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diff --git a/bin/delv/delv.rst b/bin/delv/delv.rst new file mode 100644 index 0000000..bf6cce1 --- /dev/null +++ b/bin/delv/delv.rst @@ -0,0 +1,364 @@ +.. Copyright (C) Internet Systems Consortium, Inc. ("ISC") +.. +.. SPDX-License-Identifier: MPL-2.0 +.. +.. This Source Code Form is subject to the terms of the Mozilla Public +.. License, v. 2.0. If a copy of the MPL was not distributed with this +.. file, you can obtain one at https://mozilla.org/MPL/2.0/. +.. +.. See the COPYRIGHT file distributed with this work for additional +.. information regarding copyright ownership. + +.. highlight: console + +.. iscman:: delv +.. program:: delv +.. _man_delv: + +delv - DNS lookup and validation utility +---------------------------------------- + +Synopsis +~~~~~~~~ + +:program:`delv` [@server] [ [**-4**] | [**-6**] ] [**-a** anchor-file] [**-b** address] [**-c** class] [**-d** level] [**-i**] [**-m**] [**-p** port#] [**-q** name] [**-t** type] [**-x** addr] [name] [type] [class] [queryopt...] + +:program:`delv` [**-h**] + +:program:`delv` [**-v**] + +:program:`delv` [queryopt...] [query...] + +Description +~~~~~~~~~~~ + +:program:`delv` is a tool for sending DNS queries and validating the results, +using the same internal resolver and validator logic as :iscman:`named`. + +:program:`delv` sends to a specified name server all queries needed to +fetch and validate the requested data; this includes the original +requested query, subsequent queries to follow CNAME or DNAME chains, +queries for DNSKEY, and DS records to establish a chain of trust for +DNSSEC validation. It does not perform iterative resolution, but +simulates the behavior of a name server configured for DNSSEC validating +and forwarding. + +By default, responses are validated using the built-in DNSSEC trust anchor +for the root zone ("."). Records returned by :program:`delv` are either fully +validated or were not signed. If validation fails, an explanation of the +failure is included in the output; the validation process can be traced +in detail. Because :program:`delv` does not rely on an external server to carry +out validation, it can be used to check the validity of DNS responses in +environments where local name servers may not be trustworthy. + +Unless it is told to query a specific name server, :program:`delv` tries +each of the servers listed in ``/etc/resolv.conf``. If no usable server +addresses are found, :program:`delv` sends queries to the localhost +addresses (127.0.0.1 for IPv4, ::1 for IPv6). + +When no command-line arguments or options are given, :program:`delv` +performs an NS query for "." (the root zone). + +Simple Usage +~~~~~~~~~~~~ + +A typical invocation of :program:`delv` looks like: + +:: + + delv @server name type + +where: + +.. option:: server + + is the name or IP address of the name server to query. This can be an + IPv4 address in dotted-decimal notation or an IPv6 address in + colon-delimited notation. When the supplied ``server`` argument is a + hostname, :program:`delv` resolves that name before querying that name + server (note, however, that this initial lookup is *not* validated by + DNSSEC). + + If no ``server`` argument is provided, :program:`delv` consults + ``/etc/resolv.conf``; if an address is found there, it queries the + name server at that address. If either of the :option:`-4` or :option:`-6` + options is in use, then only addresses for the corresponding + transport are tried. If no usable addresses are found, :program:`delv` + sends queries to the localhost addresses (127.0.0.1 for IPv4, ::1 + for IPv6). + +.. option:: name + + is the domain name to be looked up. + +.. option:: type + + indicates what type of query is required - ANY, A, MX, etc. + ``type`` can be any valid query type. If no ``type`` argument is + supplied, :program:`delv` performs a lookup for an A record. + +Options +~~~~~~~ + +.. option:: -a anchor-file + + This option specifies a file from which to read DNSSEC trust anchors. The default + is |bind_keys|, which is included with BIND 9 and contains one + or more trust anchors for the root zone ("."). + + Keys that do not match the root zone name are ignored. An alternate + key name can be specified using the :option:`+root` option. + + Note: When reading the trust anchor file, :program:`delv` treats ``trust-anchors``, + ``initial-key``, and ``static-key`` identically. That is, for a managed key, + it is the *initial* key that is trusted; :rfc:`5011` key management is not + supported. :program:`delv` does not consult the managed-keys database maintained by + :iscman:`named`, which means that if either of the keys in |bind_keys| is + revoked and rolled over, |bind_keys| must be updated to + use DNSSEC validation