1DNSSEC-TRUST-ANCHORS.D(5) dnssec-trust-anchors.d DNSSEC-TRUST-ANCHORS.D(5)
2
6 dnssec-trust-anchors.d, systemd.positive, systemd.negative - DNSSEC
7 trust anchor configuration files
8
10 /etc/dnssec-trust-anchors.d/*.positive
11 /run/dnssec-trust-anchors.d/*.positive
13 /usr/lib/dnssec-trust-anchors.d/*.positive
15 /etc/dnssec-trust-anchors.d/*.negative
17 /run/dnssec-trust-anchors.d/*.negative
19 /usr/lib/dnssec-trust-anchors.d/*.negative
21
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
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 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").
42 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
47 <consant>DS</consant> resource record is specified like in the
48 following example:
49 . IN DS 19036 8 2 49aac11d7b6f6446702e54a1607371607a1a41855200fd2ce1cdde32f24e8fb5
51 The first word specifies the domain, use "." for the root domain. The
53 domain may be specified with or without trailing dot, which is
54 considered equivalent. The second word must be "IN" the third word
55 "DS". The following words specify the key tag, signature algorithm,
56 digest algorithm, followed by the hex-encoded key fingerprint. See RFC
57 4034, Section 5[3] for details about the precise syntax and meaning of
58 these fields.
59 Alternatively, DNSKEY resource records may be used to define trust
61 anchors, like in the following example:
62 . IN DNSKEY 257 3 8 AwEAAagAIKlVZrpC6Ia7gEzahOR+9W29euxhJhVVLOyQbSEW0O8gcCjFFVQUTf6v58fLjwBd0YI0EzrAcQqBGCzh/RStIoO8g0NfnfL2MTJRkxoXbfDaUeVPQuYEhg37NZWAJQ9VnMVDxP/VHL496M/QZxkjf5/Efucp2gaDX6RS6CXpoY68LsvPVjR0ZSwzz1apAzvN9dlzEheX7ICJBBtuA6G3LQpzW5hOA2hzCTMjJPJ8LbqF6dsV6DoBQzgul0sGIcGOYl7OyQdXfZ57relSQageu+ipAdTTJ25AsRTAoub8ONGcLmqrAmRLKBP1dfwhYB4N7knNnulqQxA+Uk1ihz0=
64 The first word specifies the domain again, the second word must be
66 "IN", followed by "DNSKEY". The subsequent words encode the DNSKEY
67 flags, protocol and algorithm fields, followed by the key data encoded
68 in Base64. See RFC 4034, Section 2[4] for details about the precise
69 syntax and meaning of these fields.
70 If multiple DS or DNSKEY records are defined for the same domain
72 (possibly even in different trust anchor files), all keys are used and
73 are considered equivalent as base for DNSSEC proofs.
74 Note that systemd-resolved will automatically use a built-in trust
76 anchor key for the Internet root domain if no positive trust anchors
77 are defined for the root domain. In most cases it is hence unnecessary
78 to define an explicit key with trust anchor files. The built-in key is
79 disabled as soon as at least one trust anchor key for the root domain
80 is defined in trust anchor files.
81 It is generally recommended to encode trust anchors in DS resource
83 records, rather than DNSKEY resource records.
84 If a trust anchor specified via a DS record is found revoked it is
86 automatically removed from the trust anchor database for the runtime.
87 See RFC 5011[5] for details about revoked trust anchors. Note that
88 systemd-resolved will not update its trust anchor database from DNS
89 servers automatically. Instead, it is recommended to update the
90 resolver software or update the new trust anchor via adding in new
91 trust anchor files.
92 The current DNSSEC trust anchor for the Internet's root domain is
94 available at the IANA Trust Anchor and Keys[6] page.
95
97 Negative trust anchors define domains where DNSSEC validation shall be
98 turned off. Negative trust anchor files are found at the same location
99 as positive trust anchor files, and follow the same overriding rules.
100 They are text files with the .negative suffix. Empty lines and lines
101 whose first character is ";" are ignored. Each line specifies one
102 domain name which is the root of a DNS subtree where validation shall
103 be disabled. For example:
104 # Reverse IPv4 mappings
106 10.in-addr.arpa
107 16.172.in-addr.arpa
108 168.192.in-addr.arpa
109 ...
110 # Some custom domains
111 prod
112 stag
113 Negative trust anchors are useful to support private DNS subtrees that
115 are not referenced from the Internet DNS hierarchy, and not signed.
116 RFC 7646[7] for details on negative trust anchors.
118 If no negative trust anchor files are configured a built-in set of
120 well-known private DNS zone domains is used as negative trust anchors.
121 It is also possibly to define per-interface negative trust anchors
123 using the DNSSECNegativeTrustAnchors= setting in systemd.network(5)
124 files.
125
127 systemd(1), systemd-resolved.service(8), resolved.conf(5),
128 systemd.network(5)
129
131 1. RFC 4035, Section 4.4
132 https://tools.ietf.org/html/rfc4035#section-4.4
133 2. RFC 1035, Section 5
135 https://tools.ietf.org/html/rfc1035#section-5
136 3. RFC 4034, Section 5
138 https://tools.ietf.org/html/rfc4034#section-5
139 4. RFC 4034, Section 2
141 https://tools.ietf.org/html/rfc4034#section-2
142 5. RFC 5011
144 https://tools.ietf.org/html/rfc5011
145 6. IANA Trust Anchor and Keys
147 https://data.iana.org/root-anchors/root-anchors.xml
148 7. RFC 7646
150 https://tools.ietf.org/html/rfc7646
151systemd 249 DNSSEC-TRUST-ANCHORS.D(5)