SEARCH
NEW RPMS
DIRECTORIES
ABOUT
FAQ
VARIOUS
BLOG
DONATE


YUM REPOSITORY

 
 

MAN page from Scientific Linux 7 bind-utils-9.11.4-26.P2.el7_9.5.x86_64.rpm

DELV

Section: BIND9 (1)
Updated: 2014-04-23
Index 

NAME

delv - DNS lookup and validation utility 

SYNOPSIS

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...]
delv [-h]
delv [-v]
delv [queryopt...] [query...]
 

DESCRIPTION

delv

is a tool for sending DNS queries and validating the results, using the same internal resolver and validator logic asnamed.

delvwill send 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, and queries for DNSKEY, DS and DLV 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 built-in DNSSEC trust anchor for the root zone ("."). Records returned bydelvare 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. Becausedelvdoes 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,delvwill try each of the servers listed in/etc/resolv.conf. If no usable server addresses are found,delvwill send queries to the localhost addresses (127.0.0.1 for IPv4, ::1 for IPv6).

When no command line arguments or options are given,delvwill perform an NS query for "." (the root zone). 

SIMPLE USAGE

A typical invocation ofdelvlooks like:

 delv @server name type 

where:

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 suppliedserverargument is a hostname,delvresolves that name before querying that name server (note, however, that this initial lookup isnotvalidated by DNSSEC).

If noserverargument is provided,delvconsults/etc/resolv.conf; if an address is found there, it queries the name server at that address. If either of the-4or-6options are in use, then only addresses for the corresponding transport will be tried. If no usable addresses are found,delvwill send queries to the localhost addresses (127.0.0.1 for IPv4, ::1 for IPv6).

name

is the domain name to be looked up.

type

indicates what type of query is required --- ANY, A, MX, etc.typecan be any valid query type. If notypeargument is supplied,delvwill perform a lookup for an A record.
 

OPTIONS

-a anchor-file

Specifies a file from which to read DNSSEC trust anchors. The default is/etc/bind.keys, which is included withBIND9 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+root=NAMEoptions. DNSSEC Lookaside Validation can also be turned on by using the+dlv=NAMEto specify the name of a zone containing DLV records.

Note: When reading the trust anchor file,delvtreatsmanaged-keysstatements andtrusted-keysstatements identically. That is, for a managed key, it is theinitialkey that is trusted; RFC 5011 key management is not supported.delvwill not consult the managed-keys database maintained bynamed. This means that if either of the keys in/etc/bind.keysis revoked and rolled over, it will be necessary to update/etc/bind.keysto use DNSSEC validation indelv.

-b address

Sets the source IP address of the query toaddress. 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>"

-c class

Sets the query class for the requested data. Currently, only class "IN" is supported indelvand any other value is ignored.

-d level

Set the systemwide debug level tolevel. The allowed range is from 0 to 99. The default is 0 (no debugging). Debugging traces fromdelvbecome more verbose as the debug level increases. See the+mtrace,+rtrace, and+vtraceoptions below for additional debugging details.

-h

Display thedelvhelp usage output and exit.

-i

Insecure mode. This disables internal DNSSEC validation. (Note, however, this does not set the CD bit on upstream queries. If the server being queried is performing DNSSEC validation, then it will not return invalid data; this can causedelvto time out. When it is necessary to examine invalid data to debug a DNSSEC problem, usedig +cd.)

-m

Enables memory usage debugging.

-p port#

Specifies a destination port to use for queries instead of the standard DNS port number 53. This option would be used with a name server that has been configured to listen for queries on a non-standard port number.

-q name

Sets the query name toname. While the query name can be specified without using the-q, 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).

-t type

Sets the query type totype, which can be any valid query type supported in BIND 9 except for zone transfer types AXFR and IXFR. As with-q, this is useful to distinguish query name type or class when they are ambiguous. it is sometimes necessary to disambiguate names from types.