in :program:`delv`. + +.. option:: -b address + + This option sets the source IP address of the query to ``address``. This must be + a valid address on one of the host's network interfaces, or ``0.0.0.0``, + or ``::``. An optional source port may be specified by appending + ``#<port>`` + +.. option:: -c class + + This option sets the query class for the requested data. Currently, only class + "IN" is supported in :program:`delv` and any other value is ignored. + +.. option:: -d level + + This option sets the systemwide debug level to ``level``. The allowed range is + from 0 to 99. The default is 0 (no debugging). Debugging traces from + :program:`delv` become more verbose as the debug level increases. See the + :option:`+mtrace`, :option:`+rtrace`, and :option:`+vtrace` options below for + additional debugging details. + +.. option:: -h + + This option displays the :program:`delv` help usage output and exits. + +.. option:: -i + + This option sets insecure mode, which disables internal DNSSEC validation. (Note, + however, that this does not set the CD bit on upstream queries. If the + server being queried is performing DNSSEC validation, then it does + not return invalid data; this can cause :program:`delv` to time out. When it + is necessary to examine invalid data to debug a DNSSEC problem, use + :option:`dig +cd`.) + +.. option:: -m + + This option enables memory usage debugging. + +.. option:: -p port# + + This option specifies a destination port to use for queries, instead of the + standard DNS port number 53. This option is used with a name + server that has been configured to listen for queries on a + non-standard port number. + +.. option:: -q name + + This option sets the query name to ``name``. While the query name can be + specified without using the :option:`-q` option, it is sometimes necessary to + disambiguate names from types or classes (for example, when looking + up the name "ns", which could be misinterpreted as the type NS, or + "ch", which could be misinterpreted as class CH). + +.. option:: -t type + + This option sets the query type to ``type``, which can be any valid query type + supported in BIND 9 except for zone transfer types AXFR and IXFR. As + with :option:`-q`, this is useful to distinguish query-name types or classes + when they are ambiguous. It is sometimes necessary to disambiguate + names from types. + + The default query type is "A", unless the :option:`-x` option is supplied + to indicate a reverse lookup, in which case it is "PTR". + +.. option:: -v + + This option prints the :program:`delv` version and exits. + +.. option:: -x addr + + This option performs a reverse lookup, mapping an address to a name. ``addr`` + is an IPv4 address in dotted-decimal notation, or a colon-delimited + IPv6 address. When :option:`-x` is used, there is no need to provide the + ``name`` or ``type`` arguments; :program:`delv` automatically performs a + lookup for a name like ``11.12.13.10.in-addr.arpa`` and sets the + query type to PTR. IPv6 addresses are looked up using nibble format + under the IP6.ARPA domain. + +.. option:: -4 + + This option forces :program:`delv` to only use IPv4. + +.. option:: -6 + + This option forces :program:`delv` to only use IPv6. + +Query Options +~~~~~~~~~~~~~ + +:program:`delv` provides a number of query options which affect the way results +are displayed, and in some cases the way lookups are performed. + +Each query option is identified by a keyword preceded by a plus sign +(``+``). Some keywords set or reset an option. These may be preceded by +the string ``no`` to negate the meaning of that keyword. Other keywords +assign values to options like the timeout interval. They have the form +``+keyword=value``. The query options are: + +.. option:: +cdflag, +nocdflag + + This option controls whether to set the CD (checking disabled) bit in queries + sent by :program:`delv`. This may be useful when troubleshooting DNSSEC + problems from behind a validating resolver. A validating resolver + blocks invalid responses, making it difficult to retrieve them + for analysis. Setting the CD flag on queries causes the resolver + to return invalid responses, which :program:`delv` can then validate + internally and report the errors in detail. + +.. option:: +class, +noclass + + This option controls whether to display the CLASS when printing a record. The + default is to display the CLASS. + +.. option:: +ttl, +nottl + + This option controls whether to display the TTL when printing a record. The + default is to display the TTL. + +.. option:: +rtrace, +nortrace + + This option toggles resolver fetch logging. This reports the name and type of each + query sent by :program:`delv` in the process of carrying out the resolution + and validation