words specify the key tag, signature algorithm,
55       digest algorithm, followed by the hex-encoded key fingerprint. See RFC
56       4034, Section 5[3] for details about the precise syntax and meaning of
57       these fields.
58
59       Alternatively, DNSKEY resource records may be used to define trust
60       anchors, like in the following example:
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62           . IN DNSKEY 257 3 8 AwEAAagAIKlVZrpC6Ia7gEzahOR+9W29euxhJhVVLOyQbSEW0O8gcCjFFVQUTf6v58fLjwBd0YI0EzrAcQqBGCzh/RStIoO8g0NfnfL2MTJRkxoXbfDaUeVPQuYEhg37NZWAJQ9VnMVDxP/VHL496M/QZxkjf5/Efucp2gaDX6RS6CXpoY68LsvPVjR0ZSwzz1apAzvN9dlzEheX7ICJBBtuA6G3LQpzW5hOA2hzCTMjJPJ8LbqF6dsV6DoBQzgul0sGIcGOYl7OyQdXfZ57relSQageu+ipAdTTJ25AsRTAoub8ONGcLmqrAmRLKBP1dfwhYB4N7knNnulqQxA+Uk1ihz0=
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64       The first word specifies the domain again, the second word must be
65       "IN", followed by "DNSKEY". The subsequent words encode the DNSKEY
66       flags, protocol and algorithm fields, followed by the key data encoded
67       in Base64. See RFC 4034, Section 2[4] for details about the precise
68       syntax and meaning of these fields.
69
70       If multiple DS or DNSKEY records are defined for the same domain
71       (possibly even in different trust anchor files), all keys are used and
72       are considered equivalent as base for DNSSEC proofs.
73
74       Note that systemd-resolved will automatically use a built-in trust
75       anchor key for the Internet root domain if no positive trust anchors
76       are defined for the root domain. In most cases it is hence unnecessary
77       to define an explicit key with trust anchor files. The built-in key is
78       disabled as soon as at least one trust anchor key for the root domain
79       is defined in trust anchor files.
80
81       It is generally recommended to encode trust anchors in DS resource
82       records, rather than DNSKEY resource records.
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84       If a trust anchor specified via a DS record is found revoked it is
85       automatically removed from the trust anchor database for the runtime.
86       See RFC 5011[5] for details about revoked trust anchors. Note that
87       systemd-resolved will not update its trust anchor database from DNS
88       servers automatically. Instead, it is recommended to update the
89       resolver software or update the new trust anchor via adding in new
90       trust anchor files.
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92       The current DNSSEC trust anchor for the Internet's root domain is
93       available at the IANA Trust Anchor and Keys[6] page.
94

NEGATIVE TRUST ANCHORS

96       Negative trust anchors define domains where DNSSEC validation shall be
97       turned off. Negative trust anchor files are found at the same location
98       as positive trust anchor files, and follow the same overriding rules.
99       They are text files with the .negative suffix. Empty lines and lines
100       whose first character is ";" are ignored. Each line specifies one
101       domain name which is the root of a DNS subtree where validation shall
102       be disabled. For example:
103
104           # Reverse IPv4 mappings
105           10.in-addr.arpa
106           16.172.in-addr.arpa
107           168.192.in-addr.arpa
108           ...
109           # Some custom domains
110           prod
111           stag
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113       Negative trust anchors are useful to support private DNS subtrees that
114       are not referenced from the Internet DNS hierarchy, and not signed.
115
116       RFC 7646[7] for details on negative trust anchors.
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118       If no negative trust anchor files are configured a built-in set of
119       well-known private DNS zone domains is used as negative trust anchors.
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121       It is also possibly to define per-interface negative trust anchors
122       using the DNSSECNegativeTrustAnchors= setting in systemd.network(5)
123       files.
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SEE ALSO

126       systemd(1), systemd-resolved.service(8), resolved.conf(5),
127       systemd.network(5)
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NOTES

130        1. RFC 4035, Section 4.4
131           https://tools.ietf.org/html/rfc4035#section-4.4
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133        2. RFC 1035, Section 5
134           https://tools.ietf.org/html/rfc1035#section-5
135
136        3. RFC 4034, Section 5
137           https://tools.ietf.org/html/rfc4034#section-5
138
139        4. RFC 4034, Section 2
140           https://tools.ietf.org/html/rfc4034#section-2
141
142        5. RFC 5011
143           https://tools.ietf.org/html/rfc5011
144
145        6. IANA Trust Anchor and Keys
146           https://data.iana.org/root-anchors/root-anchors.xml
147
148        7. RFC 7646
149           https://tools.ietf.org/html/rfc7646
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153systemd 254                                          DNSSEC-TRUST-ANCHORS.D(5)
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