The default query type is "A", unless the-xoption is supplied to indicate a reverse lookup, in which case it is "PTR".

-v

Print thedelvversion and exit.

-x addr

Performs a reverse lookup, mapping an addresses to a name.addris an IPv4 address in dotted-decimal notation, or a colon-delimited IPv6 address. When-xis used, there is no need to provide thenameortypearguments.delvautomatically performs a lookup for a name like11.12.13.10.in-addr.arpaand sets the query type to PTR. IPv6 addresses are looked up using nibble format under the IP6.ARPA domain.

-4

Forcesdelvto only use IPv4.

-6

Forcesdelvto only use IPv6.
 

QUERY OPTIONS

delvprovides 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 stringnoto 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:

+[no]cdflag

Controls whether to set the CD (checking disabled) bit in queries sent bydelv. This may be useful when troubleshooting DNSSEC problems from behind a validating resolver. A validating resolver will block invalid responses, making it difficult to retrieve them for analysis. Setting the CD flag on queries will cause the resolver to return invalid responses, whichdelvcan then validate internally and report the errors in detail.

+[no]class

Controls whether to display the CLASS when printing a record. The default is to display the CLASS.

+[no]ttl

Controls whether to display the TTL when printing a record. The default is to display the TTL.

+[no]rtrace

Toggle resolver fetch logging. This reports the name and type of each query sent bydelvin the process of carrying out the resolution and validation process: this includes 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-doption will product the same output (but will affect other logging categories as well).

+[no]mtrace

Toggle message logging. This produces a detailed dump of the responses received bydelvin 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-doption will produce the same output (but will affect other logging categories as well).

+[no]vtrace

Toggle 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-doption will produce the same output (but will affect other logging categories as well).

+[no]short

Provide a terse answer. The default is to print the answer in a verbose form.

+[no]comments

Toggle the display of comment lines in the output. The default is to print comments.

+[no]rrcomments

Toggle 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.

+[no]crypto

Toggle the display of cryptographic fields in DNSSEC records. The contents of these field 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 ]".

+[no]trust

Controls whether to display the trust level when printing a record. The default is to display the trust level.

+[no]split[=W]

Split long hex- or base64-formatted fields in resource records into chunks ofWcharacters (whereWis rounded up to the nearest multiple of 4).+nosplitor+split=0causes fields not to be split at all. The default is 56 characters, or 44 characters when multiline mode is active.

+[no]all

Set or clear the display options+[no]comments,+[no]rrcomments, and+[no]trustas a group.

+[no]multiline

Print 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 thedelvoutput.

+[no]dnssec

Indicates whether to display RRSIG records in thedelvoutput. The default is to do so. Note that (unlike indig) this doesnotcontrol whether to request DNSSEC records or whether to validate them. DNSSEC records are always requested, and validation will always occur unless suppressed by the use of-ior+norootand+nodlv.

+[no]root[=ROOT]

Indicates whether to perform conventional (non-lookaside) 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-amust be used to specify a file containing the key.

+[no]dlv[=DLV]

Indicates whether to perform DNSSEC lookaside validation, and if so, specifies the name of the DLV trust anchor. The-aoption must also be used to specify a file containing the DLV key.

+[no]tcp

Controls whether to use TCP when sending queries. The default is to use UDP unless a truncated response has been received.

+[no]unknownformat

Print 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.
 

FILES

/etc/bind.keys

/etc/resolv.conf 

SEE ALSO

dig(1),named(8),RFC4034,RFC4035,RFC4431,RFC5074,RFC5155. 

AUTHOR

Internet Systems Consortium, Inc. 

COPYRIGHT


Copyright © 2014-2018 Internet Systems Consortium, Inc. ("ISC")


 

Index

NAME
SYNOPSIS
DESCRIPTION
SIMPLE USAGE
OPTIONS
QUERY OPTIONS
FILES
SEE ALSO
AUTHOR
COPYRIGHT

This document was created byman2html,using the manual pages.