process, including the original query + and all subsequent queries to follow CNAMEs and to establish a chain + of trust for DNSSEC validation. + + This is equivalent to setting the debug level to 1 in the "resolver" + logging category. Setting the systemwide debug level to 1 using the + :option:`-d` option produces the same output, but affects other + logging categories as well. + +.. option:: +mtrace, +nomtrace + + This option toggles message logging. This produces a detailed dump of the + responses received by :program:`delv` in the process of carrying out the + resolution and validation process. + + This is equivalent to setting the debug level to 10 for the "packets" + module of the "resolver" logging category. Setting the systemwide + debug level to 10 using the :option:`-d` option produces the same + output, but affects other logging categories as well. + +.. option:: +vtrace, +novtrace + + This option toggles validation logging. This shows the internal process of the + validator as it determines whether an answer is validly signed, + unsigned, or invalid. + + This is equivalent to setting the debug level to 3 for the + "validator" module of the "dnssec" logging category. Setting the + systemwide debug level to 3 using the :option:`-d` option produces the + same output, but affects other logging categories as well. + +.. option:: +short, +noshort + + This option toggles between verbose and terse answers. The default is to print the answer in a + verbose form. + +.. option:: +comments, +nocomments + + This option toggles the display of comment lines in the output. The default is to + print comments. + +.. option:: +rrcomments, +norrcomments + + This option toggles the display of per-record comments in the output (for example, + human-readable key information about DNSKEY records). The default is + to print per-record comments. + +.. option:: +crypto, +nocrypto + + This option toggles the display of cryptographic fields in DNSSEC records. The + contents of these fields are unnecessary to debug most DNSSEC + validation failures and removing them makes it easier to see the + common failures. The default is to display the fields. When omitted, + they are replaced by the string ``[omitted]`` or, in the DNSKEY case, the + key ID is displayed as the replacement, e.g. ``[ key id = value ]``. + +.. option:: +trust, +notrust + + This option controls whether to display the trust level when printing a record. + The default is to display the trust level. + +.. option:: +split[=W], +nosplit + + This option splits long hex- or base64-formatted fields in resource records into + chunks of ``W`` characters (where ``W`` is rounded up to the nearest + multiple of 4). ``+nosplit`` or ``+split=0`` causes fields not to be + split at all. The default is 56 characters, or 44 characters when + multiline mode is active. + +.. option:: +all, +noall + + This option sets or clears the display options :option:`+comments`, + :option:`+rrcomments`, and :option:`+trust` as a group. + +.. option:: +multiline, +nomultiline + + This option prints long records (such as RRSIG, DNSKEY, and SOA records) in a + verbose multi-line format with human-readable comments. The default + is to print each record on a single line, to facilitate machine + parsing of the :program:`delv` output. + +.. option:: +dnssec, +nodnssec + + This option indicates whether to display RRSIG records in the :program:`delv` output. + The default is to do so. Note that (unlike in :iscman:`dig`) this does + *not* control whether to request DNSSEC records or to + validate them. DNSSEC records are always requested, and validation + always occurs unless suppressed by the use of :option:`-i` or + :option:`+noroot`. + +.. option:: +root[=ROOT], +noroot + + This option indicates whether to perform conventional DNSSEC validation, and if so, + specifies the name of a trust anchor. The default is to validate using a + trust anchor of "." (the root zone), for which there is a built-in key. If + specifying a different trust anchor, then :option:`-a` must be used to specify a + file containing the key. + +.. option:: +tcp, +notcp + + This option controls whether to use TCP when sending queries. The default is to + use UDP unless a truncated response has been received. + +.. option:: +unknownformat, +nounknownformat + + This option prints all RDATA in unknown RR-type presentation format (:rfc:`3597`). + The default is to print RDATA for known types in the type's + presentation format. + +.. option:: +yaml, +noyaml + + This option prints response data in YAML format. + +Files +~~~~~ + +|bind_keys| + +``/etc/resolv.conf`` + +See Also +~~~~~~~~ + +:iscman:`dig(1) <dig>`, :iscman:`named(8) <named>`, :rfc:`4034`, :rfc:`4035`, :rfc:`4431`, :rfc:`5074`, :rfc:`5155`. |